fg.1p (5234B)
- '\" et
- .TH FG "1P" 2017 "IEEE/The Open Group" "POSIX Programmer's Manual"
- .\"
- .SH PROLOG
- This manual page is part of the POSIX Programmer's Manual.
- The Linux implementation of this interface may differ (consult
- the corresponding Linux manual page for details of Linux behavior),
- or the interface may not be implemented on Linux.
- .\"
- .SH NAME
- fg
- \(em run jobs in the foreground
- .SH SYNOPSIS
- .LP
- .nf
- fg \fB[\fIjob_id\fB]\fR
- .fi
- .SH DESCRIPTION
- If job control is enabled (see the description of
- .IR set
- .BR \-m ),
- the
- .IR fg
- utility shall move a background job from the current environment (see
- .IR "Section 2.12" ", " "Shell Execution Environment")
- into the foreground.
- .P
- Using
- .IR fg
- to place a job into the foreground shall remove its process ID from the
- list of those ``known in the current shell execution environment''; see
- .IR "Section 2.9.3.1" ", " "Examples".
- .SH OPTIONS
- None.
- .SH OPERANDS
- The following operand shall be supported:
- .IP "\fIjob_id\fR" 10
- Specify the job to be run as a foreground job. If no
- .IR job_id
- operand is given, the
- .IR job_id
- for the job that was most recently suspended, placed in the background,
- or run as a background job shall be used. The format of
- .IR job_id
- is described in the Base Definitions volume of POSIX.1\(hy2017,
- .IR "Section 3.204" ", " "Job Control Job ID".
- .SH STDIN
- Not used.
- .SH "INPUT FILES"
- None.
- .SH "ENVIRONMENT VARIABLES"
- The following environment variables shall affect the execution of
- .IR fg :
- .IP "\fILANG\fP" 10
- Provide a default value for the internationalization variables that are
- unset or null. (See the Base Definitions volume of POSIX.1\(hy2017,
- .IR "Section 8.2" ", " "Internationalization Variables"
- for the precedence of internationalization variables used to determine
- the values of locale categories.)
- .IP "\fILC_ALL\fP" 10
- If set to a non-empty string value, override the values of all the
- other internationalization variables.
- .IP "\fILC_CTYPE\fP" 10
- Determine the locale for the interpretation of sequences of bytes of
- text data as characters (for example, single-byte as opposed to
- multi-byte characters in arguments).
- .IP "\fILC_MESSAGES\fP" 10
- .br
- Determine the locale that should be used to affect the format and
- contents of diagnostic messages written to standard error.
- .IP "\fINLSPATH\fP" 10
- Determine the location of message catalogs for the processing of
- .IR LC_MESSAGES .
- .SH "ASYNCHRONOUS EVENTS"
- Default.
- .SH STDOUT
- The
- .IR fg
- utility shall write the command line of the job to standard output
- in the following format:
- .sp
- .RS 4
- .nf
- "%s\en", <\fIcommand\fR>
- .fi
- .P
- .RE
- .SH STDERR
- The standard error shall be used only for diagnostic messages.
- .SH "OUTPUT FILES"
- None.
- .SH "EXTENDED DESCRIPTION"
- None.
- .SH "EXIT STATUS"
- The following exit values shall be returned:
- .IP "\00" 6
- Successful completion.
- .IP >0 6
- An error occurred.
- .SH "CONSEQUENCES OF ERRORS"
- If job control is disabled, the
- .IR fg
- utility shall exit with an error and no job shall be placed in the
- foreground.
- .LP
- .IR "The following sections are informative."
- .SH "APPLICATION USAGE"
- The
- .IR fg
- utility does not work as expected when it is operating in its own
- utility execution environment because that environment has no
- applicable jobs to manipulate. See the APPLICATION USAGE section for
- .IR "\fIbg\fR\^".
- For this reason,
- .IR fg
- is generally implemented as a shell regular built-in.
- .SH EXAMPLES
- None.
- .SH RATIONALE
- The extensions to the shell specified in this volume of POSIX.1\(hy2017 have mostly been based
- on features provided by the KornShell. The job control features
- provided by
- .IR bg ,
- .IR fg ,
- and
- .IR jobs
- are also based on the KornShell. The standard developers examined the
- characteristics of the C shell versions of these utilities and found
- that differences exist. Despite widespread use of the C shell, the
- KornShell versions were selected for this volume of POSIX.1\(hy2017 to maintain a degree of
- uniformity with the rest of the KornShell features selected (such as
- the very popular command line editing features).
- .SH "FUTURE DIRECTIONS"
- None.
- .SH "SEE ALSO"
- .IR "Section 2.9.3.1" ", " "Examples",
- .IR "Section 2.12" ", " "Shell Execution Environment",
- .IR "\fIbg\fR\^",
- .IR "\fIkill\fR\^",
- .IR "\fIjobs\fR\^",
- .IR "\fIwait\fR\^"
- .P
- The Base Definitions volume of POSIX.1\(hy2017,
- .IR "Section 3.204" ", " "Job Control Job ID",
- .IR "Chapter 8" ", " "Environment Variables"
- .\"
- .SH COPYRIGHT
- Portions of this text are reprinted and reproduced in electronic form
- from IEEE Std 1003.1-2017, Standard for Information Technology
- -- Portable Operating System Interface (POSIX), The Open Group Base
- Specifications Issue 7, 2018 Edition,
- Copyright (C) 2018 by the Institute of
- Electrical and Electronics Engineers, Inc and The Open Group.
- In the event of any discrepancy between this version and the original IEEE and
- The Open Group Standard, the original IEEE and The Open Group Standard
- is the referee document. The original Standard can be obtained online at
- http://www.opengroup.org/unix/online.html .
- .PP
- Any typographical or formatting errors that appear
- in this page are most likely
- to have been introduced during the conversion of the source files to
- man page format. To report such errors, see
- https://www.kernel.org/doc/man-pages/reporting_bugs.html .