setsid — creates a session and sets the process group ID
setsid() creates a new
session if the calling process is not a process group leader.
The calling process is the leader of the new session (i.e.,
its session ID is made the same as its process ID). The
calling process also becomes the process group leader of a
new process group in the session (i.e., its process group ID
is made the same as its process ID).
The calling process will be the only process in the new process group and in the new session. The new session has no controlling terminal.
On success, the (new) session ID of the calling process is
returned. On error, (pid_t)
−1 is returned, and
errno is set to indicate the error.
The process group ID of any process equals the PID
of the calling process. Thus, in particular,
setsid() fails if the
calling process is already a process group leader.
A process group leader is a process whose process group ID
equals its PID. Disallowing a process group leader from
setsid() prevents the
possibility that a process group leader places itself in a
new session while other processes in the process group remain
in the original session; such a scenario would break the
strict two-level hierarchy of sessions and process groups. In
order to be sure that
will succeed, fork(2) and _exit(2), and have the
This page is part of release 4.07 of the Linux
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and the latest version of this page, can be found at
Copyright Michael Haardt (michaelcantor.informatik.rwth-aachen.de)
Sat Aug 27 20:43:50 MET DST 1994
and Copyright (C) 2014, Michael Kerrisk <mtk.manpagesgmail.com>
This is free documentation; you can redistribute it and/or
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Modified Sun Sep 11 19:19:05 1994 <faithcs.unc.edu>
Modified Mon Mar 25 10:19:00 1996 <aebcwi.nl> (merged a few
tiny changes from a man page by Charles Livingston).
Modified Sun Jul 21 14:45:46 1996 <aebcwi.nl>