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

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