whoami.c

/* whoami -- print effective userid
   Copyright (C) 89,90, 1991-1997, 1999-2002 Free Software Foundation, Inc.
 
   This program is free software; you can redistribute it and/or modify
   it under the terms of the GNU General Public License as published by
   the Free Software Foundation; either version 2, or (at your option)
   any later version.
 
   This program is distributed in the hope that it will be useful,
   but WITHOUT ANY WARRANTY; without even the implied warranty of
   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
   GNU General Public License for more details.
 
   You should have received a copy of the GNU General Public License
   along with this program; if not, write to the Free Software Foundation,
   Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.  */
 
/* Equivalent to `id -un'. */
/* Written by Richard Mlynarik. */
 
#include <config.h>
#include <stdio.h>
#include <sys/types.h>
#include <pwd.h>
#include <getopt.h>
 
#include "system.h"
#include "long-options.h"
#include "closeout.h"
 
/* The official name of this program (e.g., no `g' prefix).  */
#define PROGRAM_NAME "whoami"
 
#define AUTHORS "Richard Mlynarik"
 
/* The name this program was run with. */
char *program_name;
 
static struct option const long_options[] =
{
  {0, 0, 0, 0}
};
 
void
usage (int status)
{
  if (status != 0)
    fprintf (stderr, _("Try `%s --help' for more information.\n"),
         program_name);
  else
    {
      printf (_("Usage: %s [OPTION]...\n"), program_name);
      fputs (_("\
Print the user name associated with the current effective user id.\n\
Same as id -un.\n\
\n\
"), stdout);
      fputs (HELP_OPTION_DESCRIPTION, stdout);
      fputs (VERSION_OPTION_DESCRIPTION, stdout);
      printf (_("\nReport bugs to <%s>.\n"), PACKAGE_BUGREPORT);
    }
  exit (status);
}
 
int
main (int argc, char **argv)
{
  register struct passwd *pw;
  register uid_t uid;
  int c;
 
  program_name = argv[0];
  setlocale (LC_ALL, "");
  bindtextdomain (PACKAGE, LOCALEDIR);
  textdomain (PACKAGE);
 
  atexit (close_stdout);
 
  parse_long_options (argc, argv, PROGRAM_NAME, GNU_PACKAGE, VERSION,
              AUTHORS, usage);
 
  while ((c = getopt_long (argc, argv, "", long_options, NULL)) != -1)
    {
      switch (c)
    {
    case 0:
      break;
 
    default:
      usage (EXIT_FAILURE);
    }
    }
 
  if (optind != argc)
    usage (EXIT_FAILURE);
 
  uid = geteuid ();
  pw = getpwuid (uid);
  if (pw)
    {
      puts (pw->pw_name);
      exit (EXIT_SUCCESS);
    }
  fprintf (stderr, _("%s: cannot find username for UID %u\n"),
       program_name, (unsigned) uid);
  exit (EXIT_FAILURE);
}