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Neither the name of the University nor the names of its contributors .\" may be used to endorse or promote products derived from this software .\" without specific prior written permission. .\" .\" THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND .\" ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE .\" IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE .\" ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE .\" FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL .\" DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS .\" OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) .\" HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT .\" LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY .\" OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF .\" SUCH DAMAGE. .\" .\" @(#)getpgrp.2 6.4 (Berkeley) 3/10/91 .\" .\" Modified 1993-07-24 by Rik Faith .\" Modified 1995-04-15 by Michael Chastain : .\" Added 'getpgid'. .\" Modified 1996-07-21 by Andries Brouwer .\" Modified 1996-11-06 by Eric S. Raymond .\" Modified 1999-09-02 by Michael Haardt .\" Modified 2002-01-18 by Michael Kerrisk .\" Modified 2003-01-20 by Andries Brouwer .\" .TH SETPGID 2 2003-01-20 "Linux" "Linux Programmer's Manual" .SH NAME setpgid, getpgid, setpgrp, getpgrp \- set/get process group .SH SYNOPSIS .B #include .sp .BI "int setpgid(pid_t " pid ", pid_t " pgid ); .br .BI "pid_t getpgid(pid_t " pid ); .br .B int setpgrp(void); .br .B pid_t getpgrp(void); .SH DESCRIPTION .BR setpgid () sets the process group ID of the process specified by .I pid to .IR pgid . If .I pid is zero, the process ID of the current process is used. If .I pgid is zero, the process ID of the process specified by .I pid is used. If \fBsetpgid\fP() is used to move a process from one process group to another (as is done by some shells when creating pipelines), both process groups must be part of the same session. In this case, the \fIpgid\fP specifies an existing process group to be joined and the session ID of that group must match the session ID of the joining process. .BR getpgid () returns the process group ID of the process specified by .IR pid . If .I pid is zero, the process ID of the current process is used. The call .BR setpgrp () is equivalent to .BR setpgid(0,0) . Similarly, .BR getpgrp () is equivalent to .BR getpgid(0) . Each process group is a member of a session and each process is a member of the session of which its process group is a member. Process groups are used for distribution of signals, and by terminals to arbitrate requests for their input: Processes that have the same process group as the terminal are foreground and may read, while others will block with a signal if they attempt to read. These calls are thus used by programs such as .BR csh (1) to create process groups in implementing job control. The .B TIOCGPGRP and .B TIOCSPGRP calls described in .BR termios (3) are used to get/set the process group of the control terminal. If a session has a controlling terminal, CLOCAL is not set and a hangup occurs, then the session leader is sent a SIGHUP. If the session leader exits, the SIGHUP signal will be sent to each process in the foreground process group of the controlling terminal. If the exit of the process causes a process group to become orphaned, and if any member of the newly-orphaned process group is stopped, then a SIGHUP signal followed by a SIGCONT signal will be sent to each process in the newly-orphaned process group. .SH "RETURN VALUE" On success, .BR setpgid () and .BR setpgrp () return zero. On error, \-1 is returned, and .I errno is set appropriately. .BR getpgid () returns a process group on success. On error, \-1 is returned, and .I errno is set appropriately. .BR getpgrp () always returns the current process group. .SH ERRORS .TP .B EACCES An attempt was made to change the process group ID of one of the children of the calling process and the child had already performed an \fBexecve\fP() (\fBsetpgid\fP(), \fBsetpgrp\fP()). .TP .B EINVAL .I pgid is less than 0 (\fBsetpgid\fP(), \fBsetpgrp\fP()). .TP .B EPERM An attempt was made to move a process into a process group in a different session, or to change the process group ID of one of the children of the calling process and the child was in a different session, or to change the process group ID of a session leader (\fBsetpgid\fP(), \fBsetpgrp\fP()). .TP .B ESRCH For .BR getpgid (): .I pid does not match any process. For .BR setpgid (): .I pid is not the current process and not a child of the current process. .SH "CONFORMING TO" The functions .BR setpgid () and .BR getpgrp () conform to POSIX.1. The function .BR setpgrp () is from 4.2BSD. The function .BR getpgid () conforms to SVr4. .SH NOTES POSIX took .BR setpgid () from the BSD function .BR setpgrp (). Also System V has a function with the same name, but it is identical to .BR setsid (2). .LP To get the prototypes under glibc, define both _XOPEN_SOURCE and _XOPEN_SOURCE_EXTENDED, or use "#define _XOPEN_SOURCE \fIn\fP" for some integer \fIn\fP larger than or equal to 500. .SH "SEE ALSO" .BR getuid (2), .BR setsid (2), .BR tcgetpgrp (3), .BR tcsetpgrp (3), .BR termios (3)