source: MondoRescue/branches/3.2/mindi-busybox/coreutils/nohup.c@ 3274

/* vi: set sw=4 ts=4: */
/* nohup - invoke a utility immune to hangups.
 *
 * Busybox version based on nohup specification at
 * http://www.opengroup.org/onlinepubs/007904975/utilities/nohup.html
 *
 * Copyright 2006 Rob Landley <rob@landley.net>
 * Copyright 2006 Bernhard Reutner-Fischer
 *
 * Licensed under GPLv2 or later, see file LICENSE in this source tree.
 */

//usage:#define nohup_trivial_usage
//usage:       "PROG ARGS"
//usage:#define nohup_full_usage "\n\n"
//usage:       "Run PROG immune to hangups, with output to a non-tty"
//usage:
//usage:#define nohup_example_usage
//usage:       "$ nohup make &"

#include "libbb.h"

/* Compat info: nohup (GNU coreutils 6.8) does this:
# nohup true
nohup: ignoring input and appending output to `nohup.out'
# nohup true 1>/dev/null
nohup: ignoring input and redirecting stderr to stdout
# nohup true 2>zz
# cat zz
nohup: ignoring input and appending output to `nohup.out'
# nohup true 2>zz 1>/dev/null
# cat zz
nohup: ignoring input
# nohup true </dev/null 1>/dev/null
nohup: redirecting stderr to stdout
# nohup true </dev/null 2>zz 1>/dev/null
# cat zz
  (nothing)
#
*/

int nohup_main(int argc, char **argv) MAIN_EXTERNALLY_VISIBLE;
int nohup_main(int argc UNUSED_PARAM, char **argv)
{
    const char *nohupout;
    char *home;

    xfunc_error_retval = 127;

    if (!argv[1]) {
        bb_show_usage();
    }

    /* If stdin is a tty, detach from it. */
    if (isatty(STDIN_FILENO)) {
        /* bb_error_msg("ignoring input"); */
        close(STDIN_FILENO);
        xopen(bb_dev_null, O_RDONLY); /* will be fd 0 (STDIN_FILENO) */
    }

    nohupout = "nohup.out";
    /* Redirect stdout to nohup.out, either in "." or in "$HOME". */
    if (isatty(STDOUT_FILENO)) {
        close(STDOUT_FILENO);
        if (open(nohupout, O_CREAT|O_WRONLY|O_APPEND, S_IRUSR|S_IWUSR) < 0) {
            home = getenv("HOME");
            if (home) {
                nohupout = concat_path_file(home, nohupout);
                xopen3(nohupout, O_CREAT|O_WRONLY|O_APPEND, S_IRUSR|S_IWUSR);
            } else {
                xopen(bb_dev_null, O_RDONLY); /* will be fd 1 */
            }
        }
        bb_error_msg("appending output to %s", nohupout);
    }

    /* If we have a tty on stderr, redirect to stdout. */
    if (isatty(STDERR_FILENO)) {
        /* if (stdout_wasnt_a_tty)
            bb_error_msg("redirecting stderr to stdout"); */
        dup2(STDOUT_FILENO, STDERR_FILENO);
    }

    signal(SIGHUP, SIG_IGN);

    argv++;
    BB_EXECVP_or_die(argv);
}