src/whoami.c

   1 /* whoami -- print effective userid
   2
   3    Copyright (C) 89,90, 1991-1997, 1999-2002, 2004, 2005, 2007 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 3 of the License, or
   9    (at your option) 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, see <http://www.gnu.org/licenses/>.  */
  18
  19 /* Equivalent to `id -un'. */
  20 /* Written by Richard Mlynarik. */
  21
  22 #include <config.h>
  23 #include <stdio.h>
  24 #include <sys/types.h>
  25 #include <pwd.h>
  26 #include <getopt.h>
  27
  28 #include "system.h"
  29 #include "error.h"
  30 #include "long-options.h"
  31 #include "quote.h"
  32
  33 /* The official name of this program (e.g., no `g' prefix).  */
  34 #define PROGRAM_NAME "whoami"
  35
  36 #define AUTHORS "Richard Mlynarik"
  37
  38 /* The name this program was run with. */
  39 char *program_name;
  40
  41 void
  42 usage (int status)
  43 {
  44   if (status != EXIT_SUCCESS)
  45     fprintf (stderr, _("Try `%s --help' for more information.\n"),
  46              program_name);
  47   else
  48     {
  49       printf (_("Usage: %s [OPTION]...\n"), program_name);
  50       fputs (_("\
  51 Print the user name associated with the current effective user ID.\n\
  52 Same as id -un.\n\
  53 \n\
  54 "), stdout);
  55       fputs (HELP_OPTION_DESCRIPTION, stdout);
  56       fputs (VERSION_OPTION_DESCRIPTION, stdout);
  57       emit_bug_reporting_address ();
  58     }
  59   exit (status);
  60 }
  61
  62 int
  63 main (int argc, char **argv)
  64 {
  65   struct passwd *pw;
  66   uid_t uid;
  67
  68   initialize_main (&argc, &argv);
  69   program_name = argv[0];
  70   setlocale (LC_ALL, "");
  71   bindtextdomain (PACKAGE, LOCALEDIR);
  72   textdomain (PACKAGE);
  73
  74   atexit (close_stdout);
  75
  76   parse_long_options (argc, argv, PROGRAM_NAME, PACKAGE_NAME, VERSION,
  77                       usage, AUTHORS, (char const *) NULL);
  78   if (getopt_long (argc, argv, "", NULL, NULL) != -1)
  79     usage (EXIT_FAILURE);
  80
  81   if (optind != argc)
  82     {
  83       error (0, 0, _("extra operand %s"), quote (argv[optind]));
  84       usage (EXIT_FAILURE);
  85     }
  86
  87   uid = geteuid ();
  88   pw = getpwuid (uid);
  89   if (pw)
  90     {
  91       puts (pw->pw_name);
  92       exit (EXIT_SUCCESS);
  93     }
  94   fprintf (stderr, _("%s: cannot find name for user ID %lu\n"),
  95            program_name, (unsigned long int) uid);
  96   exit (EXIT_FAILURE);
  97 }