src/whoami.c

   1 /* whoami -- print effective userid
   2    Copyright (C) 89,90, 1991-1997, 1999, 2000, 2001 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 #include "long-options.h"
  29 #include "closeout.h"
  30
  31 /* The official name of this program (e.g., no `g' prefix).  */
  32 #define PROGRAM_NAME "whoami"
  33
  34 #define AUTHORS "Richard Mlynarik"
  35
  36 /* The name this program was run with. */
  37 char *program_name;
  38
  39 static struct option const long_options[] =
  40 {
  41   {0, 0, 0, 0}
  42 };
  43
  44 void
  45 usage (int status)
  46 {
  47   if (status != 0)
  48     fprintf (stderr, _("Try `%s --help' for more information.\n"),
  49              program_name);
  50   else
  51     {
  52       printf (_("Usage: %s [OPTION]...\n"), program_name);
  53       fputs (_("\
  54 Print the user name associated with the current effective user id.\n\
  55 Same as id -un.\n\
  56 \n\
  57 "), stdout);
  58       fputs (HELP_OPTION_DESCRIPTION, stdout);
  59       fputs (VERSION_OPTION_DESCRIPTION, stdout);
  60       printf (_("\nReport bugs to <%s>.\n"), PACKAGE_BUGREPORT);
  61     }
  62   exit (status);
  63 }
  64
  65 int
  66 main (int argc, char **argv)
  67 {
  68   register struct passwd *pw;
  69   register uid_t uid;
  70   int c;
  71
  72   program_name = argv[0];
  73   setlocale (LC_ALL, "");
  74   bindtextdomain (PACKAGE, LOCALEDIR);
  75   textdomain (PACKAGE);
  76
  77   atexit (close_stdout);
  78
  79   parse_long_options (argc, argv, PROGRAM_NAME, GNU_PACKAGE, VERSION,
  80                       AUTHORS, usage);
  81
  82   while ((c = getopt_long (argc, argv, "", long_options, NULL)) != -1)
  83     {
  84       switch (c)
  85         {
  86         case 0:
  87           break;
  88
  89         default:
  90           usage (1);
  91         }
  92     }
  93
  94   if (optind != argc)
  95     usage (1);
  96
  97   uid = geteuid ();
  98   pw = getpwuid (uid);
  99   if (pw)
 100     {
 101       puts (pw->pw_name);
 102       exit (0);
 103     }
 104   fprintf (stderr, _("%s: cannot find username for UID %u\n"),
 105            program_name, (unsigned) uid);
 106   exit (1);
 107 }