src/whoami.c

   1 /* whoami -- print effective userid
   2
   3    Copyright (C) 89,90, 1991-1997, 1999-2002, 2004, 2005 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., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, 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 "error.h"
  31 #include "long-options.h"
  32 #include "quote.h"
  33
  34 /* The official name of this program (e.g., no `g' prefix).  */
  35 #define PROGRAM_NAME "whoami"
  36
  37 #define AUTHORS "Richard Mlynarik"
  38
  39 /* The name this program was run with. */
  40 char *program_name;
  41
  42 void
  43 usage (int status)
  44 {
  45   if (status != EXIT_SUCCESS)
  46     fprintf (stderr, _("Try `%s --help' for more information.\n"),
  47              program_name);
  48   else
  49     {
  50       printf (_("Usage: %s [OPTION]...\n"), program_name);
  51       fputs (_("\
  52 Print the user name associated with the current effective user ID.\n\
  53 Same as id -un.\n\
  54 \n\
  55 "), stdout);
  56       fputs (HELP_OPTION_DESCRIPTION, stdout);
  57       fputs (VERSION_OPTION_DESCRIPTION, stdout);
  58       printf (_("\nReport bugs to <%s>.\n"), PACKAGE_BUGREPORT);
  59     }
  60   exit (status);
  61 }
  62
  63 int
  64 main (int argc, char **argv)
  65 {
  66   struct passwd *pw;
  67   uid_t uid;
  68
  69   initialize_main (&argc, &argv);
  70   program_name = argv[0];
  71   setlocale (LC_ALL, "");
  72   bindtextdomain (PACKAGE, LOCALEDIR);
  73   textdomain (PACKAGE);
  74
  75   atexit (close_stdout);
  76
  77   parse_long_options (argc, argv, PROGRAM_NAME, GNU_PACKAGE, VERSION,
  78                       usage, AUTHORS, (char const *) NULL);
  79   if (getopt_long (argc, argv, "", NULL, NULL) != -1)
  80     usage (EXIT_FAILURE);
  81
  82   if (optind != argc)
  83     {
  84       error (0, 0, _("extra operand %s"), quote (argv[optind]));
  85       usage (EXIT_FAILURE);
  86     }
  87
  88   uid = geteuid ();
  89   pw = getpwuid (uid);
  90   if (pw)
  91     {
  92       puts (pw->pw_name);
  93       exit (EXIT_SUCCESS);
  94     }
  95   fprintf (stderr, _("%s: cannot find name for user ID %lu\n"),
  96            program_name, (unsigned long int) uid);
  97   exit (EXIT_FAILURE);
  98 }