setsid(2)                                                  setsid(2)


       NAME
             setsid - set session ID

       SYNOPSIS
             #include <sys/types.h>
             #include <unistd.h>
             pid_t setsid(void);

       DESCRIPTION
             If the calling process is not already a process group leader,
             setsid sets the process group ID and session ID of the calling
             process to the process ID of the calling process, and releases
             the process's controlling terminal.

          Return Values
             On success, setsid returns the calling process's session ID.
             On failure, setsid returns -1 and sets errno to identify the
             error.

          Errors
             In the following conditions, setsid fails and sets errno to:

             EPERM          The calling process is already a process group
                            leader, or there are processes other than the
                            calling process whose process group ID is equal
                            to the process ID of the calling process.

       REFERENCES
             exec(2), exit(2), fork(2), getpid(2), getsid(2), intro(2),
             setpgid(2), setpgrp, signal(2), sigsend(2)

       NOTICES
             If the calling process is the last member of a pipeline
             started by a job control shell, the shell may make the calling
             process a process group leader.  The other processes of the
             pipeline become members of that process group.  In this case,
             the call to setsid will fail.  For this reason, a process that
             calls setsid and expects to be part of a pipeline should
             always first fork; the parent should exit and the child should
             call setsid, thereby insuring that the process will work
             reliably when started by both job control shells and non-job
             control shells.

          Considerations for Threads Programming
             This ID number is an attribute of the containing process and
             is shared by sibling threads.


                           Copyright 1994 Novell, Inc.               Page 1