src/logname.c

   1 /* logname -- print user's login name
   2    Copyright (C) 1990-2024 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
  21 #include "system.h"
  22 #include "long-options.h"
  23 #include "quote.h"
  24
  25 /* The official name of this program (e.g., no 'g' prefix).  */
  26 #define PROGRAM_NAME "logname"
  27
  28 #define AUTHORS proper_name ("FIXME: unknown")
  29
  30 void
  31 usage (int status)
  32 {
  33   if (status != EXIT_SUCCESS)
  34     emit_try_help ();
  35   else
  36     {
  37       printf (_("Usage: %s [OPTION]\n"), program_name);
  38       fputs (_("\
  39 Print the user's login name.\n\
  40 \n\
  41 "), stdout);
  42       fputs (HELP_OPTION_DESCRIPTION, stdout);
  43       fputs (VERSION_OPTION_DESCRIPTION, stdout);
  44       emit_ancillary_info (PROGRAM_NAME);
  45     }
  46   exit (status);
  47 }
  48
  49 int
  50 main (int argc, char **argv)
  51 {
  52   char *cp;
  53
  54   initialize_main (&argc, &argv);
  55   set_program_name (argv[0]);
  56   setlocale (LC_ALL, "");
  57   bindtextdomain (PACKAGE, LOCALEDIR);
  58   textdomain (PACKAGE);
  59
  60   atexit (close_stdout);
  61
  62   parse_gnu_standard_options_only (argc, argv, PROGRAM_NAME, PACKAGE_NAME,
  63                                    Version, true, usage, AUTHORS,
  64                                    (char const *) nullptr);
  65
  66   if (optind < argc)
  67     {
  68       error (0, 0, _("extra operand %s"), quote (argv[optind]));
  69       usage (EXIT_FAILURE);
  70     }
  71
  72   /* POSIX requires using getlogin (or equivalent code) and prohibits
  73      using a fallback technique.  */
  74   cp = getlogin ();
  75   if (! cp)
  76     error (EXIT_FAILURE, 0, _("no login name"));
  77
  78   puts (cp);
  79   return EXIT_SUCCESS;
  80 }