/*************************************************************************\
*                  Copyright (C) Michael Kerrisk, 2026.                   *
*                                                                         *
* This program is free software. You may use, modify, and redistribute it *
* under the terms of the GNU General Public License as published by the   *
* Free Software Foundation, either version 3 or (at your option) any      *
* later version. This program is distributed without any warranty.  See   *
* the file COPYING.gpl-v3 for details.                                    *
\*************************************************************************/

/* t_setsid.c

   Demonstrate the use of setsid(2) to start a new session.
*/
#if ! defined(_XOPEN_SOURCE) || _XOPEN_SOURCE < 500
#define _XOPEN_SOURCE 500
#endif
#include <unistd.h>
#include <fcntl.h>
#include "tlpi_hdr.h"

int
main(int argc, char *argv[])
{
    if (fork() != 0)            /* Exit if parent, or on error */
        _exit(EXIT_SUCCESS);

    if (setsid() == -1)
        errExit("setsid");

    printf("PID=%ld, PGID=%ld, SID=%ld\n", (long) getpid(),
            (long) getpgrp(), (long) getsid(0));

    /* Following should fail, since we don't have a controlling terminal */

    if (open("/dev/tty", O_RDWR) == -1)
        errExit("open /dev/tty");
    exit(EXIT_SUCCESS);
}