source: MondoRescue/branches/stable/mindi-busybox/coreutils/tty.c@ 1247

/* vi: set sw=4 ts=4: */
/*
 * tty implementation for busybox
 *
 * Copyright (C) 2003  Manuel Novoa III  <mjn3@codepoet.org>
 *
 * This program is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation; either version 2 of the License, or
 * (at your option) any later version.
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
 * General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program; if not, write to the Free Software
 * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
 *
 */

/* BB_AUDIT SUSv3 compliant */
/* http://www.opengroup.org/onlinepubs/007904975/utilities/tty.html */

#include <stdio.h>
#include <stdlib.h>
#include <unistd.h>
#include "busybox.h"

int tty_main(int argc, char **argv)
{
    const char *s;
    int silent;     /* Note: No longer relevant in SUSv3. */
    int retval;

    bb_default_error_retval = 2;    /* SUSv3 requires > 1 for error. */

    silent = bb_getopt_ulflags(argc, argv, "s");

    /* gnu tty outputs a warning that it is ignoring all args. */
    bb_warn_ignoring_args(argc - optind);

    retval = 0;

    if ((s = ttyname(0)) == NULL) {
    /* According to SUSv3, ttyname can on fail with EBADF or ENOTTY.
     * We know the file descriptor is good, so failure means not a tty. */
        s = "not a tty";
        retval = 1;
    }

    if (!silent) {
        puts(s);
    }

    bb_fflush_stdout_and_exit(retval);
}