NAME
setsid - creates a session and sets the process group ID
SYNOPSIS
#include <unistd.h>
pid_t setsid(void);
DESCRIPTION
R 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, the process group leader of the new process group, and has no
controlling tty.
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.
RETURN VALUE
The session ID of the calling process.
ERRORS
On error, -1 is returned, and
errno
is set.
The only error which can happen is
R EPERM .
It is returned when the process group ID of any process
equals the PID of the calling process.
Thus, in particular,
R setsid ()
fails if the calling process is already a process group leader.
CONFORMING TO
SVr4, POSIX.1-2001.
NOTES
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
R setsid ()
will succeed,
fork(2)
and
_exit(2),
and have the child do
R setsid ().
SEE ALSO
ČLÁNKY DO MAILU