Ubuntu Unleashed 2013 Edition: Covering 12.10 and 13.04, Eighth Edition

Paging Through Output with less

The less command enables you to view large amounts of text in a more convenient way than the cat command. For example, your /etc/passwd file is probably more than a screen long, so if you run cat /etc/passwd, you are not able to see what the lines at the top were. Using less /etc/passwd enables you to use the cursor keys to scroll up and down the output freely. Type q to quit and return to the shell.

On the surface, less sounds like an easy command; however, it has the infamy of being one of the few Linux commands that have a parameter for every letter of the alphabet. That is, -a does something, -b does something else, -c, -d, -e ... -x, -y, -z; they all do things, with some letters even differentiating between ...