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 control-
       ling 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 will be returned.  The only  error  which  can  happen  is
       EPERM.  It  is returned when 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.

NOTES

       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 and  exit,  and
       have the child do setsid().

CONFORMING TO

       POSIX, SVr4.

SEE ALSO

       setpgid(2), setpgrp(2)

Linux 1.0.0                       1994-08-27                         setsid(2)