manual/examples/db.c

   1 /* User and Group Database Example
   2    Copyright (C) 1991-2014 Free Software Foundation, Inc.
   3
   4    This program is free software; you can redistribute it and/or
   5    modify it under the terms of the GNU General Public License
   6    as published by the Free Software Foundation; either version 2
   7    of the License, or (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, if not, see <http://www.gnu.org/licenses/>.
  16 */
  17
  18 #include <grp.h>
  19 #include <pwd.h>
  20 #include <sys/types.h>
  21 #include <unistd.h>
  22 #include <stdlib.h>
  23
  24 int
  25 main (void)
  26 {
  27   uid_t me;
  28   struct passwd *my_passwd;
  29   struct group *my_group;
  30   char **members;
  31
  32   /* Get information about the user ID. */
  33   me = getuid ();
  34   my_passwd = getpwuid (me);
  35   if (!my_passwd)
  36     {
  37       printf ("Couldn't find out about user %d.\n", (int) me);
  38       exit (EXIT_FAILURE);
  39     }
  40
  41   /* Print the information. */
  42   printf ("I am %s.\n", my_passwd->pw_gecos);
  43   printf ("My login name is %s.\n", my_passwd->pw_name);
  44   printf ("My uid is %d.\n", (int) (my_passwd->pw_uid));
  45   printf ("My home directory is %s.\n", my_passwd->pw_dir);
  46   printf ("My default shell is %s.\n", my_passwd->pw_shell);
  47
  48   /* Get information about the default group ID. */
  49   my_group = getgrgid (my_passwd->pw_gid);
  50   if (!my_group)
  51     {
  52       printf ("Couldn't find out about group %d.\n",
  53               (int) my_passwd->pw_gid);
  54       exit (EXIT_FAILURE);
  55     }
  56
  57   /* Print the information. */
  58   printf ("My default group is %s (%d).\n",
  59           my_group->gr_name, (int) (my_passwd->pw_gid));
  60   printf ("The members of this group are:\n");
  61   members = my_group->gr_mem;
  62   while (*members)
  63     {
  64       printf ("  %s\n", *(members));
  65       members++;
  66     }
  67
  68   return EXIT_SUCCESS;
  69 }