src/logname.c

   1 /* logname -- print user's login name
   2    Copyright (C) 1990-1997, 1999-2005, 2007-2011 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 3 of the License, or
   7    (at your option) 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, see <http://www.gnu.org/licenses/>.  */
  16
  17 #include <config.h>
  18 #include <stdio.h>
  19 #include <sys/types.h>
  20 #include <getopt.h>
  21
  22 #include "system.h"
  23 #include "error.h"
  24 #include "long-options.h"
  25 #include "quote.h"
  26
  27 /* The official name of this program (e.g., no `g' prefix).  */
  28 #define PROGRAM_NAME "logname"
  29
  30 #define AUTHORS proper_name ("FIXME: unknown")
  31
  32 void
  33 usage (int status)
  34 {
  35   if (status != EXIT_SUCCESS)
  36     fprintf (stderr, _("Try `%s --help' for more information.\n"),
  37              program_name);
  38   else
  39     {
  40       printf (_("Usage: %s [OPTION]\n"), program_name);
  41       fputs (_("\
  42 Print the name of the current user.\n\
  43 \n\
  44 "), stdout);
  45       fputs (HELP_OPTION_DESCRIPTION, stdout);
  46       fputs (VERSION_OPTION_DESCRIPTION, stdout);
  47       emit_ancillary_info ();
  48     }
  49   exit (status);
  50 }
  51
  52 int
  53 main (int argc, char **argv)
  54 {
  55   char *cp;
  56
  57   initialize_main (&argc, &argv);
  58   set_program_name (argv[0]);
  59   setlocale (LC_ALL, "");
  60   bindtextdomain (PACKAGE, LOCALEDIR);
  61   textdomain (PACKAGE);
  62
  63   atexit (close_stdout);
  64
  65   parse_long_options (argc, argv, PROGRAM_NAME, PACKAGE_NAME, Version,
  66                       usage, AUTHORS, (char const *) NULL);
  67   if (getopt_long (argc, argv, "", NULL, NULL) != -1)
  68     usage (EXIT_FAILURE);
  69
  70   if (optind < argc)
  71     {
  72       error (0, 0, _("extra operand %s"), quote (argv[optind]));
  73       usage (EXIT_FAILURE);
  74     }
  75
  76   /* POSIX requires using getlogin (or equivalent code).  */
  77   cp = getlogin ();
  78   if (cp)
  79     {
  80       puts (cp);
  81       exit (EXIT_SUCCESS);
  82     }
  83   /* POSIX prohibits using a fallback technique.  */
  84
  85   error (0, 0, _("no login name"));
  86   exit (EXIT_FAILURE);
  87 }