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35 .\" @(#)getpgrp.2 6.4 (Berkeley) 3/10/91
37 .\" Modified 1993-07-24 by Rik Faith <faith@cs.unc.edu>
38 .\" Modified 1995-04-15 by Michael Chastain <mec@shell.portal.com>:
40 .\" Modified 1996-07-21 by Andries Brouwer <aeb@cwi.nl>
41 .\" Modified 1996-11-06 by Eric S. Raymond <esr@thyrsus.com>
42 .\" Modified 1999-09-02 by Michael Haardt <michael@moria.de>
43 .\" Modified 2002-01-18 by Michael Kerrisk <mtk.manpages@gmail.com>
44 .\" Modified 2003-01-20 by Andries Brouwer <aeb@cwi.nl>
45 .\" 2007-07-25, mtk, fairly substantial rewrites and rearrangements
48 .TH SETPGID 2 2014-01-07 "Linux" "Linux Programmer's Manual"
50 setpgid, getpgid, setpgrp, getpgrp \- set/get process group
52 .B #include <unistd.h>
54 .BI "int setpgid(pid_t " pid ", pid_t " pgid );
56 .BI "pid_t getpgid(pid_t " pid );
58 .BR "pid_t getpgrp(void);" " /* POSIX.1 version */"
60 .BI "pid_t getpgrp(pid_t " pid ");\ \ \ \ \ \ \ \ \ \ \ "
63 .BR "int setpgrp(void);" " /* System V version */"
65 .BI "int setpgrp(pid_t " pid ", pid_t " pgid ");\ "
69 Feature Test Macro Requirements for glibc (see
70 .BR feature_test_macros (7)):
77 _XOPEN_SOURCE\ >=\ 500 ||
78 _XOPEN_SOURCE\ &&\ _XOPEN_SOURCE_EXTENDED
80 || /* Since glibc 2.12: */ _POSIX_C_SOURCE\ >=\ 200809L
83 .BR setpgrp "() (POSIX.1):"
85 _SVID_SOURCE || _XOPEN_SOURCE\ >=\ 500 ||
86 _XOPEN_SOURCE\ &&\ _XOPEN_SOURCE_EXTENDED
88 || /* Since glibc 2.19: */ _BSD_SOURCE
91 .BR setpgrp "()\ (BSD),"
92 .BR getpgrp "()\ (BSD) [before glibc 2.19]:"
95 !\ (_POSIX_SOURCE || _POSIX_C_SOURCE || _XOPEN_SOURCE ||
96 _XOPEN_SOURCE_EXTENDED || _GNU_SOURCE || _SVID_SOURCE)
101 All of these interfaces are available on Linux,
102 and are used for getting and setting the
103 process group ID (PGID) of a process.
104 The preferred, POSIX.1-specified ways of doing this are:
106 for retrieving the calling process's PGID; and
108 for setting a process's PGID.
111 sets the PGID of the process specified by
117 is zero, then the process ID of the calling process is used.
120 is zero, then the PGID of the process specified by
122 is made the same as its process ID.
125 is used to move a process from one process
126 group to another (as is done by some shells when creating pipelines),
127 both process groups must be part of the same session (see
130 .BR credentials (7)).
132 the \fIpgid\fP specifies an existing process group to be joined and the
133 session ID of that group must match the session ID of the joining process.
135 The POSIX.1 version of
137 which takes no arguments,
138 returns the PGID of the calling process.
141 returns the PGID of the process specified by
145 is zero, the process ID of the calling process is used.
146 (Retrieving the PGID of a process other than the caller is rarely
147 necessary, and the POSIX.1
149 is preferred for that task.)
153 which takes no arguments, is equivalent to
154 .IR "setpgid(0,\ 0)" .
158 call, which takes arguments
162 is is a wrapper function that calls
166 .\" The true BSD setpgrp() system call differs in allowing the PGID
167 .\" to be set to arbitrary values, rather than being restricted to
168 .\" PGIDs in the same session.
169 Since glibc 2.19, the BSD-specific
171 function is no longer exposed by
173 calls should be replaced with the
179 call, which takes a single
181 argument, is a wrapper function that calls
185 Since glibc 2.19, the BSD-specific
187 function is no longer exposed by
189 calls should be replaced with calls to the POSIX.1
191 which takes no arguments (if the intent is to obtain the caller's PGID),
201 On error, \-1 is returned, and
203 is set appropriately.
207 always returns the PGID of the caller.
212 return a process group on success.
213 On error, \-1 is returned, and
215 is set appropriately.
219 An attempt was made to change the process group ID
220 of one of the children of the calling process and the child had
233 An attempt was made to move a process into a process group in a
234 different session, or to change the process
235 group ID of one of the children of the calling process and the
236 child was in a different session, or to change the process group ID of
245 does not match any process.
249 is not the calling process and not a child of the calling process.
255 conform to POSIX.1-2001.
257 POSIX.1-2001 also specifies
261 that takes no arguments.
262 (POSIX.1-2008 marks this
264 specification as obsolete.)
268 with one argument and the version of
270 that takes two arguments derive from 4.2BSD,
271 and are not specified by POSIX.1.
275 inherits its parent's process group ID.
276 The PGID is preserved across an
279 Each process group is a member of a session and each process is a
280 member of the session of which its process group is a member.
282 A session can have a controlling terminal.
283 At any time, one (and only one) of the process groups
284 in the session can be the foreground process group
286 the remaining process groups are in the background.
287 If a signal is generated from the terminal (e.g., typing the
288 interrupt key to generate
290 that signal is sent to the foreground process group.
293 for a description of the characters that generate signals.)
294 Only the foreground process group may
297 if a background process group tries to
299 from the terminal, then the group is sent a
301 signal, which suspends it.
306 functions are used to get/set the foreground
307 process group of the controlling terminal.
313 calls are used by programs such as
315 to create process groups in order to implement shell job control.
317 If a session has a controlling terminal, and the
319 flag for that terminal is not set,
320 and a terminal hangup occurs, then the session leader is sent a
322 If the session leader exits, then a
324 signal will also be sent to each process in the foreground
325 process group of the controlling terminal.
327 If the exit of the process causes a process group to become orphaned,
328 and if any member of the newly orphaned process group is stopped, then a
332 signal will be sent to each process
333 in the newly orphaned process group.
334 .\" exit.3 refers to the following text:
335 An orphaned process group is one in which the parent of
336 every member of process group is either itself also a member
337 of the process group or is a member of a process group
338 in a different session (see also
339 .BR credentials (7)).
348 This page is part of release 3.79 of the Linux
351 A description of the project,
352 information about reporting bugs,
353 and the latest version of this page,
355 \%http://www.kernel.org/doc/man\-pages/.