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sys_sem.h.0p (3856B)

    

  1. '\" et
  2. .TH sys_sem.h "0P" 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. sys/sem.h
  12. \(em XSI semaphore facility
  13. .SH SYNOPSIS
  14. .LP
  15. .nf
  16. #include <sys/sem.h>
  17. .fi
  18. .SH DESCRIPTION
  19. The
  20. .IR <sys/sem.h> 
  21. header shall define the following symbolic constant for use as a
  22. semaphore operation flag:
  23. .IP SEM_UNDO 12
  24. Set up adjust on exit entry.
  25. .P
  26. The
  27. .IR <sys/sem.h> 
  28. header shall define the following symbolic constants for use as
  29. commands for the
  30. \fIsemctl\fR()
  31. function:
  32. .IP GETNCNT 12
  33. Get
  34. .IR semncnt .
  35. .IP GETPID 12
  36. Get
  37. .IR sempid .
  38. .IP GETVAL 12
  39. Get
  40. .IR semval .
  41. .IP GETALL 12
  42. Get all cases of
  43. .IR semval .
  44. .IP GETZCNT 12
  45. Get
  46. .IR semzcnt .
  47. .IP SETVAL 12
  48. Set
  49. .IR semval .
  50. .IP SETALL 12
  51. Set all cases of
  52. .IR semval .
  53. .P
  54. The
  55. .IR <sys/sem.h> 
  56. header shall define the
  57. .BR semid_ds
  58. structure, which shall include the following members:
  59. .sp
  60. .RS 4
  61. .nf
  63. struct ipc_perm  sem_perm  \fROperation permission structure.\fR
  64. unsigned short   sem_nsems \fRNumber of semaphores in set.\fR
  65. time_t           sem_otime \fRLast \fIsemop\fP\^(\|) time.\fR
  66. time_t           sem_ctime \fRLast time changed by \fIsemctl\fP\^(\|).\fR
  67. .fi
  68. .P
  69. .RE
  70. .P
  71. The
  72. .IR <sys/sem.h> 
  73. header shall define the
  74. .BR pid_t ,
  75. .BR size_t ,
  76. and
  77. .BR time_t
  78. types as described in
  79. .IR <sys/types.h> .
  80. .P
  81. A semaphore shall be represented by an anonymous structure,
  82. which shall include the following members:
  83. .sp
  84. .RS 4
  85. .nf
  87. unsigned short  semval   \fRSemaphore value.\fR
  88. pid_t           sempid   \fRProcess ID of last operation.\fR
  89. unsigned short  semncnt  \fRNumber of processes waiting for \fIsemval\fR
  90.                          \fRto become greater than current value.\fR
  91. unsigned short  semzcnt  \fRNumber of processes waiting for \fIsemval\fR
  92.                          \fRto become 0.\fR
  93. .fi
  94. .P
  95. .RE
  96. .P
  97. The
  98. .IR <sys/sem.h> 
  99. header shall define the
  100. .BR sembuf
  101. structure, which shall include the following members:
  102. .sp
  103. .RS 4
  104. .nf
  106. unsigned short  sem_num   \fRSemaphore number.\fR
  107. short           sem_op    \fRSemaphore operation.\fR
  108. short           sem_flg   \fROperation flags.\fR
  109. .fi
  110. .P
  111. .RE
  112. .P
  113. The following shall be declared as functions and may also be defined as
  114. macros. Function prototypes shall be provided.
  115. .sp
  116. .RS 4
  117. .nf
  119. int   semctl(int, int, int, ...);
  120. int   semget(key_t, int, int);
  121. int   semop(int, struct sembuf *, size_t);
  122. .fi
  123. .P
  124. .RE
  125. .P
  126. In addition, the
  127. .IR <sys/sem.h> 
  128. header shall include the
  129. .IR <sys/ipc.h> 
  130. header.
  131. .LP
  132. .IR "The following sections are informative."
  133. .SH "APPLICATION USAGE"
  134. None.
  135. .SH RATIONALE
  136. None.
  137. .SH "FUTURE DIRECTIONS"
  138. None.
  139. .SH "SEE ALSO"
  140. .IR "\fB<sys_ipc.h>\fP",
  141. .IR "\fB<sys_types.h>\fP"
  142. .P
  143. The System Interfaces volume of POSIX.1\(hy2017,
  144. .IR "\fIsemctl\fR\^(\|)",
  145. .IR "\fIsemget\fR\^(\|)",
  146. .IR "\fIsemop\fR\^(\|)"
  147. .\"
  148. .SH COPYRIGHT
  149. Portions of this text are reprinted and reproduced in electronic form
  150. from IEEE Std 1003.1-2017, Standard for Information Technology
  151. -- Portable Operating System Interface (POSIX), The Open Group Base
  152. Specifications Issue 7, 2018 Edition,
  153. Copyright (C) 2018 by the Institute of
  154. Electrical and Electronics Engineers, Inc and The Open Group.
  155. In the event of any discrepancy between this version and the original IEEE and
  156. The Open Group Standard, the original IEEE and The Open Group Standard
  157. is the referee document. The original Standard can be obtained online at
  158. http://www.opengroup.org/unix/online.html .
  159. .PP
  160. Any typographical or formatting errors that appear
  161. in this page are most likely
  162. to have been introduced during the conversion of the source files to
  163. man page format. To report such errors, see
  164. https://www.kernel.org/doc/man-pages/reporting_bugs.html .