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SETPGID(2)                 Linux Programmer's Manual                SETPGID(2)

NAME
       setpgid, getpgid, setpgrp, getpgrp - set/get process group

SYNOPSIS
       #include <unistd.h>

       int setpgid(pid_t pid, pid_t pgid);
       pid_t getpgid(pid_t pid);
       int setpgrp(void);
       pid_t getpgrp(void);

DESCRIPTION
       setpgid sets the process group ID of the process specified by pid to
       pgid.  If pid is zero, the process ID of the current process is used.
       If pgid is zero, the process ID of the process specified by pid is
       used.  If setpgid 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
       pgid specifies an existing process group to be joined and the session
       ID of that group must match the session ID of the joining process.

       getpgid returns the process group ID of the process specified by pid.
       If pid is zero, the process ID of the current process is used.

       In the Linux DLL 4.4.1 library, setpgrp simply calls setpgid(0,0).

       getpgrp is equivalent to 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 csh(1) to create process groups in
       implementing job control.  The TIOCGPGRP and TIOCSPGRP calls described
       in 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.

RETURN VALUE
       On success, setpgid and setpgrp return zero.  On error, -1 is returned,
       and errno is set appropriately.

       getpgid returns a process group on success.  On error, -1 is returned,
       and errno is set appropriately.

       getpgrp always returns the current process group.

ERRORS
       EINVAL pgid is less than 0 (setpgid, setpgrp).

       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 execve (setpgid, setpgrp).

       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 (setpgid, setpgrp).

       ESRCH  pid does not match any process.

CONFORMING TO
       The functions setpgid and getpgrp conform to POSIX.1.  The function
       setpgrp is from BSD 4.2.  The function getpgid conforms to SVr4.

NOTES
       POSIX took setpgid from the BSD function setpgrp.  Also SysV has a
       function with the same name, but it is identical to setsid(2).

       To get the prototypes under glibc, define both _XOPEN_SOURCE and
       _XOPEN_SOURCE_EXTENDED, or use "#define _XOPEN_SOURCE n" for some
       integer n larger than or equal to 500.

SEE ALSO
       getuid(2), setsid(2), tcsetpgrp(3), termios(3)

Linux                             1999-09-02                        SETPGID(2)

NAME | SYNOPSIS | DESCRIPTION | RETURN VALUE | ERRORS | CONFORMING TO | NOTES | SEE ALSO

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