SETSID(2)                 FreeBSD System Calls Manual                SETSID(2)

NAME
     setsid - create session and set process group ID

LIBRARY
     Standard C Library (libc, -lc)

SYNOPSIS
     #include <unistd.h>

     pid_t
     setsid(void);

DESCRIPTION
     The setsid() system call creates a new session.  The calling process is
     the session leader of the new session, is the process group leader of a
     new process group and has no controlling terminal.  The calling process
     is the only process in either the session or the process group.

RETURN VALUES
     Upon successful completion, the setsid() system call returns the value of
     the process group ID of the new process group, which is the same as the
     process ID of the calling process.  If an error occurs, setsid() returns
     -1 and the global variable errno is set to indicate the error.

ERRORS
     The setsid() system call will fail if:

     [EPERM]            The calling process is already a process group leader,
                        or the process group ID of a process other than the
                        calling process matches the process ID of the calling
                        process.

SEE ALSO
     setpgid(2), tcgetpgrp(3), tcsetpgrp(3)

STANDARDS
     The setsid() system call is expected to be compliant with the IEEE Std
     1003.1-1990 ("POSIX.1") specification.

FreeBSD 13.1-RELEASE-p6          June 4, 1993          FreeBSD 13.1-RELEASE-p6