centos man page for setsid

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

NAME
       setsid - creates a session and sets the process group ID

SYNOPSIS
       #include <unistd.h>

       pid_t setsid(void);

DESCRIPTION
       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 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.

RETURN VALUE
       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.

ERRORS
       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.

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 setsid() will  succeed,  fork(2)  and
       _exit(2), and have the child do setsid().

SEE ALSO
       setsid(1), getsid(2), setpgid(2), setpgrp(2), tcgetsid(3), credentials(7)

COLOPHON
       This  page is part of release 3.53 of the Linux man-pages project.  A description of the project, and information about reporting bugs, can
       be found at http://www.kernel.org/doc/man-pages/.

Linux								    2013-02-11								 SETSID(2)