src/logname.c

   1 /* logname -- print user's login name
   2    Copyright (C) 1990-2022 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 "die.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     emit_try_help ();
  37   else
  38     {
  39       printf (_("Usage: %s [OPTION]\n"), program_name);
  40       fputs (_("\
  41 Print the user's login name.\n\
  42 \n\
  43 "), stdout);
  44       fputs (HELP_OPTION_DESCRIPTION, stdout);
  45       fputs (VERSION_OPTION_DESCRIPTION, stdout);
  46       emit_ancillary_info (PROGRAM_NAME);
  47     }
  48   exit (status);
  49 }
  50
  51 int
  52 main (int argc, char **argv)
  53 {
  54   char *cp;
  55
  56   initialize_main (&argc, &argv);
  57   set_program_name (argv[0]);
  58   setlocale (LC_ALL, "");
  59   bindtextdomain (PACKAGE, LOCALEDIR);
  60   textdomain (PACKAGE);
  61
  62   atexit (close_stdout);
  63
  64   parse_gnu_standard_options_only (argc, argv, PROGRAM_NAME, PACKAGE_NAME,
  65                                    Version, true, usage, AUTHORS,
  66                                    (char const *) NULL);
  67
  68   if (optind < argc)
  69     {
  70       error (0, 0, _("extra operand %s"), quote (argv[optind]));
  71       usage (EXIT_FAILURE);
  72     }
  73
  74   /* POSIX requires using getlogin (or equivalent code) and prohibits
  75      using a fallback technique.  */
  76   cp = getlogin ();
  77   if (! cp)
  78     die (EXIT_FAILURE, 0, _("no login name"));
  79
  80   puts (cp);
  81   return EXIT_SUCCESS;
  82 }