1  /* logname -- print user's login name
       2     Copyright (C) 1990-2023 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  }