coreutils/nohup.c

   1 /* vi: set sw=4 ts=4: */
   2 /*
   3  * nohup - invoke a utility immune to hangups.
   4  *
   5  * Busybox version based on nohup specification at
   6  * http://www.opengroup.org/onlinepubs/007904975/utilities/nohup.html
   7  *
   8  * Copyright 2006 Rob Landley <rob@landley.net>
   9  * Copyright 2006 Bernhard Reutner-Fischer
  10  *
  11  * Licensed under GPLv2 or later, see file LICENSE in this source tree.
  12  */
  13 //config:config NOHUP
  14 //config:       bool "nohup (2 kb)"
  15 //config:       default y
  16 //config:       help
  17 //config:       run a command immune to hangups, with output to a non-tty.
  18
  19 //applet:IF_NOHUP(APPLET_NOEXEC(nohup, nohup, BB_DIR_USR_BIN, BB_SUID_DROP, nohup))
  20
  21 //kbuild:lib-$(CONFIG_NOHUP) += nohup.o
  22
  23 //usage:#define nohup_trivial_usage
  24 //usage:       "PROG ARGS"
  25 //usage:#define nohup_full_usage "\n\n"
  26 //usage:       "Run PROG immune to hangups, with output to a non-tty"
  27 //usage:
  28 //usage:#define nohup_example_usage
  29 //usage:       "$ nohup make &"
  30
  31 #include "libbb.h"
  32
  33 /* Compat info: nohup (GNU coreutils 6.8) does this:
  34 # nohup true
  35 nohup: ignoring input and appending output to 'nohup.out'
  36 # nohup true 1>/dev/null
  37 nohup: ignoring input and redirecting stderr to stdout
  38 # nohup true 2>zz
  39 # cat zz
  40 nohup: ignoring input and appending output to 'nohup.out'
  41 # nohup true 2>zz 1>/dev/null
  42 # cat zz
  43 nohup: ignoring input
  44 # nohup true </dev/null 1>/dev/null
  45 nohup: redirecting stderr to stdout
  46 # nohup true </dev/null 2>zz 1>/dev/null
  47 # cat zz
  48   (nothing)
  49 #
  50 */
  51
  52 int nohup_main(int argc, char **argv) MAIN_EXTERNALLY_VISIBLE;
  53 int nohup_main(int argc UNUSED_PARAM, char **argv)
  54 {
  55         const char *nohupout;
  56         char *home;
  57
  58         xfunc_error_retval = 127;
  59
  60         if (!argv[1]) {
  61                 bb_show_usage();
  62         }
  63
  64         /* If stdin is a tty, detach from it. */
  65         if (isatty(STDIN_FILENO)) {
  66                 /* bb_error_msg("ignoring input"); */
  67                 close(STDIN_FILENO);
  68                 xopen(bb_dev_null, O_RDONLY); /* will be fd 0 (STDIN_FILENO) */
  69         }
  70
  71         nohupout = "nohup.out";
  72         /* Redirect stdout to nohup.out, either in "." or in "$HOME". */
  73         if (isatty(STDOUT_FILENO)) {
  74                 close(STDOUT_FILENO);
  75                 if (open(nohupout, O_CREAT|O_WRONLY|O_APPEND, S_IRUSR|S_IWUSR) < 0) {
  76                         home = getenv("HOME");
  77                         if (home) {
  78                                 nohupout = concat_path_file(home, nohupout);
  79                                 xopen3(nohupout, O_CREAT|O_WRONLY|O_APPEND, S_IRUSR|S_IWUSR);
  80                         } else {
  81                                 xopen(bb_dev_null, O_RDONLY); /* will be fd 1 */
  82                         }
  83                 }
  84                 bb_error_msg("appending output to %s", nohupout);
  85         }
  86
  87         /* If we have a tty on stderr, redirect to stdout. */
  88         if (isatty(STDERR_FILENO)) {
  89                 /* if (stdout_wasnt_a_tty)
  90                         bb_error_msg("redirecting stderr to stdout"); */
  91                 dup2(STDOUT_FILENO, STDERR_FILENO);
  92         }
  93
  94         signal(SIGHUP, SIG_IGN);
  95
  96         argv++;
  97         BB_EXECVP_or_die(argv);
  98 }