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| <h3 class="section">29.15 User and Group Database Example</h3> |
| |
| <p>Here is an example program showing the use of the system database inquiry |
| functions. The program prints some information about the user running |
| the program. |
| |
| <pre class="smallexample"> #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; |
| |
| /* <span class="roman">Get information about the user ID.</span> */ |
| me = getuid (); |
| my_passwd = getpwuid (me); |
| if (!my_passwd) |
| { |
| printf ("Couldn't find out about user %d.\n", (int) me); |
| exit (EXIT_FAILURE); |
| } |
| |
| /* <span class="roman">Print the information.</span> */ |
| 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); |
| |
| /* <span class="roman">Get information about the default group ID.</span> */ |
| 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); |
| } |
| |
| /* <span class="roman">Print the information.</span> */ |
| 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; |
| } |
| </pre> |
| <p>Here is some output from this program: |
| |
| <pre class="smallexample"> I am Throckmorton Snurd. |
| My login name is snurd. |
| My uid is 31093. |
| My home directory is /home/fsg/snurd. |
| My default shell is /bin/sh. |
| My default group is guest (12). |
| The members of this group are: |
| friedman |
| tami |
| </pre> |
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