setsid(2)                                                     setsid(2)

  setsid()

  NAME

    setsid() - create session and set process group ID

  SYNOPSIS

    #include 

    pid_t setsid(void)

  DESCRIPTION

    Setsid(2) 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(2) function 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(2) returns -1 and the global variable errno is
    set.

  ERRORS

    Setsid(2) can fail for the following reasons:

    [ENOMEM]
        Not enough free memory is available to create the session.

    [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(2)

    tcsetpgrp(2)

  USAGE NOTES

    The setsid function is thread safe.

    The setsid function is async-signal safe.