This section describes all about how to search and scan the database of registered users. The database itself is kept in the file `/etc/passwd' on most systems, but on some systems a special network server gives access to it.
| User Data Structure | What each user record contains. |
| Lookup User | How to look for a particular user. |
| Scanning All Users | Scanning the list of all users, one by one. |
| Writing a User Entry | How a program can rewrite a user's record. |