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ex.1p (221925B)

    

  1. '\" et
  2. .TH EX "1P" 2017 "IEEE/The Open Group" "POSIX Programmer's Manual"
  3. .\"
  4. .SH PROLOG
  5. This manual page is part of the POSIX Programmer's Manual.
  6. The Linux implementation of this interface may differ (consult
  7. the corresponding Linux manual page for details of Linux behavior),
  8. or the interface may not be implemented on Linux.
  9. .\"
  10. .SH NAME
  11. ex
  12. \(em text editor
  13. .SH SYNOPSIS
  14. .LP
  15. .nf
  16. ex \fB[\fR-rR\fB] [\fR-s|-v\fB] [\fR-c \fIcommand\fB] [\fR-t \fItagstring\fB] [\fR-w \fIsize\fB] [\fIfile\fR...\fB]\fR
  17. .fi
  18. .SH DESCRIPTION
  19. The
  20. .IR ex
  21. utility is a line-oriented text editor. There are two other modes of
  22. the editor\(emopen and visual\(emin which screen-oriented editing is
  23. available. This is described more fully by the
  24. .IR ex
  25. .BR open
  26. and
  27. .BR visual
  28. commands and in
  29. .IR "\fIvi\fR\^".
  30. .P
  31. If an operand is
  32. .BR '\-' ,
  33. the results are unspecified.
  34. .P
  35. This section uses the term
  36. .IR "edit buffer"
  37. to describe the current working text. No specific implementation is
  38. implied by this term. All editing changes are performed on the edit
  39. buffer, and no changes to it shall affect any file until an editor
  40. command writes the file.
  41. .P
  42. Certain terminals do not have all the capabilities necessary to support
  43. the complete
  44. .IR ex
  45. definition, such as the full-screen editing commands (\c
  46. .IR "visual mode"
  47. or
  48. .IR "open mode" ).
  49. When these commands cannot be supported on such terminals, this
  50. condition shall not produce an error message such as ``not an editor
  51. command'' or report a syntax error. The implementation may either
  52. accept the commands and produce results on the screen that are the
  53. result of an unsuccessful attempt to meet the requirements of this volume of POSIX.1\(hy2017 or
  54. report an error describing the terminal-related deficiency.
  55. .SH OPTIONS
  56. The
  57. .IR ex
  58. utility shall conform to the Base Definitions volume of POSIX.1\(hy2017,
  59. .IR "Section 12.2" ", " "Utility Syntax Guidelines",
  60. except for the unspecified usage of
  61. .BR '\-' ,
  62. and that
  63. .BR '\(pl' 
  64. may be recognized as an option delimiter as well as
  65. .BR '\-' .
  66. .P
  67. The following options shall be supported:
  68. .IP "\fB\-c\ \fIcommand\fR" 10
  69. Specify an initial command to be executed in the first edit buffer
  70. loaded from an existing file (see the EXTENDED DESCRIPTION section).
  71. Implementations may support more than a single
  72. .BR \-c
  73. option. In such implementations, the specified commands shall be
  74. executed in the order specified on the command line.
  75. .IP "\fB\-r\fP" 10
  76. Recover the named files (see the EXTENDED DESCRIPTION section).
  77. Recovery information for a file shall be saved during an editor or
  78. system crash (for example, when the editor is terminated by a signal
  79. which the editor can catch), or after the use of an
  80. .IR ex
  81. .BR preserve
  82. command.
  83. .RS 10 
  84. .P
  85. A
  86. .IR crash
  87. in this context is an unexpected failure of the system or utility that
  88. requires restarting the failed system or utility. A system crash
  89. implies that any utilities running at the time also crash. In the case
  90. of an editor or system crash, the number of changes to the edit buffer
  91. (since the most recent
  92. .BR preserve
  93. command) that will be recovered is unspecified.
  94. .P
  95. If no
  96. .IR file
  97. operands are given and the
  98. .BR \-t
  99. option is not specified, all other options, the
  100. .IR EXINIT
  101. variable, and any
  102. .BR .exrc
  103. files shall be ignored; a list of all recoverable files available to
  104. the invoking user shall be written, and the editor shall exit normally
  105. without further action.
  106. .RE
  107. .IP "\fB\-R\fP" 10
  108. Set
  109. .BR readonly
  110. edit option.
  111. .IP "\fB\-s\fP" 10
  112. Prepare
  113. .IR ex
  114. for batch use by taking the following actions:
  115. .RS 10 
  116. .IP " *" 4
  117. Suppress writing prompts and informational (but not diagnostic)
  118. messages.
  119. .IP " *" 4
  120. Ignore the value of
  121. .IR TERM
  122. and any implementation default terminal type and assume the terminal is
  123. a type incapable of supporting open or visual modes; see the
  124. .BR visual
  125. command and the description of
  126. .IR "\fIvi\fR\^".
  127. .IP " *" 4
  128. Suppress the use of the
  129. .IR EXINIT
  130. environment variable and the reading of any
  131. .BR .exrc
  132. file; see the EXTENDED DESCRIPTION section.
  133. .IP " *" 4
  134. Suppress autoindentation, ignoring the value of the
  135. .BR autoindent
  136. edit option.
  137. .RE
  138. .IP "\fB\-t\ \fItagstring\fR" 10
  139. Edit the file containing the specified
  140. .IR tagstring ;
  141. see
  142. .IR "\fIctags\fR\^".
  143. The tags feature represented by
  144. .BR \-t
  145. .IR tagstring
  146. and the
  147. .BR tag
  148. command is optional. It shall be provided on any system that also
  149. provides a conforming implementation of
  150. .IR ctags ;
  151. otherwise, the use of
  152. .BR \-t
  153. produces undefined results. On any system, it shall be an error to
  154. specify more than a single
  155. .BR \-t
  156. option.
  157. .IP "\fB\-v\fP" 10
  158. Begin in visual mode (see
  159. .IR "\fIvi\fR\^").
  160. .IP "\fB\-w\ \fIsize\fR" 10
  161. Set the value of the
  162. .IR window
  163. editor option to
  164. .IR size .
  165. .SH OPERANDS
  166. The following operand shall be supported:
  167. .IP "\fIfile\fR" 10
  168. A pathname of a file to be edited.
  169. .SH STDIN
  170. The standard input consists of a series of commands and input text, as
  171. described in the EXTENDED DESCRIPTION section. The implementation may
  172. limit each line of standard input to a length of
  173. {LINE_MAX}.
  174. .P
  175. If the standard input is not a terminal device, it shall be as if the
  176. .BR \-s
  177. option had been specified.
  178. .P
  179. If a read from the standard input returns an error, or if the editor
  180. detects an end-of-file condition from the standard input, it shall be
  181. equivalent to a SIGHUP asynchronous event.
  182. .SH "INPUT FILES"
  183. Input files shall be text files or files that would be text files
  184. except for an incomplete last line that is not longer than
  185. {LINE_MAX}\-1
  186. bytes in length and contains no NUL characters. By default, any
  187. incomplete last line shall be treated as if it had a trailing
  188. <newline>.
  189. The editing of other forms of files may optionally be allowed by
  190. .IR ex
  191. implementations.
  192. .P
  193. The
  194. .BR .exrc
  195. files and source files shall be text files consisting of
  196. .IR ex
  197. commands; see the EXTENDED DESCRIPTION section.
  198. .P
  199. By default, the editor shall read lines from the files to be edited
  200. without interpreting any of those lines as any form of editor command.
  201. .SH "ENVIRONMENT VARIABLES"
  202. The following environment variables shall affect the execution of
  203. .IR ex :
  204. .IP "\fICOLUMNS\fP" 10
  205. Override the system-selected horizontal screen size. See the Base Definitions volume of POSIX.1\(hy2017,
  206. .IR "Chapter 8" ", " "Environment Variables"
  207. for valid values and results when it is unset or null.
  208. .IP "\fIEXINIT\fP" 10
  209. Determine a list of
  210. .IR ex
  211. commands that are executed on editor start-up. See the EXTENDED
  212. DESCRIPTION section for more details of the initialization phase.
  213. .IP "\fIHOME\fP" 10
  214. Determine a pathname of a directory that shall be searched for an
  215. editor start-up file named
  216. .BR .exrc ;
  217. see the EXTENDED DESCRIPTION section.
  218. .IP "\fILANG\fP" 10
  219. Provide a default value for the internationalization variables that are
  220. unset or null. (See the Base Definitions volume of POSIX.1\(hy2017,
  221. .IR "Section 8.2" ", " "Internationalization Variables"
  222. for the precedence of internationalization variables used to determine
  223. the values of locale categories.)
  224. .IP "\fILC_ALL\fP" 10
  225. If set to a non-empty string value, override the values of all the
  226. other internationalization variables.
  227. .IP "\fILC_COLLATE\fP" 10
  228. .br
  229. Determine the locale for the behavior of ranges, equivalence classes,
  230. and multi-character collating elements within regular expressions.
  231. .IP "\fILC_CTYPE\fP" 10
  232. Determine the locale for the interpretation of sequences of bytes of
  233. text data as characters (for example, single-byte as opposed to
  234. multi-byte characters in arguments and input files), the behavior of
  235. character classes within regular expressions, the classification of
  236. characters as uppercase or lowercase letters, the case conversion of
  237. letters, and the detection of word boundaries.
  238. .IP "\fILC_MESSAGES\fP" 10
  239. .br
  240. Determine the locale that should be used to affect the format and
  241. contents of diagnostic messages written to standard error.
  242. .IP "\fILINES\fP" 10
  243. Override the system-selected vertical screen size, used as the number
  244. of lines in a screenful and the vertical screen size in visual mode.
  245. See the Base Definitions volume of POSIX.1\(hy2017,
  246. .IR "Chapter 8" ", " "Environment Variables"
  247. for valid values and results when it is unset or null.
  248. .IP "\fINLSPATH\fP" 10
  249. Determine the location of message catalogs for the processing of
  250. .IR LC_MESSAGES .
  251. .IP "\fIPATH\fP" 10
  252. Determine the search path for the shell command specified in the
  253. .IR ex
  254. editor commands
  255. .BR ! ,
  256. .BR shell ,
  257. .BR read ,
  258. and
  259. .BR write ,
  260. and the open and visual mode command
  261. .BR ! ;
  262. see the description of command search and execution in
  263. .IR "Section 2.9.1.1" ", " "Command Search and Execution".
  264. .IP "\fISHELL\fP" 10
  265. Determine the preferred command line interpreter for use as the default
  266. value of the
  267. .BR shell
  268. edit option.
  269. .IP "\fITERM\fP" 10
  270. Determine the name of the terminal type. If this variable is unset or
  271. null, an unspecified default terminal type shall be used.
  272. .SH "ASYNCHRONOUS EVENTS"
  273. The following term is used in this and following sections to specify
  274. command and asynchronous event actions:
  275. .IP "\fIcomplete\ write\fP" 10
  276. .br
  277. A complete write is a write of the entire contents of the edit buffer
  278. to a file of a type other than a terminal device, or the saving of the
  279. edit buffer caused by the user executing the
  280. .IR ex
  281. .BR preserve
  282. command. Writing the contents of the edit buffer to a temporary file
  283. that will be removed when the editor exits shall not be considered a
  284. complete write.
  285. .P
  286. The following actions shall be taken upon receipt of signals:
  287. .IP SIGINT 10
  288. If the standard input is not a terminal device,
  289. .IR ex
  290. shall not write the file or return to command or text input mode, and
  291. shall exit with a non-zero exit status.
  292. .RS 10 
  293. .P
  294. Otherwise, if executing an open or visual text input mode command,
  295. .IR ex
  296. in receipt of SIGINT shall behave identically to its receipt of the
  297. <ESC>
  298. character.
  299. .P
  300. Otherwise:
  301. .IP " 1." 4
  302. If executing an
  303. .IR ex
  304. text input mode command, all input lines that have been completely
  305. entered shall be resolved into the edit buffer, and any partially
  306. entered line shall be discarded.
  307. .IP " 2." 4
  308. If there is a currently executing command, it shall be aborted and a
  309. message displayed. Unless otherwise specified by the
  310. .IR ex
  311. or
  312. .IR vi
  313. command descriptions, it is unspecified whether any lines modified by
  314. the executing command appear modified, or as they were before being
  315. modified by the executing command, in the buffer.
  316. .RS 4 
  317. .P
  318. If the currently executing command was a motion command, its associated
  319. command shall be discarded.
  320. .RE
  321. .IP " 3." 4
  322. If in open or visual command mode, the terminal shall be alerted.
  323. .IP " 4." 4
  324. The editor shall then return to command mode.
  325. .RE
  326. .IP SIGCONT 10
  327. The screen shall be refreshed if in open or visual mode.
  328. .IP SIGHUP 10
  329. If the edit buffer has been modified since the last complete write,
  330. .IR ex
  331. shall attempt to save the edit buffer so that it can be recovered later
  332. using the
  333. .BR \-r
  334. option or the
  335. .IR ex
  336. .BR recover
  337. command. The editor shall not write the file or return to command or
  338. text input mode, and shall terminate with a non-zero exit status.
  339. .IP SIGTERM 10
  340. Refer to SIGHUP.
  341. .P
  342. The action taken for all other signals is unspecified.
  343. .SH STDOUT
  344. The standard output shall be used only for writing prompts to the user,
  345. for informational messages, and for writing lines from the file.
  346. .SH STDERR
  347. The standard error shall be used only for diagnostic messages.
  348. .SH "OUTPUT FILES"
  349. The output from
  350. .IR ex
  351. shall be text files.
  352. .SH "EXTENDED DESCRIPTION"
  353. Only the
  354. .IR ex
  355. mode of the editor is described in this section. See
  356. .IR "\fIvi\fR\^"
  357. for additional editing capabilities available in
  358. .IR ex .
  359. .P
  360. When an error occurs,
  361. .IR ex
  362. shall write a message. If the terminal supports a standout mode (such
  363. as inverse video), the message shall be written in standout mode. If
  364. the terminal does not support a standout mode, and the edit option
  365. .BR errorbells
  366. is set, an alert action shall precede the error message.
  367. .P
  368. By default,
  369. .IR ex
  370. shall start in command mode, which shall be indicated by a
  371. .BR :
  372. prompt; see the
  373. .BR prompt
  374. command. Text input mode can be entered by the
  375. .BR append ,
  376. .BR insert ,
  377. or
  378. .BR change
  379. commands; it can be exited (and command mode re-entered) by typing a
  380. <period>
  381. (\c
  382. .BR '.' )
  383. alone at the beginning of a line.
  384. .SS "Initialization in ex and vi"
  385. .P
  386. The following symbols are used in this and following sections to
  387. specify locations in the edit buffer:
  388. .IP "\fIalternate\ and\ current\ pathnames\fP" 6
  389. .br
  390. Two pathnames, named
  391. .IR current
  392. and
  393. .IR alternate ,
  394. are maintained by the editor. Any
  395. .IR ex
  396. commands that take filenames as arguments shall set them as follows:
  397. .RS 6 
  398. .IP " 1." 4
  399. If a
  400. .IR file
  401. argument is specified to the
  402. .IR ex
  403. .BR edit ,
  404. .BR ex ,
  405. or
  406. .BR recover
  407. commands, or if an
  408. .IR ex
  409. .BR tag
  410. command replaces the contents of the edit buffer.
  411. .RS 4 
  412. .IP " a." 4
  413. If the command replaces the contents of the edit buffer, the current
  414. pathname shall be set to the
  415. .IR file
  416. argument or the file indicated by the tag, and the alternate pathname
  417. shall be set to the previous value of the current pathname.
  418. .IP " b." 4
  419. Otherwise, the alternate pathname shall be set to the
  420. .IR file
  421. argument.
  422. .RE
  423. .IP " 2." 4
  424. If a
  425. .IR file
  426. argument is specified to the
  427. .IR ex
  428. .BR next
  429. command:
  430. .RS 4 
  431. .IP " a." 4
  432. If the command replaces the contents of the edit buffer, the current
  433. pathname shall be set to the first
  434. .IR file
  435. argument, and the alternate pathname shall be set to the previous
  436. value of the current pathname.
  437. .RE
  438. .IP " 3." 4
  439. If a
  440. .IR file
  441. argument is specified to the
  442. .IR ex
  443. .BR file
  444. command, the current pathname shall be set to the
  445. .IR file
  446. argument, and the alternate pathname shall be set to the previous
  447. value of the current pathname.
  448. .IP " 4." 4
  449. If a
  450. .IR file
  451. argument is specified to the
  452. .IR ex
  453. .BR read
  454. and
  455. .BR write
  456. commands (that is, when reading or writing a file, and not to the
  457. program named by the
  458. .BR shell
  459. edit option), or a
  460. .IR file
  461. argument is specified to the
  462. .IR ex
  463. .BR xit
  464. command:
  465. .RS 4 
  466. .IP " a." 4
  467. If the current pathname has no value, the current pathname shall be
  468. set to the
  469. .IR file
  470. argument.
  471. .IP " b." 4
  472. Otherwise, the alternate pathname shall be set to the
  473. .IR file
  474. argument.
  475. .RE
  476. .P
  477. If the alternate pathname is set to the previous value of the current
  478. pathname when the current pathname had no previous value, then the
  479. alternate pathname shall have no value as a result.
  480. .RE
  481. .IP "\fIcurrent\ line\fP" 6
  482. .br
  483. The line of the edit buffer referenced by the cursor. Each command
  484. description specifies the current line after the command has been
  485. executed, as the
  486. .IR "current line value" .
  487. When the edit buffer contains no lines, the current line shall be zero;
  488. see
  489. .IR "Addressing in ex".
  490. .IP "\fIcurrent\ column\fP" 6
  491. .br
  492. The current display line column occupied by the cursor. (The columns
  493. shall be numbered beginning at 1.) Each command description specifies
  494. the current column after the command has been executed, as the
  495. .IR "current column"
  496. value. This column is an
  497. .IR ideal
  498. column that is remembered over the lifetime of the editor. The actual
  499. display line column upon which the cursor rests may be different from
  500. the current column; see the cursor positioning discussion in
  501. .IR "Command Descriptions in vi".
  502. .IP "\fIset\ to\ non-<blank>\fP" 6
  503. .br
  504. A description for a current column value, meaning that the current
  505. column shall be set to the last display line column on which is
  506. displayed any part of the first non-\c
  507. <blank>
  508. of the line. If the line has no non-\c
  509. <blank>
  510. non-\c
  511. <newline>
  512. characters, the current column shall be set to the last display line
  513. column on which is displayed any part of the last non-\c
  514. <newline>
  515. character in the line. If the line is empty, the current column shall
  516. be set to column position 1.
  517. .P
  518. The length of lines in the edit buffer may be limited to
  519. {LINE_MAX}
  520. bytes. In open and visual mode, the length of lines in the edit buffer
  521. may be limited to the number of characters that will fit in the
  522. display. If either limit is exceeded during editing, an error message
  523. shall be written. If either limit is exceeded by a line read in from a
  524. file, an error message shall be written and the edit session may be
  525. terminated.
  526. .P
  527. If the editor stops running due to any reason other than a user
  528. command, and the edit buffer has been modified since the last complete
  529. write, it shall be equivalent to a SIGHUP asynchronous event. If the
  530. system crashes, it shall be equivalent to a SIGHUP asynchronous event.
  531. .P
  532. During initialization (before the first file is copied into the edit
  533. buffer or any user commands from the terminal are processed) the
  534. following shall occur:
  535. .IP " 1." 4
  536. If the environment variable
  537. .IR EXINIT
  538. is set, the editor shall execute the
  539. .IR ex
  540. commands contained in that variable.
  541. .IP " 2." 4
  542. If the
  543. .IR EXINIT
  544. variable is not set, and all of the following are true:
  545. .RS 4 
  546. .IP " a." 4
  547. The
  548. .IR HOME
  549. environment variable is not null and not empty.
  550. .IP " b." 4
  551. The file
  552. .BR .exrc
  553. in the directory referred to by the
  554. .IR HOME
  555. environment variable:
  556. .RS 4 
  557. .IP " i." 5
  558. Exists
  559. .IP ii. 5
  560. Is owned by the same user ID as the real user ID of the process or the
  561. process has appropriate privileges
  562. .IP iii. 5
  563. Is not writable by anyone other than the owner
  564. .RE
  565. .P
  566. the editor shall execute the
  567. .IR ex
  568. commands contained in that file.
  569. .RE
  570. .IP " 3." 4
  571. If and only if all of the following are true:
  572. .RS 4 
  573. .IP " a." 4
  574. The current directory is not referred to by the
  575. .IR HOME
  576. environment variable.
  577. .IP " b." 4
  578. A command in the
  579. .IR EXINIT
  580. environment variable or a command in the
  581. .BR .exrc
  582. file in the directory referred to by the
  583. .IR HOME
  584. environment variable sets the editor option
  585. .BR exrc .
  586. .IP " c." 4
  587. The
  588. .BR .exrc
  589. file in the current directory:
  590. .RS 4 
  591. .IP " i." 5
  592. Exists
  593. .IP ii. 5
  594. Is owned by the same user ID as the real user ID of the process, or by
  595. one of a set of implementation-defined user IDs
  596. .IP iii. 5
  597. Is not writable by anyone other than the owner
  598. .RE
  599. .P
  600. the editor shall attempt to execute the
  601. .IR ex
  602. commands contained in that file.
  603. .RE
  604. .P
  605. Lines in any
  606. .BR .exrc
  607. file that are blank lines shall be ignored. If any
  608. .BR .exrc
  609. file exists, but is not read for ownership or permission reasons, it
  610. shall be an error.
  611. .P
  612. After the
  613. .IR EXINIT
  614. variable and any
  615. .BR .exrc
  616. files are processed, the first file specified by the user shall be
  617. edited, as follows:
  618. .IP " 1." 4
  619. If the user specified the
  620. .BR \-t
  621. option, the effect shall be as if the
  622. .IR ex
  623. .BR tag
  624. command was entered with the specified argument, with the exception
  625. that if tag processing does not result in a file to edit, the effect
  626. shall be as described in step 3. below.
  627. .IP " 2." 4
  628. Otherwise, if the user specified any command line
  629. .IR file
  630. arguments, the effect shall be as if the
  631. .IR ex
  632. .BR edit
  633. command was entered with the first of those arguments as its
  634. .IR file
  635. argument.
  636. .IP " 3." 4
  637. Otherwise, the effect shall be as if the
  638. .IR ex
  639. .BR edit
  640. command was entered with a nonexistent filename as its
  641. .IR file
  642. argument. It is unspecified whether this action shall set the current
  643. pathname. In an implementation where this action does not set the
  644. current pathname, any editor command using the current pathname shall
  645. fail until an editor command sets the current pathname.
  646. .P
  647. If the
  648. .BR \-r
  649. option was specified, the first time a file in the initial argument
  650. list or a file specified by the
  651. .BR \-t
  652. option is edited, if recovery information has previously been saved
  653. about it, that information shall be recovered and the editor shall
  654. behave as if the contents of the edit buffer have already been
  655. modified. If there are multiple instances of the file to be recovered,
  656. the one most recently saved shall be recovered, and an informational
  657. message that there are previous versions of the file that can be
  658. recovered shall be written. If no recovery information about a file is
  659. available, an informational message to this effect shall be written,
  660. and the edit shall proceed as usual.
  661. .P
  662. If the
  663. .BR \-c
  664. option was specified, the first time a file that already exists
  665. (including a file that might not exist but for which recovery
  666. information is available, when the
  667. .BR \-r
  668. option is specified) replaces or initializes the contents of the edit
  669. buffer, the current line shall be set to the last line of the edit
  670. buffer, the current column shall be set to non-\c
  671. <blank>,
  672. and the
  673. .IR ex
  674. commands specified with the
  675. .BR \-c
  676. option shall be executed. In this case, the current line and current
  677. column shall not be set as described for the command associated with
  678. the replacement or initialization of the edit buffer contents. However,
  679. if the
  680. .BR \-t
  681. option or a
  682. .BR tag
  683. command is associated with this action, the
  684. .BR \-c
  685. option commands shall be executed and then the movement to the tag
  686. shall be performed.
  687. .P
  688. The current argument list shall initially be set to the filenames
  689. specified by the user on the command line. If no filenames are
  690. specified by the user, the current argument list shall be empty. If the
  691. .BR \-t
  692. option was specified, it is unspecified whether any filename resulting
  693. from tag processing shall be prepended to the current argument list. In
  694. the case where the filename is added as a prefix to the current
  695. argument list, the current argument list reference shall be set to that
  696. filename. In the case where the filename is not added as a prefix to
  697. the current argument list, the current argument list reference shall
  698. logically be located before the first of the filenames specified on
  699. the command line (for example, a subsequent
  700. .IR ex
  701. .BR next
  702. command shall edit the first filename from the command line). If the
  703. .BR \-t
  704. option was not specified, the current argument list reference shall be
  705. to the first of the filenames on the command line.
  706. .SS "Addressing in ex"
  707. .P
  708. Addressing in
  709. .IR ex
  710. relates to the current line and the current column; the address of a
  711. line is its 1-based line number, the address of a column is its 1-based
  712. count from the beginning of the line. Generally, the current line is
  713. the last line affected by a command. The current line number is the
  714. address of the current line. In each command description, the effect of
  715. the command on the current line number and the current column is
  716. described.
  717. .P
  718. Addresses are constructed as follows:
  719. .IP " 1." 4
  720. The character
  721. .BR '.' 
  722. (period) shall address the current line.
  723. .IP " 2." 4
  724. The character
  725. .BR '$' 
  726. shall address the last line of the edit buffer.
  727. .IP " 3." 4
  728. The positive decimal number
  729. .IR n
  730. shall address the
  731. .IR n th
  732. line of the edit buffer.
  733. .IP " 4." 4
  734. The address
  735. .BR \(dq\(aqx\(dq 
  736. refers to the line marked with the mark name character
  737. .BR 'x' ,
  738. which shall be a lowercase letter from the portable character set,
  739. the backquote character, or the single-quote character. It shall be an
  740. error if the line that was marked is not currently present in the edit
  741. buffer or the mark has not been set. Lines can be marked with the
  742. .IR ex
  743. .BR mark
  744. or
  745. .BR k
  746. commands, or the
  747. .IR vi
  748. .BR m
  749. command.
  750. .IP " 5." 4
  751. A regular expression enclosed by
  752. <slash>
  753. characters (\c
  754. .BR '/' )
  755. shall address the first line found by searching forwards from the line
  756. following the current line toward the end of the edit buffer and
  757. stopping at the first line for which the line excluding the terminating
  758. <newline>
  759. matches the regular expression. As stated in
  760. .IR "Regular Expressions in ex",
  761. an address consisting of a null regular expression delimited by
  762. <slash>
  763. characters (\c
  764. .BR \(dq//\(dq )
  765. shall address the next line for which the line excluding the
  766. terminating
  767. <newline>
  768. matches the last regular expression encountered. In addition, the second
  769. <slash>
  770. can be omitted at the end of a command line. If the
  771. .BR wrapscan
  772. edit option is set, the search shall wrap around to the beginning of
  773. the edit buffer and continue up to and including the current line, so
  774. that the entire edit buffer is searched. Within the regular expression,
  775. the sequence
  776. .BR \(dq\e/\(dq 
  777. shall represent a literal
  778. <slash>
  779. instead of the regular expression delimiter.
  780. .IP " 6." 4
  781. A regular expression enclosed in
  782. <question-mark>
  783. characters (\c
  784. .BR '?' )
  785. shall address the first line found by searching backwards from the line
  786. preceding the current line toward the beginning of the edit buffer and
  787. stopping at the first line for which the line excluding the terminating
  788. <newline>
  789. matches the regular expression. An address consisting of a null regular
  790. expression delimited by
  791. <question-mark>
  792. characters (\c
  793. .BR \(dq??\(dq )
  794. shall address the previous line for which the line excluding the
  795. terminating
  796. <newline>
  797. matches the last regular expression encountered. In addition, the second
  798. <question-mark>
  799. can be omitted at the end of a command line. If the
  800. .BR wrapscan
  801. edit option is set, the search shall wrap around from the beginning of
  802. the edit buffer to the end of the edit buffer and continue up to and
  803. including the current line, so that the entire edit buffer is
  804. searched. Within the regular expression, the sequence
  805. .BR \(dq\e?\(dq 
  806. shall represent a literal
  807. <question-mark>
  808. instead of the RE delimiter.
  809. .IP " 7." 4
  810. A
  811. <plus-sign>
  812. (\c
  813. .BR '\(pl' )
  814. or a
  815. <hyphen-minus>
  816. (\c
  817. .BR '\-' )
  818. followed by a decimal number shall address the current line plus or
  819. minus the number. A
  820. .BR '\(pl' 
  821. or
  822. .BR '\-' 
  823. not followed by a decimal number shall address the current line plus or
  824. minus 1.
  825. .P
  826. Addresses can be followed by zero or more address offsets, optionally
  827. <blank>-separated.
  828. Address offsets are constructed as follows:
  829. .IP " 1." 4
  830. A
  831. .BR '\(pl' 
  832. or
  833. .BR '\-' 
  834. immediately followed by a decimal number shall add (subtract) the
  835. indicated number of lines to (from) the address. A
  836. .BR '\(pl' 
  837. or
  838. .BR '\-' 
  839. not followed by a decimal number shall add (subtract) 1 to (from) the
  840. address.
  841. .IP " 2." 4
  842. A decimal number shall add the indicated number of lines to the
  843. address.
  844. .P
  845. It shall not be an error for an intermediate address value to be less
  846. than zero or greater than the last line in the edit buffer. It shall be
  847. an error for the final address value to be less than zero or greater
  848. than the last line in the edit buffer.
  849. .P
  850. Commands take zero, one, or two addresses; see the descriptions of
  851. .IR 1addr
  852. and
  853. .IR 2addr
  854. in
  855. .IR "Command Descriptions in ex".
  856. If more than the required number of addresses are provided to a command
  857. that requires zero addresses, it shall be an error. Otherwise, if more
  858. than the required number of addresses are provided to a command, the
  859. addresses specified first shall be evaluated and then discarded until
  860. the maximum number of valid addresses remain.
  861. .P
  862. Addresses shall be separated from each other by a
  863. <comma>
  864. (\c
  865. .BR ',' )
  866. or a
  867. <semicolon>
  868. (\c
  869. .BR ';' ).
  870. If no address is specified before or after a
  871. <comma>
  872. or
  873. <semicolon>
  874. separator, it shall be as if the address of the current line was
  875. specified before or after the separator. In the case of a
  876. <semicolon>
  877. separator, the current line (\c
  878. .BR '.' )
  879. shall be set to the first address, and only then will the next address
  880. be calculated. This feature can be used to determine the starting line
  881. for forwards and backwards searches (see rules 5. and 6.).
  882. .P
  883. A
  884. <percent-sign>
  885. (\c
  886. .BR '%' )
  887. shall be equivalent to entering the two addresses
  888. .BR \(dq1,$\(dq .
  889. .P
  890. Any delimiting
  891. <blank>
  892. characters between addresses, address separators, or address offsets
  893. shall be discarded.
  894. .SS "Command Line Parsing in ex"
  895. .P
  896. The following symbol is used in this and following sections to describe
  897. parsing behavior:
  898. .IP "\fIescape\fP" 10
  899. If a character is referred to as ``\c
  900. <backslash>-escaped''
  901. or ``\c
  902. <control>\(hyV-escaped'',
  903. it shall mean that the character acquired or lost a special
  904. meaning by virtue of being preceded, respectively, by a
  905. <backslash>
  906. or
  907. <control>\(hyV
  908. character. Unless otherwise specified, the escaping character shall be
  909. discarded at that time and shall not be further considered for any
  910. purpose.
  911. .P
  912. Command-line parsing shall be done in the following steps. For each
  913. step, characters already evaluated shall be ignored; that is, the
  914. phrase ``leading character'' refers to the next character that has not
  915. yet been evaluated.
  916. .IP " 1." 4
  917. Leading
  918. <colon>
  919. characters shall be skipped.
  920. .IP " 2." 4
  921. Leading
  922. <blank>
  923. characters shall be skipped.
  924. .IP " 3." 4
  925. If the leading character is a double-quote character, the characters up
  926. to and including the next non-\c
  927. <backslash>-escaped
  928. <newline>
  929. shall be discarded, and any subsequent characters shall be parsed as a
  930. separate command.
  931. .IP " 4." 4
  932. Leading characters that can be interpreted as addresses shall be
  933. evaluated; see
  934. .IR "Addressing in ex".
  935. .IP " 5." 4
  936. Leading
  937. <blank>
  938. characters shall be skipped.
  939. .IP " 6." 4
  940. If the next character is a
  941. <vertical-line>
  942. character or a
  943. <newline>:
  944. .RS 4 
  945. .IP " a." 4
  946. If the next character is a
  947. <newline>:
  948. .RS 4 
  949. .IP " i." 5
  950. If
  951. .IR ex
  952. is in open or visual mode, the current line shall be set to the last
  953. address specified, if any.
  954. .IP ii. 5
  955. Otherwise, if the last command was terminated by a
  956. <vertical-line>
  957. character, no action shall be taken; for example, the command
  958. .BR \(dq||<newline>\(dq 
  959. shall execute two implied commands, not three.
  960. .IP iii. 5
  961. Otherwise, step 6.b. shall apply.
  962. .RE
  963. .IP " b." 4
  964. Otherwise, the implied command shall be the
  965. .BR print
  966. command. The last
  967. .BR # ,
  968. .BR p ,
  969. and
  970. .BR l
  971. flags specified to any
  972. .IR ex
  973. command shall be remembered and shall apply to this implied command.
  974. Executing the
  975. .IR ex
  976. .BR number ,
  977. .BR print ,
  978. or
  979. .BR list
  980. command shall set the remembered flags to
  981. .BR # ,
  982. nothing, and
  983. .BR l ,
  984. respectively, plus any other flags specified for that execution of the
  985. .BR number ,
  986. .BR print ,
  987. or
  988. .BR list
  989. command.
  990. .RS 4 
  991. .P
  992. If
  993. .IR ex
  994. is not currently performing a
  995. .BR global
  996. or
  997. .BR v
  998. command, and no address or count is specified, the current line shall
  999. be incremented by 1 before the command is executed. If incrementing the
  1000. current line would result in an address past the last line in the edit
  1001. buffer, the command shall fail, and the increment shall not happen.
  1002. .RE
  1003. .IP " c." 4
  1004. The
  1005. <newline>
  1006. or
  1007. <vertical-line>
  1008. character shall be discarded and any subsequent characters shall be
  1009. parsed as a separate command.
  1010. .RE
  1011. .IP " 7." 4
  1012. The command name shall be comprised of the next character (if the
  1013. character is not alphabetic), or the next character and any subsequent
  1014. alphabetic characters (if the character is alphabetic), with the
  1015. following exceptions:
  1016. .RS 4 
  1017. .IP " a." 4
  1018. Commands that consist of any prefix of the characters in the command
  1019. name
  1020. .BR delete ,
  1021. followed immediately by any of the characters
  1022. .BR 'l' ,
  1023. .BR 'p' ,
  1024. .BR '\(pl' ,
  1025. .BR '\-' ,
  1026. or
  1027. .BR '#' 
  1028. shall be interpreted as a
  1029. .BR delete
  1030. command, followed by a
  1031. <blank>,
  1032. followed by the characters that were not part of the prefix of the
  1033. .BR delete
  1034. command. The maximum number of characters shall be matched to the
  1035. command name
  1036. .BR delete ;
  1037. for example,
  1038. .BR \(dqdel\(dq 
  1039. shall not be treated as
  1040. .BR \(dqde\(dq 
  1041. followed by the flag
  1042. .BR l .
  1043. .IP " b." 4
  1044. Commands that consist of the character
  1045. .BR 'k' ,
  1046. followed by a character that can be used as the name of a mark, shall
  1047. be equivalent to the mark command followed by a
  1048. <blank>,
  1049. followed by the character that followed the
  1050. .BR 'k' .
  1051. .IP " c." 4
  1052. Commands that consist of the character
  1053. .BR 's' ,
  1054. followed by characters that could be interpreted as valid options to
  1055. the
  1056. .BR s
  1057. command, shall be the equivalent of the
  1058. .BR s
  1059. command, without any pattern or replacement values, followed by a
  1060. <blank>,
  1061. followed by the characters after the
  1062. .BR 's' .
  1063. .RE
  1064. .IP " 8." 4
  1065. The command name shall be matched against the possible command names,
  1066. and a command name that contains a prefix matching the characters
  1067. specified by the user shall be the executed command. In the case of
  1068. commands where the characters specified by the user could be ambiguous,
  1069. the executed command shall be as follows:
  1070. .TS
  1071. center tab(!) box;
  1072. lB | lB || lB | lB || lB | lB.
  1073. a!append!n!next!t!t
  1074. c!change!p!print!u!undo
  1075. ch!change!pr!print!un!undo
  1076. e!edit!r!read!v!v
  1077. m!move!re!read!w!write
  1078. ma!mark!s!s
  1079. .TE
  1080. .RS 4 
  1081. .P
  1082. Implementation extensions with names causing similar ambiguities shall
  1083. not be checked for a match until all possible matches for commands
  1084. specified by POSIX.1\(hy2008 have been checked.
  1085. .RE
  1086. .IP " 9." 4
  1087. If the command is a
  1088. .BR !
  1089. command, or if the command is a
  1090. .BR read
  1091. command followed by zero or more
  1092. <blank>
  1093. characters and a
  1094. .BR ! ,
  1095. or if the command is a
  1096. .BR write
  1097. command followed by one or more
  1098. <blank>
  1099. characters and a
  1100. .BR ! ,
  1101. the rest of the command shall include all characters up to a non-\c
  1102. <backslash>-escaped
  1103. <newline>.
  1104. The
  1105. <newline>
  1106. shall be discarded and any subsequent characters shall be parsed as a
  1107. separate
  1108. .IR ex
  1109. command.
  1110. .IP 10. 4
  1111. Otherwise, if the command is an
  1112. .BR edit ,
  1113. .BR ex ,
  1114. or
  1115. .BR next
  1116. command, or a
  1117. .BR visual
  1118. command while in open or visual mode, the next part of the command
  1119. shall be parsed as follows:
  1120. .RS 4 
  1121. .IP " a." 4
  1122. Any
  1123. .BR '!' 
  1124. character immediately following the command shall be skipped and be
  1125. part of the command.
  1126. .IP " b." 4
  1127. Any leading
  1128. <blank>
  1129. characters shall be skipped and be part of the command.
  1130. .IP " c." 4
  1131. If the next character is a
  1132. .BR '\(pl' ,
  1133. characters up to the first non-\c
  1134. <backslash>-escaped
  1135. <newline>
  1136. or non-\c
  1137. <backslash>-escaped
  1138. <blank>
  1139. shall be skipped and be part of the command.
  1140. .IP " d." 4
  1141. The rest of the command shall be determined by the steps specified in
  1142. paragraph 12.
  1143. .RE
  1144. .IP 11. 4
  1145. Otherwise, if the command is a
  1146. .BR global ,
  1147. .BR open ,
  1148. .BR s ,
  1149. or
  1150. .BR v
  1151. command, the next part of the command shall be parsed as follows:
  1152. .RS 4 
  1153. .IP " a." 4
  1154. Any leading
  1155. <blank>
  1156. characters shall be skipped and be part of the command.
  1157. .IP " b." 4
  1158. If the next character is not an alphanumeric, double-quote,
  1159. <newline>,
  1160. <backslash>,
  1161. or
  1162. <vertical-line>
  1163. character:
  1164. .RS 4 
  1165. .IP " i." 5
  1166. The next character shall be used as a command delimiter.
  1167. .IP ii. 5
  1168. If the command is a
  1169. .BR global ,
  1170. .BR open ,
  1171. or
  1172. .BR v
  1173. command, characters up to the first non-\c
  1174. <backslash>-escaped
  1175. <newline>,
  1176. or first non-\c
  1177. <backslash>-escaped
  1178. delimiter character, shall be skipped and be part of the command.
  1179. .IP iii. 5
  1180. If the command is an
  1181. .BR s
  1182. command, characters up to the first non-\c
  1183. <backslash>-escaped
  1184. <newline>,
  1185. or second non-\c
  1186. <backslash>-escaped
  1187. delimiter character, shall be skipped and be part of the command.
  1188. .RE
  1189. .IP " c." 4
  1190. If the command is a
  1191. .BR global
  1192. or
  1193. .BR v
  1194. command, characters up to the first non-\c
  1195. <backslash>-escaped
  1196. <newline>
  1197. shall be skipped and be part of the command.
  1198. .IP " d." 4
  1199. Otherwise, the rest of the command shall be determined by the steps
  1200. specified in paragraph 12.
  1201. .RE
  1202. .IP 12. 4
  1203. Otherwise:
  1204. .RS 4 
  1205. .IP " a." 4
  1206. If the command was a
  1207. .BR map ,
  1208. .BR unmap ,
  1209. .BR abbreviate ,
  1210. or
  1211. .BR unabbreviate
  1212. command, characters up to the first non-\c
  1213. <control>\(hyV-escaped
  1214. <newline>,
  1215. <vertical-line>,
  1216. or double-quote character shall be skipped and be part of the command.
  1217. .IP " b." 4
  1218. Otherwise, characters up to the first non-\c
  1219. <backslash>-escaped
  1220. <newline>,
  1221. <vertical-line>,
  1222. or double-quote character shall be skipped and be part of the command.
  1223. .IP " c." 4
  1224. If the command was an
  1225. .BR append ,
  1226. .BR change ,
  1227. or
  1228. .BR insert
  1229. command, and the step 12.b. ended at a
  1230. <vertical-line>
  1231. character, any subsequent characters, up to the next non-\c
  1232. <backslash>-escaped
  1233. <newline>
  1234. shall be used as input text to the command.
  1235. .IP " d." 4
  1236. If the command was ended by a double-quote character, all subsequent
  1237. characters, up to the next non-\c
  1238. <backslash>-escaped
  1239. <newline>,
  1240. shall be discarded.
  1241. .IP " e." 4
  1242. The terminating
  1243. <newline>
  1244. or
  1245. <vertical-line>
  1246. character shall be discarded and any subsequent characters shall be
  1247. parsed as a separate
  1248. .IR ex
  1249. command.
  1250. .RE
  1251. .P
  1252. Command arguments shall be parsed as described by the Synopsis and
  1253. Description of each individual
  1254. .IR ex
  1255. command. This parsing shall not be
  1256. <blank>-sensitive,
  1257. except for the
  1258. .BR !
  1259. argument, which must follow the command name without intervening
  1260. <blank>
  1261. characters, and where it would otherwise be ambiguous. For example,
  1262. .IR count
  1263. and
  1264. .IR flag
  1265. arguments need not be
  1266. <blank>-separated
  1267. because
  1268. .BR \(dqd22p\(dq 
  1269. is not ambiguous, but
  1270. .IR file
  1271. arguments to the
  1272. .IR ex
  1273. .BR next
  1274. command must be separated by one or more
  1275. <blank>
  1276. characters. Any
  1277. <blank>
  1278. in command arguments for the
  1279. .BR abbreviate ,
  1280. .BR unabbreviate ,
  1281. .BR map ,
  1282. and
  1283. .BR unmap
  1284. commands can be
  1285. <control>\(hyV-escaped,
  1286. in which case the
  1287. <blank>
  1288. shall not be used as an argument delimiter. Any
  1289. <blank>
  1290. in the command argument for any other command can be
  1291. <backslash>-escaped,
  1292. in which case that
  1293. <blank>
  1294. shall not be used as an argument delimiter.
  1295. .P
  1296. Within command arguments for the
  1297. .BR abbreviate ,
  1298. .BR unabbreviate ,
  1299. .BR map ,
  1300. and
  1301. .BR unmap
  1302. commands, any character can be
  1303. <control>\(hyV-escaped.
  1304. All such escaped characters shall be treated literally and shall have
  1305. no special meaning. Within command arguments for all other
  1306. .IR ex
  1307. commands that are not regular expressions or replacement strings, any
  1308. character that would otherwise have a special meaning can be
  1309. <backslash>-escaped.
  1310. Escaped characters shall be treated literally, without special meaning
  1311. as shell expansion characters or
  1312. .BR '!' ,
  1313. .BR '%' ,
  1314. and
  1315. .BR '#' 
  1316. expansion characters. See
  1317. .IR "Regular Expressions in ex"
  1318. and
  1319. .IR "Replacement Strings in ex"
  1320. for descriptions of command arguments that are regular expressions or
  1321. replacement strings.
  1322. .P
  1323. Non-\c
  1324. <backslash>-escaped
  1325. .BR '%' 
  1326. characters appearing in
  1327. .IR file
  1328. arguments to any
  1329. .IR ex
  1330. command shall be replaced by the current pathname; unescaped
  1331. .BR '#' 
  1332. characters shall be replaced by the alternate pathname. It shall be an
  1333. error if
  1334. .BR '%' 
  1335. or
  1336. .BR '#' 
  1337. characters appear unescaped in an argument and their corresponding
  1338. values are not set.
  1339. .P
  1340. Non-\c
  1341. <backslash>-escaped
  1342. .BR '!' 
  1343. characters in the arguments to either the
  1344. .IR ex
  1345. .BR !
  1346. command or the open and visual mode
  1347. .BR !
  1348. command, or in the arguments to the
  1349. .IR ex
  1350. .BR read
  1351. command, where the first non-\c
  1352. <blank>
  1353. after the command name is a
  1354. .BR '!' 
  1355. character, or in the arguments to the
  1356. .IR ex
  1357. .BR write
  1358. command where the command name is followed by one or more
  1359. <blank>
  1360. characters and the first non-\c
  1361. <blank>
  1362. after the command name is a
  1363. .BR '!' 
  1364. character, shall be replaced with the arguments to the last of those
  1365. three commands as they appeared after all unescaped
  1366. .BR '%' ,
  1367. .BR '#' ,
  1368. and
  1369. .BR '!' 
  1370. characters were replaced. It shall be an error if
  1371. .BR '!' 
  1372. characters appear unescaped in one of these commands and there has been
  1373. no previous execution of one of these commands.
  1374. .P
  1375. If an error occurs during the parsing or execution of an
  1376. .IR ex
  1377. command:
  1378. .IP " *" 4
  1379. An informational message to this effect shall be written. Execution of
  1380. the
  1381. .IR ex
  1382. command shall stop, and the cursor (for example, the current line and
  1383. column) shall not be further modified.
  1384. .IP " *" 4
  1385. If the
  1386. .IR ex
  1387. command resulted from a map expansion, all characters from that map
  1388. expansion shall be discarded, except as otherwise specified by the
  1389. .BR map
  1390. command.
  1391. .IP " *" 4
  1392. Otherwise, if the
  1393. .IR ex
  1394. command resulted from the processing of an
  1395. .IR EXINIT
  1396. environment variable, a
  1397. .BR .exrc
  1398. file, a
  1399. .BR :source
  1400. command, a
  1401. .BR \-c
  1402. option, or a
  1403. .BR + \c
  1404. .IR command
  1405. specified to an
  1406. .IR ex
  1407. .BR edit ,
  1408. .BR ex ,
  1409. .BR next ,
  1410. or
  1411. .BR visual
  1412. command, no further commands from the source of the commands shall be
  1413. executed.
  1414. .IP " *" 4
  1415. Otherwise, if the
  1416. .IR ex
  1417. command resulted from the execution of a buffer or a
  1418. .BR global
  1419. or
  1420. .BR v
  1421. command, no further commands caused by the execution of the buffer or
  1422. the
  1423. .BR global
  1424. or
  1425. .BR v
  1426. command shall be executed.
  1427. .IP " *" 4
  1428. Otherwise, if the
  1429. .IR ex
  1430. command was not terminated by a
  1431. <newline>,
  1432. all characters up to and including the next non-\c
  1433. <backslash>-escaped
  1434. <newline>
  1435. shall be discarded.
  1436. .SS "Input Editing in ex"
  1437. .P
  1438. The following symbol is used in this and the following sections to
  1439. specify command actions:
  1440. .IP "\fIword\fP" 10
  1441. In the POSIX locale, a word consists of a maximal sequence of letters,
  1442. digits, and underscores, delimited at both ends by characters other
  1443. than letters, digits, or underscores, or by the beginning or end of a
  1444. line or the edit buffer.
  1445. .P
  1446. When accepting input characters from the user, in either
  1447. .IR ex
  1448. command mode or
  1449. .IR ex
  1450. text input mode,
  1451. .IR ex
  1452. shall enable canonical mode input processing, as defined in the System Interfaces volume of POSIX.1\(hy2017.
  1453. .br
  1454. .P
  1455. If in
  1456. .IR ex
  1457. text input mode:
  1458. .IP " 1." 4
  1459. If the
  1460. .BR number
  1461. edit option is set,
  1462. .IR ex
  1463. shall prompt for input using the line number that would be assigned to
  1464. the line if it is entered, in the format specified for the
  1465. .IR ex
  1466. .BR number
  1467. command.
  1468. .IP " 2." 4
  1469. If the
  1470. .BR autoindent
  1471. edit option is set,
  1472. .IR ex
  1473. shall prompt for input using
  1474. .BR autoindent
  1475. characters, as described by the
  1476. .BR autoindent
  1477. edit option.
  1478. .BR autoindent
  1479. characters shall follow the line number, if any.
  1480. .P
  1481. If in
  1482. .IR ex
  1483. command mode:
  1484. .IP " 1." 4
  1485. If the
  1486. .BR prompt
  1487. edit option is set, input shall be prompted for using a single
  1488. .BR ':' 
  1489. character; otherwise, there shall be no prompt.
  1490. .P
  1491. The input characters in the following sections shall have the following
  1492. effects on the input line.
  1493. .SS "Scroll"
  1494. .IP "\fISynopsis\fR:" 10
  1495. .sp -1v
  1496. .RS 10 
  1497. .sp
  1498. .RS 4
  1499. .nf
  1501. eof
  1502. .fi
  1503. .P
  1504. .RE
  1505. .RE
  1506. .P
  1507. See the description of the
  1508. .IR stty
  1509. .IR eof
  1510. character in
  1511. .IR "\fIstty\fR\^".
  1512. .P
  1513. If in
  1514. .IR ex
  1515. command mode:
  1516. .sp
  1517. .RS
  1518. If the
  1519. .IR eof
  1520. character is the first character entered on the line, the line shall be
  1521. evaluated as if it contained two characters: a
  1522. <control>\(hyD
  1523. and a
  1524. <newline>.
  1525. .P
  1526. Otherwise, the
  1527. .IR eof
  1528. character shall have no special meaning.
  1529. .RE
  1530. .br
  1531. .P
  1532. If in
  1533. .IR ex
  1534. text input mode:
  1535. .sp
  1536. .RS
  1537. If the cursor follows an
  1538. .BR autoindent
  1539. character, the
  1540. .BR autoindent
  1541. characters in the line shall be modified so that a part of the next
  1542. text input character will be displayed on the first column in the line
  1543. after the previous
  1544. .BR shiftwidth
  1545. edit option column boundary, and the user shall be prompted again for
  1546. input for the same line.
  1547. .P
  1548. Otherwise, if the cursor follows a
  1549. .BR '0' ,
  1550. which follows an
  1551. .BR autoindent
  1552. character, and the
  1553. .BR '0' 
  1554. was the previous text input character, the
  1555. .BR '0' 
  1556. and all
  1557. .BR autoindent
  1558. characters in the line shall be discarded, and the user shall be
  1559. prompted again for input for the same line.
  1560. .P
  1561. Otherwise, if the cursor follows a
  1562. .BR '\(ha' ,
  1563. which follows an
  1564. .BR autoindent
  1565. character, and the
  1566. .BR '\(ha' 
  1567. was the previous text input character, the
  1568. .BR '\(ha' 
  1569. and all
  1570. .BR autoindent
  1571. characters in the line shall be discarded, and the user shall be
  1572. prompted again for input for the same line. In addition, the
  1573. .BR autoindent
  1574. level for the next input line shall be derived from the same line from
  1575. which the
  1576. .BR autoindent
  1577. level for the current input line was derived.
  1578. .P
  1579. Otherwise, if there are no
  1580. .BR autoindent
  1581. or text input characters in the line, the
  1582. .IR eof
  1583. character shall be discarded.
  1584. .P
  1585. Otherwise, the
  1586. .IR eof
  1587. character shall have no special meaning.
  1588. .RE
  1589. .SS "<newline>"
  1590. .IP "\fISynopsis\fR:" 10
  1591. .sp -1v
  1592. .RS 10 
  1593. .sp
  1594. .RS 4
  1595. .nf
  1597. <newline>
  1598. .br
  1599. <control>-J
  1600. .fi
  1601. .P
  1602. .RE
  1603. .RE
  1604. .P
  1605. If in
  1606. .IR ex
  1607. command mode:
  1608. .sp
  1609. .RS
  1610. Cause the command line to be parsed;
  1611. <control>\(hyJ
  1612. shall be mapped to the
  1613. <newline>
  1614. for this purpose.
  1615. .RE
  1616. .br
  1617. .P
  1618. If in
  1619. .IR ex
  1620. text input mode:
  1621. .sp
  1622. .RS
  1623. Terminate the current line. If there are no characters other than
  1624. .BR autoindent
  1625. characters on the line, all characters on the line shall be discarded.
  1626. .P
  1627. Prompt for text input on a new line after the current line. If the
  1628. .BR autoindent
  1629. edit option is set, an appropriate number of
  1630. .BR autoindent
  1631. characters shall be added as a prefix to the line as described by the
  1632. .IR ex
  1633. .BR autoindent
  1634. edit option.
  1635. .RE
  1636. .SS "<backslash>"
  1637. .IP "\fISynopsis\fR:" 10
  1638. .sp -1v
  1639. .RS 10 
  1640. .sp
  1641. .RS 4
  1642. .nf
  1644. <backslash>
  1645. .fi
  1646. .P
  1647. .RE
  1648. .RE
  1649. .P
  1650. Allow the entry of a subsequent
  1651. <newline>
  1652. or
  1653. <control>\(hyJ
  1654. as a literal character, removing any special meaning that it may have
  1655. to the editor during text input mode. The
  1656. <backslash>
  1657. character shall be retained and evaluated when the command line is
  1658. parsed, or retained and included when the input text becomes part of
  1659. the edit buffer.
  1660. .SS "<control>\(hyV"
  1661. .IP "\fISynopsis\fR:" 10
  1662. .sp -1v
  1663. .RS 10 
  1664. .sp
  1665. .RS 4
  1666. .nf
  1668. <control>-V
  1669. .fi
  1670. .P
  1671. .RE
  1672. .RE
  1673. .P
  1674. Allow the entry of any subsequent character as a literal character,
  1675. removing any special meaning that it may have to the editor during text
  1676. input mode. The
  1677. <control>\(hyV
  1678. character shall be discarded before the command line is parsed or the
  1679. input text becomes part of the edit buffer.
  1680. .P
  1681. If the ``literal next'' functionality is performed by the underlying
  1682. system, it is implementation-defined whether a character other than
  1683. <control>\(hyV
  1684. performs this function.
  1685. .SS "<control>\(hyW"
  1686. .IP "\fISynopsis\fR:" 10
  1687. .sp -1v
  1688. .RS 10 
  1689. .sp
  1690. .RS 4
  1691. .nf
  1693. <control>-W
  1694. .fi
  1695. .P
  1696. .RE
  1697. .RE
  1698. .P
  1699. Discard the
  1700. <control>\(hyW,
  1701. and the word previous to it in the input line, including any
  1702. <blank>
  1703. characters following the word and preceding the
  1704. <control>\(hyW.
  1705. If the ``word erase'' functionality is performed by the underlying
  1706. system, it is implementation-defined whether a character other than
  1707. <control>\(hyW
  1708. performs this function.
  1709. .SS "Command Descriptions in ex"
  1710. .P
  1711. The following symbols are used in this section to represent command
  1712. modifiers. Some of these modifiers can be omitted, in which case the
  1713. specified defaults shall be used.
  1714. .IP "\fI1addr\fR" 10
  1715. A single line address, given in any of the forms described in
  1716. .IR "Addressing in ex";
  1717. the default shall be the current line (\c
  1718. .BR '.' ),
  1719. unless otherwise specified.
  1720. .RS 10 
  1721. .P
  1722. If the line address is zero, it shall be an error, unless otherwise
  1723. specified in the following command descriptions.
  1724. .P
  1725. If the edit buffer is empty, and the address is specified with a
  1726. command other than
  1727. .BR = ,
  1728. .BR append ,
  1729. .BR insert ,
  1730. .BR open ,
  1731. .BR put ,
  1732. .BR read ,
  1733. or
  1734. .BR visual ,
  1735. or the address is not zero, it shall be an error.
  1736. .RE
  1737. .IP "\fI2addr\fP" 10
  1738. Two addresses specifying an inclusive range of lines. If no addresses
  1739. are specified, the default for
  1740. .IR 2addr
  1741. shall be the current line only (\c
  1742. .BR \(dq.,.\(dq ),
  1743. unless otherwise specified in the following command descriptions. If
  1744. one address is specified,
  1745. .IR 2addr
  1746. shall specify that line only, unless otherwise specified in the
  1747. following command descriptions.
  1748. .RS 10 
  1749. .P
  1750. It shall be an error if the first address is greater than the second
  1751. address.
  1752. .P
  1753. If the edit buffer is empty, and the two addresses are specified with a
  1754. command other than the
  1755. .BR ! ,
  1756. .BR write ,
  1757. .BR wq ,
  1758. or
  1759. .BR xit
  1760. commands, or either address is not zero, it shall be an error.
  1761. .RE
  1762. .IP "\fIcount\fP" 10
  1763. A positive decimal number. If
  1764. .IR count
  1765. is specified, it shall be equivalent to specifying an additional
  1766. address to the command, unless otherwise specified by the following
  1767. command descriptions. The additional address shall be equal to the last
  1768. address specified to the command (either explicitly or by default) plus
  1769. .IR count \-1.
  1770. .RS 10 
  1771. .P
  1772. If this would result in an address greater than the last line of the
  1773. edit buffer, it shall be corrected to equal the last line of the edit
  1774. buffer.
  1775. .RE
  1776. .IP "\fIflags\fP" 10
  1777. One or more of the characters
  1778. .BR '\(pl' ,
  1779. .BR '\-' ,
  1780. .BR '#' ,
  1781. .BR 'p' ,
  1782. or
  1783. .BR 'l' 
  1784. (ell). The flag characters can be
  1785. <blank>-separated,
  1786. and in any order or combination. The characters
  1787. .BR '#' ,
  1788. .BR 'p' ,
  1789. and
  1790. .BR 'l' 
  1791. shall cause lines to be written in the format specified by the
  1792. .BR print
  1793. command with the specified
  1794. .IR flags .
  1795. .RS 10 
  1796. .P
  1797. The lines to be written are as follows:
  1798. .IP " 1." 4
  1799. All edit buffer lines written during the execution of the
  1800. .IR ex
  1801. .BR & ,
  1802. .BR ~ ,
  1803. .BR list ,
  1804. .BR number ,
  1805. .BR open ,
  1806. .BR print ,
  1807. .BR s ,
  1808. .BR visual ,
  1809. and
  1810. .BR z
  1811. commands shall be written as specified by
  1812. .IR flags .
  1813. .IP " 2." 4
  1814. After the completion of an
  1815. .IR ex
  1816. command with a flag as an argument, the current line shall be written
  1817. as specified by
  1818. .IR flags ,
  1819. unless the current line was the last line written by the command.
  1820. .P
  1821. The characters
  1822. .BR '\(pl' 
  1823. and
  1824. .BR '\-' 
  1825. cause the value of the current line after the execution of the
  1826. .IR ex
  1827. command to be adjusted by the offset address as described in
  1828. .IR "Addressing in ex".
  1829. This adjustment shall occur before the current line is written as
  1830. described in 2. above.
  1831. .P
  1832. The default for
  1833. .IR flags
  1834. shall be none.
  1835. .RE
  1836. .IP "\fIbuffer\fP" 10
  1837. One of a number of named areas for holding text. The named buffers are
  1838. specified by the alphanumeric characters of the POSIX locale. There
  1839. shall also be one ``unnamed'' buffer. When no buffer is specified for
  1840. editor commands that use a buffer, the unnamed buffer shall be used.
  1841. Commands that store text into buffers shall store the text as it was
  1842. before the command took effect, and shall store text occurring earlier
  1843. in the file before text occurring later in the file, regardless of how
  1844. the text region was specified. Commands that store text into buffers
  1845. shall store the text into the unnamed buffer as well as any specified
  1846. buffer.
  1847. .RS 10 
  1848. .P
  1849. In
  1850. .IR ex
  1851. commands, buffer names are specified as the name by itself. In open or
  1852. visual mode commands the name is preceded by a double-quote (\c
  1853. .BR '\&"' )
  1854. character.
  1855. .P
  1856. If the specified buffer name is an uppercase character, and the buffer
  1857. contents are to be modified, the buffer shall be appended to rather
  1858. than being overwritten. If the buffer is not being modified, specifying
  1859. the buffer name in lowercase and uppercase shall have identical
  1860. results.
  1861. .P
  1862. There shall also be buffers named by the numbers 1 through 9. In open
  1863. and visual mode, if a region of text including characters from more
  1864. than a single line is being modified by the
  1865. .IR vi
  1866. .BR c
  1867. or
  1868. .BR d
  1869. commands, the motion character associated with the
  1870. .BR c
  1871. or
  1872. .BR d
  1873. commands specifies that the buffer text shall be in line mode, or the
  1874. commands
  1875. .BR % ,
  1876. .BR ` ,
  1877. .BR / ,
  1878. .BR ? ,
  1879. .BR ( ,
  1880. .BR ) ,
  1881. .BR N ,
  1882. .BR n ,
  1883. .BR { ,
  1884. or
  1885. .BR }
  1886. are used to define a region of text for the
  1887. .BR c
  1888. or
  1889. .BR d
  1890. commands, the contents of buffers 1 through 8 shall be moved into the
  1891. buffer named by the next numerically greater value, the contents of
  1892. buffer 9 shall be discarded, and the region of text shall be copied
  1893. into buffer 1. This shall be in addition to copying the text into a
  1894. user-specified buffer or unnamed buffer, or both. Numeric buffers can
  1895. be specified as a source buffer for open and visual mode commands;
  1896. however, specifying a numeric buffer as the write target of an open or
  1897. visual mode command shall have unspecified results.
  1898. .P
  1899. The text of each buffer shall have the characteristic of being in
  1900. either line or character mode. Appending text to a non-empty buffer
  1901. shall set the mode to match the characteristic of the
  1902. text being appended. Appending text to a buffer shall cause the
  1903. creation of at least one additional line in the buffer. All text stored
  1904. into buffers by
  1905. .IR ex
  1906. commands shall be in line mode. The
  1907. .IR ex
  1908. commands that use buffers as the source of text specify individually
  1909. how buffers of different modes are handled. Each open or visual mode
  1910. command that uses buffers for any purpose specifies individually the
  1911. mode of the text stored into the buffer and how buffers of different
  1912. modes are handled.
  1913. .RE
  1914. .IP "\fIfile\fP" 10
  1915. Command text used to derive a pathname. The default shall be the
  1916. current pathname, as defined previously, in which case, if no current
  1917. pathname has yet been established it shall be an error, except where
  1918. specifically noted in the individual command descriptions that follow.
  1919. If the command text contains any of the characters
  1920. .BR '\(ti' ,
  1921. .BR '{' ,
  1922. .BR '[' ,
  1923. .BR '*' ,
  1924. .BR '?' ,
  1925. .BR '$' ,
  1926. .BR '\&"' ,
  1927. backquote, single-quote, and
  1928. <backslash>,
  1929. it shall be subjected to the process of ``shell expansions'', as
  1930. described below; if more than a single pathname results and the
  1931. command expects only one, it shall be an error.
  1932. .RS 10 
  1933. .P
  1934. The process of shell expansions in the editor shall be done as
  1935. follows. The
  1936. .IR ex
  1937. utility shall pass two arguments to the program named by the shell edit
  1938. option; the first shall be
  1939. .BR \-c ,
  1940. and the second shall be the string
  1941. .BR \(dqecho\(dq 
  1942. and the command text as a single argument. The standard output and
  1943. standard error of that command shall replace the command text.
  1944. .RE
  1945. .IP "\fB!\fP" 10
  1946. A character that can be appended to the command name to modify its
  1947. operation, as detailed in the individual command descriptions. With the
  1948. exception of the
  1949. .IR ex
  1950. .BR read ,
  1951. .BR write ,
  1952. and
  1953. .BR !
  1954. commands, the
  1955. .BR '!' 
  1956. character shall only act as a modifier if there are no
  1957. <blank>
  1958. characters between it and the command name.
  1959. .IP "\fIremembered\ search\ direction\fP" 10
  1960. .br
  1961. The
  1962. .IR vi
  1963. commands
  1964. .BR N
  1965. and
  1966. .BR n
  1967. begin searching in a forwards or backwards direction in the edit buffer
  1968. based on a remembered search direction, which is initially unset, and
  1969. is set by the
  1970. .IR ex
  1971. .BR global ,
  1972. .BR v ,
  1973. .BR s ,
  1974. and
  1975. .BR tag
  1976. commands, and the
  1977. .IR vi
  1978. .BR /
  1979. and
  1980. .BR ?
  1981. commands.
  1982. .SS "Abbreviate"
  1983. .IP "\fISynopsis\fR:" 10
  1984. .sp -1v
  1985. .RS 10 
  1986. .sp
  1987. .RS 4
  1988. .nf
  1990. ab\fB[\fIbreviate\fB][\fIlhs rhs\fB]\fR
  1991. .fi
  1992. .P
  1993. .RE
  1994. .RE
  1995. .P
  1996. If
  1997. .IR lhs
  1998. and
  1999. .IR rhs
  2000. are not specified, write the current list of abbreviations and do
  2001. nothing more.
  2002. .P
  2003. Implementations may restrict the set of characters accepted in
  2004. .IR lhs
  2005. or
  2006. .IR rhs ,
  2007. except that printable characters and
  2008. <blank>
  2009. characters shall not be restricted. Additional restrictions shall be
  2010. implementation-defined.
  2011. .P
  2012. In both
  2013. .IR lhs
  2014. and
  2015. .IR rhs ,
  2016. any character may be escaped with a
  2017. <control>\(hyV,
  2018. in which case the character shall not be used to delimit
  2019. .IR lhs
  2020. from
  2021. .IR rhs ,
  2022. and the escaping
  2023. <control>\(hyV
  2024. shall be discarded.
  2025. .P
  2026. In open and visual text input mode, if a non-word or
  2027. <ESC>
  2028. character that is not escaped by a
  2029. <control>\(hyV
  2030. character is entered after a word character, a check shall be made for
  2031. a set of characters matching
  2032. .IR lhs ,
  2033. in the text input entered during this command. If it is found, the
  2034. effect shall be as if
  2035. .IR rhs
  2036. was entered instead of
  2037. .IR lhs .
  2038. .P
  2039. The set of characters that are checked is defined as follows:
  2040. .IP " 1." 4
  2041. If there are no characters inserted before the word and non-word or
  2042. <ESC>
  2043. characters that triggered the check, the set of characters shall
  2044. consist of the word character.
  2045. .IP " 2." 4
  2046. If the character inserted before the word and non-word or
  2047. <ESC>
  2048. characters that triggered the check is a word character, the set of
  2049. characters shall consist of the characters inserted immediately before
  2050. the triggering characters that are word characters, plus the triggering
  2051. word character.
  2052. .IP " 3." 4
  2053. If the character inserted before the word and non-word or
  2054. <ESC>
  2055. characters that triggered the check is not a word character, the set of
  2056. characters shall consist of the characters that were inserted before
  2057. the triggering characters that are neither
  2058. <blank>
  2059. characters nor word characters, plus the triggering word character.
  2060. .P
  2061. It is unspecified whether the
  2062. .IR lhs
  2063. argument entered for the
  2064. .IR ex
  2065. .BR abbreviate
  2066. and
  2067. .BR unabbreviate
  2068. commands is replaced in this fashion. Regardless of whether or not the
  2069. replacement occurs, the effect of the command shall be as if the
  2070. replacement had not occurred.
  2071. .P
  2072. .IR "Current line" :
  2073. Unchanged.
  2074. .P
  2075. .IR "Current column" :
  2076. Unchanged.
  2077. .SS "Append"
  2078. .IP "\fISynopsis\fR:" 10
  2079. .sp -1v
  2080. .RS 10 
  2081. .sp
  2082. .RS 4
  2083. .nf
  2085. \fB[\fI1addr\fB] \fRa\fB[\fRppend\fB][\fR!\fB]\fR
  2086. .fi
  2087. .P
  2088. .RE
  2089. .RE
  2090. .P
  2091. Enter
  2092. .IR ex
  2093. text input mode; the input text shall be placed after the specified
  2094. line. If line zero is specified, the text shall be placed at the
  2095. beginning of the edit buffer.
  2096. .P
  2097. This command shall be affected by the
  2098. .BR number
  2099. and
  2100. .BR autoindent
  2101. edit options; following the command name with
  2102. .BR '!' 
  2103. shall cause the
  2104. .BR autoindent
  2105. edit option setting to be toggled for the duration of this command
  2106. only.
  2107. .P
  2108. .IR "Current line" :
  2109. Set to the last input line; if no lines were input, set to the
  2110. specified line, or to the first line of the edit buffer if a line of
  2111. zero was specified, or zero if the edit buffer is empty.
  2112. .P
  2113. .IR "Current column" :
  2114. Set to non-\c
  2115. <blank>.
  2116. .SS "Arguments"
  2117. .IP "\fISynopsis\fR:" 10
  2118. .sp -1v
  2119. .RS 10 
  2120. .sp
  2121. .RS 4
  2122. .nf
  2124. ar\fB[\fIgs\fB]\fR
  2125. .fi
  2126. .P
  2127. .RE
  2128. .RE
  2129. .P
  2130. Write the current argument list, with the current argument-list entry,
  2131. if any, between
  2132. .BR '[' 
  2133. and
  2134. .BR ']' 
  2135. characters.
  2136. .P
  2137. .IR "Current line" :
  2138. Unchanged.
  2139. .P
  2140. .IR "Current column" :
  2141. Unchanged.
  2142. .SS "Change"
  2143. .IP "\fISynopsis\fR:" 10
  2144. .sp -1v
  2145. .RS 10 
  2146. .sp
  2147. .RS 4
  2148. .nf
  2150. \fB[\fI2addr\fB] \fRc\fB[\fRhange\fB][\fR!\fB][\fIcount\fB]\fR
  2151. .fi
  2152. .P
  2153. .RE
  2154. .RE
  2155. .P
  2156. Enter
  2157. .IR ex
  2158. text input mode; the input text shall replace the specified lines. The
  2159. specified lines shall be copied into the unnamed buffer, which shall
  2160. become a line mode buffer.
  2161. .P
  2162. This command shall be affected by the
  2163. .BR number
  2164. and
  2165. .BR autoindent
  2166. edit options; following the command name with
  2167. .BR '!' 
  2168. shall cause the
  2169. .BR autoindent
  2170. edit option setting to be toggled for the duration of this command
  2171. only.
  2172. .P
  2173. .IR "Current line" :
  2174. Set to the last input line; if no lines were input, set to the line
  2175. before the first address, or to the first line of the edit buffer if
  2176. there are no lines preceding the first address, or to zero if the edit
  2177. buffer is empty.
  2178. .P
  2179. .IR "Current column" :
  2180. Set to non-\c
  2181. <blank>.
  2182. .SS "Change Directory"
  2183. .IP "\fISynopsis\fR:" 10
  2184. .sp -1v
  2185. .RS 10 
  2186. .sp
  2187. .RS 4
  2188. .nf
  2190. chd\fB[\fRir\fB][\fR!\fB][\fIdirectory\fB]\fR
  2191. cd\fB[\fR!\fB][\fIdirectory\fB]\fR
  2192. .fi
  2193. .P
  2194. .RE
  2195. .RE
  2196. .P
  2197. Change the current working directory to
  2198. .IR directory .
  2199. .P
  2200. If no
  2201. .IR directory
  2202. argument is specified, and the
  2203. .IR HOME
  2204. environment variable is set to a non-null and non-empty value,
  2205. .IR directory
  2206. shall default to the value named in the
  2207. .IR HOME
  2208. environment variable. If the
  2209. .IR HOME
  2210. environment variable is empty or is undefined, the default value of
  2211. .IR directory
  2212. is implementation-defined.
  2213. .P
  2214. If no
  2215. .BR '!' 
  2216. is appended to the command name, and the edit buffer has been modified
  2217. since the last complete write, and the current pathname does not begin
  2218. with a
  2219. .BR '/' ,
  2220. it shall be an error.
  2221. .P
  2222. .IR "Current line" :
  2223. Unchanged.
  2224. .P
  2225. .IR "Current column" :
  2226. Unchanged.
  2227. .SS "Copy"
  2228. .IP "\fISynopsis\fR:" 10
  2229. .sp -1v
  2230. .RS 10 
  2231. .sp
  2232. .RS 4
  2233. .nf
  2235. \fB[\fI2addr\fB] \fRco\fB[\fRpy\fB] \fI1addr \fB[\fIflags\fB]
  2236. [\fI2addr\fB] \fRt \fI1addr \fB[\fIflags\fB]\fR
  2237. .fi
  2238. .P
  2239. .RE
  2240. .RE
  2241. .P
  2242. Copy the specified lines after the specified destination line; line
  2243. zero specifies that the lines shall be placed at the beginning of the
  2244. edit buffer.
  2245. .P
  2246. .IR "Current line" :
  2247. Set to the last line copied.
  2248. .P
  2249. .IR "Current column" :
  2250. Set to non-\c
  2251. <blank>.
  2252. .SS "Delete"
  2253. .IP "\fISynopsis\fR:" 10
  2254. .sp -1v
  2255. .RS 10 
  2256. .sp
  2257. .RS 4
  2258. .nf
  2260. \fB[\fI2addr\fB] \fRd\fB[\fRelete\fB][\fIbuffer\fB][\fIcount\fB][\fIflags\fB]\fR
  2261. .fi
  2262. .P
  2263. .RE
  2264. .RE
  2265. .P
  2266. Delete the specified lines into a buffer (defaulting to the unnamed
  2267. buffer), which shall become a line-mode buffer.
  2268. .P
  2269. Flags can immediately follow the command name; see
  2270. .IR "Command Line Parsing in ex".
  2271. .P
  2272. .IR "Current line" :
  2273. Set to the line following the deleted lines, or to the last line in the
  2274. edit buffer if that line is past the end of the edit buffer, or to zero
  2275. if the edit buffer is empty.
  2276. .P
  2277. .IR "Current column" :
  2278. Set to non-\c
  2279. <blank>.
  2280. .SS "Edit"
  2281. .IP "\fISynopsis\fR:" 10
  2282. .sp -1v
  2283. .RS 10 
  2284. .sp
  2285. .RS 4
  2286. .nf
  2288. e\fB[\fRdit\fB][\fR!\fB][\fR+\fIcommand\fB][\fIfile\fB]\fR
  2289. ex\fB[\fR!\fB][\fR+\fIcommand\fB][\fIfile\fB]\fR
  2290. .fi
  2291. .P
  2292. .RE
  2293. .RE
  2294. .P
  2295. If no
  2296. .BR '!' 
  2297. is appended to the command name, and the edit buffer has been modified
  2298. since the last complete write, it shall be an error.
  2299. .P
  2300. If
  2301. .IR file
  2302. is specified, replace the current contents of the edit buffer with the
  2303. current contents of
  2304. .IR file ,
  2305. and set the current pathname to
  2306. .IR file .
  2307. If
  2308. .IR file
  2309. is not specified, replace the current contents of the edit buffer with
  2310. the current contents of the file named by the current pathname. If for
  2311. any reason the current contents of the file cannot be accessed, the
  2312. edit buffer shall be empty.
  2313. .P
  2314. The
  2315. .BR + \c
  2316. .IR command
  2317. option shall be
  2318. <blank>-delimited;
  2319. <blank>
  2320. characters within the
  2321. .BR + \c
  2322. .IR command
  2323. can be escaped by preceding them with a
  2324. <backslash>
  2325. character. The
  2326. .BR + \c
  2327. .IR command
  2328. shall be interpreted as an
  2329. .IR ex
  2330. command immediately after the contents of the edit buffer have been
  2331. replaced and the current line and column have been set.
  2332. .P
  2333. If the edit buffer is empty:
  2334. .P
  2335. .IR "Current line" :
  2336. Set to 0.
  2337. .P
  2338. .IR "Current column" :
  2339. Set to 1.
  2340. .P
  2341. Otherwise, if executed while in
  2342. .IR ex
  2343. command mode or if the
  2344. .BR + \c
  2345. .IR command
  2346. argument is specified:
  2347. .P
  2348. .IR "Current line" :
  2349. Set to the last line of the edit buffer.
  2350. .P
  2351. .IR "Current column" :
  2352. Set to non-\c
  2353. <blank>.
  2354. .P
  2355. Otherwise, if
  2356. .IR file
  2357. is omitted or results in the current pathname:
  2358. .P
  2359. .IR "Current line" :
  2360. Set to the first line of the edit buffer.
  2361. .P
  2362. .IR "Current column" :
  2363. Set to non-\c
  2364. <blank>.
  2365. .P
  2366. Otherwise, if
  2367. .IR file
  2368. is the same as the last file edited, the line and column shall be set
  2369. as follows; if the file was previously edited, the line and column may
  2370. be set as follows:
  2371. .P
  2372. .IR "Current line" :
  2373. Set to the last value held when that file was last edited. If this
  2374. value is not a valid line in the new edit buffer, set to the first line
  2375. of the edit buffer.
  2376. .P
  2377. .IR "Current column" :
  2378. If the current line was set to the last value held when the file was
  2379. last edited, set to the last value held when the file was last edited.
  2380. Otherwise, or if the last value is not a valid column in the new edit
  2381. buffer, set to non-\c
  2382. <blank>.
  2383. .br
  2384. .P
  2385. Otherwise:
  2386. .P
  2387. .IR "Current line" :
  2388. Set to the first line of the edit buffer.
  2389. .P
  2390. .IR "Current column" :
  2391. Set to non-\c
  2392. <blank>.
  2393. .SS "File"
  2394. .IP "\fISynopsis\fR:" 10
  2395. .sp -1v
  2396. .RS 10 
  2397. .sp
  2398. .RS 4
  2399. .nf
  2401. f\fB[\fRile\fB][\fIfile\fB]\fR
  2402. .fi
  2403. .P
  2404. .RE
  2405. .RE
  2406. .P
  2407. If a
  2408. .IR file
  2409. argument is specified, the alternate pathname shall be set to the
  2410. current pathname, and the current pathname shall be set to
  2411. .IR file .
  2412. .P
  2413. Write an informational message. If the file has a current pathname, it
  2414. shall be included in this message; otherwise, the message shall
  2415. indicate that there is no current pathname. If the edit buffer
  2416. contains lines, the current line number and the number of lines in the
  2417. edit buffer shall be included in this message; otherwise, the message
  2418. shall indicate that the edit buffer is empty. If the edit buffer has
  2419. been modified since the last complete write, this fact shall be
  2420. included in this message. If the
  2421. .BR readonly
  2422. edit option is set, this fact shall be included in this message. The
  2423. message may contain other unspecified information.
  2424. .P
  2425. .IR "Current line" :
  2426. Unchanged.
  2427. .P
  2428. .IR "Current column" :
  2429. Unchanged.
  2430. .SS "Global"
  2431. .IP "\fISynopsis\fR:" 10
  2432. .sp -1v
  2433. .RS 10 
  2434. .sp
  2435. .RS 4
  2436. .nf
  2438. \fB[\fI2addr\fB] \fRg\fB[\fRlobal\fB] \fR/\fIpattern\fR/ \fB[\fIcommands\fB]
  2439. [\fI2addr\fB] \fRv /\fIpattern\fR/ \fB[\fIcommands\fB]\fR
  2440. .fi
  2441. .P
  2442. .RE
  2443. .RE
  2444. .P
  2445. The optional
  2446. .BR '!' 
  2447. character after the
  2448. .BR global
  2449. command shall be the same as executing the
  2450. .BR v
  2451. command.
  2452. .P
  2453. If
  2454. .IR pattern
  2455. is empty (for example,
  2456. .BR \(dq//\(dq )
  2457. or not specified, the last regular expression used in the editor
  2458. command shall be used as the
  2459. .IR pattern .
  2460. The
  2461. .IR pattern
  2462. can be delimited by
  2463. <slash>
  2464. characters (shown in the Synopsis), as well as any non-alphanumeric
  2465. or non-\c
  2466. <blank>
  2467. other than
  2468. <backslash>,
  2469. <vertical-line>,
  2470. <newline>,
  2471. or double-quote.
  2472. .P
  2473. If no lines are specified, the lines shall default to the entire file.
  2474. .P
  2475. The
  2476. .BR global
  2477. and
  2478. .BR v
  2479. commands are logically two-pass operations. First, mark the lines
  2480. within the specified lines for which the line excluding the terminating
  2481. <newline>
  2482. matches (\c
  2483. .BR global )
  2484. or does not match (\c
  2485. .BR v
  2486. or
  2487. .BR global! )
  2488. the specified pattern. Second, execute the
  2489. .IR ex
  2490. commands given by
  2491. .IR commands ,
  2492. with the current line (\c
  2493. .BR '.' )
  2494. set to each marked line. If an error occurs during this process, or the
  2495. contents of the edit buffer are replaced (for example, by the
  2496. .IR ex
  2497. .BR :edit
  2498. command) an error message shall be written and no more commands
  2499. resulting from the execution of this command shall be processed.
  2500. .P
  2501. Multiple
  2502. .IR ex
  2503. commands can be specified by entering multiple commands on a single
  2504. line using a
  2505. <vertical-line>
  2506. to delimit them, or one per line, by escaping each
  2507. <newline>
  2508. with a
  2509. <backslash>.
  2510. .P
  2511. If no commands are specified:
  2512. .IP " 1." 4
  2513. If in
  2514. .IR ex
  2515. command mode, it shall be as if the
  2516. .BR print
  2517. command were specified.
  2518. .IP " 2." 4
  2519. Otherwise, no command shall be executed.
  2520. .P
  2521. For the
  2522. .BR append ,
  2523. .BR change ,
  2524. and
  2525. .BR insert
  2526. commands, the input text shall be included as part of the command, and
  2527. the terminating
  2528. <period>
  2529. can be omitted if the command ends the list of commands. The
  2530. .BR open
  2531. and
  2532. .BR visual
  2533. commands can be specified as one of the commands, in which case each
  2534. marked line shall cause the editor to enter open or visual mode. If
  2535. open or visual mode is exited using the
  2536. .IR vi
  2537. .BR Q
  2538. command, the current line shall be set to the next marked line, and
  2539. open or visual mode reentered, until the list of marked lines is
  2540. exhausted.
  2541. .P
  2542. The
  2543. .BR global ,
  2544. .BR v ,
  2545. and
  2546. .BR undo
  2547. commands cannot be used in
  2548. .IR commands .
  2549. Marked lines may be deleted by commands executed for lines occurring
  2550. earlier in the file than the marked lines. In this case, no commands
  2551. shall be executed for the deleted lines.
  2552. .P
  2553. If the remembered search direction is not set, the
  2554. .BR global
  2555. and
  2556. .BR v
  2557. commands shall set it to forward.
  2558. .P
  2559. The
  2560. .BR autoprint
  2561. and
  2562. .BR autoindent
  2563. edit options shall be inhibited for the duration of the
  2564. .BR g
  2565. or
  2566. .BR v
  2567. command.
  2568. .P
  2569. .IR "Current line" :
  2570. If no commands executed, set to the last marked line. Otherwise, as
  2571. specified for the executed
  2572. .IR ex
  2573. commands.
  2574. .P
  2575. .IR "Current column" :
  2576. If no commands are executed, set to non-\c
  2577. <blank>;
  2578. otherwise, as specified for the individual
  2579. .IR ex
  2580. commands.
  2581. .SS "Insert"
  2582. .IP "\fISynopsis\fR:" 10
  2583. .sp -1v
  2584. .RS 10 
  2585. .sp
  2586. .RS 4
  2587. .nf
  2589. \fB[\fI1addr\fB] \fRi\fB[\fRnsert\fB][\fR!\fB]\fR
  2590. .fi
  2591. .P
  2592. .RE
  2593. .RE
  2594. .P
  2595. Enter
  2596. .IR ex
  2597. text input mode; the input text shall be placed before the specified
  2598. line. If the line is zero or 1, the text shall be placed at the
  2599. beginning of the edit buffer.
  2600. .P
  2601. This command shall be affected by the
  2602. .BR number
  2603. and
  2604. .BR autoindent
  2605. edit options; following the command name with
  2606. .BR '!' 
  2607. shall cause the
  2608. .BR autoindent
  2609. edit option setting to be toggled for the duration of this command
  2610. only.
  2611. .P
  2612. .IR "Current line" :
  2613. Set to the last input line; if no lines were input, set to the line
  2614. before the specified line, or to the first line of the edit buffer if
  2615. there are no lines preceding the specified line, or zero if the edit
  2616. buffer is empty.
  2617. .P
  2618. .IR "Current column" :
  2619. Set to non-\c
  2620. <blank>.
  2621. .SS "Join"
  2622. .IP "\fISynopsis\fR:" 10
  2623. .sp -1v
  2624. .RS 10 
  2625. .sp
  2626. .RS 4
  2627. .nf
  2629. \fB[\fI2addr\fB] \fRj\fB[\fRoin\fB][\fR!\fB][\fIcount\fB][\fIflags\fB]\fR
  2630. .fi
  2631. .P
  2632. .RE
  2633. .RE
  2634. .P
  2635. If
  2636. .IR count
  2637. is specified:
  2638. .sp
  2639. .RS
  2640. If no address was specified, the
  2641. .BR join
  2642. command shall behave as if
  2643. .IR 2addr
  2644. were the current line and the current line plus
  2645. .IR count
  2646. (.\|,\|. +
  2647. .IR count ).
  2648. .P
  2649. If one address was specified, the
  2650. .BR join
  2651. command shall behave as if
  2652. .IR 2addr
  2653. were the specified address and the specified address plus
  2654. .IR count
  2655. (\c
  2656. .IR addr ,\c
  2657. .IR addr
  2658. +
  2659. .IR count ).
  2660. .P
  2661. If two addresses were specified, the
  2662. .BR join
  2663. command shall behave as if an additional address, equal to the last
  2664. address plus
  2665. .IR count
  2666. \-1 (\c
  2667. .IR addr1 ,\c
  2668. .IR addr2 ,\c
  2669. .IR addr2
  2670. +
  2671. .IR count
  2672. \-1), was specified.
  2673. .P
  2674. If this would result in a second address greater than the last line of
  2675. the edit buffer, it shall be corrected to be equal to the last line of
  2676. the edit buffer.
  2677. .RE
  2678. .P
  2679. If no
  2680. .IR count
  2681. is specified:
  2682. .sp
  2683. .RS
  2684. If no address was specified, the
  2685. .BR join
  2686. command shall behave as if
  2687. .IR 2addr
  2688. were the current line and the next line (.\|,\|. +1).
  2689. .P
  2690. If one address was specified, the
  2691. .BR join
  2692. command shall behave as if
  2693. .IR 2addr
  2694. were the specified address and the next line (\c
  2695. .IR addr ,\c
  2696. .IR addr
  2697. +1).
  2698. .RE
  2699. .P
  2700. Join the text from the specified lines together into a single line,
  2701. which shall replace the specified lines.
  2702. .P
  2703. If a
  2704. .BR '!' 
  2705. character is appended to the command name, the
  2706. .BR join
  2707. shall be without modification of any line, independent of the current
  2708. locale.
  2709. .P
  2710. Otherwise, in the POSIX locale, set the current line to the first of
  2711. the specified lines, and then, for each subsequent line, proceed as
  2712. follows:
  2713. .IP " 1." 4
  2714. Discard leading
  2715. <space>
  2716. characters from the line to be joined.
  2717. .IP " 2." 4
  2718. If the line to be joined is now empty, delete it, and skip steps 3
  2719. through 5.
  2720. .IP " 3." 4
  2721. If the current line ends in a
  2722. <blank>,
  2723. or the first character of the line to be joined is a
  2724. .BR ')' 
  2725. character, join the lines without further modification.
  2726. .IP " 4." 4
  2727. If the last character of the current line is a
  2728. .BR '.' ,
  2729. join the lines with two
  2730. <space>
  2731. characters between them.
  2732. .IP " 5." 4
  2733. Otherwise, join the lines with a single
  2734. <space>
  2735. between them.
  2736. .P
  2737. .IR "Current line" :
  2738. Set to the first line specified.
  2739. .P
  2740. .IR "Current column" :
  2741. Set to non-\c
  2742. <blank>.
  2743. .SS "List"
  2744. .IP "\fISynopsis\fR:" 10
  2745. .sp -1v
  2746. .RS 10 
  2747. .sp
  2748. .RS 4
  2749. .nf
  2751. \fB[\fI2addr\fB] \fRl\fB[\fRist\fB][\fIcount\fB][\fIflags\fB]\fR
  2752. .fi
  2753. .P
  2754. .RE
  2755. .RE
  2756. .P
  2757. This command shall be equivalent to the
  2758. .IR ex
  2759. command:
  2760. .sp
  2761. .RS 4
  2762. .nf
  2764. \fB[\fI2addr\fB] \fRp\fB[\fRrint\fB][\fIcount\fB] \fRl\fB[\fIflags\fB]\fR
  2765. .fi
  2766. .P
  2767. .RE
  2768. .P
  2769. See
  2770. .IR "Print".
  2771. .SS "Map"
  2772. .IP "\fISynopsis\fR:" 10
  2773. .sp -1v
  2774. .RS 10 
  2775. .sp
  2776. .RS 4
  2777. .nf
  2779. map\fB[\fR!\fB][\fIlhs rhs\fB]\fR
  2780. .fi
  2781. .P
  2782. .RE
  2783. .RE
  2784. .P
  2785. If
  2786. .IR lhs
  2787. and
  2788. .IR rhs
  2789. are not specified:
  2790. .IP " 1." 4
  2791. If
  2792. .BR '!' 
  2793. is specified, write the current list of text input mode maps.
  2794. .IP " 2." 4
  2795. Otherwise, write the current list of command mode maps.
  2796. .IP " 3." 4
  2797. Do nothing more.
  2798. .P
  2799. Implementations may restrict the set of characters accepted in
  2800. .IR lhs
  2801. or
  2802. .IR rhs ,
  2803. except that printable characters and
  2804. <blank>
  2805. characters shall not be restricted. Additional restrictions shall be
  2806. implementation-defined. In both
  2807. .IR lhs
  2808. and
  2809. .IR rhs ,
  2810. any character can be escaped with a
  2811. <control>\(hyV,
  2812. in which case the character shall not be used to delimit
  2813. .IR lhs
  2814. from
  2815. .IR rhs ,
  2816. and the escaping
  2817. <control>\(hyV
  2818. shall be discarded.
  2819. .P
  2820. If the character
  2821. .BR '!' 
  2822. is appended to the
  2823. .BR map
  2824. command name, the mapping shall be effective during open or visual text
  2825. input mode rather than
  2826. .BR open
  2827. or
  2828. .BR visual
  2829. command mode. This allows
  2830. .IR lhs
  2831. to have two different
  2832. .BR map
  2833. definitions at the same time: one for command mode and one for text
  2834. input mode.
  2835. .br
  2836. .P
  2837. For command mode mappings:
  2838. .sp
  2839. .RS
  2840. When the
  2841. .IR lhs
  2842. is entered as any part of a
  2843. .IR vi
  2844. command in open or visual mode (but not as part of the arguments to the
  2845. command), the action shall be as if the corresponding
  2846. .IR rhs
  2847. had been entered.
  2848. .P
  2849. If any character in the command, other than the first, is escaped using
  2850. a
  2851. <control>\(hyV
  2852. character, that character shall not be part of a match to an
  2853. .IR lhs .
  2854. .P
  2855. It is unspecified whether implementations shall support
  2856. .BR map
  2857. commands where the
  2858. .IR lhs
  2859. is more than a single character in length, where the first character of
  2860. the
  2861. .IR lhs
  2862. is printable.
  2863. .RE
  2864. .P
  2865. .sp
  2866. .RS
  2867. If
  2868. .IR lhs
  2869. contains more than one character and the first character is
  2870. .BR '#' ,
  2871. followed by a sequence of digits corresponding to a numbered function
  2872. key, then when this function key is typed it shall be mapped to
  2873. .IR rhs .
  2874. Characters other than digits following a
  2875. .BR '#' 
  2876. character also represent the function key named by the characters in
  2877. the
  2878. .IR lhs
  2879. following the
  2880. .BR '#' 
  2881. and may be mapped to
  2882. .IR rhs .
  2883. It is unspecified how function keys are named or what function keys are
  2884. supported.
  2885. .RE
  2886. .P
  2887. For text input mode mappings:
  2888. .sp
  2889. .RS
  2890. When the
  2891. .IR lhs
  2892. is entered as any part of text entered in open or visual text input
  2893. modes, the action shall be as if the corresponding
  2894. .IR rhs
  2895. had been entered.
  2896. .P
  2897. If any character in the input text is escaped using a
  2898. <control>\(hyV
  2899. character, that character shall not be part of a match to an
  2900. .IR lhs .
  2901. .P
  2902. It is unspecified whether the
  2903. .IR lhs
  2904. text entered for subsequent
  2905. .BR map
  2906. or
  2907. .BR unmap
  2908. commands is replaced with the
  2909. .IR rhs
  2910. text for the purposes of the screen display; regardless of whether or
  2911. not the display appears as if the corresponding
  2912. .IR rhs
  2913. text was entered, the effect of the command shall be as if the
  2914. .IR lhs
  2915. text was entered.
  2916. .RE
  2917. .P
  2918. If only part of the
  2919. .IR lhs
  2920. is entered, it is unspecified how long the editor will wait for
  2921. additional, possibly matching characters before treating the already
  2922. entered characters as not matching the
  2923. .IR lhs .
  2924. .P
  2925. The
  2926. .IR rhs
  2927. characters shall themselves be subject to remapping, unless otherwise
  2928. specified by the
  2929. .BR remap
  2930. edit option, except that if the characters in
  2931. .IR lhs
  2932. occur as prefix characters in
  2933. .IR rhs ,
  2934. those characters shall not be remapped.
  2935. .P
  2936. On block-mode terminals, the mapping need not occur immediately (for
  2937. example, it may occur after the terminal transmits a group of
  2938. characters to the system), but it shall achieve the same results as if
  2939. it occurred immediately.
  2940. .P
  2941. .IR "Current line" :
  2942. Unchanged.
  2943. .P
  2944. .IR "Current column" :
  2945. Unchanged.
  2946. .SS "Mark"
  2947. .IP "\fISynopsis\fR:" 10
  2948. .sp -1v
  2949. .RS 10 
  2950. .sp
  2951. .RS 4
  2952. .nf
  2954. \fB[\fI1addr\fB] \fRma\fB[\fRrk\fB] \fIcharacter
  2955. \fB[\fI1addr\fB] \fRk \fIcharacter\fR
  2956. .fi
  2957. .P
  2958. .RE
  2959. .RE
  2960. .P
  2961. Implementations shall support
  2962. .IR character
  2963. values of a single lowercase letter of the POSIX locale and the
  2964. backquote and single-quote characters; support of other characters is
  2965. implementation-defined.
  2966. .P
  2967. If executing the
  2968. .IR vi
  2969. .BR m
  2970. command, set the specified mark to the current line and 1-based
  2971. numbered character referenced by the current column, if any; otherwise,
  2972. column position 1.
  2973. .P
  2974. Otherwise, set the specified mark to the specified line and 1-based
  2975. numbered first non-\c
  2976. <blank>
  2977. non-\c
  2978. <newline>
  2979. in the line, if any; otherwise, the last non-\c
  2980. <newline>
  2981. in the line, if any; otherwise, column position 1.
  2982. .P
  2983. The mark shall remain associated with the line until the mark is reset
  2984. or the line is deleted. If a deleted line is restored by a subsequent
  2985. .BR undo
  2986. command, any marks previously associated with the line, which have not
  2987. been reset, shall be restored as well. Any use of a mark not associated
  2988. with a current line in the edit buffer shall be an error.
  2989. .P
  2990. The marks
  2991. .BR `
  2992. and
  2993. .BR \(aq
  2994. shall be set as described previously, immediately before the following
  2995. events occur in the editor:
  2996. .IP " 1." 4
  2997. The use of
  2998. .BR '$' 
  2999. as an
  3000. .IR ex
  3001. address
  3002. .IP " 2." 4
  3003. The use of a positive decimal number as an
  3004. .IR ex
  3005. address
  3006. .IP " 3." 4
  3007. The use of a search command as an
  3008. .IR ex
  3009. address
  3010. .IP " 4." 4
  3011. The use of a mark reference as an
  3012. .IR ex
  3013. address
  3014. .IP " 5." 4
  3015. The use of the following open and visual mode commands:
  3016. <control>\(hy],
  3017. .BR % ,
  3018. .BR ( ,
  3019. .BR ) ,
  3020. .BR [ ,
  3021. .BR ] ,
  3022. .BR { ,
  3023. .BR }
  3024. .IP " 6." 4
  3025. The use of the following open and visual mode commands:
  3026. .BR \(aq ,
  3027. .BR G ,
  3028. .BR H ,
  3029. .BR L ,
  3030. .BR M ,
  3031. .BR z
  3032. if the current line will change as a result of the command
  3033. .IP " 7." 4
  3034. The use of the open and visual mode commands:
  3035. .BR / ,
  3036. .BR ? ,
  3037. .BR N ,
  3038. .BR ` ,
  3039. .BR n
  3040. if the current line or column will change as a result of the command
  3041. .IP " 8." 4
  3042. The use of the
  3043. .IR ex
  3044. mode commands:
  3045. .BR z ,
  3046. .BR undo ,
  3047. .BR global ,
  3048. .BR v
  3049. .P
  3050. For rules 1., 2., 3., and 4., the
  3051. .BR `
  3052. and
  3053. .BR \(aq
  3054. marks shall not be set if the
  3055. .IR ex
  3056. command is parsed as specified by rule 6.a. in
  3057. .IR "Command Line Parsing in ex".
  3058. .P
  3059. For rules 5., 6., and 7., the
  3060. .BR `
  3061. and
  3062. .BR \(aq
  3063. marks shall not be set if the commands are used as motion commands in
  3064. open and visual mode.
  3065. .P
  3066. For rules 1., 2., 3., 4., 5., 6., 7., and 8., the
  3067. .BR `
  3068. and
  3069. .BR \(aq
  3070. marks shall not be set if the command fails.
  3071. .P
  3072. The
  3073. .BR `
  3074. and
  3075. .BR \(aq
  3076. marks shall be set as described previously, each time the contents of
  3077. the edit buffer are replaced (including the editing of the initial
  3078. buffer), if in open or visual mode, or if in
  3079. .BR ex
  3080. mode and the edit buffer is not empty, before any commands or movements
  3081. (including commands or movements specified by the
  3082. .BR \-c
  3083. or
  3084. .BR \-t
  3085. options or the
  3086. .BR + \c
  3087. .IR command
  3088. argument) are executed on the edit buffer. If in open or visual mode,
  3089. the marks shall be set as if executing the
  3090. .IR vi
  3091. .BR m
  3092. command; otherwise, as if executing the
  3093. .IR ex
  3094. .BR mark
  3095. command.
  3096. .P
  3097. When changing from
  3098. .BR ex
  3099. mode to open or visual mode, if the
  3100. .BR `
  3101. and
  3102. .BR \(aq
  3103. marks are not already set, the
  3104. .BR `
  3105. and
  3106. .BR \(aq
  3107. marks shall be set as described previously.
  3108. .P
  3109. .IR "Current line" :
  3110. Unchanged.
  3111. .P
  3112. .IR "Current column" :
  3113. Unchanged.
  3114. .SS "Move"
  3115. .IP "\fISynopsis\fR:" 10
  3116. .sp -1v
  3117. .RS 10 
  3118. .sp
  3119. .RS 4
  3120. .nf
  3122. \fB[\fI2addr\fB] \fRm\fB[\fRove\fB] \fI1addr\fR \fB[\fIflags\fB]\fR
  3123. .fi
  3124. .P
  3125. .RE
  3126. .RE
  3127. .P
  3128. Move the specified lines after the specified destination line. A
  3129. destination of line zero specifies that the lines shall be placed at
  3130. the beginning of the edit buffer. It shall be an error if the
  3131. destination line is within the range of lines to be moved.
  3132. .P
  3133. .IR "Current line" :
  3134. Set to the last of the moved lines.
  3135. .P
  3136. .IR "Current column" :
  3137. Set to non-\c
  3138. <blank>.
  3139. .SS "Next"
  3140. .IP "\fISynopsis\fR:" 10
  3141. .sp -1v
  3142. .RS 10 
  3143. .sp
  3144. .RS 4
  3145. .nf
  3147. n\fB[\fRext\fB][\fR!\fB][\fR+\fIcommand\fB][\fIfile \fR...\fB]\fR
  3148. .fi
  3149. .P
  3150. .RE
  3151. .RE
  3152. .P
  3153. If no
  3154. .BR '!' 
  3155. is appended to the command name, and the edit buffer has been modified
  3156. since the last complete write, it shall be an error, unless the file is
  3157. successfully written as specified by the
  3158. .BR autowrite
  3159. option.
  3160. .br
  3161. .P
  3162. If one or more files is specified:
  3163. .IP " 1." 4
  3164. Set the argument list to the specified filenames.
  3165. .IP " 2." 4
  3166. Set the current argument list reference to be the first entry in the
  3167. argument list.
  3168. .IP " 3." 4
  3169. Set the current pathname to the first filename specified.
  3170. .P
  3171. Otherwise:
  3172. .IP " 1." 4
  3173. It shall be an error if there are no more filenames in the argument
  3174. list after the filename currently referenced.
  3175. .IP " 2." 4
  3176. Set the current pathname and the current argument list reference to
  3177. the filename after the filename currently referenced in the argument
  3178. list.
  3179. .P
  3180. Replace the contents of the edit buffer with the contents of the file
  3181. named by the current pathname. If for any reason the contents of the
  3182. file cannot be accessed, the edit buffer shall be empty.
  3183. .P
  3184. This command shall be affected by the
  3185. .BR autowrite
  3186. and
  3187. .BR writeany
  3188. edit options.
  3189. .P
  3190. The
  3191. .BR + \c
  3192. .IR command
  3193. option shall be
  3194. <blank>-delimited;
  3195. <blank>
  3196. characters can be escaped by preceding them with a
  3197. <backslash>
  3198. character. The
  3199. .BR + \c
  3200. .IR command
  3201. shall be interpreted as an
  3202. .IR ex
  3203. command immediately after the contents of the edit buffer have been
  3204. replaced and the current line and column have been set.
  3205. .P
  3206. .IR "Current line" :
  3207. Set as described for the
  3208. .BR edit
  3209. command.
  3210. .P
  3211. .IR "Current column" :
  3212. Set as described for the
  3213. .BR edit
  3214. command.
  3215. .SS "Number"
  3216. .IP "\fISynopsis\fR:" 10
  3217. .sp -1v
  3218. .RS 10 
  3219. .sp
  3220. .RS 4
  3221. .nf
  3223. \fB[\fI2addr\fB] \fRnu\fB[\fRmber\fB][\fIcount\fB][\fIflags\fB]
  3224. [\fI2addr\fB] \fR#\fB[\fIcount\fB][\fIflags\fB]\fR
  3225. .fi
  3226. .P
  3227. .RE
  3228. .RE
  3229. .P
  3230. These commands shall be equivalent to the
  3231. .IR ex
  3232. command:
  3233. .sp
  3234. .RS 4
  3235. .nf
  3237. \fB[\fI2addr\fB] \fRp\fB[\fRrint\fB][\fIcount\fB] \fR#\fB[\fIflags\fB]\fR
  3238. .fi
  3239. .P
  3240. .RE
  3241. .P
  3242. See
  3243. .IR "Print".
  3244. .SS "Open"
  3245. .IP "\fISynopsis\fR:" 10
  3246. .sp -1v
  3247. .RS 10 
  3248. .sp
  3249. .RS 4
  3250. .nf
  3252. \fB[\fI1addr\fB] \fRo\fB[\fRpen\fB]\fR /\fIpattern\fR/ \fB[\fIflags\fB]\fR
  3253. .fi
  3254. .P
  3255. .RE
  3256. .RE
  3257. .P
  3258. This command need not be supported on block-mode terminals or terminals
  3259. with insufficient capabilities. If standard input, standard output, or
  3260. standard error are not terminal devices, the results are unspecified.
  3261. .P
  3262. Enter open mode.
  3263. .P
  3264. The trailing delimiter can be omitted from
  3265. .IR pattern
  3266. at the end of the command line. If
  3267. .IR pattern
  3268. is empty (for example,
  3269. .BR \(dq//\(dq )
  3270. or not specified, the last regular expression used in the editor shall
  3271. be used as the pattern. The pattern can be delimited by
  3272. <slash>
  3273. characters (shown in the Synopsis), as well as any alphanumeric, or non-\c
  3274. <blank>
  3275. other than
  3276. <backslash>,
  3277. <vertical-line>,
  3278. <newline>,
  3279. or
  3280. double-quote.
  3281. .P
  3282. .IR "Current line" :
  3283. Set to the specified line.
  3284. .P
  3285. .IR "Current column" :
  3286. Set to non-\c
  3287. <blank>.
  3288. .SS "Preserve"
  3289. .IP "\fISynopsis\fR:" 10
  3290. .sp -1v
  3291. .RS 10 
  3292. .sp
  3293. .RS 4
  3294. .nf
  3296. pre\fB[\fRserve\fB]\fR
  3297. .fi
  3298. .P
  3299. .RE
  3300. .RE
  3301. .P
  3302. Save the edit buffer in a form that can later be recovered by using the
  3303. .BR \-r
  3304. option or by using the
  3305. .IR ex
  3306. .BR recover
  3307. command. After the file has been preserved, a mail message shall be
  3308. sent to the user. This message shall be readable by invoking the
  3309. .IR mailx
  3310. utility. The message shall contain the name of the file, the time of
  3311. preservation, and an
  3312. .IR ex
  3313. command that could be used to recover the file. Additional information
  3314. may be included in the mail message.
  3315. .P
  3316. .IR "Current line" :
  3317. Unchanged.
  3318. .P
  3319. .IR "Current column" :
  3320. Unchanged.
  3321. .SS "Print"
  3322. .IP "\fISynopsis\fR:" 10
  3323. .sp -1v
  3324. .RS 10 
  3325. .sp
  3326. .RS 4
  3327. .nf
  3329. \fB[\fI2addr\fB] \fRp\fB[\fRrint\fB][\fIcount\fB][\fIflags\fB]\fR
  3330. .fi
  3331. .P
  3332. .RE
  3333. .RE
  3334. .P
  3335. Write the addressed lines. The behavior is unspecified if the number of
  3336. columns on the display is less than the number of columns required to
  3337. write any single character in the lines being written.
  3338. .P
  3339. Non-printable characters, except for the
  3340. <tab>,
  3341. shall be written as implementation-defined multi-character sequences.
  3342. .P
  3343. If the
  3344. .BR #
  3345. flag is specified or the
  3346. .BR number
  3347. edit option is set, each line shall be preceded by its line number in
  3348. the following format:
  3349. .sp
  3350. .RS 4
  3351. .nf
  3353. "%6d  ", <\fIline number\fR>
  3354. .fi
  3355. .P
  3356. .RE
  3357. .P
  3358. If the
  3359. .BR l
  3360. flag is specified or the
  3361. .BR list
  3362. edit option is set:
  3363. .IP " 1." 4
  3364. The characters listed in the Base Definitions volume of POSIX.1\(hy2017,
  3365. .IR "Table 5-1" ", " "Escape Sequences and Associated Actions"
  3366. shall be written as the corresponding escape sequence.
  3367. .IP " 2." 4
  3368. Non-printable characters not in the Base Definitions volume of POSIX.1\(hy2017,
  3369. .IR "Table 5-1" ", " "Escape Sequences and Associated Actions"
  3370. shall be written as one three-digit octal number (with a preceding
  3371. <backslash>)
  3372. for each byte in the character (most significant byte first).
  3373. .IP " 3." 4
  3374. The end of each line shall be marked with a
  3375. .BR '$' ,
  3376. and literal
  3377. .BR '$' 
  3378. characters within the line shall be written with a preceding
  3379. <backslash>.
  3380. .P
  3381. Long lines shall be folded; the length at which folding occurs is
  3382. unspecified, but should be appropriate for the output terminal,
  3383. considering the number of columns of the terminal.
  3384. .P
  3385. If a line is folded, and the
  3386. .BR l
  3387. flag is not specified and the
  3388. .BR list
  3389. edit option is not set, it is unspecified whether a multi-column
  3390. character at the folding position is separated; it shall not be
  3391. discarded.
  3392. .P
  3393. .IR "Current line" :
  3394. Set to the last written line.
  3395. .P
  3396. .IR "Current column" :
  3397. Unchanged if the current line is unchanged; otherwise, set to non-\c
  3398. <blank>.
  3399. .SS "Put"
  3400. .IP "\fISynopsis\fR:" 10
  3401. .sp -1v
  3402. .RS 10 
  3403. .sp
  3404. .RS 4
  3405. .nf
  3407. \fB[\fI1addr\fB] \fRpu\fB[\fRt\fB][\fIbuffer\fB]\fR
  3408. .fi
  3409. .P
  3410. .RE
  3411. .RE
  3412. .P
  3413. Append text from the specified buffer (by default, the unnamed buffer)
  3414. to the specified line; line zero specifies that the text shall be
  3415. placed at the beginning of the edit buffer. Each portion of a line in
  3416. the buffer shall become a new line in the edit buffer, regardless of
  3417. the mode of the buffer.
  3418. .P
  3419. .IR "Current line" :
  3420. Set to the last line entered into the edit buffer.
  3421. .P
  3422. .IR "Current column" :
  3423. Set to non-\c
  3424. <blank>.
  3425. .SS "Quit"
  3426. .IP "\fISynopsis\fR:" 10
  3427. .sp -1v
  3428. .RS 10 
  3429. .sp
  3430. .RS 4
  3431. .nf
  3433. q\fB[\fRuit\fB][\fR!\fB]\fR
  3434. .fi
  3435. .P
  3436. .RE
  3437. .RE
  3438. .P
  3439. If no
  3440. .BR '!' 
  3441. is appended to the command name:
  3442. .IP " 1." 4
  3443. If the edit buffer has been modified since the last complete write, it
  3444. shall be an error.
  3445. .IP " 2." 4
  3446. If there are filenames in the argument list after the filename
  3447. currently referenced, and the last command was not a
  3448. .BR quit ,
  3449. .BR wq ,
  3450. .BR xit ,
  3451. or
  3452. .BR ZZ
  3453. (see
  3454. .IR "Exit")
  3455. command, it shall be an error.
  3456. .P
  3457. Otherwise, terminate the editing session.
  3458. .SS "Read"
  3459. .IP "\fISynopsis\fR:" 10
  3460. .sp -1v
  3461. .RS 10 
  3462. .sp
  3463. .RS 4
  3464. .nf
  3466. \fB[\fI1addr\fB] \fRr\fB[\fRead\fB][\fR!\fB][\fIfile\fB]\fR
  3467. .fi
  3468. .P
  3469. .RE
  3470. .RE
  3471. .P
  3472. If
  3473. .BR '!' 
  3474. is not the first non-\c
  3475. <blank>
  3476. to follow the command name, a copy of the specified file shall be
  3477. appended into the edit buffer after the specified line; line zero
  3478. specifies that the copy shall be placed at the beginning of the edit
  3479. buffer. The number of lines and bytes read shall be written. If no
  3480. .IR file
  3481. is named, the current pathname shall be the default. If there is no
  3482. current pathname, then
  3483. .IR file
  3484. shall become the current pathname. If there is no current pathname or
  3485. .IR file
  3486. operand, it shall be an error. Specifying a
  3487. .IR file
  3488. that is not of type regular shall have unspecified results.
  3489. .P
  3490. Otherwise, if
  3491. .IR file
  3492. is preceded by
  3493. .BR '!' ,
  3494. the rest of the line after the
  3495. .BR '!' 
  3496. shall have
  3497. .BR '%' ,
  3498. .BR '#' ,
  3499. and
  3500. .BR '!' 
  3501. characters expanded as described in
  3502. .IR "Command Line Parsing in ex".
  3503. .P
  3504. The
  3505. .IR ex
  3506. utility shall then pass two arguments to the program named by the
  3507. shell edit option; the first shall be
  3508. .BR \-c
  3509. and the second shall be the expanded arguments to the
  3510. .BR read
  3511. command as a single argument. The standard input of the program shall
  3512. be set to the standard input of the
  3513. .IR ex
  3514. program when it was invoked. The standard error and standard output of
  3515. the program shall be appended into the edit buffer after the specified
  3516. line.
  3517. .P
  3518. Each line in the copied file or program output (as delimited by
  3519. <newline>
  3520. characters or the end of the file or output if it is not immediately
  3521. preceded by a
  3522. <newline>),
  3523. shall be a separate line in the edit buffer. Any occurrences of
  3524. <carriage-return>
  3525. and
  3526. <newline>
  3527. pairs in the output shall be treated as single
  3528. <newline>
  3529. characters.
  3530. .P
  3531. The special meaning of the
  3532. .BR '!' 
  3533. following the
  3534. .BR read
  3535. command can be overridden by escaping it with a
  3536. <backslash>
  3537. character.
  3538. .P
  3539. .IR "Current line" :
  3540. If no lines are added to the edit buffer, unchanged. Otherwise, if in
  3541. open or visual mode, set to the first line entered into the edit
  3542. buffer. Otherwise, set to the last line entered into the edit buffer.
  3543. .P
  3544. .IR "Current column" :
  3545. Set to non-\c
  3546. <blank>.
  3547. .SS "Recover"
  3548. .IP "\fISynopsis\fR:" 10
  3549. .sp -1v
  3550. .RS 10 
  3551. .sp
  3552. .RS 4
  3553. .nf
  3555. rec\fB[\fRover\fB][\fR!\fB] \fIfile\fR
  3556. .fi
  3557. .P
  3558. .RE
  3559. .RE
  3560. .P
  3561. If no
  3562. .BR '!' 
  3563. is appended to the command name, and the edit buffer has been modified
  3564. since the last complete write, it shall be an error.
  3565. .P
  3566. If no
  3567. .IR file
  3568. operand is specified, then the current pathname shall be used. If
  3569. there is no current pathname or
  3570. .IR file
  3571. operand, it shall be an error.
  3572. .P
  3573. If no recovery information has previously been saved about
  3574. .IR file ,
  3575. the
  3576. .BR recover
  3577. command shall behave identically to the
  3578. .BR edit
  3579. command, and an informational message to this effect shall be written.
  3580. .P
  3581. Otherwise, set the current pathname to
  3582. .IR file ,
  3583. and replace the current contents of the edit buffer with the recovered
  3584. contents of
  3585. .IR file .
  3586. If there are multiple instances of the file to be recovered, the one
  3587. most recently saved shall be recovered, and an informational message
  3588. that there are previous versions of the file that can be recovered
  3589. shall be written. The editor shall behave as if the contents of the
  3590. edit buffer have already been modified.
  3591. .P
  3592. .IR "Current file" :
  3593. Set as described for the
  3594. .BR edit
  3595. command.
  3596. .P
  3597. .IR "Current column" :
  3598. Set as described for the
  3599. .BR edit
  3600. command.
  3601. .SS "Rewind"
  3602. .IP "\fISynopsis\fR:" 10
  3603. .sp -1v
  3604. .RS 10 
  3605. .sp
  3606. .RS 4
  3607. .nf
  3609. rew\fB[\fRind\fB][\fR!\fB]\fR
  3610. .fi
  3611. .P
  3612. .RE
  3613. .RE
  3614. .P
  3615. If no
  3616. .BR '!' 
  3617. is appended to the command name, and the edit buffer has been modified
  3618. since the last complete write, it shall be an error, unless the file is
  3619. successfully written as specified by the
  3620. .BR autowrite
  3621. option.
  3622. .P
  3623. If the argument list is empty, it shall be an error.
  3624. .P
  3625. The current argument list reference and the current pathname shall be
  3626. set to the first filename in the argument list.
  3627. .P
  3628. Replace the contents of the edit buffer with the contents of the file
  3629. named by the current pathname. If for any reason the contents of the
  3630. file cannot be accessed, the edit buffer shall be empty.
  3631. .P
  3632. This command shall be affected by the
  3633. .BR autowrite
  3634. and
  3635. .BR writeany
  3636. edit options.
  3637. .P
  3638. .IR "Current line" :
  3639. Set as described for the
  3640. .BR edit
  3641. command.
  3642. .P
  3643. .IR "Current column" :
  3644. Set as described for the
  3645. .BR edit
  3646. command.
  3647. .SS "Set"
  3648. .IP "\fISynopsis\fR:" 10
  3649. .sp -1v
  3650. .RS 10 
  3651. .sp
  3652. .RS 4
  3653. .nf
  3655. se\fB[\fRt\fB][\fIoption\fB[\fR=\fB[\fIvalue\fB]]\fR ...\fB][\fRno\fIoption\fR ...\fB][\fIoption\fR? ...\fB][\fRall\fB]\fR
  3656. .fi
  3657. .P
  3658. .RE
  3659. .RE
  3660. .P
  3661. When no arguments are specified, write the value of the
  3662. .BR term
  3663. edit option and those options whose values have been changed from the
  3664. default settings; when the argument
  3665. .IR all
  3666. is specified, write all of the option values.
  3667. .P
  3668. Giving an option name followed by the character
  3669. .BR '?' 
  3670. shall cause the current value of that option to be written. The
  3671. .BR '?' 
  3672. can be separated from the option name by zero or more
  3673. <blank>
  3674. characters. The
  3675. .BR '?' 
  3676. shall be necessary only for Boolean valued options. Boolean options can
  3677. be given values by the form
  3678. .BR set
  3679. .IR option
  3680. to turn them on or
  3681. .BR set
  3682. .BR no \c
  3683. .IR option
  3684. to turn them off; string and numeric options can be assigned by the
  3685. form
  3686. .BR set
  3687. .IR option =\c
  3688. .IR value .
  3689. Any
  3690. <blank>
  3691. characters in strings can be included as is by preceding each
  3692. <blank>
  3693. with an escaping
  3694. <backslash>.
  3695. More than one option can be set or listed by a single set command by
  3696. specifying multiple arguments, each separated from the next by one or more
  3697. <blank>
  3698. characters.
  3699. .P
  3700. See
  3701. .IR "Edit Options in ex"
  3702. for details about specific options.
  3703. .P
  3704. .IR "Current line" :
  3705. Unchanged.
  3706. .P
  3707. .IR "Current column" :
  3708. Unchanged.
  3709. .SS "Shell"
  3710. .IP "\fISynopsis\fR:" 10
  3711. .sp -1v
  3712. .RS 10 
  3713. .sp
  3714. .RS 4
  3715. .nf
  3717. sh\fB[\fRell\fB]\fR
  3718. .fi
  3719. .P
  3720. .RE
  3721. .RE
  3722. .P
  3723. Invoke the program named in the
  3724. .BR shell
  3725. edit option with the single argument
  3726. .BR \-i
  3727. (interactive mode). Editing shall be resumed when the program exits.
  3728. .P
  3729. .IR "Current line" :
  3730. Unchanged.
  3731. .P
  3732. .IR "Current column" :
  3733. Unchanged.
  3734. .SS "Source"
  3735. .IP "\fISynopsis\fR:" 10
  3736. .sp -1v
  3737. .RS 10 
  3738. .sp
  3739. .RS 4
  3740. .nf
  3742. so\fB[\fRurce\fB] \fIfile\fR
  3743. .fi
  3744. .P
  3745. .RE
  3746. .RE
  3747. .P
  3748. Read and execute
  3749. .IR ex
  3750. commands from
  3751. .IR file .
  3752. Lines in the file that are blank lines shall be ignored.
  3753. .P
  3754. .IR "Current line" :
  3755. As specified for the individual
  3756. .IR ex
  3757. commands.
  3758. .P
  3759. .IR "Current column" :
  3760. As specified for the individual
  3761. .IR ex
  3762. commands.
  3763. .SS "Substitute"
  3764. .IP "\fISynopsis\fR:" 10
  3765. .sp -1v
  3766. .RS 10 
  3767. .sp
  3768. .RS 4
  3769. .nf
  3771. \fB[\fI2addr\fB] \fRs\fB[\fRubstitute\fB][\fR/\fIpattern\fR/\fIrepl\fR/\fB[\fIoptions\fB][\fIcount\fB][\fIflags\fB]]\fR
  3772. .br
  3773. \fB[\fI2addr\fB] \fR&\fB[\fIoptions\fB][\fIcount\fB][\fIflags\fB]]\fR
  3774. .br
  3775. \fB[\fI2addr\fB] \fR\(ti\fB[\fIoptions\fB][\fIcount\fB][\fIflags\fB]]\fR
  3776. .fi
  3777. .P
  3778. .RE
  3779. .RE
  3780. .P
  3781. Replace the first instance of the pattern
  3782. .IR pattern
  3783. by the string
  3784. .IR repl
  3785. on each specified line. (See
  3786. .IR "Regular Expressions in ex"
  3787. and
  3788. .IR "Replacement Strings in ex".)
  3789. Any non-alphabetic, non-\c
  3790. <blank>
  3791. delimiter other than
  3792. <backslash>,
  3793. .BR '|' ,
  3794. <newline>,
  3795. or double-quote
  3796. can be used instead of
  3797. .BR '/' .
  3798. <backslash>
  3799. characters can be used to escape delimiters,
  3800. <backslash>
  3801. characters, and other special characters.
  3802. .P
  3803. The trailing delimiter can be omitted from
  3804. .IR pattern
  3805. or from
  3806. .IR repl
  3807. at the end of the command line. If both
  3808. .IR pattern
  3809. and
  3810. .IR repl
  3811. are not specified or are empty (for example,
  3812. .BR \(dq//\(dq ),
  3813. the last
  3814. .BR s
  3815. command shall be repeated. If only
  3816. .IR pattern
  3817. is not specified or is empty, the last regular expression used in the
  3818. editor shall be used as the pattern. If only
  3819. .IR repl
  3820. is not specified or is empty, the pattern shall be replaced by nothing.
  3821. If the entire replacement pattern is
  3822. .BR '%' ,
  3823. the last replacement pattern to an
  3824. .BR s
  3825. command shall be used.
  3826. .P
  3827. Entering a
  3828. <carriage-return>
  3829. in
  3830. .IR repl
  3831. (which requires an escaping
  3832. <backslash>
  3833. in
  3834. .IR ex
  3835. mode and an escaping
  3836. <control>\(hyV
  3837. in open or
  3838. .IR vi
  3839. mode) shall split the line at that point, creating a new line in the
  3840. edit buffer. The
  3841. <carriage-return>
  3842. shall be discarded.
  3843. .P
  3844. If
  3845. .IR options
  3846. includes the letter
  3847. .BR 'g' 
  3848. (\c
  3849. .BR global ),
  3850. all non-overlapping instances of the pattern in the line shall be
  3851. replaced.
  3852. .P
  3853. If
  3854. .IR options
  3855. includes the letter
  3856. .BR 'c' 
  3857. (\c
  3858. .BR confirm ),
  3859. then before each substitution the line shall be written; the written
  3860. line shall reflect all previous substitutions. On the following line,
  3861. <space>
  3862. characters shall be written beneath the characters from the line that
  3863. are before the
  3864. .IR pattern
  3865. to be replaced, and
  3866. .BR '\(ha' 
  3867. characters written beneath the characters included in the
  3868. .IR pattern
  3869. to be replaced. The
  3870. .IR ex
  3871. utility shall then wait for a response from the user. An affirmative
  3872. response shall cause the substitution to be done, while any other input
  3873. shall not make the substitution. An affirmative response shall consist
  3874. of a line with the affirmative response (as defined by the current
  3875. locale) at the beginning of the line. This line shall be subject to
  3876. editing in the same way as the
  3877. .IR ex
  3878. command line.
  3879. .P
  3880. If interrupted (see the ASYNCHRONOUS EVENTS section), any modifications
  3881. confirmed by the user shall be preserved in the edit buffer after the
  3882. interrupt.
  3883. .P
  3884. If the remembered search direction is not set, the
  3885. .BR s
  3886. command shall set it to forward.
  3887. .P
  3888. In the second Synopsis, the
  3889. .BR &
  3890. command shall repeat the previous substitution, as if the
  3891. .BR &
  3892. command were replaced by:
  3893. .sp
  3894. .RS 4
  3895. .nf
  3897. s/\fIpattern\fR/\fIrepl\fR/
  3898. .fi
  3899. .P
  3900. .RE
  3901. .P
  3902. where
  3903. .IR pattern
  3904. and
  3905. .IR repl
  3906. are as specified in the previous
  3907. .BR s ,
  3908. .BR & ,
  3909. or
  3910. .BR ~
  3911. command.
  3912. .P
  3913. In the third Synopsis, the
  3914. .BR ~
  3915. command shall repeat the previous substitution, as if the
  3916. .BR '\(ti' 
  3917. were replaced by:
  3918. .sp
  3919. .RS 4
  3920. .nf
  3922. s/\fIpattern\fR/\fIrepl\fR/
  3923. .fi
  3924. .P
  3925. .RE
  3926. .P
  3927. where
  3928. .IR pattern
  3929. shall be the last regular expression specified to the editor, and
  3930. .IR repl
  3931. shall be from the previous substitution (including
  3932. .BR &
  3933. and
  3934. .BR ~ )
  3935. command.
  3936. .P
  3937. These commands shall be affected by the
  3938. .IR LC_MESSAGES
  3939. environment variable.
  3940. .P
  3941. .IR "Current line" :
  3942. Set to the last line in which a substitution occurred, or, unchanged if
  3943. no substitution occurred.
  3944. .P
  3945. .IR "Current column":
  3946. Set to non-\c
  3947. <blank>.
  3948. .SS "Suspend"
  3949. .IP "\fISynopsis\fR:" 10
  3950. .sp -1v
  3951. .RS 10 
  3952. .sp
  3953. .RS 4
  3954. .nf
  3956. su\fB[\fRspend\fB][\fR!\fB]\fR
  3957. st\fB[\fRop\fB][\fR!\fB]\fR
  3958. .fi
  3959. .P
  3960. .RE
  3961. .RE
  3962. .P
  3963. Allow control to return to the invoking process;
  3964. .IR ex
  3965. shall suspend itself as if it had received the SIGTSTP signal. The
  3966. suspension shall occur only if job control is enabled in the invoking
  3967. shell (see the description of
  3968. .IR set
  3969. .BR \-m ).
  3970. .P
  3971. These commands shall be affected by the
  3972. .BR autowrite
  3973. and
  3974. .BR writeany
  3975. edit options.
  3976. .P
  3977. The current
  3978. .BR susp
  3979. character (see
  3980. .IR "\fIstty\fR\^")
  3981. shall be equivalent to the
  3982. .BR suspend
  3983. command.
  3984. .SS "Tag"
  3985. .IP "\fISynopsis\fR:" 10
  3986. .sp -1v
  3987. .RS 10 
  3988. .sp
  3989. .RS 4
  3990. .nf
  3992. ta\fB[\fRg\fB][\fR!\fB] \fItagstring\fR
  3993. .fi
  3994. .P
  3995. .RE
  3996. .RE
  3997. .P
  3998. The results are unspecified if the format of a tags file is not as
  3999. specified by the
  4000. .IR ctags
  4001. utility (see
  4002. .IR "\fIctags\fR\^")
  4003. description.
  4004. .P
  4005. The
  4006. .BR tag
  4007. command shall search for
  4008. .IR tagstring
  4009. in the tag files referred to by the
  4010. .BR tag
  4011. edit option, in the order they are specified, until a reference to
  4012. .IR tagstring
  4013. is found. Files shall be searched from beginning to end. If no
  4014. reference is found, it shall be an error and an error message to this
  4015. effect shall be written. If the reference is not found, or if an error
  4016. occurs while processing a file referred to in the
  4017. .BR tag
  4018. edit option, it shall be an error, and an error message shall be
  4019. written at the first occurrence of such an error.
  4020. .P
  4021. Otherwise, if the tags file contained a pattern, the pattern shall be
  4022. treated as a regular expression used in the editor; for example, for
  4023. the purposes of the
  4024. .BR s
  4025. command.
  4026. .P
  4027. If the
  4028. .IR tagstring
  4029. is in a file with a different name than the current pathname, set the
  4030. current pathname to the name of that file, and replace the contents of
  4031. the edit buffer with the contents of that file. In this case, if no
  4032. .BR '!' 
  4033. is appended to the command name, and the edit buffer has been modified
  4034. since the last complete write, it shall be an error, unless the file is
  4035. successfully written as specified by the
  4036. .BR autowrite
  4037. option.
  4038. .P
  4039. This command shall be affected by the
  4040. .BR autowrite ,
  4041. .BR tag ,
  4042. .BR taglength ,
  4043. and
  4044. .BR writeany
  4045. edit options.
  4046. .P
  4047. .IR "Current line" :
  4048. If the tags file contained a line number, set to that line number. If
  4049. the line number is larger than the last line in the edit buffer, an
  4050. error message shall be written and the current line shall be set as
  4051. specified for the
  4052. .BR edit
  4053. command.
  4054. .P
  4055. If the tags file contained a pattern, set to the first occurrence of
  4056. the pattern in the file. If no matching pattern is found, an error
  4057. message shall be written and the current line shall be set as specified
  4058. for the
  4059. .BR edit
  4060. command.
  4061. .P
  4062. .IR "Current column" :
  4063. If the tags file contained a line-number reference and that line-number
  4064. was not larger than the last line in the edit buffer, or if the tags
  4065. file contained a pattern and that pattern was found, set to non-\c
  4066. <blank>.
  4067. Otherwise, set as specified for the
  4068. .BR edit
  4069. command.
  4070. .SS "Unabbreviate"
  4071. .IP "\fISynopsis\fR:" 10
  4072. .sp -1v
  4073. .RS 10 
  4074. .sp
  4075. .RS 4
  4076. .nf
  4078. una\fB[\fRbbrev\fB] \fIlhs\fR
  4079. .fi
  4080. .P
  4081. .RE
  4082. .RE
  4083. .P
  4084. If
  4085. .IR lhs
  4086. is not an entry in the current list of abbreviations (see
  4087. .IR "Abbreviate"),
  4088. it shall be an error. Otherwise, delete
  4089. .IR lhs
  4090. from the list of abbreviations.
  4091. .P
  4092. .IR "Current line" :
  4093. Unchanged.
  4094. .P
  4095. .IR "Current column" :
  4096. Unchanged.
  4097. .SS "Undo"
  4098. .IP "\fISynopsis\fR:" 10
  4099. .sp -1v
  4100. .RS 10 
  4101. .sp
  4102. .RS 4
  4103. .nf
  4105. u\fB[\fRndo\fB]\fR
  4106. .fi
  4107. .P
  4108. .RE
  4109. .RE
  4110. .P
  4111. Reverse the changes made by the last command that modified the contents
  4112. of the edit buffer, including
  4113. .BR undo .
  4114. For this purpose, the
  4115. .BR global ,
  4116. .BR v ,
  4117. .BR open ,
  4118. and
  4119. .BR visual
  4120. commands, and commands resulting from buffer executions and mapped
  4121. character expansions, are considered single commands.
  4122. .P
  4123. If no action that can be undone preceded the
  4124. .BR undo
  4125. command, it shall be an error.
  4126. .P
  4127. If the
  4128. .BR undo
  4129. command restores lines that were marked, the mark shall also be
  4130. restored unless it was reset subsequent to the deletion of the lines.
  4131. .P
  4132. .IR "Current line" :
  4133. .IP " 1." 4
  4134. If lines are added or changed in the file, set to the first line added
  4135. or changed.
  4136. .IP " 2." 4
  4137. Set to the line before the first line deleted, if it exists.
  4138. .IP " 3." 4
  4139. Set to 1 if the edit buffer is not empty.
  4140. .IP " 4." 4
  4141. Set to zero.
  4142. .P
  4143. .IR "Current column" :
  4144. Set to non-\c
  4145. <blank>.
  4146. .SS "Unmap"
  4147. .IP "\fISynopsis\fR:" 10
  4148. .sp -1v
  4149. .RS 10 
  4150. .sp
  4151. .RS 4
  4152. .nf
  4154. unm\fB[\fRap\fB][\fR!\fB] \fIlhs\fR
  4155. .fi
  4156. .P
  4157. .RE
  4158. .RE
  4159. .P
  4160. If
  4161. .BR '!' 
  4162. is appended to the command name, and if
  4163. .IR lhs
  4164. is not an entry in the list of text input mode map definitions, it
  4165. shall be an error. Otherwise, delete
  4166. .IR lhs
  4167. from the list of text input mode map definitions.
  4168. .P
  4169. If no
  4170. .BR '!' 
  4171. is appended to the command name, and if
  4172. .IR lhs
  4173. is not an entry in the list of command mode map definitions, it shall
  4174. be an error. Otherwise, delete
  4175. .IR lhs
  4176. from the list of command mode map definitions.
  4177. .P
  4178. .IR "Current line" :
  4179. Unchanged.
  4180. .P
  4181. .IR "Current column" :
  4182. Unchanged.
  4183. .SS "Version"
  4184. .IP "\fISynopsis\fR:" 10
  4185. .sp -1v
  4186. .RS 10 
  4187. .sp
  4188. .RS 4
  4189. .nf
  4191. ve\fB[\fRrsion\fB]\fR
  4192. .fi
  4193. .P
  4194. .RE
  4195. .RE
  4196. .P
  4197. Write a message containing version information for the editor. The
  4198. format of the message is unspecified.
  4199. .P
  4200. .IR "Current line" :
  4201. Unchanged.
  4202. .P
  4203. .IR "Current column" :
  4204. Unchanged.
  4205. .SS "Visual"
  4206. .IP "\fISynopsis\fR:" 10
  4207. .sp -1v
  4208. .RS 10 
  4209. .sp
  4210. .RS 4
  4211. .nf
  4213. \fB[\fI1addr\fB] \fRvi\fB[\fRsual\fB][\fItype\fB][\fIcount\fB][\fIflags\fB]\fR
  4214. .fi
  4215. .P
  4216. .RE
  4217. .RE
  4218. .P
  4219. If
  4220. .IR ex
  4221. is currently in open or visual mode, the Synopsis and behavior of the
  4222. visual command shall be the same as the
  4223. .BR edit
  4224. command, as specified by
  4225. .IR "Edit".
  4226. .P
  4227. Otherwise, this command need not be supported on block-mode terminals
  4228. or terminals with insufficient capabilities. If standard input,
  4229. standard output, or standard error are not terminal devices, the
  4230. results are unspecified.
  4231. .P
  4232. If
  4233. .IR count
  4234. is specified, the value of the
  4235. .BR window
  4236. edit option shall be set to
  4237. .IR count
  4238. (as described in
  4239. .IR "window").
  4240. If the
  4241. .BR '\(ha' 
  4242. type character was also specified, the
  4243. .BR window
  4244. edit option shall be set before being used by the type character.
  4245. .P
  4246. Enter visual mode. If
  4247. .IR type
  4248. is not specified, it shall be as if a
  4249. .IR type
  4250. of
  4251. .BR '\(pl' 
  4252. was specified. The
  4253. .IR type
  4254. shall cause the following effects:
  4255. .IP "\fR+\fP" 6
  4256. Place the beginning of the specified line at the top of the display.
  4257. .IP "\fR-\fP" 6
  4258. Place the end of the specified line at the bottom of the display.
  4259. .IP "\fR.\fP" 6
  4260. Place the beginning of the specified line in the middle of the display.
  4261. .IP "\fR^\fP" 6
  4262. If the specified line is less than or equal to the value of the
  4263. .BR window
  4264. edit option, set the line to 1; otherwise, decrement the line by the
  4265. value of the
  4266. .BR window
  4267. edit option minus 1. Place the beginning of this line as close to the
  4268. bottom of the displayed lines as possible, while still displaying the
  4269. value of the
  4270. .BR window
  4271. edit option number of lines.
  4272. .P
  4273. .IR "Current line" :
  4274. Set to the specified line.
  4275. .P
  4276. .IR "Current column" :
  4277. Set to non-\c
  4278. <blank>.
  4279. .SS "Write"
  4280. .IP "\fISynopsis\fR:" 10
  4281. .sp -1v
  4282. .RS 10 
  4283. .sp
  4284. .RS 4
  4285. .nf
  4287. \fB[\fI2addr\fB] \fRw\fB[\fRrite\fB][\fR!\fB][\fR>>\fB][\fIfile\fB]
  4288. [\fI2addr\fB] \fRw\fB[\fRrite\fB][\fR!\fB][\fIfile\fB]
  4289. [\fI2addr\fB] \fRwq\fB[\fR!\fB][\fR>>\fB][\fIfile\fB]\fR
  4290. .fi
  4291. .P
  4292. .RE
  4293. .RE
  4294. .P
  4295. If no lines are specified, the lines shall default to the entire file.
  4296. .P
  4297. The command
  4298. .BR wq
  4299. shall be equivalent to a
  4300. .BR write
  4301. command followed by a
  4302. .BR quit
  4303. command;
  4304. .BR wq!
  4305. shall be equivalent to
  4306. .BR write!
  4307. followed by
  4308. .BR quit .
  4309. In both cases, if the
  4310. .BR write
  4311. command fails, the
  4312. .BR quit
  4313. shall not be attempted.
  4314. .P
  4315. If the command name is not followed by one or more
  4316. <blank>
  4317. characters, or
  4318. .IR file
  4319. is not preceded by a
  4320. .BR '!' 
  4321. character, the
  4322. .BR write
  4323. shall be to a file.
  4324. .IP " 1." 4
  4325. If the
  4326. .BR >>
  4327. argument is specified, and the file already exists, the lines shall be
  4328. appended to the file instead of replacing its contents. If the
  4329. .BR >>
  4330. argument is specified, and the file does not already exist, it is
  4331. unspecified whether the write shall proceed as if the
  4332. .BR >>
  4333. argument had not been specified or if the write shall fail.
  4334. .IP " 2." 4
  4335. If the
  4336. .BR readonly
  4337. edit option is set (see
  4338. .IR "readonly"),
  4339. the
  4340. .BR write
  4341. shall fail.
  4342. .IP " 3." 4
  4343. If
  4344. .IR file
  4345. is specified, and is not the current pathname, and the file exists,
  4346. the
  4347. .BR write
  4348. shall fail.
  4349. .IP " 4." 4
  4350. If
  4351. .IR file
  4352. is not specified, the current pathname shall be used. If there is no
  4353. current pathname, the
  4354. .BR write
  4355. command shall fail.
  4356. .IP " 5." 4
  4357. If the current pathname is used, and the current pathname has been
  4358. changed by the
  4359. .BR file
  4360. or
  4361. .BR read
  4362. commands, and the file exists, the
  4363. .BR write
  4364. shall fail. If the
  4365. .BR write
  4366. is successful, subsequent
  4367. .BR write s
  4368. shall not fail for this reason (unless the current pathname is changed
  4369. again).
  4370. .IP " 6." 4
  4371. If the whole edit buffer is not being written, and the file to be
  4372. written exists, the
  4373. .BR write
  4374. shall fail.
  4375. .P
  4376. For rules 1., 2., 3., and 5., the
  4377. .BR write
  4378. can be forced by appending the character
  4379. .BR '!' 
  4380. to the command name.
  4381. .P
  4382. For rules 2., 3., and 5., the
  4383. .BR write
  4384. can be forced by setting the
  4385. .BR writeany
  4386. edit option.
  4387. .P
  4388. Additional, implementation-defined tests may cause the
  4389. .BR write
  4390. to fail.
  4391. .P
  4392. If the edit buffer is empty, a file without any contents shall be written.
  4393. .P
  4394. An informational message shall be written noting the number of lines
  4395. and bytes written.
  4396. .P
  4397. Otherwise, if the command is followed by one or more
  4398. <blank>
  4399. characters, and the file is preceded by
  4400. .BR '!' ,
  4401. the rest of the line after the
  4402. .BR '!' 
  4403. shall have
  4404. .BR '%' ,
  4405. .BR '#' ,
  4406. and
  4407. .BR '!' 
  4408. characters expanded as described in
  4409. .IR "Command Line Parsing in ex".
  4410. .P
  4411. The
  4412. .IR ex
  4413. utility shall then pass two arguments to the program named by the
  4414. .BR shell
  4415. edit option; the first shall be
  4416. .BR \-c
  4417. and the second shall be the expanded arguments to the
  4418. .BR write
  4419. command as a single argument. The specified lines shall be written to
  4420. the standard input of the command. The standard error and standard
  4421. output of the program, if any, shall be written as described for the
  4422. .BR print
  4423. command. If the last character in that output is not a
  4424. <newline>,
  4425. a
  4426. <newline>
  4427. shall be written at the end of the output.
  4428. .P
  4429. The special meaning of the
  4430. .BR '!' 
  4431. following the
  4432. .BR write
  4433. command can be overridden by escaping it with a
  4434. <backslash>
  4435. character.
  4436. .P
  4437. .IR "Current line" :
  4438. Unchanged.
  4439. .P
  4440. .IR "Current column" :
  4441. Unchanged.
  4442. .SS "Write and Exit"
  4443. .IP "\fISynopsis\fR:" 10
  4444. .sp -1v
  4445. .RS 10 
  4446. .sp
  4447. .RS 4
  4448. .nf
  4450. \fB[\fI2addr\fB] \fRx\fB[\fRit\fB][\fR!\fB][\fIfile\fB]\fR
  4451. .fi
  4452. .P
  4453. .RE
  4454. .RE
  4455. .P
  4456. If the edit buffer has not been modified since the last complete
  4457. .BR write ,
  4458. .BR xit
  4459. shall be equivalent to the
  4460. .BR quit
  4461. command, or if a
  4462. .BR '!' 
  4463. is appended to the command name, to
  4464. .BR quit! .
  4465. .P
  4466. Otherwise,
  4467. .BR xit
  4468. shall be equivalent to the
  4469. .BR wq
  4470. command, or if a
  4471. .BR '!' 
  4472. is appended to the command name, to
  4473. .BR wq! .
  4474. .P
  4475. .IR "Current line" :
  4476. Unchanged.
  4477. .P
  4478. .IR "Current column" :
  4479. Unchanged.
  4480. .SS "Yank"
  4481. .IP "\fISynopsis\fR:" 10
  4482. .sp -1v
  4483. .RS 10 
  4484. .sp
  4485. .RS 4
  4486. .nf
  4488. \fB[\fI2addr\fB] \fRya\fB[\fRnk\fB][\fIbuffer\fB][\fIcount\fB]\fR
  4489. .fi
  4490. .P
  4491. .RE
  4492. .RE
  4493. .P
  4494. Copy the specified lines to the specified buffer (by default, the
  4495. unnamed buffer), which shall become a line-mode buffer.
  4496. .P
  4497. .IR "Current line" :
  4498. Unchanged.
  4499. .P
  4500. .IR "Current column" :
  4501. Unchanged.
  4502. .SS "Adjust Window"
  4503. .IP "\fISynopsis\fR:" 10
  4504. .sp -1v
  4505. .RS 10 
  4506. .sp
  4507. .RS 4
  4508. .nf
  4510. \fB[\fI1addr\fB] \fRz\fB[\fR!\fB][\fItype \fR...\fB][\fIcount\fB][\fIflags\fB]\fR
  4511. .fi
  4512. .P
  4513. .RE
  4514. .RE
  4515. .P
  4516. If no line is specified, the current line shall be the default; if
  4517. .IR type
  4518. is omitted as well, the current line value shall first be incremented
  4519. by 1. If incrementing the current line would cause it to be greater
  4520. than the last line in the edit buffer, it shall be an error.
  4521. .P
  4522. If there are
  4523. <blank>
  4524. characters between the
  4525. .IR type
  4526. argument and the preceding
  4527. .BR z
  4528. command name or optional
  4529. .BR '!' 
  4530. character, it shall be an error.
  4531. .P
  4532. If
  4533. .IR count
  4534. is specified, the value of the
  4535. .BR window
  4536. edit option shall be set to
  4537. .IR count
  4538. (as described in
  4539. .IR "window").
  4540. If
  4541. .IR count
  4542. is omitted, it shall default to 2 times the value of the
  4543. .BR scroll
  4544. edit option, or if
  4545. .BR !
  4546. was specified, the number of lines in the display minus 1.
  4547. .P
  4548. If
  4549. .IR type
  4550. is omitted, then
  4551. .IR count
  4552. lines starting with the specified line shall be written. Otherwise,
  4553. .IR count
  4554. lines starting with the line specified by the
  4555. .IR type
  4556. argument shall be written.
  4557. .P
  4558. The
  4559. .IR type
  4560. argument shall change the lines to be written. The possible values of
  4561. .IR type
  4562. are as follows:
  4563. .IP "\fR\-\fP" 6
  4564. The specified line shall be decremented by the following value:
  4565. .RS 6 
  4566. .sp
  4567. .RS 4
  4568. .nf
  4570. (((number of \(aq-\(aq characters) x \fIcount\fR) -1)
  4571. .fi
  4572. .P
  4573. .RE
  4574. .P
  4575. If the calculation would result in a number less than 1, it shall be an
  4576. error. Write lines from the edit buffer, starting at the new value of
  4577. line, until
  4578. .IR count
  4579. lines or the last line in the edit buffer has been written.
  4580. .RE
  4581. .IP "\fR+\fP" 6
  4582. The specified line shall be incremented by the following value:
  4583. .RS 6 
  4584. .sp
  4585. .RS 4
  4586. .nf
  4588. (((number of \(aq+\(aq characters) -1) x \fIcount\fR) +1
  4589. .fi
  4590. .P
  4591. .RE
  4592. .P
  4593. If the calculation would result in a number greater than the last line
  4594. in the edit buffer, it shall be an error. Write lines from the edit
  4595. buffer, starting at the new value of line, until
  4596. .IR count
  4597. lines or the last line in the edit buffer has been written.
  4598. .RE
  4599. .IP "\fR=\fR,\fR.\fR" 6
  4600. If more than a single
  4601. .BR '.' 
  4602. or
  4603. .BR '=' 
  4604. is specified, it shall be an error. The following steps shall be
  4605. taken:
  4606. .RS 6 
  4607. .IP " 1." 4
  4608. If
  4609. .IR count
  4610. is zero, nothing shall be written.
  4611. .IP " 2." 4
  4612. Write as many of the
  4613. .IR N
  4614. lines before the current line in the edit buffer as exist. If
  4615. .IR count
  4616. or
  4617. .BR '!' 
  4618. was specified,
  4619. .IR N
  4620. shall be:
  4621. .RS 4 
  4622. .sp
  4623. .RS 4
  4624. .nf
  4626. (\fIcount\fR -1) /2
  4627. .fi
  4628. .P
  4629. .RE
  4630. .P
  4631. Otherwise,
  4632. .IR N
  4633. shall be:
  4634. .sp
  4635. .RS 4
  4636. .nf
  4638. (\fIcount\fP -3) /2
  4639. .fi
  4640. .P
  4641. .RE
  4642. .P
  4643. If
  4644. .IR N
  4645. is a number less than 3, no lines shall be written.
  4646. .RE
  4647. .IP " 3." 4
  4648. If
  4649. .BR '=' 
  4650. was specified as the type character, write a line consisting of the
  4651. smaller of the number of columns in the display divided by two, or 40
  4652. .BR '\-' 
  4653. characters.
  4654. .IP " 4." 4
  4655. Write the current line.
  4656. .IP " 5." 4
  4657. Repeat step 3.
  4658. .IP " 6." 4
  4659. Write as many of the
  4660. .IR N
  4661. lines after the current line in the edit buffer as exist.
  4662. .IR N
  4663. shall be defined as in step 2. If
  4664. .IR N
  4665. is a number less than 3, no lines shall be written. If
  4666. .IR count
  4667. is less than 3, no lines shall be written.
  4668. .RE
  4669. .IP "\fR^\fP" 6
  4670. The specified line shall be decremented by the following value:
  4671. .RS 6 
  4672. .sp
  4673. .RS 4
  4674. .nf
  4676. (((number of \(aq\(ha\(aq characters) +1) x \fIcount\fR) -1
  4677. .fi
  4678. .P
  4679. .RE
  4680. .P
  4681. If the calculation would result in a number less than 1, it shall be an
  4682. error. Write lines from the edit buffer, starting at the new value of
  4683. line, until
  4684. .IR count
  4685. lines or the last line in the edit buffer has been written.
  4686. .RE
  4687. .P
  4688. .IR "Current line" :
  4689. Set to the last line written, unless the type is
  4690. .BR = ,
  4691. in which case, set to the specified line.
  4692. .P
  4693. .IR "Current column" :
  4694. Set to non-\c
  4695. <blank>.
  4696. .SS "Escape"
  4697. .IP "\fISynopsis\fR:" 10
  4698. .sp -1v
  4699. .RS 10 
  4700. .sp
  4701. .RS 4
  4702. .nf
  4704. ! \fIcommand
  4705. \fB[\fIaddr\fB]\fR! \fIcommand\fR
  4706. .fi
  4707. .P
  4708. .RE
  4709. .RE
  4710. .P
  4711. The contents of the line after the
  4712. .BR '!' 
  4713. shall have
  4714. .BR '%' ,
  4715. .BR '#' ,
  4716. and
  4717. .BR '!' 
  4718. characters expanded as described in
  4719. .IR "Command Line Parsing in ex".
  4720. If the expansion causes the text of the line to change, it shall be
  4721. redisplayed, preceded by a single
  4722. .BR '!' 
  4723. character.
  4724. .P
  4725. The
  4726. .IR ex
  4727. utility shall execute the program named by the
  4728. .BR shell
  4729. edit option. It shall pass two arguments to the program; the first
  4730. shall be
  4731. .BR \-c ,
  4732. and the second shall be the expanded arguments to the
  4733. .BR !
  4734. command as a single argument.
  4735. .P
  4736. If no lines are specified, the standard input, standard output, and
  4737. standard error of the program shall be set to the standard input,
  4738. standard output, and standard error of the
  4739. .IR ex
  4740. program when it was invoked. In addition, a warning message shall be
  4741. written if the edit buffer has been modified since the last complete
  4742. write, and the
  4743. .BR warn
  4744. edit option is set.
  4745. .P
  4746. If lines are specified, they shall be passed to the program as standard
  4747. input, and the standard output and standard error of the program shall
  4748. replace those lines in the edit buffer. Each line in the program output
  4749. (as delimited by
  4750. <newline>
  4751. characters or the end of the output if it is not immediately preceded by a
  4752. <newline>),
  4753. shall be a separate line in the edit buffer. Any occurrences of
  4754. <carriage-return>
  4755. and
  4756. <newline>
  4757. pairs in the output shall be treated as single
  4758. <newline>
  4759. characters. The specified lines shall be copied into the unnamed buffer
  4760. before they are replaced, and the unnamed buffer shall become a line-mode
  4761. buffer.
  4762. .P
  4763. If in
  4764. .IR ex
  4765. mode, a single
  4766. .BR '!' 
  4767. character shall be written when the program completes.
  4768. .P
  4769. This command shall be affected by the
  4770. .BR shell
  4771. and
  4772. .BR warn
  4773. edit options. If no lines are specified, this command shall be affected
  4774. by the
  4775. .BR autowrite
  4776. and
  4777. .BR writeany
  4778. edit options. If lines are specified, this command shall be affected by
  4779. the
  4780. .BR autoprint
  4781. edit option.
  4782. .br
  4783. .P
  4784. .IR "Current line" :
  4785. .IP " 1." 4
  4786. If no lines are specified, unchanged.
  4787. .IP " 2." 4
  4788. Otherwise, set to the last line read in, if any lines are read in.
  4789. .IP " 3." 4
  4790. Otherwise, set to the line before the first line of the lines
  4791. specified, if that line exists.
  4792. .IP " 4." 4
  4793. Otherwise, set to the first line of the edit buffer if the edit buffer
  4794. is not empty.
  4795. .IP " 5." 4
  4796. Otherwise, set to zero.
  4797. .P
  4798. .IR "Current column" :
  4799. If no lines are specified, unchanged. Otherwise, set to non-\c
  4800. <blank>.
  4801. .SS "Shift Left"
  4802. .IP "\fISynopsis\fR:" 10
  4803. .sp -1v
  4804. .RS 10 
  4805. .sp
  4806. .RS 4
  4807. .nf
  4809. \fB[\fI2addr\fB]\fR <\fB[\fR< ...\fB][\fIcount\fB][\fIflags\fB]\fR
  4810. .fi
  4811. .P
  4812. .RE
  4813. .RE
  4814. .P
  4815. Shift the specified lines to the start of the line; the number of
  4816. column positions to be shifted shall be the number of command
  4817. characters times the value of the
  4818. .BR shiftwidth
  4819. edit option. Only leading
  4820. <blank>
  4821. characters shall be deleted or changed into other
  4822. <blank>
  4823. characters in shifting; other characters shall not be affected.
  4824. .P
  4825. Lines to be shifted shall be copied into the unnamed buffer, which
  4826. shall become a line-mode buffer.
  4827. .P
  4828. This command shall be affected by the
  4829. .BR autoprint
  4830. edit option.
  4831. .P
  4832. .IR "Current line" :
  4833. Set to the last line in the lines specified.
  4834. .P
  4835. .IR "Current column" :
  4836. Set to non-\c
  4837. <blank>.
  4838. .SS "Shift Right"
  4839. .IP "\fISynopsis\fR:" 10
  4840. .sp -1v
  4841. .RS 10 
  4842. .sp
  4843. .RS 4
  4844. .nf
  4846. \fB[\fI2addr\fB]\fR >\fB[\fR> ...\fB][\fIcount\fB][\fIflags\fB]\fR
  4847. .fi
  4848. .P
  4849. .RE
  4850. .RE
  4851. .P
  4852. Shift the specified lines away from the start of the line; the number
  4853. of column positions to be shifted shall be the number of command
  4854. characters times the value of the
  4855. .BR shiftwidth
  4856. edit option. The shift shall be accomplished by adding
  4857. <blank>
  4858. characters as a prefix to the line or changing leading
  4859. <blank>
  4860. characters into other
  4861. <blank>
  4862. characters. Empty lines shall not be changed.
  4863. .P
  4864. Lines to be shifted shall be copied into the unnamed buffer, which
  4865. shall become a line-mode buffer.
  4866. .P
  4867. This command shall be affected by the
  4868. .BR autoprint
  4869. edit option.
  4870. .P
  4871. .IR "Current line" :
  4872. Set to the last line in the lines specified.
  4873. .P
  4874. .IR "Current column" :
  4875. Set to non-\c
  4876. <blank>.
  4877. .SS "<control>\(hyD"
  4878. .IP "\fISynopsis\fR:" 10
  4879. .sp -1v
  4880. .RS 10 
  4881. .sp
  4882. .RS 4
  4883. .nf
  4885. <control>-D
  4886. .fi
  4887. .P
  4888. .RE
  4889. .RE
  4890. .P
  4891. Write the next
  4892. .IR n
  4893. lines, where
  4894. .IR n
  4895. is the minimum of the values of the
  4896. .BR scroll
  4897. edit option and the number of lines after the current line in the edit
  4898. buffer. If the current line is the last line of the edit buffer it
  4899. shall be an error.
  4900. .P
  4901. .IR "Current line" :
  4902. Set to the last line written.
  4903. .P
  4904. .IR "Current column" :
  4905. Set to non-\c
  4906. <blank>.
  4907. .SS "Write Line Number"
  4908. .IP "\fISynopsis\fR:" 10
  4909. .sp -1v
  4910. .RS 10 
  4911. .sp
  4912. .RS 4
  4913. .nf
  4915. \fB[\fI1addr\fB] \fR= \fB[\fIflags\fB]\fR
  4916. .fi
  4917. .P
  4918. .RE
  4919. .RE
  4920. .P
  4921. If
  4922. .IR line
  4923. is not specified, it shall default to the last line in the edit buffer.
  4924. Write the line number of the specified line.
  4925. .P
  4926. .IR "Current line" :
  4927. Unchanged.
  4928. .P
  4929. .IR "Current column" :
  4930. Unchanged.
  4931. .SS "Execute"
  4932. .IP "\fISynopsis\fR:" 10
  4933. .sp -1v
  4934. .RS 10 
  4935. .sp
  4936. .RS 4
  4937. .nf
  4939. \fB[\fI2addr\fB]\fR @ \fIbuffer\fR
  4940. \fB[\fI2addr\fB]\fR * \fIbuffer\fR
  4941. .fi
  4942. .P
  4943. .RE
  4944. .RE
  4945. .P
  4946. If no buffer is specified or is specified as
  4947. .BR '@' 
  4948. or
  4949. .BR '*' ,
  4950. the last buffer executed shall be used. If no previous buffer has been
  4951. executed, it shall be an error.
  4952. .P
  4953. For each line specified by the addresses, set the current line (\c
  4954. .BR '.' )
  4955. to the specified line, and execute the contents of the named
  4956. .IR buffer
  4957. (as they were at the time the
  4958. .BR @
  4959. command was executed) as
  4960. .IR ex
  4961. commands. For each line of a line-mode buffer, and all but the last
  4962. line of a character-mode buffer, the
  4963. .IR ex
  4964. command parser shall behave as if the line was terminated by a
  4965. <newline>.
  4966. .P
  4967. If an error occurs during this process, or a line specified by the
  4968. addresses does not exist when the current line would be set to it, or
  4969. more than a single line was specified by the addresses, and the
  4970. contents of the edit buffer are replaced (for example, by the
  4971. .IR ex
  4972. .BR :edit
  4973. command) an error message shall be written, and no more commands
  4974. resulting from the execution of this command shall be processed.
  4975. .P
  4976. .IR "Current line" :
  4977. As specified for the individual
  4978. .IR ex
  4979. commands.
  4980. .P
  4981. .IR "Current column" :
  4982. As specified for the individual
  4983. .IR ex
  4984. commands.
  4985. .SS "Regular Expressions in ex"
  4986. .P
  4987. The
  4988. .IR ex
  4989. utility shall support regular expressions that are a superset of the
  4990. basic regular expressions described in the Base Definitions volume of POSIX.1\(hy2017,
  4991. .IR "Section 9.3" ", " "Basic Regular Expressions".
  4992. A null regular expression (\c
  4993. .BR \(dq//\(dq )
  4994. shall be equivalent to the last regular expression encountered.
  4995. .P
  4996. Regular expressions can be used in addresses to specify lines and, in
  4997. some commands (for example, the
  4998. .BR substitute
  4999. command), to specify portions of a line to be substituted.
  5000. .P
  5001. The following constructs can be used to enhance the basic regular
  5002. expressions:
  5003. .IP "\fR\e<\fR" 6
  5004. Match the beginning of a
  5005. .IR word .
  5006. (See the definition of
  5007. .IR word
  5008. at the beginning of
  5009. .IR "Command Descriptions in ex".)
  5010. .IP "\fR\e>\fR" 6
  5011. Match the end of a
  5012. .IR word .
  5013. .IP "\fR~\fR" 6
  5014. Match the replacement part of the last
  5015. .BR substitute
  5016. command. The
  5017. <tilde>
  5018. (\c
  5019. .BR '\(ti' )
  5020. character can be escaped in a regular expression to become a normal
  5021. character with no special meaning. The
  5022. <backslash>
  5023. shall be discarded.
  5024. .P
  5025. When the editor option
  5026. .BR magic
  5027. is not set, the only characters with special meanings shall be
  5028. .BR '\(ha' 
  5029. at the beginning of a pattern,
  5030. .BR '$' 
  5031. at the end of a pattern, and
  5032. <backslash>.
  5033. The characters
  5034. .BR '.' ,
  5035. .BR '*' ,
  5036. .BR '[' ,
  5037. and
  5038. .BR '\(ti' 
  5039. shall be treated as ordinary characters unless preceded by a
  5040. <backslash>;
  5041. when preceded by a
  5042. <backslash>
  5043. they shall regain their special meaning, or in the case of
  5044. <backslash>,
  5045. be handled as a single
  5046. <backslash>.
  5047. <backslash>
  5048. characters used to escape other characters shall be discarded.
  5049. .SS "Replacement Strings in ex"
  5050. .P
  5051. The character
  5052. .BR '&' 
  5053. (\c
  5054. .BR '\e&' 
  5055. if the editor option
  5056. .BR magic
  5057. is not set) in the replacement string shall stand for the text matched
  5058. by the pattern to be replaced. The character
  5059. .BR '\(ti' 
  5060. (\c
  5061. .BR '\e\(ti' 
  5062. if
  5063. .BR magic
  5064. is not set) shall be replaced by the replacement part of the previous
  5065. .BR substitute
  5066. command. The sequence
  5067. .BR '\en' ,
  5068. where
  5069. .IR n
  5070. is an integer, shall be replaced by the text matched by the
  5071. corresponding back-reference expression. If the corresponding
  5072. back-reference expression does not match, then the characters
  5073. .BR '\en' 
  5074. shall be replaced by the empty string.
  5075. .P
  5076. The strings
  5077. .BR '\el' ,
  5078. .BR '\eu' ,
  5079. .BR '\eL' ,
  5080. and
  5081. .BR '\eU' 
  5082. can be used to modify the case of elements in the replacement string
  5083. (using the
  5084. .BR '\e&' 
  5085. or
  5086. .BR \(dq\e\(dq digit)
  5087. notation. The string
  5088. .BR '\el' 
  5089. (\c
  5090. .BR '\eu' )
  5091. shall cause the character that follows to be converted to lowercase
  5092. (uppercase). The string
  5093. .BR '\eL' 
  5094. (\c
  5095. .BR '\eU' )
  5096. shall cause all characters subsequent to it to be converted to
  5097. lowercase (uppercase) as they are inserted by the substitution until
  5098. the string
  5099. .BR '\ee' 
  5100. or
  5101. .BR '\eE' ,
  5102. or the end of the replacement string, is encountered.
  5103. .P
  5104. Otherwise, any character following a
  5105. <backslash>
  5106. shall be treated as that literal character, and the escaping
  5107. <backslash>
  5108. shall be discarded.
  5109. .P
  5110. An example of case conversion with the
  5111. .BR s
  5112. command is as follows:
  5113. .sp
  5114. .RS 4
  5115. .nf
  5117. \fB:\fRp
  5118. \fBThe cat sat on the mat.
  5119. \fB:\fRs/\e<.at\e>/\eu&/gp
  5120. \fBThe Cat Sat on the Mat.
  5121. \fB:\fRs/S\e(.*\e)M/S\eU\e1\eeM/p
  5122. \fBThe Cat SAT ON THE Mat.\fR
  5123. .fi
  5124. .P
  5125. .RE
  5126. .SS "Edit Options in ex"
  5127. .P
  5128. The
  5129. .IR ex
  5130. utility has a number of options that modify its behavior. These options
  5131. have default settings, which can be changed using the
  5132. .BR set
  5133. command.
  5134. .P
  5135. Options are Boolean unless otherwise specified.
  5136. .SS "autoindent, ai"
  5137. .P
  5138. [Default \fIunset\fR]
  5139. .P
  5140. If
  5141. .BR autoindent
  5142. is set, each line in input mode shall be indented (using first as many
  5143. <tab>
  5144. characters as possible, as determined by the editor option
  5145. .BR tabstop ,
  5146. and then using
  5147. <space>
  5148. characters) to align with another line, as follows:
  5149. .IP " 1." 4
  5150. If in open or visual mode and the text input is part of a line-oriented
  5151. command (see the EXTENDED DESCRIPTION in
  5152. .IR "\fIvi\fR\^"),
  5153. align to the first column.
  5154. .IP " 2." 4
  5155. Otherwise, if in open or visual mode, indentation for each line shall
  5156. be set as follows:
  5157. .RS 4 
  5158. .IP " a." 4
  5159. If a line was previously inserted as part of this command, it shall be
  5160. set to the indentation of the last inserted line by default, or as
  5161. otherwise specified for the
  5162. <control>\(hyD
  5163. character in
  5164. .IR "Input Mode Commands in vi".
  5165. .IP " b." 4
  5166. Otherwise, it shall be set to the indentation of the previous current
  5167. line, if any; otherwise, to the first column.
  5168. .RE
  5169. .IP " 3." 4
  5170. For the
  5171. .IR ex
  5172. .BR a ,
  5173. .BR i ,
  5174. and
  5175. .BR c
  5176. commands, indentation for each line shall be set as follows:
  5177. .RS 4 
  5178. .IP " a." 4
  5179. If a line was previously inserted as part of this command, it shall be
  5180. set to the indentation of the last inserted line by default, or as
  5181. otherwise specified for the
  5182. .IR eof
  5183. character in
  5184. .IR "Scroll".
  5185. .IP " b." 4
  5186. Otherwise, if the command is the
  5187. .IR ex
  5188. .BR a
  5189. command, it shall be set to the line appended after, if any; otherwise
  5190. to the first column.
  5191. .IP " c." 4
  5192. Otherwise, if the command is the
  5193. .IR ex
  5194. .BR i
  5195. command, it shall be set to the line inserted before, if any; otherwise
  5196. to the first column.
  5197. .IP " d." 4
  5198. Otherwise, if the command is the
  5199. .IR ex
  5200. .BR c
  5201. command, it shall be set to the indentation of the line replaced.
  5202. .RE
  5203. .SS "autoprint, ap"
  5204. .P
  5205. [Default \fIset\fR]
  5206. .P
  5207. If
  5208. .BR autoprint
  5209. is set, the current line shall be written after each
  5210. .IR ex
  5211. command that modifies the contents of the current edit buffer, and
  5212. after each
  5213. .BR tag
  5214. command for which the tag search pattern was found or tag line number
  5215. was valid, unless:
  5216. .IP " 1." 4
  5217. The command was executed while in open or visual mode.
  5218. .IP " 2." 4
  5219. The command was executed as part of a
  5220. .BR global
  5221. or
  5222. .BR v
  5223. command or
  5224. .BR @
  5225. buffer execution.
  5226. .IP " 3." 4
  5227. The command was the form of the
  5228. .BR read
  5229. command that reads a file into the edit buffer.
  5230. .IP " 4." 4
  5231. The command was the
  5232. .BR append ,
  5233. .BR change ,
  5234. or
  5235. .BR insert
  5236. command.
  5237. .IP " 5." 4
  5238. The command was not terminated by a
  5239. <newline>.
  5240. .IP " 6." 4
  5241. The current line shall be written by a flag specified to the command;
  5242. for example,
  5243. .BR "delete #"
  5244. shall write the current line as specified for the flag modifier to the
  5245. .BR delete
  5246. command, and not as specified by the
  5247. .BR autoprint
  5248. edit option.
  5249. .SS "autowrite, aw"
  5250. .P
  5251. [Default \fIunset\fR]
  5252. .P
  5253. If
  5254. .BR autowrite
  5255. is set, and the edit buffer has been modified since it was last
  5256. completely written to any file, the contents of the edit buffer shall
  5257. be written as if the
  5258. .IR ex
  5259. .BR write
  5260. command had been specified without arguments, before each command
  5261. affected by the
  5262. .BR autowrite
  5263. edit option is executed. Appending the character
  5264. .BR '!' 
  5265. to the command name of any of the
  5266. .IR ex
  5267. commands except
  5268. .BR '!' 
  5269. shall prevent the write. If the write fails, it shall be an error and
  5270. the command shall not be executed.
  5271. .SS "beautify, bf"
  5272. .P
  5273. [Default \fIunset\fR]
  5274. .P
  5275. If
  5276. .BR beautify
  5277. is set, all non-printable characters, other than
  5278. <tab>,
  5279. <newline>,
  5280. and
  5281. <form-feed>
  5282. characters, shall be discarded from text read in from files.
  5283. .SS "directory, dir"
  5284. .P
  5285. [Default \fIimplementation-defined\fR]
  5286. .P
  5287. The value of this option specifies the directory in which the editor
  5288. buffer is to be placed. If this directory is not writable by the user,
  5289. the editor shall quit.
  5290. .SS "edcompatible, ed"
  5291. .P
  5292. [Default \fIunset\fR]
  5293. .P
  5294. Causes the presence of
  5295. .BR g
  5296. and
  5297. .BR c
  5298. suffixes on substitute commands to be remembered, and toggled by
  5299. repeating the suffixes.
  5300. .SS "errorbells, eb"
  5301. .P
  5302. [Default \fIunset\fR]
  5303. .P
  5304. If the editor is in
  5305. .IR ex
  5306. mode, and the terminal does not support a standout mode (such as
  5307. inverse video), and
  5308. .BR errorbells
  5309. is set, error messages shall be preceded by alerting the terminal.
  5310. .SS "exrc"
  5311. .P
  5312. [Default \fIunset\fR]
  5313. .P
  5314. If
  5315. .BR exrc
  5316. is set,
  5317. .IR ex
  5318. shall access any
  5319. .BR .exrc
  5320. file in the current directory, as described in
  5321. .IR "Initialization in ex and vi".
  5322. If
  5323. .BR exrc
  5324. is not set,
  5325. .IR ex
  5326. shall ignore any
  5327. .BR .exrc
  5328. file in the current directory during initialization, unless the current
  5329. directory is that named by the
  5330. .IR HOME
  5331. environment variable.
  5332. .SS "ignorecase, ic"
  5333. .P
  5334. [Default \fIunset\fR]
  5335. .P
  5336. If
  5337. .BR ignorecase
  5338. is set, characters that have uppercase and lowercase representations
  5339. shall have those representations considered as equivalent for purposes
  5340. of regular expression comparison.
  5341. .P
  5342. The
  5343. .BR ignorecase
  5344. edit option shall affect all remembered regular expressions; for
  5345. example, unsetting the
  5346. .BR ignorecase
  5347. edit option shall cause a subsequent
  5348. .IR vi
  5349. .BR n
  5350. command to search for the last basic regular expression in a
  5351. case-sensitive fashion.
  5352. .SS "list"
  5353. .P
  5354. [Default \fIunset\fR]
  5355. .P
  5356. If
  5357. .BR list
  5358. is set, edit buffer lines written while in
  5359. .IR ex
  5360. command mode shall be written as specified for the
  5361. .BR print
  5362. command with the
  5363. .BR l
  5364. flag specified. In open or visual mode, each edit buffer line shall be
  5365. displayed as specified for the
  5366. .IR ex
  5367. .BR print
  5368. command with the
  5369. .BR l
  5370. flag specified. In open or visual text input mode, when the cursor
  5371. does not rest on any character in the line, it shall rest on the
  5372. .BR '$' 
  5373. marking the end of the line.
  5374. .SS "magic"
  5375. .P
  5376. [Default \fIset\fR]
  5377. .P
  5378. If
  5379. .BR magic
  5380. is set, modify the interpretation of characters in regular expressions
  5381. and substitution replacement strings (see
  5382. .IR "Regular Expressions in ex"
  5383. and
  5384. .IR "Replacement Strings in ex").
  5385. .SS "mesg"
  5386. .P
  5387. [Default \fIset\fR]
  5388. .P
  5389. If
  5390. .BR mesg
  5391. is set, the permission for others to use the
  5392. .BR write
  5393. or
  5394. .BR talk
  5395. commands to write to the terminal shall be turned on while in open or
  5396. visual mode. The shell-level command
  5397. .IR mesg
  5398. .BR n
  5399. shall take precedence over any setting of the
  5400. .IR ex
  5401. .BR mesg
  5402. option; that is, if
  5403. .BR "mesg y"
  5404. was issued before the editor started (or in a shell escape), such as:
  5405. .sp
  5406. .RS 4
  5407. .nf
  5409. :!mesg y
  5410. .fi
  5411. .P
  5412. .RE
  5413. .P
  5414. the
  5415. .BR mesg
  5416. option in
  5417. .IR ex
  5418. shall suppress incoming messages, but the
  5419. .BR mesg
  5420. option shall not enable incoming messages if
  5421. .BR "mesg n"
  5422. was issued.
  5423. .SS "number, nu"
  5424. .P
  5425. [Default \fIunset\fR]
  5426. .P
  5427. If
  5428. .BR number
  5429. is set, edit buffer lines written while in
  5430. .IR ex
  5431. command mode shall be written with line numbers, in the format
  5432. specified by the
  5433. .BR print
  5434. command with the
  5435. .BR #
  5436. flag specified. In
  5437. .IR ex
  5438. text input mode, each line shall be preceded by the line number it will
  5439. have in the file.
  5440. .P
  5441. In open or visual mode, each edit buffer line shall be displayed with a
  5442. preceding line number, in the format specified by the
  5443. .IR ex
  5444. .BR print
  5445. command with the
  5446. .BR #
  5447. flag specified. This line number shall not be considered part of the
  5448. line for the purposes of evaluating the current column; that is, column
  5449. position 1 shall be the first column position after the format
  5450. specified by the
  5451. .BR print
  5452. command.
  5453. .SS "paragraphs, para"
  5454. .P
  5455. [Default in the POSIX locale \fRIPLPPPQPP LIpplpipbp\fR]
  5456. .P
  5457. The
  5458. .BR paragraphs
  5459. edit option shall define additional paragraph boundaries for the open
  5460. and visual mode commands. The
  5461. .BR paragraphs
  5462. edit option can be set to a character string consisting of zero or more
  5463. character pairs. It shall be an error to set it to an odd number of
  5464. characters.
  5465. .SS "prompt"
  5466. .P
  5467. [Default \fIset\fR]
  5468. .P
  5469. If
  5470. .BR prompt
  5471. is set,
  5472. .IR ex
  5473. command mode input shall be prompted for with a
  5474. <colon>
  5475. (\c
  5476. .BR ':' );
  5477. when unset, no prompt shall be written.
  5478. .SS "readonly"
  5479. .P
  5480. [Default \fIsee text\fR]
  5481. .P
  5482. If the
  5483. .BR readonly
  5484. edit option is set, read-only mode shall be enabled (see
  5485. .IR "Write").
  5486. The
  5487. .BR readonly
  5488. edit option shall be initialized to set if either of the following
  5489. conditions are true:
  5490. .IP " *" 4
  5491. The command-line option
  5492. \-R
  5493. was specified.
  5494. .IP " *" 4
  5495. Performing actions equivalent to the
  5496. \fIaccess\fR()
  5497. function called with the following arguments indicates that the file
  5498. lacks write permission:
  5499. .RS 4 
  5500. .IP " 1." 4
  5501. The current pathname is used as the
  5502. .IR path
  5503. argument.
  5504. .IP " 2." 4
  5505. The constant
  5506. .BR W_OK
  5507. is used as the
  5508. .IR amode
  5509. argument.
  5510. .RE
  5511. .P
  5512. The
  5513. .BR readonly
  5514. edit option may be initialized to set for other,
  5515. implementation-defined reasons. The
  5516. .BR readonly
  5517. edit option shall not be initialized to unset based on any special
  5518. privileges of the user or process. The
  5519. .BR readonly
  5520. edit option shall be reinitialized each time that the contents of the
  5521. edit buffer are replaced (for example, by an
  5522. .BR edit
  5523. or
  5524. .BR next
  5525. command) unless the user has explicitly set it, in which case it shall
  5526. remain set until the user explicitly unsets it. Once unset, it shall
  5527. again be reinitialized each time that the contents of the edit buffer
  5528. are replaced.
  5529. .SS "redraw"
  5530. .P
  5531. [Default \fIunset\fR]
  5532. .P
  5533. The editor simulates an intelligent terminal on a dumb terminal.
  5534. (Since this is likely to require a large amount of output to the
  5535. terminal, it is useful only at high transmission speeds.)
  5536. .SS "remap"
  5537. .P
  5538. [Default \fIset\fR]
  5539. .P
  5540. If
  5541. .BR remap
  5542. is set, map translation shall allow for maps defined in terms of other
  5543. maps; translation shall continue until a final product is obtained. If
  5544. unset, only a one-step translation shall be done.
  5545. .SS "report"
  5546. .P
  5547. [Default 5]
  5548. .P
  5549. The value of this
  5550. .BR report
  5551. edit option specifies what number of lines being added, copied,
  5552. deleted, or modified in the edit buffer will cause an informational
  5553. message to be written to the user. The following conditions shall cause
  5554. an informational message. The message shall contain the number of lines
  5555. added, copied, deleted, or modified, but is otherwise unspecified.
  5556. .IP " *" 4
  5557. An
  5558. .IR ex
  5559. or
  5560. .IR vi
  5561. editor command, other than
  5562. .BR open ,
  5563. .BR undo ,
  5564. or
  5565. .BR visual ,
  5566. that modifies at least the value of the
  5567. .BR report
  5568. edit option number of lines, and which is not part of an
  5569. .IR ex
  5570. .BR global
  5571. or
  5572. .BR v
  5573. command, or
  5574. .IR ex
  5575. or
  5576. .IR vi
  5577. buffer execution, shall cause an informational message to be written.
  5578. .IP " *" 4
  5579. An
  5580. .IR ex
  5581. .BR yank
  5582. or
  5583. .IR vi
  5584. .BR y
  5585. or
  5586. .BR Y
  5587. command, that copies at least the value of the
  5588. .BR report
  5589. edit option plus 1 number of lines, and which is not part of an
  5590. .IR ex
  5591. .BR global
  5592. or
  5593. .BR v
  5594. command, or
  5595. .IR ex
  5596. or
  5597. .IR vi
  5598. buffer execution, shall cause an informational message to be written.
  5599. .IP " *" 4
  5600. An
  5601. .IR ex
  5602. .BR global ,
  5603. .BR v ,
  5604. .BR open ,
  5605. .BR undo ,
  5606. or
  5607. .BR visual
  5608. command or
  5609. .IR ex
  5610. or
  5611. .IR vi
  5612. buffer execution, that adds or deletes a total of at least the value of
  5613. the
  5614. .BR report
  5615. edit option number of lines, and which is not part of an
  5616. .IR ex
  5617. .BR global
  5618. or
  5619. .BR v
  5620. command, or
  5621. .IR ex
  5622. or
  5623. .IR vi
  5624. buffer execution, shall cause an informational message to be written.
  5625. (For example, if 3 lines were added and 8 lines deleted during an
  5626. .IR ex
  5627. .BR visual
  5628. command, 5 would be the number compared against the
  5629. .BR report
  5630. edit option after the command completed.)
  5631. .SS "scroll, scr"
  5632. .P
  5633. [Default (number of lines in the display \-1)/2]
  5634. .P
  5635. The value of the
  5636. .BR scroll
  5637. edit option shall determine the number of lines scrolled by the
  5638. .IR ex
  5639. <control>\(hyD
  5640. and
  5641. .BR z
  5642. commands. For the
  5643. .IR vi
  5644. <control>\(hyD
  5645. and
  5646. <control>\(hyU
  5647. commands, it shall be the initial number of lines to scroll when no
  5648. previous
  5649. <control>\(hyD
  5650. or
  5651. <control>\(hyU
  5652. command has been executed.
  5653. .SS "sections"
  5654. .P
  5655. [Default in the POSIX locale \fRNHSHH HUnhsh\fR]
  5656. .P
  5657. The
  5658. .BR sections
  5659. edit option shall define additional section boundaries for the open and
  5660. visual mode commands. The
  5661. .BR sections
  5662. edit option can be set to a character string consisting of zero or more
  5663. character pairs; it shall be an error to set it to an odd number of
  5664. characters.
  5665. .SS "shell, sh"
  5666. .P
  5667. [Default from the environment variable
  5668. .IR SHELL ]
  5669. .P
  5670. The value of this option shall be a string. The default shall be taken
  5671. from the
  5672. .IR SHELL
  5673. environment variable. If the
  5674. .IR SHELL
  5675. environment variable is null or empty, the
  5676. .IR sh
  5677. (see
  5678. .IR "\fIsh\fR\^")
  5679. utility shall be the default.
  5680. .SS "shiftwidth, sw"
  5681. .P
  5682. [Default 8]
  5683. .P
  5684. The value of this option shall give the width in columns of an
  5685. indentation level used during autoindentation and by the shift commands
  5686. (\c
  5687. .BR <
  5688. and
  5689. .BR > ).
  5690. .SS "showmatch, sm"
  5691. .P
  5692. [Default \fIunset\fR]
  5693. .P
  5694. The functionality described for the
  5695. .BR showmatch
  5696. edit option need not be supported on block-mode terminals or terminals
  5697. with insufficient capabilities.
  5698. .P
  5699. If
  5700. .BR showmatch
  5701. is set, in open or visual mode, when a
  5702. .BR ')' 
  5703. or
  5704. .BR '}' 
  5705. is typed, if the matching
  5706. .BR '(' 
  5707. or
  5708. .BR '{' 
  5709. is currently visible on the display, the matching
  5710. .BR '(' 
  5711. or
  5712. .BR '{' 
  5713. shall be flagged moving the cursor to its location for an unspecified
  5714. amount of time.
  5715. .SS "showmode"
  5716. .P
  5717. [Default \fIunset\fP]
  5718. .P
  5719. If
  5720. .BR showmode
  5721. is set, in open or visual mode, the current mode that the editor is in
  5722. shall be displayed on the last line of the display. Command mode and
  5723. text input mode shall be differentiated; other unspecified modes and
  5724. implementation-defined information may be displayed.
  5725. .SS "slowopen"
  5726. .P
  5727. [Default \fIunset\fR]
  5728. .P
  5729. If
  5730. .BR slowopen
  5731. is set during open and visual text input modes, the editor shall not
  5732. update portions of the display other than those display line columns
  5733. that display the characters entered by the user (see
  5734. .IR "Input Mode Commands in vi").
  5735. .SS "tabstop, ts"
  5736. .P
  5737. [Default 8]
  5738. .P
  5739. The value of this edit option shall specify the column boundary used by
  5740. a
  5741. <tab>
  5742. in the display (see
  5743. .IR "autoprint" ", " "ap"
  5744. and
  5745. .IR "Input Mode Commands in vi").
  5746. .SS "taglength, tl"
  5747. .P
  5748. [Default zero]
  5749. .P
  5750. The value of this edit option shall specify the maximum number of
  5751. characters that are considered significant in the user-specified tag
  5752. name and in the tag name from the tags file. If the value is zero, all
  5753. characters in both tag names shall be significant.
  5754. .SS "tags"
  5755. .P
  5756. [Default \fIsee text\fP]
  5757. .P
  5758. The value of this edit option shall be a string of
  5759. <blank>-delimited
  5760. pathnames of files used by the
  5761. .BR tag
  5762. command. The default value is unspecified.
  5763. .SS "term"
  5764. .P
  5765. [Default from the environment variable
  5766. .IR TERM ]
  5767. .P
  5768. The value of this edit option shall be a string. The default shall be
  5769. taken from the
  5770. .IR TERM
  5771. variable in the environment. If the
  5772. .IR TERM
  5773. environment variable is empty or null, the default is unspecified. The
  5774. editor shall use the value of this edit option to determine the type of
  5775. the display device.
  5776. .P
  5777. The results are unspecified if the user changes the value of the term
  5778. edit option after editor initialization.
  5779. .SS "terse"
  5780. .P
  5781. [Default \fIunset\fR]
  5782. .P
  5783. If
  5784. .BR terse
  5785. is set, error messages may be less verbose. However, except for this
  5786. caveat, error messages are unspecified. Furthermore, not all error
  5787. messages need change for different settings of this option.
  5788. .SS "warn"
  5789. .P
  5790. [Default \fIset\fR]
  5791. .P
  5792. If
  5793. .BR warn
  5794. is set, and the contents of the edit buffer have been modified since
  5795. they were last completely written, the editor shall write a warning
  5796. message before certain
  5797. .BR !
  5798. commands (see
  5799. .IR "Escape").
  5800. .SS "window"
  5801. .P
  5802. [Default \fIsee text\fR]
  5803. .P
  5804. A value used in open and visual mode, by the
  5805. <control>\(hyB
  5806. and
  5807. <control>\(hyF
  5808. commands, and, in visual mode, to specify the number of lines displayed
  5809. when the screen is repainted.
  5810. .P
  5811. If the
  5812. .BR \-w
  5813. command-line option is not specified, the default value shall be set to
  5814. the value of the
  5815. .IR LINES
  5816. environment variable. If the
  5817. .IR LINES
  5818. environment variable is empty or null, the default shall be the number
  5819. of lines in the display minus 1.
  5820. .P
  5821. Setting the
  5822. .BR window
  5823. edit option to zero or to a value greater than the number of lines in
  5824. the display minus 1 (either explicitly or based on the
  5825. .BR \-w
  5826. option or the
  5827. .IR LINES
  5828. environment variable) shall cause the
  5829. .BR window
  5830. edit option to be set to the number of lines in the display minus 1.
  5831. .P
  5832. The baud rate of the terminal line may change the default in an
  5833. implementation-defined manner.
  5834. .SS "wrapmargin, wm"
  5835. .P
  5836. [Default 0]
  5837. .P
  5838. If the value of this edit option is zero, it shall have no effect.
  5839. .P
  5840. If not in the POSIX locale, the effect of this edit option is
  5841. implementation-defined.
  5842. .P
  5843. Otherwise, it shall specify a number of columns from the ending margin
  5844. of the terminal.
  5845. .P
  5846. During open and visual text input modes, for each character for which
  5847. any part of the character is displayed in a column that is less than
  5848. .BR wrapmargin
  5849. columns from the ending margin of the display line, the editor shall
  5850. behave as follows:
  5851. .IP " 1." 4
  5852. If the character triggering this event is a
  5853. <blank>,
  5854. it, and all immediately preceding
  5855. <blank>
  5856. characters on the current line entered during the execution of the
  5857. current text input command, shall be discarded, and the editor shall
  5858. behave as if the user had entered a single
  5859. <newline>
  5860. instead. In addition, if the next user-entered character is a
  5861. <space>,
  5862. it shall be discarded as well.
  5863. .IP " 2." 4
  5864. Otherwise, if there are one or more
  5865. <blank>
  5866. characters on the current line immediately preceding the last group of
  5867. inserted non-\c
  5868. <blank>
  5869. characters which was entered during the execution of the current text
  5870. input command, the
  5871. <blank>
  5872. characters shall be replaced as if the user had entered a single
  5873. <newline>
  5874. instead.
  5875. .P
  5876. If the
  5877. .BR autoindent
  5878. edit option is set, and the events described in 1. or 2. are performed,
  5879. any
  5880. <blank>
  5881. characters at or after the cursor in the current line shall be discarded.
  5882. .P
  5883. The ending margin shall be determined by the system or overridden by
  5884. the user, as described for
  5885. .IR COLUMNS
  5886. in the ENVIRONMENT VARIABLES section and the Base Definitions volume of POSIX.1\(hy2017,
  5887. .IR "Chapter 8" ", " "Environment Variables".
  5888. .SS "wrapscan, ws"
  5889. .P
  5890. [Default \fIset\fR]
  5891. .P
  5892. If
  5893. .BR wrapscan
  5894. is set, searches (the
  5895. .IR ex
  5896. .BR /
  5897. or
  5898. .BR ?
  5899. addresses, or open and visual mode
  5900. .BR / ,
  5901. .BR ? ,
  5902. .BR N ,
  5903. and
  5904. .BR n
  5905. commands) shall wrap around the beginning or end of the edit buffer;
  5906. when unset, searches shall stop at the beginning or end of the edit
  5907. buffer.
  5908. .SS "writeany, wa"
  5909. .P
  5910. [Default \fIunset\fR]
  5911. .P
  5912. If
  5913. .BR writeany
  5914. is set, some of the checks performed when executing the
  5915. .IR ex
  5916. .BR write
  5917. commands shall be inhibited, as described in editor option
  5918. .BR autowrite .
  5919. .SH "EXIT STATUS"
  5920. The following exit values shall be returned:
  5921. .IP "\00" 6
  5922. Successful completion.
  5923. .IP >0 6
  5924. An error occurred.
  5925. .SH "CONSEQUENCES OF ERRORS"
  5926. When any error is encountered and the standard input is not a terminal
  5927. device file,
  5928. .IR ex
  5929. shall not write the file or return to command or text input mode, and
  5930. shall terminate with a non-zero exit status.
  5931. .P
  5932. Otherwise, when an unrecoverable error is encountered, it shall be
  5933. equivalent to a SIGHUP asynchronous event.
  5934. .P
  5935. Otherwise, when an error is encountered, the editor shall behave as
  5936. specified in
  5937. .IR "Command Line Parsing in ex".
  5938. .LP
  5939. .IR "The following sections are informative."
  5940. .SH "APPLICATION USAGE"
  5941. If a SIGSEGV signal is received while
  5942. .IR ex
  5943. is saving a file, the file might not be successfully saved.
  5944. .P
  5945. The
  5946. .BR next
  5947. command can accept more than one file, so usage such as:
  5948. .sp
  5949. .RS 4
  5950. .nf
  5952. next `ls [abc]*`
  5953. .fi
  5954. .P
  5955. .RE
  5956. .P
  5957. is valid; it would not be valid for the
  5958. .BR edit
  5959. or
  5960. .BR read
  5961. commands, for example, because they expect only one file and
  5962. unspecified results occur.
  5963. .SH EXAMPLES
  5964. None.
  5965. .SH RATIONALE
  5966. The
  5967. .IR ex /\c
  5968. .IR vi
  5969. specification is based on the historical practice found in the 4 BSD and
  5970. System V implementations of
  5971. .IR ex
  5972. and
  5973. .IR vi .
  5974. .P
  5975. A
  5976. .IR "restricted editor"
  5977. (both the historical
  5978. .IR red
  5979. utility and modifications to
  5980. .IR ex )
  5981. were considered and rejected for inclusion. Neither option provided the
  5982. level of security that users might expect.
  5983. .P
  5984. It is recognized that
  5985. .IR ex
  5986. visual mode and related features would be difficult, if not impossible,
  5987. to implement satisfactorily on a block-mode terminal, or a terminal
  5988. without any form of cursor addressing; thus, it is not a mandatory
  5989. requirement that such features should work on all terminals. It is the
  5990. intention, however, that an
  5991. .IR ex
  5992. implementation should provide the full set of capabilities on all
  5993. terminals capable of supporting them.
  5994. .SS "Options"
  5995. .P
  5996. The
  5997. .BR \-c
  5998. replacement for
  5999. .BR + \c
  6000. .IR command
  6001. was inspired by the
  6002. .BR \-e
  6003. option of
  6004. .IR sed .
  6005. Historically, all such commands (see
  6006. .BR edit
  6007. and
  6008. .BR next
  6009. as well) were executed from the last line of the edit buffer. This
  6010. meant, for example, that
  6011. .BR \(dq+/pattern\(dq 
  6012. would fail unless the
  6013. .BR wrapscan
  6014. option was set. POSIX.1\(hy2008 requires conformance to historical practice. The
  6015. .BR \(pl \c
  6016. .IR command
  6017. option is no longer specified by POSIX.1\(hy2008 but may be present in
  6018. some implementations. Historically, some implementations restricted the
  6019. .IR ex
  6020. commands that could be listed as part of the command line arguments.
  6021. For consistency, POSIX.1\(hy2008 does not permit these restrictions.
  6022. .P
  6023. In historical implementations of the editor, the
  6024. .BR \-R
  6025. option (and the
  6026. .BR readonly
  6027. edit option) only prevented overwriting of files; appending to files
  6028. was still permitted, mapping loosely into the
  6029. .IR csh
  6030. .BR noclobber
  6031. variable. Some implementations, however, have not followed this
  6032. semantic, and
  6033. .BR readonly
  6034. does not permit appending either. POSIX.1\(hy2008 follows the latter practice,
  6035. believing that it is a more obvious and intuitive meaning of
  6036. .BR readonly .
  6037. .P
  6038. The
  6039. .BR \-s
  6040. option suppresses all interactive user feedback and is useful for
  6041. editing scripts in batch jobs. The list of specific effects is
  6042. historical practice. The terminal type ``incapable of supporting open
  6043. and visual modes'' has historically been named ``dumb''.
  6044. .P
  6045. The
  6046. .BR \-t
  6047. option was required because the
  6048. .IR ctags
  6049. utility appears in POSIX.1\(hy2008 and the option is available in all historical
  6050. implementations of
  6051. .IR ex .
  6052. .P
  6053. Historically, the
  6054. .IR ex
  6055. and
  6056. .IR vi
  6057. utilities accepted a
  6058. .BR \-x
  6059. option, which did encryption based on the algorithm found in the
  6060. historical
  6061. .IR crypt
  6062. utility. The
  6063. .BR \-x
  6064. option for encryption, and the associated
  6065. .IR crypt
  6066. utility, were omitted because the algorithm used was not specifiable
  6067. and the export control laws of some nations make it difficult to export
  6068. cryptographic technology. In addition, it did not historically provide
  6069. the level of security that users might expect.
  6070. .SS "Standard Input"
  6071. .P
  6072. An end-of-file condition is not equivalent to an end-of-file character.
  6073. A common end-of-file character,
  6074. <control>\(hyD,
  6075. is historically an
  6076. .IR ex
  6077. command.
  6078. .P
  6079. There was no maximum line length in historical implementations of
  6080. .IR ex .
  6081. Specifically, as it was parsed in chunks, the addresses had a different
  6082. maximum length than the filenames. Further, the maximum line buffer
  6083. size was declared as BUFSIZ, which was different lengths on different
  6084. systems. This version selected the value of
  6085. {LINE_MAX}
  6086. to impose a reasonable restriction on portable usage of
  6087. .IR ex
  6088. and to aid test suite writers in their development of realistic tests
  6089. that exercise this limit.
  6090. .SS "Input Files"
  6091. .P
  6092. It was an explicit decision by the standard developers that a
  6093. <newline>
  6094. be added to any file lacking one. It was believed that this feature of
  6095. .IR ex
  6096. and
  6097. .IR vi
  6098. was relied on by users in order to make text files lacking a trailing
  6099. <newline>
  6100. more portable. It is recognized that this will require a user-specified
  6101. option or extension for implementations that permit
  6102. .IR ex
  6103. and
  6104. .IR vi
  6105. to edit files of type other than text if such files are not otherwise
  6106. identified by the system. It was agreed that the ability to edit files
  6107. of arbitrary type can be useful, but it was not considered necessary to
  6108. mandate that an
  6109. .IR ex
  6110. or
  6111. .IR vi
  6112. implementation be required to handle files other than text files.
  6113. .P
  6114. The paragraph in the INPUT FILES section, ``By default, .\|.\|.'', is
  6115. intended to close a long-standing security problem in
  6116. .IR ex
  6117. and
  6118. .IR vi ;
  6119. that of the ``modeline'' or ``modelines'' edit option. This feature
  6120. allows any line in the first or last five lines of the file containing
  6121. the strings
  6122. .BR \(dqex:\(dq 
  6123. or
  6124. .BR \(dqvi:\(dq 
  6125. (and, apparently,
  6126. .BR \(dqei:\(dq 
  6127. or
  6128. .BR \(dqvx:\(dq )
  6129. to be a line containing editor commands, and
  6130. .IR ex
  6131. interprets all the text up to the next
  6132. .BR ':' 
  6133. or
  6134. <newline>
  6135. as a command. Consider the consequences, for example, of an
  6136. unsuspecting user using
  6137. .IR ex
  6138. or
  6139. .IR vi
  6140. as the editor when replying to a mail message in which a line such as:
  6141. .sp
  6142. .RS 4
  6143. .nf
  6145. ex:! rm -rf :
  6146. .fi
  6147. .P
  6148. .RE
  6149. .P
  6150. appeared in the signature lines. The standard developers believed
  6151. strongly that an editor should not by default interpret any lines of a
  6152. file. Vendors are strongly urged to delete this feature from their
  6153. implementations of
  6154. .IR ex
  6155. and
  6156. .IR vi .
  6157. .SS "Asynchronous Events"
  6158. .P
  6159. The intention of the phrase ``complete write'' is that the entire edit
  6160. buffer be written to stable storage. The note regarding temporary files
  6161. is intended for implementations that use temporary files to back edit
  6162. buffers unnamed by the user.
  6163. .P
  6164. Historically, SIGQUIT was ignored by
  6165. .IR ex ,
  6166. but was the equivalent of the
  6167. .BR Q
  6168. command in visual mode; that is, it exited visual mode and entered
  6169. .IR ex
  6170. mode. POSIX.1\(hy2008 permits, but does not require, this behavior. Historically,
  6171. SIGINT was often used by
  6172. .IR vi
  6173. users to terminate text input mode (\c
  6174. <control>\(hyC
  6175. is often easier to enter than
  6176. <ESC>).
  6177. Some implementations of
  6178. .IR vi
  6179. alerted the terminal on this event, and some did not. POSIX.1\(hy2008 requires
  6180. that SIGINT behave identically to
  6181. <ESC>,
  6182. and that the terminal not be alerted.
  6183. .P
  6184. Historically, suspending the
  6185. .IR ex
  6186. editor during text input mode was similar to SIGINT, as completed lines
  6187. were retained, but any partial line discarded, and the editor returned
  6188. to command mode. POSIX.1\(hy2008 is silent on this issue; implementations are
  6189. encouraged to follow historical practice, where possible.
  6190. .P
  6191. Historically, the
  6192. .IR vi
  6193. editor did not treat SIGTSTP as an asynchronous event, and it was
  6194. therefore impossible to suspend the editor in visual text input mode.
  6195. There are two major reasons for this. The first is that SIGTSTP is a
  6196. broadcast signal on UNIX systems, and the chain of events where the
  6197. shell
  6198. .IR exec s
  6199. an application that then
  6200. .IR exec s
  6201. .IR vi
  6202. usually caused confusion for the terminal state if SIGTSTP was delivered
  6203. to the process group in the default manner. The second was that most
  6204. implementations of the UNIX
  6205. .IR curses
  6206. package did not handle SIGTSTP safely, and the receipt of SIGTSTP at
  6207. the wrong time would cause them to crash. POSIX.1\(hy2008 is silent on this issue;
  6208. implementations are encouraged to treat suspension as an asynchronous
  6209. event if possible.
  6210. .P
  6211. Historically, modifications to the edit buffer made before SIGINT
  6212. interrupted an operation were retained; that is, anywhere from zero to
  6213. all of the lines to be modified might have been modified by the time
  6214. the SIGINT arrived. These changes were not discarded by the arrival of
  6215. SIGINT. POSIX.1\(hy2008 permits this behavior, noting that the
  6216. .BR undo
  6217. command is required to be able to undo these partially completed
  6218. commands.
  6219. .P
  6220. The action taken for signals other than SIGINT, SIGCONT, SIGHUP, and
  6221. SIGTERM is unspecified because some implementations attempt to save the
  6222. edit buffer in a useful state when other signals are received.
  6223. .SS "Standard Error"
  6224. .P
  6225. For
  6226. .IR ex /\c
  6227. .IR vi ,
  6228. diagnostic messages are those messages reported as a result of a failed
  6229. attempt to invoke
  6230. .IR ex
  6231. or
  6232. .IR vi ,
  6233. such as invalid options or insufficient resources, or an abnormal
  6234. termination condition. Diagnostic messages should not be confused with
  6235. the error messages generated by inappropriate or illegal user
  6236. commands.
  6237. .SS "Initialization in ex and vi"
  6238. .P
  6239. If an
  6240. .IR ex
  6241. command (other than
  6242. .BR cd ,
  6243. .BR chdir ,
  6244. or
  6245. .BR source )
  6246. has a filename argument, one or both of the alternate and current
  6247. pathnames will be set. Informally, they are set as follows:
  6248. .IP " 1." 4
  6249. If the
  6250. .IR ex
  6251. command is one that replaces the contents of the edit buffer, and it
  6252. succeeds, the current pathname will be set to the filename argument
  6253. (the first filename argument in the case of the
  6254. .BR next
  6255. command) and the alternate pathname will be set to the previous
  6256. current pathname, if there was one.
  6257. .IP " 2." 4
  6258. In the case of the file read/write forms of the
  6259. .BR read
  6260. and
  6261. .BR write
  6262. commands, if there is no current pathname, the current pathname will
  6263. be set to the filename argument.
  6264. .IP " 3." 4
  6265. Otherwise, the alternate pathname will be set to the filename
  6266. argument.
  6267. .P
  6268. For example,
  6269. .BR ":edit foo"
  6270. and
  6271. .BR ":recover foo" ,
  6272. when successful, set the current pathname, and, if there was a
  6273. previous current pathname, the alternate pathname. The commands
  6274. .BR :write ,
  6275. .BR !command ,
  6276. and
  6277. .BR :edit
  6278. set neither the current or alternate pathnames. If the
  6279. .BR ":edit foo"
  6280. command were to fail for some reason, the alternate pathname would be
  6281. set. The
  6282. .BR read
  6283. and
  6284. .BR write
  6285. commands set the alternate pathname to their
  6286. .IR file
  6287. argument, unless the current pathname is not set, in which case they
  6288. set the current pathname to their
  6289. .IR file
  6290. arguments. The alternate pathname was not historically set by the
  6291. .BR :source
  6292. command. POSIX.1\(hy2008 requires conformance to historical practice.
  6293. Implementations adding commands that take filenames as arguments are
  6294. encouraged to set the alternate pathname as described here.
  6295. .P
  6296. Historically,
  6297. .IR ex
  6298. and
  6299. .IR vi
  6300. read the
  6301. .BR .exrc
  6302. file in the
  6303. .IR $HOME
  6304. directory twice, if the editor was executed in the
  6305. .IR $HOME
  6306. directory. POSIX.1\(hy2008 prohibits this behavior.
  6307. .P
  6308. Historically, the 4 BSD
  6309. .IR ex
  6310. and
  6311. .IR vi
  6312. read the
  6313. .IR $HOME
  6314. and local
  6315. .BR .exrc
  6316. files if they were owned by the real ID of the user, or the
  6317. .BR sourceany
  6318. option was set, regardless of other considerations. This was a security
  6319. problem because it is possible to put normal UNIX system commands
  6320. inside a
  6321. .BR .exrc
  6322. file. POSIX.1\(hy2008 does not specify the
  6323. .BR sourceany
  6324. option, and historical implementations are encouraged to delete it.
  6325. .P
  6326. The
  6327. .BR .exrc
  6328. files must be owned by the real ID of the user, and not writable by
  6329. anyone other than the owner. The appropriate privileges exception is
  6330. intended to permit users to acquire special privileges, but continue to
  6331. use the
  6332. .BR .exrc
  6333. files in their home directories.
  6334. .P
  6335. System V Release 3.2 and later
  6336. .IR vi
  6337. implementations added the option
  6338. .BR [no]exrc .
  6339. The behavior is that local
  6340. .BR .exrc
  6341. files are read-only if the
  6342. .BR exrc
  6343. option is set. The default for the
  6344. .BR exrc
  6345. option was off, so by default, local
  6346. .BR .exrc
  6347. files were not read. The problem this was intended to solve was that
  6348. System V permitted users to give away files, so there is no possible
  6349. ownership or writeability test to ensure that the file is safe. This is
  6350. still a security problem on systems where users can give away files,
  6351. but there is nothing additional that POSIX.1\(hy2008 can do. The
  6352. implementation-defined exception is intended to permit groups to have
  6353. local
  6354. .BR .exrc
  6355. files that are shared by users, by creating pseudo-users to own the
  6356. shared files.
  6357. .P
  6358. POSIX.1\(hy2008 does not mention system-wide
  6359. .IR ex
  6360. and
  6361. .IR vi
  6362. start-up files. While they exist in several implementations of
  6363. .IR ex
  6364. and
  6365. .IR vi ,
  6366. they are not present in any implementations considered historical
  6367. practice by POSIX.1\(hy2008. Implementations that have such files should use them
  6368. only if they are owned by the real user ID or an appropriate user (for
  6369. example, root on UNIX systems) and if they are not writable by any
  6370. user other than their owner. System-wide start-up files should be read
  6371. before the
  6372. .IR EXINIT
  6373. variable,
  6374. .BR $HOME/.exrc ,
  6375. or local
  6376. .BR .exrc
  6377. files are evaluated.
  6378. .P
  6379. Historically, any
  6380. .IR ex
  6381. command could be entered in the
  6382. .IR EXINIT
  6383. variable or the
  6384. .BR .exrc
  6385. file, although ones requiring that the edit buffer already contain
  6386. lines of text generally caused historical implementations of the editor
  6387. to drop
  6388. .BR core .
  6389. POSIX.1\(hy2008 requires that any
  6390. .IR ex
  6391. command be permitted in the
  6392. .IR EXINIT
  6393. variable and
  6394. .BR .exrc
  6395. files, for simplicity of specification and consistency, although many
  6396. of them will obviously fail under many circumstances.
  6397. .P
  6398. The initialization of the contents of the edit buffer uses the phrase
  6399. ``the effect shall be'' with regard to various
  6400. .IR ex
  6401. commands. The intent of this phrase is that edit buffer contents loaded
  6402. during the initialization phase not be lost; that is, loading the edit
  6403. buffer should fail if the
  6404. .BR .exrc
  6405. file read in the contents of a file and did not subsequently write the
  6406. edit buffer. An additional intent of this phrase is to specify that the
  6407. initial current line and column is set as specified for the individual
  6408. .IR ex
  6409. commands.
  6410. .P
  6411. Historically, the
  6412. .BR \-t
  6413. option behaved as if the tag search were a
  6414. .BR + \c
  6415. .IR command ;
  6416. that is, it was executed from the last line of the file specified by
  6417. the tag. This resulted in the search failing if the pattern was a
  6418. forward search pattern and the
  6419. .BR wrapscan
  6420. edit option was not set. POSIX.1\(hy2008 does not permit this behavior, requiring
  6421. that the search for the tag pattern be performed on the entire file,
  6422. and, if not found, that the current line be set to a more reasonable
  6423. location in the file.
  6424. .P
  6425. Historically, the empty edit buffer presented for editing when a file
  6426. was not specified by the user was unnamed. This is permitted by POSIX.1\(hy2008;
  6427. however, implementations are encouraged to provide users a temporary
  6428. filename for this buffer because it permits them the use of
  6429. .IR ex
  6430. commands that use the current pathname during temporary edit
  6431. sessions.
  6432. .P
  6433. Historically, the file specified using the
  6434. .BR \-t
  6435. option was not part of the current argument list. This practice is
  6436. permitted by POSIX.1\(hy2008; however, implementations are encouraged to include
  6437. its name in the current argument list for consistency.
  6438. .P
  6439. Historically, the
  6440. .BR \-c
  6441. command was generally not executed until a file that already exists was
  6442. edited. POSIX.1\(hy2008 requires conformance to this historical practice.
  6443. Commands that could cause the
  6444. .BR \-c
  6445. command to be executed include the
  6446. .IR ex
  6447. commands
  6448. .BR edit ,
  6449. .BR next ,
  6450. .BR recover ,
  6451. .BR rewind ,
  6452. and
  6453. .BR tag ,
  6454. and the
  6455. .IR vi
  6456. commands
  6457. <control>\(hy^
  6458. and
  6459. <control>\(hy].
  6460. Historically, reading a file into an edit buffer did not cause the
  6461. .BR \-c
  6462. command to be executed (even though it might set the current pathname)
  6463. with the exception that it did cause the
  6464. .BR \-c
  6465. command to be executed if: the editor was in
  6466. .IR ex
  6467. mode, the edit buffer had no current pathname, the edit buffer was
  6468. empty, and no read commands had yet been attempted. For consistency and
  6469. simplicity of specification, POSIX.1\(hy2008 does not permit this behavior.
  6470. .P
  6471. Historically, the
  6472. .BR \-r
  6473. option was the same as a normal edit session if there was no recovery
  6474. information available for the file. This allowed users to enter:
  6475. .sp
  6476. .RS 4
  6477. .nf
  6479. vi -r *.c
  6480. .fi
  6481. .P
  6482. .RE
  6483. .P
  6484. and recover whatever files were recoverable. In some implementations,
  6485. recovery was attempted only on the first file named, and the file was
  6486. not entered into the argument list; in others, recovery was attempted
  6487. for each file named. In addition, some historical implementations
  6488. ignored
  6489. .BR \-r
  6490. if
  6491. .BR \-t
  6492. was specified or did not support command line
  6493. .IR file
  6494. arguments with the
  6495. .BR \-t
  6496. option. For consistency and simplicity of specification, POSIX.1\(hy2008
  6497. disallows these special cases, and requires that recovery be attempted
  6498. the first time each file is edited.
  6499. .P
  6500. Historically,
  6501. .IR vi
  6502. initialized the
  6503. .BR `
  6504. and
  6505. .BR \(aq
  6506. marks, but
  6507. .IR ex
  6508. did not. This meant that if the first command in
  6509. .IR ex
  6510. mode was
  6511. .BR visual
  6512. or if an
  6513. .IR ex
  6514. command was executed first (for example,
  6515. .IR vi
  6516. +10
  6517. .IR file ),
  6518. .IR vi
  6519. was entered without the marks being initialized. Because the standard
  6520. developers believed the marks to be generally useful, and for
  6521. consistency and simplicity of specification, POSIX.1\(hy2008 requires that they
  6522. always be initialized if in open or visual mode, or if in
  6523. .IR ex
  6524. mode and the edit buffer is not empty. Not initializing it in
  6525. .IR ex
  6526. mode if the edit buffer is empty is historical practice; however, it
  6527. has always been possible to set (and use) marks in empty edit buffers
  6528. in open and visual mode edit sessions.
  6529. .SS "Addressing"
  6530. .P
  6531. Historically,
  6532. .IR ex
  6533. and
  6534. .IR vi
  6535. accepted the additional addressing forms
  6536. .BR '\e/' 
  6537. and
  6538. .BR '\e?' .
  6539. They were equivalent to
  6540. .BR \(dq//\(dq 
  6541. and
  6542. .BR \(dq??\(dq ,
  6543. respectively. They are not required by POSIX.1\(hy2008, mostly because nobody can
  6544. remember whether they ever did anything different historically.
  6545. .P
  6546. Historically,
  6547. .IR ex
  6548. and
  6549. .IR vi
  6550. permitted an address of zero for several commands, and permitted the
  6551. .BR %
  6552. address in empty files for others. For consistency, POSIX.1\(hy2008 requires
  6553. support for the former in the few commands where it makes sense, and
  6554. disallows it otherwise. In addition, because POSIX.1\(hy2008 requires that
  6555. .BR %
  6556. be logically equivalent to
  6557. .BR \(dq1,$\(dq ,
  6558. it is also supported where it makes sense and disallowed otherwise.
  6559. .P
  6560. Historically, the
  6561. .BR %
  6562. address could not be followed by further addresses. For consistency and
  6563. simplicity of specification, POSIX.1\(hy2008 requires that additional addresses
  6564. be supported.
  6565. .P
  6566. All of the following are valid
  6567. .IR addresses :
  6568. .IP "\fR+++\fP" 10
  6569. Three lines after the current line.
  6570. .IP "\fR/\fIre\fR/\-\fR" 10
  6571. One line before the next occurrence of
  6572. .IR re .
  6573. .IP "\fR\-2\fR" 10
  6574. Two lines before the current line.
  6575. .IP "\fR3\0\-\|\-\|\-\|\-\02\fR" 10
  6576. Line one (note intermediate negative address).
  6577. .IP "\fR1\02\03\fR" 10
  6578. Line six.
  6579. .P
  6580. Any number of addresses can be provided to commands taking addresses;
  6581. for example,
  6582. .BR \(dq1,2,3,4,5p\(dq 
  6583. prints lines 4 and 5, because two is the greatest valid number of
  6584. addresses accepted by the
  6585. .BR print
  6586. command. This, in combination with the
  6587. <semicolon>
  6588. delimiter, permits users to create commands based on ordered patterns
  6589. in the file. For example, the command
  6590. .BR "3;/foo/;+2print"
  6591. will display the first line after line 3 that contains the pattern
  6592. .IR foo ,
  6593. plus the next two lines. Note that the address
  6594. .BR "3;"
  6595. must be evaluated before being discarded because the search origin for
  6596. the
  6597. .BR /foo/
  6598. command depends on this.
  6599. .P
  6600. Historically, values could be added to addresses by including them
  6601. after one or more
  6602. <blank>
  6603. characters; for example,
  6604. .BR "3\0\-\05p"
  6605. wrote the seventh line of the file, and
  6606. .BR "/foo/\05"
  6607. was the same as
  6608. .BR "/foo/+5" .
  6609. However, only absolute values could be added; for example,
  6610. .BR "5\0/foo/"
  6611. was an error. POSIX.1\(hy2008 requires conformance to historical practice.
  6612. Address offsets are separately specified from addresses because they
  6613. could historically be provided to visual mode search commands.
  6614. .P
  6615. Historically, any missing addresses defaulted to the current line. This
  6616. was true for leading and trailing
  6617. <comma>-delimited
  6618. addresses, and for trailing
  6619. <semicolon>-delimited
  6620. addresses. For consistency, POSIX.1\(hy2008 requires it for leading
  6621. <semicolon>
  6622. addresses as well.
  6623. .P
  6624. Historically,
  6625. .IR ex
  6626. and
  6627. .IR vi
  6628. accepted the
  6629. .BR '\(ha' 
  6630. character as both an address and as a flag offset for commands. In both
  6631. cases it was identical to the
  6632. .BR '\-' 
  6633. character. POSIX.1\(hy2008 does not require or prohibit this behavior.
  6634. .P
  6635. Historically, the enhancements to basic regular expressions could be
  6636. used in addressing; for example,
  6637. .BR '\(ti' ,
  6638. .BR '\e<' ,
  6639. and
  6640. .BR '\e>' .
  6641. POSIX.1\(hy2008 requires conformance to historical practice; that is, that
  6642. regular expression usage be consistent, and that regular expression
  6643. enhancements be supported wherever regular expressions are used.
  6644. .SS "Command Line Parsing in ex"
  6645. .P
  6646. Historical
  6647. .IR ex
  6648. command parsing was even more complex than that described here. POSIX.1\(hy2008
  6649. requires the subset of the command parsing that the standard developers
  6650. believed was documented and that users could reasonably be expected to
  6651. use in a portable fashion, and that was historically consistent between
  6652. implementations. (The discarded functionality is obscure, at best.)
  6653. Historical implementations will require changes in order to comply with
  6654. POSIX.1\(hy2008; however, users are not expected to notice any of these changes.
  6655. Most of the complexity in
  6656. .IR ex
  6657. parsing is to handle three special termination cases:
  6658. .IP " 1." 4
  6659. The
  6660. .BR ! ,
  6661. .BR global ,
  6662. .BR v ,
  6663. and the filter versions of the
  6664. .BR read
  6665. and
  6666. .BR write
  6667. commands are delimited by
  6668. <newline>
  6669. characters (they can contain
  6670. <vertical-line>
  6671. characters that are usually shell pipes).
  6672. .IP " 2." 4
  6673. The
  6674. .BR ex ,
  6675. .BR edit ,
  6676. .BR next ,
  6677. and
  6678. .BR visual
  6679. in open and visual mode commands all take
  6680. .IR ex
  6681. commands, optionally containing
  6682. <vertical-line>
  6683. characters, as their first arguments.
  6684. .IP " 3." 4
  6685. The
  6686. .BR s
  6687. command takes a regular expression as its first argument, and uses the
  6688. delimiting characters to delimit the command.
  6689. .P
  6690. Historically,
  6691. <vertical-line>
  6692. characters in the
  6693. .BR + \c
  6694. .IR command
  6695. argument of the
  6696. .BR ex ,
  6697. .BR edit ,
  6698. .BR next ,
  6699. .BR vi ,
  6700. and
  6701. .BR visual
  6702. commands, and in the
  6703. .IR pattern
  6704. and
  6705. .IR replacement
  6706. parts of the
  6707. .BR s
  6708. command, did not delimit the command, and in the filter cases for
  6709. .BR read
  6710. and
  6711. .BR write ,
  6712. and the
  6713. .BR ! ,
  6714. .BR global ,
  6715. and
  6716. .BR v
  6717. commands, they did not delimit the command at all. For example, the
  6718. following commands are all valid:
  6719. .sp
  6720. .RS 4
  6721. .nf
  6723. \fB:\fRedit +25 | s/abc/ABC/ file.c
  6724. \fB:\fRs/ | /PIPE/
  6725. \fB:\fRread !spell % | columnate
  6726. \fB:\fRglobal/pattern/p | l
  6727. \fB:\fRs/a/b/ | s/c/d | set
  6728. .fi
  6729. .P
  6730. .RE
  6731. .P
  6732. Historically, empty or
  6733. <blank>
  6734. filled lines in
  6735. .BR .exrc
  6736. files and
  6737. .BR source d
  6738. files (as well as
  6739. .IR EXINIT
  6740. variables and
  6741. .IR ex
  6742. command scripts) were treated as default commands; that is,
  6743. .BR print
  6744. commands. POSIX.1\(hy2008 specifically requires that they be ignored when
  6745. encountered in
  6746. .BR .exrc
  6747. and
  6748. .BR source d
  6749. files to eliminate a common source of new user error.
  6750. .P
  6751. Historically,
  6752. .IR ex
  6753. commands with multiple adjacent (or
  6754. <blank>-separated)
  6755. vertical lines were handled oddly when executed from
  6756. .IR ex
  6757. mode. For example, the command
  6758. .BR "|||"
  6759. <carriage-return>,
  6760. when the cursor was on line 1, displayed lines 2, 3, and 5 of the file.
  6761. In addition, the command
  6762. .BR |
  6763. would only display the line after the next line, instead of the next
  6764. two lines. The former worked more logically when executed from
  6765. .IR vi
  6766. mode, and displayed lines 2, 3, and 4. POSIX.1\(hy2008 requires the
  6767. .IR vi
  6768. behavior; that is, a single default command and line number increment
  6769. for each command separator, and trailing
  6770. <newline>
  6771. characters after
  6772. <vertical-line>
  6773. separators are discarded.
  6774. .P
  6775. Historically,
  6776. .IR ex
  6777. permitted a single extra
  6778. <colon>
  6779. as a leading command character; for example,
  6780. .BR ":g/pattern/:p"
  6781. was a valid command. POSIX.1\(hy2008 generalizes this to require that any number
  6782. of leading
  6783. <colon>
  6784. characters be stripped.
  6785. .P
  6786. Historically, any prefix of the
  6787. .BR delete
  6788. command could be followed without intervening
  6789. <blank>
  6790. characters by a flag character because in the command
  6791. .BR "d\0p" ,
  6792. .IR p
  6793. is interpreted as the buffer
  6794. .IR p .
  6795. POSIX.1\(hy2008 requires conformance to historical practice.
  6796. .P
  6797. Historically, the
  6798. .BR k
  6799. command could be followed by the mark name without intervening
  6800. <blank>
  6801. characters. POSIX.1\(hy2008 requires conformance to historical practice.
  6802. .P
  6803. Historically, the
  6804. .BR s
  6805. command could be immediately followed by flag and option characters;
  6806. for example,
  6807. .BR "s/e/E/|s|sgc3p"
  6808. was a valid command. However, flag characters could not stand alone;
  6809. for example, the commands
  6810. .BR sp
  6811. and
  6812. .BR s\0l
  6813. would fail, while the command
  6814. .BR sgp
  6815. and
  6816. .BR "s\0gl"
  6817. would succeed. (Obviously, the
  6818. .BR '#' 
  6819. flag character was used as a delimiter character if it followed the
  6820. command.) Another issue was that option characters had to precede flag
  6821. characters even when the command was fully specified; for example, the
  6822. command
  6823. .BR s/e/E/pg
  6824. would fail, while the command
  6825. .BR s/e/E/gp
  6826. would succeed. POSIX.1\(hy2008 requires conformance to historical practice.
  6827. .P
  6828. Historically, the first command name that had a prefix matching the
  6829. input from the user was the executed command; for example,
  6830. .BR ve ,
  6831. .BR ver ,
  6832. and
  6833. .BR vers
  6834. all executed the
  6835. .BR version
  6836. command. Commands were in a specific order, however, so that
  6837. .BR a
  6838. matched
  6839. .BR append ,
  6840. not
  6841. .BR abbreviate .
  6842. POSIX.1\(hy2008 requires conformance to historical practice. The restriction on
  6843. command search order for implementations with extensions is to avoid
  6844. the addition of commands such that the historical prefixes would fail
  6845. to work portably.
  6846. .P
  6847. Historical implementations of
  6848. .IR ex
  6849. and
  6850. .IR vi
  6851. did not correctly handle multiple
  6852. .IR ex
  6853. commands, separated by
  6854. <vertical-line>
  6855. characters, that entered or exited visual mode or the editor. Because
  6856. implementations of
  6857. .IR vi
  6858. exist that do not exhibit this failure mode, POSIX.1\(hy2008 does not permit it.
  6859. .P
  6860. The requirement that alphabetic command names consist of all following
  6861. alphabetic characters up to the next non-alphabetic character means
  6862. that alphabetic command names must be separated from their arguments by
  6863. one or more non-alphabetic characters, normally a
  6864. <blank>
  6865. or
  6866. .BR '!' 
  6867. character, except as specified for the exceptions, the
  6868. .BR delete ,
  6869. .BR k ,
  6870. and
  6871. .BR s
  6872. commands.
  6873. .P
  6874. Historically, the repeated execution of the
  6875. .IR ex
  6876. default
  6877. .BR print
  6878. commands (\c
  6879. <control>\(hyD,
  6880. .IR eof ,
  6881. <newline>,
  6882. <carriage-return>)
  6883. erased any prompting character and displayed the next lines without
  6884. scrolling the terminal; that is, immediately below any previously
  6885. displayed lines. This provided a cleaner presentation of the lines in
  6886. the file for the user. POSIX.1\(hy2008 does not require this behavior because it
  6887. may be impossible in some situations; however, implementations are
  6888. strongly encouraged to provide this semantic if possible.
  6889. .P
  6890. Historically, it was possible to change files in the middle of a command,
  6891. and have the rest of the command executed in the new file; for example:
  6892. .sp
  6893. .RS 4
  6894. .nf
  6896. :edit +25 file.c | s/abc/ABC/ | 1
  6897. .fi
  6898. .P
  6899. .RE
  6900. .P
  6901. was a valid command, and the substitution was attempted in the newly
  6902. edited file. POSIX.1\(hy2008 requires conformance to historical practice. The
  6903. following commands are examples that exercise the
  6904. .IR ex
  6905. parser:
  6906. .sp
  6907. .RS 4
  6908. .nf
  6910. echo \(aqfoo | bar\(aq > file1; echo \(aqfoo/bar\(aq > file2;
  6911. vi
  6912. :edit +1 | s/|/PIPE/ | w file1 | e file2 | 1 | s/\e//SLASH/ | wq
  6913. .fi
  6914. .P
  6915. .RE
  6916. .P
  6917. Historically, there was no protection in editor implementations to
  6918. avoid
  6919. .IR ex
  6920. .BR global ,
  6921. .BR v ,
  6922. .BR @ ,
  6923. or
  6924. .BR *
  6925. commands changing edit buffers during execution of their associated
  6926. commands. Because this would almost invariably result in catastrophic
  6927. failure of the editor, and implementations exist that do exhibit these
  6928. problems, POSIX.1\(hy2008 requires that changing the edit buffer during a
  6929. .BR global
  6930. or
  6931. .BR v
  6932. command, or during a
  6933. .BR @
  6934. or
  6935. .BR *
  6936. command for which there will be more than a single execution, be an
  6937. error. Implementations supporting multiple edit buffers simultaneously
  6938. are strongly encouraged to apply the same semantics to switching
  6939. between buffers as well.
  6940. .P
  6941. The
  6942. .IR ex
  6943. command quoting required by POSIX.1\(hy2008 is a superset of the quoting in
  6944. historical implementations of the editor. For example, it was not
  6945. historically possible to escape a
  6946. <blank>
  6947. in a filename; for example,
  6948. .BR ":edit\0foo\e\e\e\0bar"
  6949. would report that too many filenames had been entered for the edit
  6950. command, and there was no method of escaping a
  6951. <blank>
  6952. in the first argument of an
  6953. .BR edit ,
  6954. .BR ex ,
  6955. .BR next ,
  6956. or
  6957. .BR visual
  6958. command at all. POSIX.1\(hy2008 extends historical practice, requiring that
  6959. quoting behavior be made consistent across all
  6960. .IR ex
  6961. commands, except for the
  6962. .BR map ,
  6963. .BR unmap ,
  6964. .BR abbreviate ,
  6965. and
  6966. .BR unabbreviate
  6967. commands, which historically used
  6968. <control>\(hyV
  6969. instead of
  6970. <backslash>
  6971. characters for quoting. For those four commands, POSIX.1\(hy2008 requires
  6972. conformance to historical practice.
  6973. .P
  6974. Backslash quoting in
  6975. .IR ex
  6976. is non-intuitive.
  6977. <backslash>-escapes
  6978. are ignored unless they escape a special character; for example, when
  6979. performing
  6980. .IR file
  6981. argument expansion, the string
  6982. .BR \(dq\e\e%\(dq 
  6983. is equivalent to
  6984. .BR '\e%' ,
  6985. not \fR"\e<\fIcurrent\ pathname\fR>"\fR.
  6986. This can be confusing for users because
  6987. <backslash>
  6988. is usually one of the characters that causes shell expansion to
  6989. be performed, and therefore shell quoting rules must be taken into
  6990. consideration. Generally, quoting characters are only considered if they
  6991. escape a special character, and a quoting character must be provided
  6992. for each layer of parsing for which the character is special. As another
  6993. example, only a single
  6994. <backslash>
  6995. is necessary for the
  6996. .BR '\el' 
  6997. sequence in substitute replacement patterns, because the character
  6998. .BR 'l' 
  6999. is not special to any parsing layer above it.
  7000. .P
  7001. <control>\(hyV
  7002. quoting in
  7003. .IR ex
  7004. is slightly different from backslash quoting. In the four commands
  7005. where
  7006. <control>\(hyV
  7007. quoting applies (\c
  7008. .BR abbreviate ,
  7009. .BR unabbreviate ,
  7010. .BR map ,
  7011. and
  7012. .BR unmap ),
  7013. any character may be escaped by a
  7014. <control>\(hyV
  7015. whether it would have a special meaning or not. POSIX.1\(hy2008 requires
  7016. conformance to historical practice.
  7017. .P
  7018. Historical implementations of the editor did not require delimiters
  7019. within character classes to be escaped; for example, the command
  7020. .BR ":s/[/]//"
  7021. on the string
  7022. .BR \(dqxxx/yyy\(dq 
  7023. would delete the
  7024. .BR '/' 
  7025. from the string. POSIX.1\(hy2008 disallows this historical practice for
  7026. consistency and because it places a large burden on implementations by
  7027. requiring that knowledge of regular expressions be built into the
  7028. editor parser.
  7029. .P
  7030. Historically, quoting
  7031. <newline>
  7032. characters in
  7033. .IR ex
  7034. commands was handled inconsistently. In most cases, the
  7035. <newline>
  7036. character always terminated the command, regardless of any preceding
  7037. escape character, because
  7038. <backslash>
  7039. characters did not escape
  7040. <newline>
  7041. characters for most
  7042. .IR ex
  7043. commands. However, some
  7044. .IR ex
  7045. commands (for example,
  7046. .BR s ,
  7047. .BR map ,
  7048. and
  7049. .BR abbreviation )
  7050. permitted
  7051. <newline>
  7052. characters to be escaped (although in the case of
  7053. .BR map
  7054. and
  7055. .BR abbreviation ,
  7056. <control>\(hyV
  7057. characters escaped them instead of
  7058. <backslash>
  7059. characters). This was true in not only the command line, but also
  7060. .BR .exrc
  7061. and
  7062. .BR source d
  7063. files. For example, the command:
  7064. .sp
  7065. .RS 4
  7066. .nf
  7068. map = foo<control-V><newline>bar
  7069. .fi
  7070. .P
  7071. .RE
  7072. .P
  7073. would succeed, although it was sometimes difficult to get the
  7074. <control>\(hyV
  7075. and the inserted
  7076. <newline>
  7077. passed to the
  7078. .IR ex
  7079. parser. For consistency and simplicity of specification, POSIX.1\(hy2008 requires
  7080. that it be possible to escape
  7081. <newline>
  7082. characters in
  7083. .IR ex
  7084. commands at all times, using
  7085. <backslash>
  7086. characters for most
  7087. .IR ex
  7088. commands, and using
  7089. <control>\(hyV
  7090. characters for the
  7091. .BR map
  7092. and
  7093. .BR abbreviation
  7094. commands. For example, the command
  7095. .BR print \c
  7096. <newline>\c
  7097. .BR list
  7098. is required to be parsed as the single command
  7099. .BR print \c
  7100. <newline>\c
  7101. .BR list .
  7102. While this differs from historical practice, POSIX.1\(hy2008 developers believed
  7103. it unlikely that any script or user depended on the historical
  7104. behavior.
  7105. .P
  7106. Historically, an error in a command specified using the
  7107. .BR \-c
  7108. option did not cause the rest of the
  7109. .BR \-c
  7110. commands to be discarded. POSIX.1\(hy2008 disallows this for consistency with
  7111. mapped keys, the
  7112. .BR @ ,
  7113. .BR global ,
  7114. .BR source ,
  7115. and
  7116. .BR v
  7117. commands, the
  7118. .IR EXINIT
  7119. environment variable, and the
  7120. .BR .exrc
  7121. files.
  7122. .SS "Input Editing in ex"
  7123. .P
  7124. One of the common uses of the historical
  7125. .IR ex
  7126. editor is over slow network connections. Editors that run in canonical
  7127. mode can require far less traffic to and from, and far less processing
  7128. on, the host machine, as well as more easily supporting block-mode
  7129. terminals. For these reasons, POSIX.1\(hy2008 requires that
  7130. .IR ex
  7131. be implemented using canonical mode input processing, as was done
  7132. historically.
  7133. .P
  7134. POSIX.1\(hy2008 does not require the historical 4 BSD input editing characters
  7135. ``word erase'' or ``literal next''. For this reason, it is unspecified
  7136. how they are handled by
  7137. .IR ex ,
  7138. although they must have the required effect. Implementations that
  7139. resolve them after the line has been ended using a
  7140. <newline>
  7141. or
  7142. <control>\(hyM
  7143. character, and implementations that rely on the underlying system
  7144. terminal support for this processing, are both conforming.
  7145. Implementations are strongly urged to use the underlying system
  7146. functionality, if at all possible, for compatibility with other system
  7147. text input interfaces.
  7148. .P
  7149. Historically, when the
  7150. .IR eof
  7151. character was used to decrement the
  7152. .BR autoindent
  7153. level, the cursor moved to display the new end of the
  7154. .BR autoindent
  7155. characters, but did not move the cursor to a new line, nor did it erase
  7156. the
  7157. <control>\(hyD
  7158. character from the line. POSIX.1\(hy2008 does not specify that the cursor remain
  7159. on the same line or that the rest of the line is erased; however,
  7160. implementations are strongly encouraged to provide the best possible
  7161. user interface; that is, the cursor should remain on the same line, and
  7162. any
  7163. <control>\(hyD
  7164. character on the line should be erased.
  7165. .P
  7166. POSIX.1\(hy2008 does not require the historical 4 BSD input editing character
  7167. ``reprint'', traditionally
  7168. <control>\(hyR,
  7169. which redisplayed the current input from the user. For this reason, and
  7170. because the functionality cannot be implemented after the line has been
  7171. terminated by the user, POSIX.1\(hy2008 makes no requirements about this
  7172. functionality. Implementations are strongly urged to make this
  7173. historical functionality available, if possible.
  7174. .P
  7175. Historically,
  7176. <control>\(hyQ
  7177. did not perform a literal next function in
  7178. .IR ex ,
  7179. as it did in
  7180. .IR vi .
  7181. POSIX.1\(hy2008 requires conformance to historical practice to avoid breaking
  7182. historical
  7183. .IR ex
  7184. scripts and
  7185. .BR .exrc
  7186. files.
  7187. .SS "eof"
  7188. .P
  7189. Whether the
  7190. .IR eof
  7191. character immediately modifies the
  7192. .BR autoindent
  7193. characters in the prompt is left unspecified so that implementations
  7194. can conform in the presence of systems that do not support this
  7195. functionality. Implementations are encouraged to modify the line and
  7196. redisplay it immediately, if possible.
  7197. .P
  7198. The specification of the handling of the
  7199. .IR eof
  7200. character differs from historical practice only in that
  7201. .IR eof
  7202. characters are not discarded if they follow normal characters in the
  7203. text input. Historically, they were always discarded.
  7204. .SS "Command Descriptions in ex"
  7205. .P
  7206. Historically, several commands (for example,
  7207. .BR global ,
  7208. .BR v ,
  7209. .BR visual ,
  7210. .BR s ,
  7211. .BR write ,
  7212. .BR wq ,
  7213. .BR yank ,
  7214. .BR ! ,
  7215. .BR < ,
  7216. .BR > ,
  7217. .BR & ,
  7218. and
  7219. .BR ~ )
  7220. were executable in empty files (that is, the default address(es) were
  7221. 0), or permitted explicit addresses of 0 (for example, 0 was a valid
  7222. address, or 0,0 was a valid range). Addresses of 0, or command
  7223. execution in an empty file, make sense only for commands that add new
  7224. text to the edit buffer or write commands (because users may wish to
  7225. write empty files). POSIX.1\(hy2008 requires this behavior for such commands and
  7226. disallows it otherwise, for consistency and simplicity of
  7227. specification.
  7228. .P
  7229. A count to an
  7230. .IR ex
  7231. command has been historically corrected to be no greater than the last
  7232. line in a file; for example, in a five-line file, the command
  7233. .BR "1,6print"
  7234. would fail, but the command
  7235. .BR "1print300"
  7236. would succeed. POSIX.1\(hy2008 requires conformance to historical practice.
  7237. .P
  7238. Historically, the use of flags in
  7239. .IR ex
  7240. commands could be obscure. General historical practice was as described
  7241. by POSIX.1\(hy2008, but there were some special cases. For instance, the
  7242. .BR list ,
  7243. .BR number ,
  7244. and
  7245. .BR print
  7246. commands ignored trailing address offsets; for example,
  7247. .BR "3p\0+++#"
  7248. would display line 3, and 3 would be the current line after the
  7249. execution of the command. The
  7250. .BR open
  7251. and
  7252. .BR visual
  7253. commands ignored both the trailing offsets and the trailing flags.
  7254. Also, flags specified to the
  7255. .BR open
  7256. and
  7257. .BR visual
  7258. commands interacted badly with the
  7259. .BR list
  7260. edit option, and setting and then unsetting it during the open/visual
  7261. session would cause
  7262. .IR vi
  7263. to stop displaying lines in the specified format. For consistency and
  7264. simplicity of specification, POSIX.1\(hy2008 does not permit any of these
  7265. exceptions to the general rule.
  7266. .P
  7267. POSIX.1\(hy2008 uses the word
  7268. .IR copy
  7269. in several places when discussing buffers. This is not intended to
  7270. imply implementation.
  7271. .P
  7272. Historically,
  7273. .IR ex
  7274. users could not specify numeric buffers because of the ambiguity this
  7275. would cause; for example, in the command
  7276. .BR "3\0delete\02" ,
  7277. it is unclear whether 2 is a buffer name or a
  7278. .IR count .
  7279. POSIX.1\(hy2008 requires conformance to historical practice by default, but does
  7280. not preclude extensions.
  7281. .P
  7282. Historically, the contents of the unnamed buffer were frequently
  7283. discarded after commands that did not explicitly affect it; for
  7284. example, when using the
  7285. .BR edit
  7286. command to switch files. For consistency and simplicity of
  7287. specification, POSIX.1\(hy2008 does not permit this behavior.
  7288. .P
  7289. The
  7290. .IR ex
  7291. utility did not historically have access to the numeric buffers, and,
  7292. furthermore, deleting lines in
  7293. .IR ex
  7294. did not modify their contents. For example, if, after doing a delete in
  7295. .IR vi ,
  7296. the user switched to
  7297. .IR ex ,
  7298. did another delete, and then switched back to
  7299. .IR vi ,
  7300. the contents of the numeric buffers would not have changed. POSIX.1\(hy2008
  7301. requires conformance to historical practice. Numeric buffers are
  7302. described in the
  7303. .IR ex
  7304. utility in order to confine the description of buffers to a single
  7305. location in POSIX.1\(hy2008.
  7306. .P
  7307. The metacharacters that trigger shell expansion in
  7308. .IR file
  7309. arguments match historical practice, as does the method for doing shell
  7310. expansion. Implementations wishing to provide users with the
  7311. flexibility to alter the set of metacharacters are encouraged to
  7312. provide a
  7313. .BR shellmeta
  7314. string edit option.
  7315. .P
  7316. Historically,
  7317. .IR ex
  7318. commands executed from
  7319. .IR vi
  7320. refreshed the screen when it did not strictly need to do so; for
  7321. example,
  7322. .BR ":!date\0>\0/dev/null"
  7323. does not require a screen refresh because the output of the UNIX
  7324. .IR date
  7325. command requires only a single line of the screen. POSIX.1\(hy2008 requires that
  7326. the screen be refreshed if it has been overwritten, but makes no
  7327. requirements as to how an implementation should make that
  7328. determination. Implementations may prompt and refresh the screen
  7329. regardless.
  7330. .SS "Abbreviate"
  7331. .P
  7332. Historical practice was that characters that were entered as part of an
  7333. abbreviation replacement were subject to
  7334. .BR map
  7335. expansions, the
  7336. .BR showmatch
  7337. edit option, further abbreviation expansions, and so on; that is, they
  7338. were logically pushed onto the terminal input queue, and were not a
  7339. simple replacement. POSIX.1\(hy2008 requires conformance to historical practice.
  7340. Historical practice was that whenever a non-word character (that had
  7341. not been escaped by a
  7342. <control>\(hyV)
  7343. was entered after a word character,
  7344. .IR vi
  7345. would check for abbreviations. The check was based on the type of the
  7346. character entered before the word character of the word/non-word pair
  7347. that triggered the check. The word character of the word/non-word pair
  7348. that triggered the check and all characters entered before the trigger
  7349. pair that were of that type were included in the check, with the
  7350. exception of
  7351. <blank>
  7352. characters, which always delimited the abbreviation.
  7353. .P
  7354. This means that, for the abbreviation to work, the
  7355. .IR lhs
  7356. must end with a word character, there can be no transitions from word
  7357. to non-word characters (or \fIvice versa\fP) other than between the
  7358. last and next-to-last characters in the
  7359. .IR lhs ,
  7360. and there can be no
  7361. <blank>
  7362. characters in the
  7363. .IR lhs .
  7364. In addition, because of the historical quoting rules, it was impossible
  7365. to enter a literal
  7366. <control>\(hyV
  7367. in the
  7368. .IR lhs .
  7369. POSIX.1\(hy2008 requires conformance to historical practice. Historical
  7370. implementations did not inform users when abbreviations that could
  7371. never be used were entered; implementations are strongly encouraged to
  7372. do so.
  7373. .br
  7374. .P
  7375. For example, the following abbreviations will work:
  7376. .sp
  7377. .RS 4
  7378. .nf
  7380. :ab (p  REPLACE
  7381. :ab p   REPLACE
  7382. :ab ((p REPLACE
  7383. .fi
  7384. .P
  7385. .RE
  7386. .P
  7387. The following abbreviations will not work:
  7388. .sp
  7389. .RS 4
  7390. .nf
  7392. :ab (   REPLACE
  7393. :ab (pp REPLACE
  7394. .fi
  7395. .P
  7396. .RE
  7397. .P
  7398. Historical practice is that words on the
  7399. .IR vi
  7400. colon command line were subject to abbreviation expansion, including
  7401. the arguments to the
  7402. .BR abbrev
  7403. (and more interestingly) the
  7404. .BR unabbrev
  7405. command. Because there are implementations that do not do abbreviation
  7406. expansion for the first argument to those commands, this is permitted,
  7407. but not required, by POSIX.1\(hy2008. However, the following sequence:
  7408. .sp
  7409. .RS 4
  7410. .nf
  7412. :ab foo bar
  7413. :ab foo baz
  7414. .fi
  7415. .P
  7416. .RE
  7417. .P
  7418. resulted in the addition of an abbreviation of
  7419. .BR \(dqbaz\(dq 
  7420. for the string
  7421. .BR \(dqbar\(dq 
  7422. in historical
  7423. .IR ex /\c
  7424. .IR vi ,
  7425. and the sequence:
  7426. .sp
  7427. .RS 4
  7428. .nf
  7430. :ab foo1 bar
  7431. :ab foo2 bar
  7432. :unabbreviate foo2
  7433. .fi
  7434. .P
  7435. .RE
  7436. .P
  7437. deleted the abbreviation
  7438. .BR \(dqfoo1\(dq ,
  7439. not
  7440. .BR \(dqfoo2\(dq .
  7441. These behaviors are not permitted by POSIX.1\(hy2008 because they clearly violate
  7442. the expectations of the user.
  7443. .P
  7444. It was historical practice that
  7445. <control>\(hyV,
  7446. not
  7447. <backslash>,
  7448. characters be interpreted as escaping subsequent characters in the
  7449. .BR abbreviate
  7450. command. POSIX.1\(hy2008 requires conformance to historical practice; however, it
  7451. should be noted that an abbreviation containing a
  7452. <blank>
  7453. will never work.
  7454. .SS "Append"
  7455. .P
  7456. Historically, any text following a
  7457. <vertical-line>
  7458. command separator after an
  7459. .BR append ,
  7460. .BR change ,
  7461. or
  7462. .BR insert
  7463. command became part of the insert text. For example, in the command:
  7464. .sp
  7465. .RS 4
  7466. .nf
  7468. :g/pattern/append|stuff1
  7469. .fi
  7470. .P
  7471. .RE
  7472. .P
  7473. a line containing the text
  7474. .BR \(dqstuff1\(dq 
  7475. would be appended to each line matching pattern. It was also
  7476. historically valid to enter:
  7477. .sp
  7478. .RS 4
  7479. .nf
  7481. :append|stuff1
  7482. stuff2
  7483. \&.
  7484. .fi
  7485. .P
  7486. .RE
  7487. .P
  7488. and the text on the
  7489. .IR ex
  7490. command line would be appended along with the text inserted after it.
  7491. There was an historical bug, however, that the user had to enter two
  7492. terminating lines (the
  7493. .BR '.' 
  7494. lines) to terminate text input mode in this case. POSIX.1\(hy2008 requires
  7495. conformance to historical practice, but disallows the historical need
  7496. for multiple terminating lines.
  7497. .SS "Change"
  7498. .P
  7499. See the RATIONALE for the
  7500. .BR append
  7501. command. Historical practice for cursor positioning after the change
  7502. command when no text is input, is as described in POSIX.1\(hy2008. However, one
  7503. System V implementation is known to have been modified such that the
  7504. cursor is positioned on the first address specified, and not on the
  7505. line before the first address. POSIX.1\(hy2008 disallows this modification for
  7506. consistency.
  7507. .P
  7508. Historically, the
  7509. .BR change
  7510. command did not support buffer arguments, although some implementations
  7511. allow the specification of an optional buffer. This behavior is neither
  7512. required nor disallowed by POSIX.1\(hy2008.
  7513. .SS "Change Directory"
  7514. .P
  7515. A common extension in
  7516. .IR ex
  7517. implementations is to use the elements of a
  7518. .BR cdpath
  7519. edit option as prefix directories for
  7520. .IR path
  7521. arguments to
  7522. .BR chdir
  7523. that are relative pathnames and that do not have
  7524. .BR '.' 
  7525. or
  7526. .BR \(dq..\(dq 
  7527. as their first component. Elements in the
  7528. .BR cdpath
  7529. edit option are
  7530. <colon>-separated.
  7531. The initial value of the
  7532. .BR cdpath
  7533. edit option is the value of the shell
  7534. .IR CDPATH
  7535. environment variable. This feature was not included in POSIX.1\(hy2008 because it
  7536. does not exist in any of the implementations considered historical
  7537. practice.
  7538. .SS "Copy"
  7539. .P
  7540. Historical implementations of
  7541. .IR ex
  7542. permitted copies to lines inside of the specified range; for example,
  7543. .BR ":2,5copy3"
  7544. was a valid command. POSIX.1\(hy2008 requires conformance to historical
  7545. practice.
  7546. .SS "Delete"
  7547. .P
  7548. POSIX.1\(hy2008 requires support for the historical parsing of a
  7549. .BR delete
  7550. command followed by flags, without any intervening
  7551. <blank>
  7552. characters. For example:
  7553. .IP "\fB1dp\fP" 8
  7554. Deletes the first line and prints the line that was second.
  7555. .IP "\fB1delep\fP" 8
  7556. As for
  7557. .BR 1dp .
  7558. .IP "\fB1d\fP" 8
  7559. Deletes the first line, saving it in buffer
  7560. .IR p .
  7561. .IP "\fB1d\0p1l\fP" 8
  7562. (Pee-one-ell.) Deletes the first line, saving it in buffer
  7563. .IR p ,
  7564. and listing the line that was second.
  7565. .SS "Edit"
  7566. .P
  7567. Historically, any
  7568. .IR ex
  7569. command could be entered as a
  7570. .BR + \c
  7571. .IR command
  7572. argument to the
  7573. .BR edit
  7574. command, although some (for example,
  7575. .BR insert
  7576. and
  7577. .BR append )
  7578. were known to confuse historical implementations. For consistency and
  7579. simplicity of specification, POSIX.1\(hy2008 requires that any command be
  7580. supported as an argument to the
  7581. .BR edit
  7582. command.
  7583. .P
  7584. Historically, the command argument was executed with the current line
  7585. set to the last line of the file, regardless of whether the
  7586. .BR edit
  7587. command was executed from visual mode or not. POSIX.1\(hy2008 requires
  7588. conformance to historical practice.
  7589. .P
  7590. Historically, the
  7591. .BR + \c
  7592. .IR command
  7593. specified to the
  7594. .BR edit
  7595. and
  7596. .BR next
  7597. commands was delimited by the first
  7598. <blank>,
  7599. and there was no way to quote them. For consistency, POSIX.1\(hy2008 requires
  7600. that the usual
  7601. .IR ex
  7602. backslash quoting be provided.
  7603. .P
  7604. Historically, specifying the
  7605. .BR + \c
  7606. .IR command
  7607. argument to the edit command required a filename to be specified as
  7608. well; for example,
  7609. .BR ":edit\0+100"
  7610. would always fail. For consistency and simplicity of specification,
  7611. POSIX.1\(hy2008 does not permit this usage to fail for that reason.
  7612. .P
  7613. Historically, only the cursor position of the last file edited was
  7614. remembered by the editor. POSIX.1\(hy2008 requires that this be supported;
  7615. however, implementations are permitted to remember and restore the
  7616. cursor position for any file previously edited.
  7617. .SS "File"
  7618. .P
  7619. Historical versions of the
  7620. .IR ex
  7621. editor
  7622. .BR file
  7623. command displayed a current line and number of lines in the edit buffer
  7624. of 0 when the file was empty, while the
  7625. .IR vi
  7626. <control>\(hyG
  7627. command displayed a current line and number of lines in the edit buffer
  7628. of 1 in the same situation. POSIX.1\(hy2008 does not permit this discrepancy,
  7629. instead requiring that a message be displayed indicating that the file
  7630. is empty.
  7631. .SS "Global"
  7632. .P
  7633. The two-pass operation of the
  7634. .BR global
  7635. and
  7636. .BR v
  7637. commands is not intended to imply implementation, only the required
  7638. result of the operation.
  7639. .P
  7640. The current line and column are set as specified for the individual
  7641. .IR ex
  7642. commands. This requirement is cumulative; that is, the current line and
  7643. column must track across all the commands executed by the
  7644. .BR global
  7645. or
  7646. .BR v
  7647. commands.
  7648. .SS "Insert"
  7649. .P
  7650. See the RATIONALE for the
  7651. .BR append
  7652. command.
  7653. .P
  7654. Historically,
  7655. .BR insert
  7656. could not be used with an address of zero; that is, not when the edit
  7657. buffer was empty. POSIX.1\(hy2008 requires that this command behave consistently
  7658. with the
  7659. .BR append
  7660. command.
  7661. .SS "Join"
  7662. .P
  7663. The action of the
  7664. .BR join
  7665. command in relation to the special characters is only defined for the
  7666. POSIX locale because the correct amount of white space after a period
  7667. varies; in Japanese none is required, in French only a single space,
  7668. and so on.
  7669. .SS "List"
  7670. .P
  7671. The historical output of the
  7672. .BR list
  7673. command was potentially ambiguous. The standard developers believed
  7674. correcting this to be more important than adhering to historical
  7675. practice, and POSIX.1\(hy2008 requires unambiguous output.
  7676. .SS "Map"
  7677. .P
  7678. Historically, command mode maps only applied to command names; for
  7679. example, if the character
  7680. .BR 'x' 
  7681. was mapped to
  7682. .BR 'y' ,
  7683. the command
  7684. .BR fx
  7685. searched for the
  7686. .BR 'x' 
  7687. character, not the
  7688. .BR 'y' 
  7689. character. POSIX.1\(hy2008 requires this behavior. Historically, entering
  7690. <control>\(hyV
  7691. as the first character of a
  7692. .IR vi
  7693. command was an error. Several implementations have extended the
  7694. semantics of
  7695. .IR vi
  7696. such that
  7697. <control>\(hyV
  7698. means that the subsequent command character is not mapped. This is
  7699. permitted, but not required, by POSIX.1\(hy2008. Regardless, using
  7700. <control>\(hyV
  7701. to escape the second or later character in a sequence of characters
  7702. that might match a
  7703. .BR map
  7704. command, or any character in text input mode, is historical practice,
  7705. and stops the entered keys from matching a map. POSIX.1\(hy2008 requires
  7706. conformance to historical practice.
  7707. .P
  7708. Historical implementations permitted digits to be used as a
  7709. .BR map
  7710. command
  7711. .IR lhs ,
  7712. but then ignored the map. POSIX.1\(hy2008 requires that the mapped digits not be
  7713. ignored.
  7714. .P
  7715. The historical implementation of the
  7716. .BR map
  7717. command did not permit
  7718. .BR map
  7719. commands that were more than a single character in length if the first
  7720. character was printable. This behavior is permitted, but not required,
  7721. by POSIX.1\(hy2008.
  7722. .P
  7723. Historically, mapped characters were remapped unless the
  7724. .BR remap
  7725. edit option was not set, or the prefix of the mapped characters matched
  7726. the mapping characters; for example, in the
  7727. .BR map :
  7728. .sp
  7729. .RS 4
  7730. .nf
  7732. :map ab abcd
  7733. .fi
  7734. .P
  7735. .RE
  7736. .P
  7737. the characters
  7738. .BR \(dqab\(dq 
  7739. were used as is and were not remapped, but the characters
  7740. .BR \(dqcd\(dq 
  7741. were mapped if appropriate. This can cause infinite loops in the
  7742. .IR vi
  7743. mapping mechanisms. POSIX.1\(hy2008 requires conformance to historical practice,
  7744. and that such loops be interruptible.
  7745. .P
  7746. Text input maps had the same problems with expanding the
  7747. .IR lhs
  7748. for the
  7749. .IR ex
  7750. .BR map!
  7751. and
  7752. .BR unmap!
  7753. command as did the
  7754. .IR ex
  7755. .BR abbreviate
  7756. and
  7757. .BR unabbreviate
  7758. commands. See the RATIONALE for the
  7759. .IR ex
  7760. .BR abbreviate
  7761. command. POSIX.1\(hy2008 requires similar modification of some historical
  7762. practice for the
  7763. .BR map
  7764. and
  7765. .BR unmap
  7766. commands, as described for the
  7767. .BR abbreviate
  7768. and
  7769. .BR unabbreviate
  7770. commands.
  7771. .P
  7772. Historically,
  7773. .BR map s
  7774. that were subsets of other
  7775. .BR map s
  7776. behaved differently depending on the order in which they were defined.
  7777. For example:
  7778. .sp
  7779. .RS 4
  7780. .nf
  7782. :map! ab     short
  7783. :map! abc    long
  7784. .fi
  7785. .P
  7786. .RE
  7787. .P
  7788. would always translate the characters
  7789. .BR \(dqab\(dq 
  7790. to
  7791. .BR \(dqshort\(dq ,
  7792. regardless of how fast the characters
  7793. .BR \(dqabc\(dq 
  7794. were entered. If the entry order was reversed:
  7795. .sp
  7796. .RS 4
  7797. .nf
  7799. :map! abc    long
  7800. :map! ab     short
  7801. .fi
  7802. .P
  7803. .RE
  7804. .P
  7805. the characters
  7806. .BR \(dqab\(dq 
  7807. would cause the editor to pause, waiting for the completing
  7808. .BR 'c' 
  7809. character, and the characters might never be mapped to
  7810. .BR \(dqshort\(dq .
  7811. For consistency and simplicity of specification, POSIX.1\(hy2008 requires that
  7812. the shortest match be used at all times.
  7813. .P
  7814. The length of time the editor spends waiting for the characters to
  7815. complete the
  7816. .IR lhs
  7817. is unspecified because the timing capabilities of systems are often
  7818. inexact and variable, and it may depend on other factors such as the
  7819. speed of the connection. The time should be long enough for the user to
  7820. be able to complete the sequence, but not long enough for the user to
  7821. have to wait. Some implementations of
  7822. .IR vi
  7823. have added a
  7824. .BR keytime
  7825. option, which permits users to set the number of 0,1 seconds the editor
  7826. waits for the completing characters. Because mapped terminal function
  7827. and cursor keys tend to start with an
  7828. <ESC>
  7829. character, and
  7830. <ESC>
  7831. is the key ending
  7832. .IR vi
  7833. text input mode,
  7834. .BR map s
  7835. starting with
  7836. <ESC>
  7837. characters are generally exempted from this timeout period, or, at
  7838. least timed out differently.
  7839. .SS "Mark"
  7840. .P
  7841. Historically, users were able to set the ``previous context'' marks
  7842. explicitly. In addition, the
  7843. .IR ex
  7844. commands
  7845. .BR \(aq\(aq
  7846. and
  7847. .BR \(aq`
  7848. and the
  7849. .IR vi
  7850. commands
  7851. .BR \(aq\(aq ,
  7852. .BR `` ,
  7853. .BR `\(aq ,
  7854. and
  7855. .BR \(aq`
  7856. all referred to the same mark. In addition, the previous context marks
  7857. were not set if the command, with which the address setting the mark
  7858. was associated, failed. POSIX.1\(hy2008 requires conformance to historical
  7859. practice. Historically, if marked lines were deleted, the mark was also
  7860. deleted, but would reappear if the change was undone. POSIX.1\(hy2008 requires
  7861. conformance to historical practice.
  7862. .P
  7863. The description of the special events that set the
  7864. .BR `
  7865. and
  7866. .BR \(aq
  7867. marks matches historical practice. For example, historically the
  7868. command
  7869. .BR "/a/,/b/"
  7870. did not set the
  7871. .BR `
  7872. and
  7873. .BR \(aq
  7874. marks, but the command
  7875. .BR "/a/,/b/delete"
  7876. did.
  7877. .SS "Next"
  7878. .P
  7879. Historically, any
  7880. .IR ex
  7881. command could be entered as a
  7882. .BR + \c
  7883. .IR command
  7884. argument to the
  7885. .BR next
  7886. command, although some (for example,
  7887. .BR insert
  7888. and
  7889. .BR append )
  7890. were known to confuse historical implementations. POSIX.1\(hy2008 requires that
  7891. any command be permitted and that it behave as specified. The
  7892. .BR next
  7893. command can accept more than one file, so usage such as:
  7894. .sp
  7895. .RS 4
  7896. .nf
  7898. next `ls [abc] `
  7899. .fi
  7900. .P
  7901. .RE
  7902. .P
  7903. is valid; it need not be valid for the
  7904. .BR edit
  7905. or
  7906. .BR read
  7907. commands, for example, because they expect only one filename.
  7908. .P
  7909. Historically, the
  7910. .BR next
  7911. command behaved differently from the
  7912. .BR :rewind
  7913. command in that it ignored the force flag if the
  7914. .BR autowrite
  7915. flag was set. For consistency, POSIX.1\(hy2008 does not permit this behavior.
  7916. .P
  7917. Historically, the
  7918. .BR next
  7919. command positioned the cursor as if the file had never been edited
  7920. before, regardless. POSIX.1\(hy2008 does not permit this behavior, for
  7921. consistency with the
  7922. .BR edit
  7923. command.
  7924. .P
  7925. Implementations wanting to provide a counterpart to the
  7926. .BR next
  7927. command that edited the previous file have used the command
  7928. .BR prev[ious],
  7929. which takes no
  7930. .IR file
  7931. argument. POSIX.1\(hy2008 does not require this command.
  7932. .SS "Open"
  7933. .P
  7934. Historically, the
  7935. .BR open
  7936. command would fail if the
  7937. .BR open
  7938. edit option was not set. POSIX.1\(hy2008 does not mention the
  7939. .BR open
  7940. edit option and does not require this behavior. Some historical
  7941. implementations do not permit entering open mode from open or visual
  7942. mode, only from
  7943. .IR ex
  7944. mode. For consistency, POSIX.1\(hy2008 does not permit this behavior.
  7945. .P
  7946. Historically, entering open mode from the command line (that is,
  7947. .IR vi
  7948. .BR +open )
  7949. resulted in anomalous behaviors; for example, the
  7950. .IR ex
  7951. file and
  7952. .IR set
  7953. commands, and the
  7954. .IR vi
  7955. command
  7956. <control>\(hyG
  7957. did not work. For consistency, POSIX.1\(hy2008 does not permit this behavior.
  7958. .P
  7959. Historically, the
  7960. .BR open
  7961. command only permitted
  7962. .BR '/' 
  7963. characters to be used as the search pattern delimiter. For consistency,
  7964. POSIX.1\(hy2008 requires that the search delimiters used by the
  7965. .BR s ,
  7966. .BR global ,
  7967. and
  7968. .BR v
  7969. commands be accepted as well.
  7970. .SS "Preserve"
  7971. .P
  7972. The
  7973. .BR preserve
  7974. command does not historically cause the file to be considered
  7975. unmodified for the purposes of future commands that may exit the
  7976. editor. POSIX.1\(hy2008 requires conformance to historical practice.
  7977. .P
  7978. Historical documentation stated that mail was not sent to the user when
  7979. preserve was executed; however, historical implementations did send
  7980. mail in this case. POSIX.1\(hy2008 requires conformance to the historical
  7981. implementations.
  7982. .SS "Print"
  7983. .P
  7984. The writing of NUL by the
  7985. .BR print
  7986. command is not specified as a special case because the standard
  7987. developers did not want to require
  7988. .IR ex
  7989. to support NUL characters. Historically, characters were displayed
  7990. using the ARPA standard mappings, which are as follows:
  7991. .IP " 1." 4
  7992. Printable characters are left alone.
  7993. .IP " 2." 4
  7994. Control characters less than \e177 are represented as
  7995. .BR '\(ha' 
  7996. followed by the character offset from the
  7997. .BR '@' 
  7998. character in the ASCII map; for example, \e007 is represented as
  7999. .BR '\(haG' .
  8000. .IP " 3." 4
  8001. \e177 is represented as
  8002. .BR '\(ha' 
  8003. followed by
  8004. .BR '?' .
  8005. .P
  8006. The display of characters having their eighth bit set was less
  8007. standard. Existing implementations use hex (0x00), octal (\e000), and a
  8008. meta-bit display. (The latter displayed bytes that had their eighth bit
  8009. set as the two characters
  8010. .BR \(dqM-\(dq 
  8011. followed by the seven-bit display as described above.) The latter
  8012. probably has the best claim to historical practice because it was used
  8013. for the
  8014. .BR \-v
  8015. option of 4 BSD and 4 BSD-derived versions of the
  8016. .IR cat
  8017. utility since 1980.
  8018. .P
  8019. No specific display format is required by POSIX.1\(hy2008.
  8020. .P
  8021. Explicit dependence on the ASCII character set has been avoided where
  8022. possible, hence the use of the phrase an ``implementation-defined
  8023. multi-character sequence'' for the display of non-printable characters
  8024. in preference to the historical usage of, for instance,
  8025. .BR \(dq\(haI\(dq 
  8026. for the
  8027. <tab>.
  8028. Implementations are encouraged to conform to historical practice in the
  8029. absence of any strong reason to diverge.
  8030. .P
  8031. Historically, all
  8032. .IR ex
  8033. commands beginning with the letter
  8034. .BR 'p' 
  8035. could be entered using capitalized versions of the commands; for
  8036. example,
  8037. .BR P[rint] ,
  8038. .BR Pre[serve] ,
  8039. and
  8040. .BR Pu[t]
  8041. were all valid command names. POSIX.1\(hy2008 permits, but does not require, this
  8042. historical practice because capital forms of the commands are used by
  8043. some implementations for other purposes.
  8044. .SS "Put"
  8045. .P
  8046. Historically, an
  8047. .IR ex
  8048. .BR put
  8049. command, executed from open or visual mode, was the same as the open or
  8050. visual mode
  8051. .BR P
  8052. command, if the buffer was named and was cut in character mode, and the
  8053. same as the
  8054. .BR p
  8055. command if the buffer was named and cut in line mode. If the unnamed
  8056. buffer was the source of the text, the entire line from which the text
  8057. was taken was usually
  8058. .BR put ,
  8059. and the buffer was handled as if in line mode, but it was possible to
  8060. get extremely anomalous behavior. In addition, using the
  8061. .BR Q
  8062. command to switch into
  8063. .IR ex
  8064. mode, and then doing a
  8065. .BR put
  8066. often resulted in errors as well, such as appending text that was
  8067. unrelated to the (supposed) contents of the buffer. For consistency and
  8068. simplicity of specification, POSIX.1\(hy2008 does not permit these behaviors. All
  8069. .IR ex
  8070. .BR put
  8071. commands are required to operate in line mode, and the contents of the
  8072. buffers are not altered by changing the mode of the editor.
  8073. .SS "Read"
  8074. .P
  8075. Historically, an
  8076. .IR ex
  8077. .BR read
  8078. command executed from open or visual mode, executed in an empty file,
  8079. left an empty line as the first line of the file. For consistency and
  8080. simplicity of specification, POSIX.1\(hy2008 does not permit this behavior.
  8081. Historically, a
  8082. .BR read
  8083. in open or visual mode from a program left the cursor at the last line
  8084. read in, not the first. For consistency, POSIX.1\(hy2008 does not permit this
  8085. behavior.
  8086. .P
  8087. Historical implementations of
  8088. .IR ex
  8089. were unable to undo
  8090. .BR read
  8091. commands that read from the output of a program. For consistency, POSIX.1\(hy2008
  8092. does not permit this behavior.
  8093. .P
  8094. Historically, the
  8095. .IR ex
  8096. and
  8097. .IR vi
  8098. message after a successful
  8099. .BR read
  8100. or
  8101. .BR write
  8102. command specified ``characters'', not ``bytes''. POSIX.1\(hy2008 requires that
  8103. the number of bytes be displayed, not the number of characters, because
  8104. it may be difficult in multi-byte implementations to determine the
  8105. number of characters read. Implementations are encouraged to clarify
  8106. the message displayed to the user.
  8107. .P
  8108. Historically, reads were not permitted on files other than type
  8109. regular, except that FIFO files could be read (probably only because
  8110. they did not exist when
  8111. .IR ex
  8112. and
  8113. .IR vi
  8114. were originally written). Because the historical
  8115. .IR ex
  8116. evaluated
  8117. .BR read!
  8118. and
  8119. .BR read\0!
  8120. equivalently, there can be no optional way to force the read. POSIX.1\(hy2008
  8121. permits, but does not require, this behavior.
  8122. .SS "Recover"
  8123. .P
  8124. Some historical implementations of the editor permitted users to
  8125. recover the edit buffer contents from a previous edit session, and then
  8126. exit without saving those contents (or explicitly discarding them). The
  8127. intent of POSIX.1\(hy2008 in requiring that the edit buffer be treated as already
  8128. modified is to prevent this user error.
  8129. .SS "Rewind"
  8130. .P
  8131. Historical implementations supported the
  8132. .BR rewind
  8133. command when the user was editing the first file in the list; that is,
  8134. the file that the
  8135. .BR rewind
  8136. command would edit. POSIX.1\(hy2008 requires conformance to historical practice.
  8137. .SS "Substitute"
  8138. .P
  8139. Historically,
  8140. .IR ex
  8141. accepted an
  8142. .BR r
  8143. option to the
  8144. .BR s
  8145. command. The effect of the
  8146. .BR r
  8147. option was to use the last regular expression used in any command as
  8148. the pattern, the same as the
  8149. .BR ~
  8150. command. The
  8151. .BR r
  8152. option is not required by POSIX.1\(hy2008. Historically, the
  8153. .BR c
  8154. and
  8155. .BR g
  8156. options were toggled; for example, the command
  8157. .BR ":s/abc/def/"
  8158. was the same as
  8159. .BR "s/abc/def/ccccgggg" .
  8160. For simplicity of specification, POSIX.1\(hy2008 does not permit this behavior.
  8161. .P
  8162. The tilde command is often used to replace the last search RE. For
  8163. example, in the sequence:
  8164. .sp
  8165. .RS 4
  8166. .nf
  8168. s/red/blue/
  8169. /green
  8170. \(ti
  8171. .fi
  8172. .P
  8173. .RE
  8174. .P
  8175. the
  8176. .BR ~
  8177. command is equivalent to:
  8178. .sp
  8179. .RS 4
  8180. .nf
  8182. s/green/blue/
  8183. .fi
  8184. .P
  8185. .RE
  8186. .P
  8187. Historically,
  8188. .IR ex
  8189. accepted all of the following forms:
  8190. .sp
  8191. .RS 4
  8192. .nf
  8194. s/abc/def/
  8195. s/abc/def
  8196. s/abc/
  8197. s/abc
  8198. .fi
  8199. .P
  8200. .RE
  8201. .P
  8202. POSIX.1\(hy2008 requires conformance to this historical practice.
  8203. .P
  8204. The
  8205. .BR s
  8206. command presumes that the
  8207. .BR '\(ha' 
  8208. character only occupies a single column in the display. Much of the
  8209. .IR ex
  8210. and
  8211. .IR vi
  8212. specification presumes that the
  8213. <space>
  8214. only occupies a single column in the display. There are no known
  8215. character sets for which this is not true.
  8216. .P
  8217. Historically, the final column position for the substitute commands was
  8218. based on previous column movements; a search for a pattern followed by
  8219. a substitution would leave the column position unchanged, while a 0
  8220. command followed by a substitution would change the column position to
  8221. the first non-\c
  8222. <blank>.
  8223. For consistency and simplicity of specification, POSIX.1\(hy2008 requires that
  8224. the final column position always be set to the first non-\c
  8225. <blank>.
  8226. .SS "Set"
  8227. .P
  8228. Historical implementations redisplayed all of the options for each
  8229. occurrence of the
  8230. .BR all
  8231. keyword. POSIX.1\(hy2008 permits, but does not require, this behavior.
  8232. .SS "Tag"
  8233. .P
  8234. No requirement is made as to where
  8235. .IR ex
  8236. and
  8237. .IR vi
  8238. shall look for the file referenced by the tag entry. Historical
  8239. practice has been to look for the path found in the
  8240. .BR tags
  8241. file, based on the current directory. A useful extension found in some
  8242. implementations is to look based on the directory containing the tags
  8243. file that held the entry, as well. No requirement is made as to which
  8244. reference for the tag in the tags file is used. This is deliberate, in
  8245. order to permit extensions such as multiple entries in a tags file for
  8246. a tag.
  8247. .P
  8248. Because users often specify many different tags files, some of which
  8249. need not be relevant or exist at any particular time, POSIX.1\(hy2008 requires
  8250. that error messages about problem tags files be displayed only if the
  8251. requested tag is not found, and then, only once for each time that the
  8252. .BR tag
  8253. edit option is changed.
  8254. .P
  8255. The requirement that the current edit buffer be unmodified is only
  8256. necessary if the file indicated by the tag entry is not the same as the
  8257. current file (as defined by the current pathname). Historically, the
  8258. file would be reloaded if the filename had changed, as well as if the
  8259. filename was different from the current pathname. For consistency and
  8260. simplicity of specification, POSIX.1\(hy2008 does not permit this behavior,
  8261. requiring that the name be the only factor in the decision.
  8262. .P
  8263. Historically,
  8264. .IR vi
  8265. only searched for tags in the current file from the current cursor to
  8266. the end of the file, and therefore, if the
  8267. .BR wrapscan
  8268. option was not set, tags occurring before the current cursor were not
  8269. found. POSIX.1\(hy2008 considers this a bug, and implementations are required to
  8270. search for the first occurrence in the file, regardless.
  8271. .SS "Undo"
  8272. .P
  8273. The
  8274. .BR undo
  8275. description deliberately uses the word ``modified''. The
  8276. .BR undo
  8277. command is not intended to undo commands that replace the contents of
  8278. the edit buffer, such as
  8279. .BR edit ,
  8280. .BR next ,
  8281. .BR tag ,
  8282. or
  8283. .BR recover .
  8284. .P
  8285. Cursor positioning after the
  8286. .BR undo
  8287. command was inconsistent in the historical
  8288. .IR vi ,
  8289. sometimes attempting to restore the original cursor position (\c
  8290. .BR global ,
  8291. .BR undo ,
  8292. and
  8293. .BR v
  8294. commands), and sometimes, in the presence of maps, placing the cursor
  8295. on the last line added or changed instead of the first. POSIX.1\(hy2008 requires
  8296. a simplified behavior for consistency and simplicity of specification.
  8297. .SS "Version"
  8298. .P
  8299. The
  8300. .BR version
  8301. command cannot be exactly specified since there is no widely-accepted
  8302. definition of what the version information should contain.
  8303. Implementations are encouraged to do something reasonably intelligent.
  8304. .SS "Write"
  8305. .P
  8306. Historically, the
  8307. .IR ex
  8308. and
  8309. .IR vi
  8310. message after a successful
  8311. .BR read
  8312. or
  8313. .BR write
  8314. command specified ``characters'', not ``bytes''. POSIX.1\(hy2008 requires that
  8315. the number of bytes be displayed, not the number of characters because
  8316. it may be difficult in multi-byte implementations to determine the
  8317. number of characters written. Implementations are encouraged to clarify
  8318. the message displayed to the user.
  8319. .P
  8320. Implementation-defined tests are permitted so that implementations
  8321. can make additional checks; for example, for locks or file modification
  8322. times.
  8323. .P
  8324. Historically, attempting to append to a nonexistent file caused an
  8325. error. It has been left unspecified in POSIX.1\(hy2008 to permit implementations
  8326. to let the
  8327. .BR write
  8328. succeed, so that the append semantics are similar to those of the
  8329. historical
  8330. .IR csh .
  8331. .P
  8332. Historical
  8333. .IR vi
  8334. permitted empty edit buffers to be written. However, since the way
  8335. .IR vi
  8336. got around dealing with ``empty'' files was to always have a line in
  8337. the edit buffer, no matter what, it wrote them as files of a single,
  8338. empty line. POSIX.1\(hy2008 does not permit this behavior.
  8339. .P
  8340. Historically,
  8341. .IR ex
  8342. restored standard output and standard error to their values as of when
  8343. .IR ex
  8344. was invoked, before writes to programs were performed. This could
  8345. disturb the terminal configuration as well as be a security issue for
  8346. some terminals. POSIX.1\(hy2008 does not permit this, requiring that the program
  8347. output be captured and displayed as if by the
  8348. .IR ex
  8349. .BR print
  8350. command.
  8351. .SS "Adjust Window"
  8352. .P
  8353. Historically, the line count was set to the value of the
  8354. .BR scroll
  8355. option if the type character was end-of-file. This feature was broken
  8356. on most historical implementations long ago, however, and is not
  8357. documented anywhere. For this reason, POSIX.1\(hy2008 is resolutely silent.
  8358. .P
  8359. Historically, the
  8360. .BR z
  8361. command was
  8362. <blank>-sensitive
  8363. and
  8364. .BR z\0+
  8365. and
  8366. .BR z\0\-
  8367. did different things than
  8368. .BR z+
  8369. and
  8370. .BR z\-
  8371. because the type could not be distinguished from a flag. (The commands
  8372. .BR z\0.
  8373. and
  8374. .BR z\0=
  8375. were historically invalid.) POSIX.1\(hy2008 requires conformance to this
  8376. historical practice.
  8377. .P
  8378. Historically, the
  8379. .BR z
  8380. command was further
  8381. <blank>-sensitive
  8382. in that the
  8383. .IR count
  8384. could not be
  8385. <blank>-delimited;
  8386. for example, the commands
  8387. .BR z=\05
  8388. and
  8389. .BR z\-\05
  8390. were also invalid. Because the
  8391. .IR count
  8392. is not ambiguous with respect to either the type character or the
  8393. flags, this is not permitted by POSIX.1\(hy2008.
  8394. .SS "Escape"
  8395. .P
  8396. Historically,
  8397. .IR ex
  8398. filter commands only read the standard output of the commands, letting
  8399. standard error appear on the terminal as usual. The
  8400. .IR vi
  8401. utility, however, read both standard output and standard error. POSIX.1\(hy2008
  8402. requires the latter behavior for both
  8403. .IR ex
  8404. and
  8405. .IR vi ,
  8406. for consistency.
  8407. .SS "Shift Left and Shift Right"
  8408. .P
  8409. Historically, it was possible to add shift characters to increase the
  8410. effect of the command; for example,
  8411. .BR <<<
  8412. outdented (or
  8413. .BR >>>
  8414. indented) the lines 3 levels of indentation instead of the default 1.
  8415. POSIX.1\(hy2008 requires conformance to historical practice.
  8416. .SS "<control>\(hyD"
  8417. .P
  8418. Historically, the
  8419. <control>\(hyD
  8420. command erased the prompt, providing the user with an unbroken
  8421. presentation of lines from the edit buffer. This is not required by
  8422. POSIX.1\(hy2008; implementations are encouraged to provide it if possible.
  8423. Historically, the
  8424. <control>\(hyD
  8425. command took, and then ignored, a
  8426. .IR count .
  8427. POSIX.1\(hy2008 does not permit this behavior.
  8428. .SS "Write Line Number"
  8429. .P
  8430. Historically, the
  8431. .IR ex
  8432. .BR =
  8433. command, when executed in
  8434. .IR ex
  8435. mode in an empty edit buffer, reported 0, and from open or visual mode,
  8436. reported 1. For consistency and simplicity of specification, POSIX.1\(hy2008 does
  8437. not permit this behavior.
  8438. .SS "Execute"
  8439. .P
  8440. Historically,
  8441. .IR ex
  8442. did not correctly handle the inclusion of text input commands (that is,
  8443. .BR append ,
  8444. .BR insert ,
  8445. and
  8446. .BR change )
  8447. in executed buffers. POSIX.1\(hy2008 does not permit this exclusion for
  8448. consistency.
  8449. .P
  8450. Historically, the logical contents of the buffer being executed did not
  8451. change if the buffer itself were modified by the commands being
  8452. executed; that is, buffer execution did not support self-modifying
  8453. code. POSIX.1\(hy2008 requires conformance to historical practice.
  8454. .P
  8455. Historically, the
  8456. .BR @
  8457. command took a range of lines, and the
  8458. .BR @
  8459. buffer was executed once per line, with the current line (\c
  8460. .BR '.' )
  8461. set to each specified line. POSIX.1\(hy2008 requires conformance to historical
  8462. practice.
  8463. .P
  8464. Some historical implementations did not notice if errors occurred
  8465. during buffer execution. This, coupled with the ability to specify a
  8466. range of lines for the
  8467. .IR ex
  8468. .BR @
  8469. command, makes it trivial to cause them to drop
  8470. .BR core .
  8471. POSIX.1\(hy2008 requires that implementations stop buffer execution if any error
  8472. occurs, if the specified line doesn't exist, or if the contents of the
  8473. edit buffer itself are replaced (for example, the buffer executes the
  8474. .IR ex
  8475. .BR :edit
  8476. command).
  8477. .SS "Regular Expressions in ex"
  8478. .P
  8479. Historical practice is that the characters in the replacement part of
  8480. the last
  8481. .BR s
  8482. command\(emthat is, those matched by entering a
  8483. .BR '\(ti' 
  8484. in the regular expression\(emwere not further expanded by the regular
  8485. expression engine. So, if the characters contained the string
  8486. .BR \(dqa.,\(dq 
  8487. they would match
  8488. .BR 'a' 
  8489. followed by
  8490. .BR \(dq.,\(dq 
  8491. and not
  8492. .BR 'a' 
  8493. followed by any character. POSIX.1\(hy2008 requires conformance to historical
  8494. practice.
  8495. .SS "Edit Options in ex"
  8496. .P
  8497. The following paragraphs describe the historical behavior of some edit
  8498. options that were not, for whatever reason, included in POSIX.1\(hy2008.
  8499. Implementations are strongly encouraged to only use these names if the
  8500. functionality described here is fully supported.
  8501. .IP "\fBextended\fP" 10
  8502. The
  8503. .BR extended
  8504. edit option has been used in some implementations of
  8505. .IR vi
  8506. to provide extended regular expressions instead of basic regular
  8507. expressions This option was omitted from POSIX.1\(hy2008 because it is not
  8508. widespread historical practice.
  8509. .IP "\fBflash\fP" 10
  8510. The
  8511. .BR flash
  8512. edit option historically caused the screen to flash instead of beeping
  8513. on error. This option was omitted from POSIX.1\(hy2008 because it is not found in
  8514. some historical implementations.
  8515. .IP "\fBhardtabs\fP" 10
  8516. The
  8517. .BR hardtabs
  8518. edit option historically defined the number of columns between hardware
  8519. tab settings. This option was omitted from POSIX.1\(hy2008 because it was
  8520. believed to no longer be generally useful.
  8521. .IP "\fBmodeline\fP" 10
  8522. The
  8523. .BR modeline
  8524. (sometimes named
  8525. .BR modelines )
  8526. edit option historically caused
  8527. .IR ex
  8528. or
  8529. .IR vi
  8530. to read the five first and last lines of the file for editor commands.
  8531. This option is a security problem, and vendors are strongly encouraged
  8532. to delete it from historical implementations.
  8533. .IP "\fBopen\fP" 10
  8534. The
  8535. .BR open
  8536. edit option historically disallowed the
  8537. .IR ex
  8538. .BR open
  8539. and
  8540. .BR visual
  8541. commands. This edit option was omitted because these commands are
  8542. required by POSIX.1\(hy2008.
  8543. .IP "\fBoptimize\fP" 10
  8544. The
  8545. .BR optimize
  8546. edit option historically expedited text throughput by setting the
  8547. terminal to not do automatic
  8548. <carriage-return>
  8549. characters when printing more than one logical line of output. This
  8550. option was omitted from POSIX.1\(hy2008 because it was intended for terminals
  8551. without addressable cursors, which are rarely, if ever, still used.
  8552. .IP "\fBruler\fP" 10
  8553. The
  8554. .BR ruler
  8555. edit option has been used in some implementations of
  8556. .IR vi
  8557. to present a current row/column ruler for the user. This option was
  8558. omitted from POSIX.1\(hy2008 because it is not widespread historical practice.
  8559. .IP "\fBsourceany\fP" 10
  8560. The
  8561. .BR sourceany
  8562. edit option historically caused
  8563. .IR ex
  8564. or
  8565. .IR vi
  8566. to source start-up files that were owned by users other than the user
  8567. running the editor. This option is a security problem, and vendors are
  8568. strongly encouraged to remove it from their implementations.
  8569. .IP "\fBtimeout\fP" 10
  8570. The
  8571. .BR timeout
  8572. edit option historically enabled the (now standard) feature of only
  8573. waiting for a short period before returning keys that could be part of
  8574. a macro. This feature was omitted from POSIX.1\(hy2008 because its behavior is
  8575. now standard, it is not widely useful, and it was rarely documented.
  8576. .IP "\fBverbose\fP" 10
  8577. The
  8578. .BR verbose
  8579. edit option has been used in some implementations of
  8580. .IR vi
  8581. to cause
  8582. .IR vi
  8583. to output error messages for common errors; for example, attempting to
  8584. move the cursor past the beginning or end of the line instead of only
  8585. alerting the screen. (The historical
  8586. .IR vi
  8587. only alerted the terminal and presented no message for such errors. The
  8588. historical editor option
  8589. .BR terse
  8590. did not select when to present error messages, it only made existing
  8591. error messages more or less verbose.) This option was omitted from
  8592. POSIX.1\(hy2008 because it is not widespread historical practice; however,
  8593. implementors are encouraged to use it if they wish to provide error
  8594. messages for naive users.
  8595. .IP "\fBwraplen\fP" 10
  8596. The
  8597. .BR wraplen
  8598. edit option has been used in some implementations of
  8599. .IR vi
  8600. to specify an automatic margin measured from the left margin instead of
  8601. from the right margin. This is useful when multiple screen sizes are
  8602. being used to edit a single file. This option was omitted from POSIX.1\(hy2008
  8603. because it is not widespread historical practice; however, implementors
  8604. are encouraged to use it if they add this functionality.
  8605. .SS "autoindent, ai"
  8606. .P
  8607. Historically, the command
  8608. .BR 0a
  8609. did not do any autoindentation, regardless of the current indentation
  8610. of line 1. POSIX.1\(hy2008 requires that any indentation present in line 1 be
  8611. used.
  8612. .SS "autoprint, ap"
  8613. .P
  8614. Historically, the
  8615. .BR autoprint
  8616. edit option was not completely consistent or based solely on
  8617. modifications to the edit buffer. Exceptions were the
  8618. .BR read
  8619. command (when reading from a file, but not from a filter), the
  8620. .BR append ,
  8621. .BR change ,
  8622. .BR insert ,
  8623. .BR global ,
  8624. and
  8625. .BR v
  8626. commands, all of which were not affected by
  8627. .BR autoprint ,
  8628. and the
  8629. .BR tag
  8630. command, which was affected by
  8631. .BR autoprint .
  8632. POSIX.1\(hy2008 requires conformance to historical practice.
  8633. .P
  8634. Historically, the
  8635. .BR autoprint
  8636. option only applied to the last of multiple commands entered using
  8637. <vertical-line>
  8638. delimiters; for example,
  8639. .BR delete
  8640. <newline>
  8641. was affected by
  8642. .BR autoprint ,
  8643. but
  8644. .BR delete|version
  8645. <newline>
  8646. was not. POSIX.1\(hy2008 requires conformance to historical practice.
  8647. .SS "autowrite, aw"
  8648. .P
  8649. Appending the
  8650. .BR '!' 
  8651. character to the
  8652. .IR ex
  8653. .BR next
  8654. command to avoid performing an automatic write was not supported in
  8655. historical implementations. POSIX.1\(hy2008 requires that the behavior match the
  8656. other
  8657. .IR ex
  8658. commands for consistency.
  8659. .SS "ignorecase, ic"
  8660. .P
  8661. Historical implementations of case-insensitive matching (the
  8662. .BR ignorecase
  8663. edit option) lead to counter-intuitive situations when uppercase
  8664. characters were used in range expressions. Historically, the process
  8665. was as follows:
  8666. .IP " 1." 4
  8667. Take a line of text from the edit buffer.
  8668. .IP " 2." 4
  8669. Convert uppercase to lowercase in text line.
  8670. .IP " 3." 4
  8671. Convert uppercase to lowercase in regular expressions, except in
  8672. character class specifications.
  8673. .IP " 4." 4
  8674. Match regular expressions against text.
  8675. .P
  8676. This would mean that, with
  8677. .BR ignorecase
  8678. in effect, the text:
  8679. .sp
  8680. .RS 4
  8681. .nf
  8683. The cat sat on the mat
  8684. .fi
  8685. .P
  8686. .RE
  8687. .P
  8688. would be matched by
  8689. .sp
  8690. .RS 4
  8691. .nf
  8693. /\(hathe/
  8694. .fi
  8695. .P
  8696. .RE
  8697. .P
  8698. but not by:
  8699. .sp
  8700. .RS 4
  8701. .nf
  8703. /\(ha[A-Z]he/
  8704. .fi
  8705. .P
  8706. .RE
  8707. .P
  8708. For consistency with other commands implementing regular expressions,
  8709. POSIX.1\(hy2008 does not permit this behavior.
  8710. .SS "paragraphs, para"
  8711. .P
  8712. The ISO\ POSIX\(hy2:\|1993 standard made the default
  8713. .BR paragraphs
  8714. and
  8715. .BR sections
  8716. edit options implementation-defined, arguing they were historically
  8717. oriented to the UNIX system
  8718. .IR troff
  8719. text formatter, and a ``portable user'' could use the
  8720. .BR { ,
  8721. .BR } ,
  8722. .BR [[ ,
  8723. .BR ]] ,
  8724. .BR ( ,
  8725. and
  8726. .BR )
  8727. commands in open or visual mode and have the cursor stop in unexpected
  8728. places. POSIX.1\(hy2008 specifies their values in the POSIX locale because the
  8729. unusual grouping (they only work when grouped into two characters at a
  8730. time) means that they cannot be used for general-purpose movement,
  8731. regardless.
  8732. .SS "readonly"
  8733. .P
  8734. Implementations are encouraged to provide the best possible information
  8735. to the user as to the read-only status of the file, with the exception
  8736. that they should not consider the current special privileges of the
  8737. process. This provides users with a safety net because they must force
  8738. the overwrite of read-only files, even when running with additional
  8739. privileges.
  8740. .P
  8741. The
  8742. .BR readonly
  8743. edit option specification largely conforms to historical practice. The
  8744. only difference is that historical implementations did not notice that
  8745. the user had set the
  8746. .BR readonly
  8747. edit option in cases where the file was already marked read-only for
  8748. some reason, and would therefore reinitialize the
  8749. .BR readonly
  8750. edit option the next time the contents of the edit buffer were
  8751. replaced. This behavior is disallowed by POSIX.1\(hy2008.
  8752. .SS "report"
  8753. .P
  8754. The requirement that lines copied to a buffer interact differently than
  8755. deleted lines is historical practice. For example, if the
  8756. .BR report
  8757. edit option is set to 3, deleting 3 lines will cause a report to be
  8758. written, but 4 lines must be copied before a report is written.
  8759. .P
  8760. The requirement that the
  8761. .IR ex
  8762. .BR global ,
  8763. .BR v ,
  8764. .BR open ,
  8765. .BR undo ,
  8766. and
  8767. .BR visual
  8768. commands present reports based on the total number of lines added or
  8769. deleted during the command execution, and that commands executed by the
  8770. .BR global
  8771. and
  8772. .BR v
  8773. commands not present reports, is historical practice. POSIX.1\(hy2008 extends
  8774. historical practice by requiring that buffer execution be treated
  8775. similarly. The reasons for this are two-fold. Historically, only the
  8776. report by the last command executed from the buffer would be seen by
  8777. the user, as each new report would overwrite the last. In addition, the
  8778. standard developers believed that buffer execution had more in common
  8779. with
  8780. .BR global
  8781. and
  8782. .BR v
  8783. commands than it did with other
  8784. .IR ex
  8785. commands, and should behave similarly, for consistency and simplicity
  8786. of specification.
  8787. .SS "showmatch, sm"
  8788. .P
  8789. The length of time the cursor spends on the matching character is
  8790. unspecified because the timing capabilities of systems are often
  8791. inexact and variable. The time should be long enough for the user to
  8792. notice, but not long enough for the user to become annoyed. Some
  8793. implementations of
  8794. .IR vi
  8795. have added a
  8796. .BR matchtime
  8797. option that permits users to set the number of 0,1 second intervals the
  8798. cursor pauses on the matching character.
  8799. .SS "showmode"
  8800. .P
  8801. The
  8802. .BR showmode
  8803. option has been used in some historical implementations of
  8804. .IR ex
  8805. and
  8806. .IR vi
  8807. to display the current editing mode when in open or visual mode. The
  8808. editing modes have generally included ``command'' and ``input'', and
  8809. sometimes other modes such as ``replace'' and ``change''. The string
  8810. was usually displayed on the bottom line of the screen at the far
  8811. right-hand corner. In addition, a preceding
  8812. .BR '*' 
  8813. character often denoted whether the contents of the edit buffer had
  8814. been modified. The latter display has sometimes been part of the
  8815. .BR showmode
  8816. option, and sometimes based on another option. This option was not
  8817. available in the 4 BSD historical implementation of
  8818. .IR vi ,
  8819. but was viewed as generally useful, particularly to novice users, and
  8820. is required by POSIX.1\(hy2008.
  8821. .P
  8822. The
  8823. .BR smd
  8824. shorthand for the
  8825. .BR showmode
  8826. option was not present in all historical implementations of the editor.
  8827. POSIX.1\(hy2008 requires it, for consistency.
  8828. .P
  8829. Not all historical implementations of the editor displayed a mode
  8830. string for command mode, differentiating command mode from text input
  8831. mode by the absence of a mode string. POSIX.1\(hy2008 permits this behavior for
  8832. consistency with historical practice, but implementations are
  8833. encouraged to provide a display string for both modes.
  8834. .SS "slowopen"
  8835. .P
  8836. Historically, the
  8837. .BR slowopen
  8838. option was automatically set if the terminal baud rate was less than
  8839. 1\|200 baud, or if the baud rate was 1\|200 baud and the
  8840. .BR redraw
  8841. option was not set. The
  8842. .BR slowopen
  8843. option had two effects. First, when inserting characters in the middle
  8844. of a line, characters after the cursor would not be pushed ahead, but
  8845. would appear to be overwritten. Second, when creating a new line of
  8846. text, lines after the current line would not be scrolled down, but
  8847. would appear to be overwritten. In both cases, ending text input mode
  8848. would cause the screen to be refreshed to match the actual contents of
  8849. the edit buffer. Finally, terminals that were sufficiently intelligent
  8850. caused the editor to ignore the
  8851. .BR slowopen
  8852. option. POSIX.1\(hy2008 permits most historical behavior, extending historical
  8853. practice to require
  8854. .BR slowopen
  8855. behaviors if the edit option is set by the user.
  8856. .SS "tags"
  8857. .P
  8858. The default path for tags files is left unspecified as implementations
  8859. may have their own
  8860. .BR tags
  8861. implementations that do not correspond to the historical ones. The
  8862. default
  8863. .BR tags
  8864. option value should probably at least include the file
  8865. .BR ./tags .
  8866. .SS "term"
  8867. .P
  8868. Historical implementations of
  8869. .IR ex
  8870. and
  8871. .IR vi
  8872. ignored changes to the
  8873. .BR term
  8874. edit option after the initial terminal information was loaded. This is
  8875. permitted by POSIX.1\(hy2008; however, implementations are encouraged to permit
  8876. the user to modify their terminal type at any time.
  8877. .SS "terse"
  8878. .P
  8879. Historically, the
  8880. .BR terse
  8881. edit option optionally provided a shorter, less descriptive error
  8882. message, for some error messages. This is permitted, but not required,
  8883. by POSIX.1\(hy2008. Historically, most common visual mode errors (for example,
  8884. trying to move the cursor past the end of a line) did not result in an
  8885. error message, but simply alerted the terminal. Implementations wishing
  8886. to provide messages for novice users are urged to do so based on the
  8887. .BR edit
  8888. option
  8889. .BR verbose ,
  8890. and not
  8891. .BR terse .
  8892. .SS "window"
  8893. .P
  8894. In historical implementations, the default for the
  8895. .BR window
  8896. edit option was based on the baud rate as follows:
  8897. .IP " 1." 4
  8898. If the baud rate was less than 1\|200, the
  8899. .BR edit
  8900. option
  8901. .BR w300
  8902. set the window value; for example, the line:
  8903. .RS 4 
  8904. .sp
  8905. .RS 4
  8906. .nf
  8908. set w300=12
  8909. .fi
  8910. .P
  8911. .RE
  8912. .P
  8913. would set the window option to 12 if the baud rate was less than
  8914. 1\|200.
  8915. .RE
  8916. .IP " 2." 4
  8917. If the baud rate was equal to 1\|200, the
  8918. .BR edit
  8919. option
  8920. .BR w1200
  8921. set the window value.
  8922. .IP " 3." 4
  8923. If the baud rate was greater than 1\|200, the
  8924. .BR edit
  8925. option
  8926. .BR w9600
  8927. set the window value.
  8928. .P
  8929. The
  8930. .BR w300 ,
  8931. .BR w1200 ,
  8932. and
  8933. .BR w9600
  8934. options do not appear in POSIX.1\(hy2008 because of their dependence on specific
  8935. baud rates.
  8936. .P
  8937. In historical implementations, the size of the window displayed by
  8938. various commands was related to, but not necessarily the same as, the
  8939. .BR window
  8940. edit option. For example, the size of the window was set by the
  8941. .IR ex
  8942. command
  8943. .BR "visual 10" ,
  8944. but it did not change the value of the
  8945. .BR window
  8946. edit option. However, changing the value of the
  8947. .BR window
  8948. edit option did change the number of lines that were displayed when the
  8949. screen was repainted. POSIX.1\(hy2008 does not permit this behavior in the
  8950. interests of consistency and simplicity of specification, and requires
  8951. that all commands that change the number of lines that are displayed do
  8952. it by setting the value of the
  8953. .BR window
  8954. edit option.
  8955. .SS "wrapmargin, wm"
  8956. .P
  8957. Historically, the
  8958. .BR wrapmargin
  8959. option did not affect maps inserting characters that also had
  8960. associated
  8961. .IR count s;
  8962. for example
  8963. .BR ":map\0K\05aABC\0DEF" .
  8964. Unfortunately, there are widely used maps that depend on this behavior.
  8965. For consistency and simplicity of specification, POSIX.1\(hy2008 does not permit
  8966. this behavior.
  8967. .P
  8968. Historically,
  8969. .BR wrapmargin
  8970. was calculated using the column display width of all characters on the
  8971. screen. For example, an implementation using
  8972. .BR \(dq\(haI\(dq 
  8973. to represent
  8974. <tab>
  8975. characters when the
  8976. .BR list
  8977. edit option was set, where
  8978. .BR '\(ha' 
  8979. and
  8980. .BR 'I' 
  8981. each took up a single column on the screen, would calculate the
  8982. .BR wrapmargin
  8983. based on a value of 2 for each
  8984. <tab>.
  8985. The
  8986. .BR number
  8987. edit option similarly changed the effective length of the line as well.
  8988. POSIX.1\(hy2008 requires conformance to historical practice.
  8989. .P
  8990. Earlier versions of this standard allowed for implementations
  8991. with bytes other than eight bits, but this has been modified in this
  8992. version.
  8993. .SH "FUTURE DIRECTIONS"
  8994. None.
  8995. .SH "SEE ALSO"
  8996. .IR "Section 2.9.1.1" ", " "Command Search and Execution",
  8997. .IR "\fIctags\fR\^",
  8998. .IR "\fIed\fR\^",
  8999. .IR "\fIsed\fR\^",
  9000. .IR "\fIsh\fR\^",
  9001. .IR "\fIstty\fR\^",
  9002. .IR "\fIvi\fR\^"
  9003. .P
  9004. The Base Definitions volume of POSIX.1\(hy2017,
  9005. .IR "Table 5-1" ", " "Escape Sequences and Associated Actions",
  9006. .IR "Chapter 8" ", " "Environment Variables",
  9007. .IR "Section 9.3" ", " "Basic Regular Expressions",
  9008. .IR "Section 12.2" ", " "Utility Syntax Guidelines"
  9009. .P
  9010. The System Interfaces volume of POSIX.1\(hy2017,
  9011. .IR "\fIaccess\fR\^(\|)"
  9012. .\"
  9013. .SH COPYRIGHT
  9014. Portions of this text are reprinted and reproduced in electronic form
  9015. from IEEE Std 1003.1-2017, Standard for Information Technology
  9016. -- Portable Operating System Interface (POSIX), The Open Group Base
  9017. Specifications Issue 7, 2018 Edition,
  9018. Copyright (C) 2018 by the Institute of
  9019. Electrical and Electronics Engineers, Inc and The Open Group.
  9020. In the event of any discrepancy between this version and the original IEEE and
  9021. The Open Group Standard, the original IEEE and The Open Group Standard
  9022. is the referee document. The original Standard can be obtained online at
  9023. http://www.opengroup.org/unix/online.html .
  9024. .PP
  9025. Any typographical or formatting errors that appear
  9026. in this page are most likely
  9027. to have been introduced during the conversion of the source files to
  9028. man page format. To report such errors, see
  9029. https://www.kernel.org/doc/man-pages/reporting_bugs.html .