/* User and Group Database Example

   Copyright (C) 1991-2018 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

   of the License, 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, if not, see <http://www.gnu.org/licenses/>.

*/

#include <grp.h>

#include <pwd.h>

#include <sys/types.h>

#include <unistd.h>

#include <stdlib.h>

int

main (void)

{

  uid_t me;

  struct passwd *my_passwd;

  struct group *my_group;

  char **members;

  /* Get information about the user ID. */

  me = getuid ();

  my_passwd = getpwuid (me);

  if (!my_passwd)

    {

      printf ("Couldn't find out about user %d.\n", (int) me);

      exit (EXIT_FAILURE);

    }

  /* Print the information. */

  printf ("I am %s.\n", my_passwd->pw_gecos);

  printf ("My login name is %s.\n", my_passwd->pw_name);

  printf ("My uid is %d.\n", (int) (my_passwd->pw_uid));

  printf ("My home directory is %s.\n", my_passwd->pw_dir);

  printf ("My default shell is %s.\n", my_passwd->pw_shell);

  /* Get information about the default group ID. */

  my_group = getgrgid (my_passwd->pw_gid);

  if (!my_group)

    {

      printf ("Couldn't find out about group %d.\n",

	      (int) my_passwd->pw_gid);

      exit (EXIT_FAILURE);

    }

  /* Print the information. */

  printf ("My default group is %s (%d).\n",

	  my_group->gr_name, (int) (my_passwd->pw_gid));

  printf ("The members of this group are:\n");

  members = my_group->gr_mem;

  while (*members)

    {

      printf ("  %s\n", *(members));

      members++;

    }

  return EXIT_SUCCESS;

}