src/logname.c

   1 /* logname -- print user's login name
   2    Copyright (C) 1990-2019 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 <https://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 "die.h"
  24 #include "error.h"
  25 #include "long-options.h"
  26 #include "quote.h"
  27
  28 /* The official name of this program (e.g., no 'g' prefix).  */
  29 #define PROGRAM_NAME "logname"
  30
  31 #define AUTHORS proper_name ("FIXME: unknown")
  32
  33 static struct option const long_options[] =
  34 {
  35   {NULL, 0, NULL, 0}
  36 };
  37
  38 void
  39 usage (int status)
  40 {
  41   if (status != EXIT_SUCCESS)
  42     emit_try_help ();
  43   else
  44     {
  45       printf (_("Usage: %s [OPTION]\n"), program_name);
  46       fputs (_("\
  47 Print the name of the current user.\n\
  48 \n\
  49 "), stdout);
  50       fputs (HELP_OPTION_DESCRIPTION, stdout);
  51       fputs (VERSION_OPTION_DESCRIPTION, stdout);
  52       emit_ancillary_info (PROGRAM_NAME);
  53     }
  54   exit (status);
  55 }
  56
  57 int
  58 main (int argc, char **argv)
  59 {
  60   char *cp;
  61
  62   initialize_main (&argc, &argv);
  63   set_program_name (argv[0]);
  64   setlocale (LC_ALL, "");
  65   bindtextdomain (PACKAGE, LOCALEDIR);
  66   textdomain (PACKAGE);
  67
  68   atexit (close_stdout);
  69
  70   parse_long_options (argc, argv, PROGRAM_NAME, PACKAGE_NAME, Version,
  71                       usage, AUTHORS, (char const *) NULL);
  72   if (getopt_long (argc, argv, "", long_options, NULL) != -1)
  73     usage (EXIT_FAILURE);
  74
  75   if (optind < argc)
  76     {
  77       error (0, 0, _("extra operand %s"), quote (argv[optind]));
  78       usage (EXIT_FAILURE);
  79     }
  80
  81   /* POSIX requires using getlogin (or equivalent code) and prohibits
  82      using a fallback technique.  */
  83   cp = getlogin ();
  84   if (! cp)
  85     die (EXIT_FAILURE, 0, _("no login name"));
  86
  87   puts (cp);
  88   return EXIT_SUCCESS;
  89 }