setsid - creates a session and sets the process group ID
() creates a new session if the calling process is not a process
group leader. The calling process is the leader of the new session, the
process group leader of the new process group, and has no controlling
terminal. The process group ID and session ID of the calling process are set
to the PID of the calling process. The calling process will be the only
process in this new process group and in this new session.
On success, the (new) session ID of the calling process is returned. On error,
is returned, and errno
is set to indicate the
- 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 child created via fork(2)
inherits its parent's session ID. The session
ID is preserved across an execve(2)
A process group leader is a process with process group ID equal to its PID. In
order to be sure that setsid
() will succeed, fork(2)
, and have the child do setsid
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