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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 2013-07-31 "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
89 .BR setpgrp "()\ (BSD),"
90 .BR getpgrp "()\ (BSD):"
93 !\ (_POSIX_SOURCE || _POSIX_C_SOURCE || _XOPEN_SOURCE ||
94 _XOPEN_SOURCE_EXTENDED || _GNU_SOURCE || _SVID_SOURCE)
99 All of these interfaces are available on Linux,
100 and are used for getting and setting the
101 process group ID (PGID) of a process.
102 The preferred, POSIX.1-specified ways of doing this are:
104 for retrieving the calling process's PGID; and
106 for setting a process's PGID.
109 sets the PGID of the process specified by
115 is zero, then the process ID of the calling process is used.
118 is zero, then the PGID of the process specified by
120 is made the same as its process ID.
123 is used to move a process from one process
124 group to another (as is done by some shells when creating pipelines),
125 both process groups must be part of the same session (see
128 .BR credentials (7)).
130 the \fIpgid\fP specifies an existing process group to be joined and the
131 session ID of that group must match the session ID of the joining process.
133 The POSIX.1 version of
135 which takes no arguments,
136 returns the PGID of the calling process.
139 returns the PGID of the process specified by
143 is zero, the process ID of the calling process is used.
144 (Retrieving the PGID of a process other than the caller is rarely
145 necessary, and the POSIX.1
147 is preferred for that task.)
151 which takes no arguments, is equivalent to
152 .IR "setpgid(0,\ 0)" .
156 call, which takes arguments
161 .IR "setpgid(pid, pgid)" .
162 .\" The true BSD setpgrp() system call differs in allowing the PGID
163 .\" to be set to arbitrary values, rather than being restricted to
164 .\" PGIDs in the same session.
168 call, which takes a single
170 argument, is equivalent to
178 On error, \-1 is returned, and
180 is set appropriately.
184 always returns the PGID of the caller.
189 return a process group on success.
190 On error, \-1 is returned, and
192 is set appropriately.
196 An attempt was made to change the process group ID
197 of one of the children of the calling process and the child had
210 An attempt was made to move a process into a process group in a
211 different session, or to change the process
212 group ID of one of the children of the calling process and the
213 child was in a different session, or to change the process group ID of
222 does not match any process.
226 is not the calling process and not a child of the calling process.
232 conform to POSIX.1-2001.
234 POSIX.1-2001 also specifies
238 that takes no arguments.
239 (POSIX.1-2008 marks this
241 specification as obsolete.)
245 with one argument and the version of
247 that takes two arguments derive from 4.2BSD,
248 and are not specified by POSIX.1.
252 inherits its parent's process group ID.
253 The PGID is preserved across an
256 Each process group is a member of a session and each process is a
257 member of the session of which its process group is a member.
259 A session can have a controlling terminal.
260 At any time, one (and only one) of the process groups
261 in the session can be the foreground process group
263 the remaining process groups are in the background.
264 If a signal is generated from the terminal (e.g., typing the
265 interrupt key to generate
267 that signal is sent to the foreground process group.
270 for a description of the characters that generate signals.)
271 Only the foreground process group may
274 if a background process group tries to
276 from the terminal, then the group is sent a
278 signal, which suspends it.
283 functions are used to get/set the foreground
284 process group of the controlling terminal.
290 calls are used by programs such as
292 to create process groups in order to implement shell job control.
294 If a session has a controlling terminal, and the
296 flag for that terminal is not set,
297 and a terminal hangup occurs, then the session leader is sent a
299 If the session leader exits, then a
301 signal will also be sent to each process in the foreground
302 process group of the controlling terminal.
304 If the exit of the process causes a process group to become orphaned,
305 and if any member of the newly orphaned process group is stopped, then a
309 signal will be sent to each process
310 in the newly orphaned process group.
311 .\" exit.3 refers to the following text:
312 An orphaned process group is one in which the parent of
313 every member of process group is either itself also a member
314 of the process group or is a member of a process group
315 in a different session (see also
316 .BR credentials (7)).