mail waiting to be read. It then checks for a .plan file in the user's home directory. The .plan file contains information that the user wishes to have displayed when another user looks him or her up. This can be any ASCII information.

As you can tell, the finger command gives quite a bit of publicly available information. The files that are accessed (passwd, .plan, and .forward) need to have information in them that is appropriate for any user that can access the system to see.

Summary

Regardless of the size of the system, user and account management is an essential part of system administration. Using tools such as who and finger, users can identify other users, and with tools such as chsh, chfn, and passwd, the user is able to change information associated with the /etc/passwd file without the assistance of the system administrator.

This chapter looks at the numerous users and groups that are necessary to run a system. The system uses the user and the group to identify ownership of processes and files. This same user and group information enables the user to manipulate files and initiate processes.