SETSID(2) manual page
Table of Contents
setsid - creates a session and sets the
process group ID
#include <unistd.h>
pid_t setsid(void);
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 it 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 it 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.
- EPERM
- 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.
SVr4, POSIX.1-2001.
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 whose process group ID equals its
PID. Disallowing a process group leader from calling 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 setsid() will succeed, fork(2)
and _exit(2), and have the child do setsid().
setsid(1)
, getsid(2)
,
setpgid(2)
, setpgrp(2)
, tcgetsid(3)
, credentials(7)
This page is
part of release 3.78 of the Linux man-pages project. A description of the
project, information about reporting bugs, and the latest version of this
page, can be found at http://www.kernel.org/doc/man-pages/.
Table of Contents
![[Go to CFHT Home Page]](/images/cfht-icon.gif){kind=icon}
Man Pages 
Back to Software Index 
Manpage Top Level