sys-utils/setsid.c

   1 /*
   2  * setsid.c -- execute a command in a new session
   3  * Rick Sladkey <jrs@world.std.com>
   4  * In the public domain.
   5  *
   6  * 1999-02-22 Arkadiusz Mi¶kiewicz <misiek@pld.ORG.PL>
   7  * - added Native Language Support
   8  *
   9  * 2001-01-18 John Fremlin <vii@penguinpowered.com>
  10  * - fork in case we are process group leader
  11  *
  12  */
  13
  14 #include <getopt.h>
  15 #include <stdio.h>
  16 #include <stdlib.h>
  17 #include <unistd.h>
  18 #include <sys/ioctl.h>
  19
  20 #include "c.h"
  21 #include "nls.h"
  22 #include "closestream.h"
  23
  24 static void __attribute__ ((__noreturn__)) usage(FILE * out)
  25 {
  26         fputs(USAGE_HEADER, out);
  27         fprintf(out, _(
  28                 " %s [options] <program> [arguments ...]\n"),
  29                 program_invocation_short_name);
  30
  31         fputs(USAGE_OPTIONS, out);
  32         fputs(_(" -c, --ctty     set the controlling terminal to the current one\n"),
  33                 out);
  34
  35         fputs(USAGE_HELP, out);
  36         fputs(USAGE_VERSION, out);
  37
  38         fprintf(out, USAGE_MAN_TAIL("setsid(1)"));
  39         exit(out == stderr ? EXIT_FAILURE : EXIT_SUCCESS);
  40 }
  41
  42 int main(int argc, char **argv)
  43 {
  44         int ch;
  45         int ctty = 0;
  46
  47         static const struct option longopts[] = {
  48                 {"ctty", no_argument, NULL, 'c'},
  49                 {"version", no_argument, NULL, 'V'},
  50                 {"help", no_argument, NULL, 'h'},
  51                 {NULL, 0, NULL, 0}
  52         };
  53
  54         setlocale(LC_ALL, "");
  55         bindtextdomain(PACKAGE, LOCALEDIR);
  56         textdomain(PACKAGE);
  57         atexit(close_stdout);
  58
  59         while ((ch = getopt_long(argc, argv, "+Vhc", longopts, NULL)) != -1)
  60                 switch (ch) {
  61                 case 'V':
  62                         printf(UTIL_LINUX_VERSION);
  63                         return EXIT_SUCCESS;
  64                 case 'c':
  65                         ctty=1;
  66                         break;
  67                 case 'h':
  68                         usage(stdout);
  69                 default:
  70                         usage(stderr);
  71                 }
  72
  73         if (argc < 2)
  74                 usage(stderr);
  75
  76         if (getpgrp() == getpid()) {
  77                 switch (fork()) {
  78                 case -1:
  79                         err(EXIT_FAILURE, _("fork"));
  80                 case 0:
  81                         /* child */
  82                         break;
  83                 default:
  84                         /* parent */
  85                         return 0;
  86                 }
  87         }
  88         if (setsid() < 0)
  89                 /* cannot happen */
  90                 err(EXIT_FAILURE, _("setsid failed"));
  91
  92         if (ctty) {
  93                 if (ioctl(STDIN_FILENO, TIOCSCTTY, 1))
  94                         warn(_("failed to set the controlling terminal"));
  95         }
  96         execvp(argv[optind], argv + optind);
  97         err(EXIT_FAILURE, _("execvp failed"));
  98 }