This chapter is from the book
Logging Out of the System
When you have finished using the system, it is important to log outespecially if you are using a computer that untrustworthy people have access to. Logging out returns the system to the login prompt so that no one else can use your account or access your private files. To log out of the system, simply type exit at the bash$ prompt. This will return the system to the login: prompt.
TIP
If you want to clear the screen before logging out so that no one else will be able to see what you were working on, simply type clear and press Enter before issuing the exit command.