1  #include <grp.h>
       2  #include <pwd.h>
       3  #include <sys/types.h>
       4  #include <unistd.h>
       5  #include <stdlib.h>
       6  #include <stdio.h>
       7  
       8  int
       9  main (int argc, char *argv[])
      10  {
      11    uid_t me;
      12    struct passwd *my_passwd;
      13    struct group *my_group = NULL;
      14    char **members;
      15  
      16    me = getuid ();
      17    my_passwd = getpwuid (me);
      18    if (my_passwd == NULL)
      19      printf ("Cannot find user entry for UID %d\n", me);
      20    else
      21      {
      22        printf ("My login name is %s.\n", my_passwd->pw_name);
      23        printf ("My uid is %d.\n", (int)(my_passwd->pw_uid));
      24        printf ("My home directory is %s.\n", my_passwd->pw_dir);
      25        printf ("My default shell is %s.\n", my_passwd->pw_shell);
      26  
      27        my_group = getgrgid (my_passwd->pw_gid);
      28        if (my_group == NULL)
      29  	printf ("No data for group %d found\n", my_passwd->pw_gid);
      30        else
      31  	{
      32  	  printf ("My default group is %s (%d).\n",
      33  		  my_group->gr_name, (int)(my_passwd->pw_gid));
      34  	  printf ("The members of this group are:\n");
      35  	  for (members = my_group->gr_mem; *members != NULL; ++members)
      36  	    printf ("  %s\n", *members);
      37  	}
      38      }
      39  
      40    return my_passwd && my_group ? EXIT_SUCCESS : EXIT_FAILURE;
      41  }