A new booklet by the MagPi. It is a PDF but it looks useful and by buying it you can sponsor the Pi foundation!
In short: if you’re one of the many Raspberry Pi users not comfortable when faced with the command prompt, don’t panic! Conquer the Command Line is designed to help you feel at home, and equip you with the skills you need to find your way around the Raspberry Pi terminal (or any other GNU/Linux computer for that matter).
Here’s a quick breakdown of what you can expect to learn:
Read and write text files
Find and install software
Manage removable storage
Use Secure Shell for remote access
Create Raspberry Pi SD cards
Customise the command line
and much, much more.