src/whoami.c

   1 /* whoami -- print effective userid
   2
   3    Copyright (C) 89,90, 1991-1997, 1999-2002, 2004 Free Software
   4    Foundation, Inc.
   5
   6    This program is free software; you can redistribute it and/or modify
   7    it under the terms of the GNU General Public License as published by
   8    the Free Software Foundation; either version 2, or (at your option)
   9    any later version.
  10
  11    This program is distributed in the hope that it will be useful,
  12    but WITHOUT ANY WARRANTY; without even the implied warranty of
  13    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  14    GNU General Public License for more details.
  15
  16    You should have received a copy of the GNU General Public License
  17    along with this program; if not, write to the Free Software Foundation,
  18    Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.  */
  19
  20 /* Equivalent to `id -un'. */
  21 /* Written by Richard Mlynarik. */
  22
  23 #include <config.h>
  24 #include <stdio.h>
  25 #include <sys/types.h>
  26 #include <pwd.h>
  27 #include <getopt.h>
  28
  29 #include "system.h"
  30 #include "long-options.h"
  31
  32 /* The official name of this program (e.g., no `g' prefix).  */
  33 #define PROGRAM_NAME "whoami"
  34
  35 #define AUTHORS "Richard Mlynarik"
  36
  37 /* The name this program was run with. */
  38 char *program_name;
  39
  40 static struct option const long_options[] =
  41 {
  42   {0, 0, 0, 0}
  43 };
  44
  45 void
  46 usage (int status)
  47 {
  48   if (status != EXIT_SUCCESS)
  49     fprintf (stderr, _("Try `%s --help' for more information.\n"),
  50              program_name);
  51   else
  52     {
  53       printf (_("Usage: %s [OPTION]...\n"), program_name);
  54       fputs (_("\
  55 Print the user name associated with the current effective user id.\n\
  56 Same as id -un.\n\
  57 \n\
  58 "), stdout);
  59       fputs (HELP_OPTION_DESCRIPTION, stdout);
  60       fputs (VERSION_OPTION_DESCRIPTION, stdout);
  61       printf (_("\nReport bugs to <%s>.\n"), PACKAGE_BUGREPORT);
  62     }
  63   exit (status);
  64 }
  65
  66 int
  67 main (int argc, char **argv)
  68 {
  69   register struct passwd *pw;
  70   register uid_t uid;
  71   int c;
  72
  73   initialize_main (&argc, &argv);
  74   program_name = argv[0];
  75   setlocale (LC_ALL, "");
  76   bindtextdomain (PACKAGE, LOCALEDIR);
  77   textdomain (PACKAGE);
  78
  79   atexit (close_stdout);
  80
  81   parse_long_options (argc, argv, PROGRAM_NAME, GNU_PACKAGE, VERSION,
  82                       usage, AUTHORS, (char const *) NULL);
  83
  84   while ((c = getopt_long (argc, argv, "", long_options, NULL)) != -1)
  85     {
  86       switch (c)
  87         {
  88         case 0:
  89           break;
  90
  91         default:
  92           usage (EXIT_FAILURE);
  93         }
  94     }
  95
  96   if (optind != argc)
  97     usage (EXIT_FAILURE);
  98
  99   uid = geteuid ();
 100   pw = getpwuid (uid);
 101   if (pw)
 102     {
 103       puts (pw->pw_name);
 104       exit (EXIT_SUCCESS);
 105     }
 106   fprintf (stderr, _("%s: cannot find username for UID %u\n"),
 107            program_name, (unsigned) uid);
 108   exit (EXIT_FAILURE);
 109 }