src/whoami.c

   1 /* whoami -- print effective userid
   2    Copyright (C) 89, 90, 91, 92, 93, 94, 95, 1996 Free Software Foundation, Inc.
   3
   4    This program is free software; you can redistribute it and/or modify
   5    it under the terms of the GNU General Public License as published by
   6    the Free Software Foundation; either version 2, or (at your option)
   7    any later version.
   8
   9    This program is distributed in the hope that it will be useful,
  10    but WITHOUT ANY WARRANTY; without even the implied warranty of
  11    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  12    GNU General Public License for more details.
  13
  14    You should have received a copy of the GNU General Public License
  15    along with this program; if not, write to the Free Software Foundation,
  16    Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.  */
  17
  18 /* Equivalent to `id -un'. */
  19 /* Written by Richard Mlynarik. */
  20
  21 #include <config.h>
  22 #include <stdio.h>
  23 #include <sys/types.h>
  24 #include <pwd.h>
  25 #include <getopt.h>
  26
  27 #include "system.h"
  28
  29 /* The name this program was run with. */
  30 char *program_name;
  31
  32 /* If nonzero, display usage information and exit.  */
  33 static int show_help;
  34
  35 /* If nonzero, print the version on standard output and exit.  */
  36 static int show_version;
  37
  38 static struct option const long_options[] =
  39 {
  40   {"help", no_argument, &show_help, 1},
  41   {"version", no_argument, &show_version, 1},
  42   {0, 0, 0, 0}
  43 };
  44
  45 static void
  46 usage (int status)
  47 {
  48   if (status != 0)
  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       printf (_("\
  55 Print the user name associated with the current effective user id.\n\
  56 Same as id -un.\n\
  57 \n\
  58   --help      display this help and exit\n\
  59   --version   output version information and exit\n"));
  60     }
  61   exit (status);
  62 }
  63
  64 int
  65 main (int argc, char **argv)
  66 {
  67   register struct passwd *pw;
  68   register uid_t uid;
  69   int c;
  70
  71   program_name = argv[0];
  72   setlocale (LC_ALL, "");
  73   bindtextdomain (PACKAGE, LOCALEDIR);
  74   textdomain (PACKAGE);
  75
  76   while ((c = getopt_long (argc, argv, "", long_options, (int *) 0)) != EOF)
  77     {
  78       switch (c)
  79         {
  80         case 0:
  81           break;
  82
  83         default:
  84           usage (1);
  85         }
  86     }
  87
  88   if (show_version)
  89     {
  90       printf ("whoami - %s\n", PACKAGE_VERSION);
  91       exit (0);
  92     }
  93
  94   if (show_help)
  95     usage (0);
  96
  97
  98   if (optind != argc)
  99     usage (1);
 100
 101   uid = geteuid ();
 102   pw = getpwuid (uid);
 103   if (pw)
 104     {
 105       puts (pw->pw_name);
 106       exit (0);
 107     }
 108   fprintf (stderr, _("%s: cannot find username for UID %u\n"),
 109            program_name, (unsigned) uid);
 110   exit (1);
 111 }