Learn all about apt-get including how to deal with the dreaded cant release lock error
Learn how to create normal and system users/groups and everything else associated with them
Learn how to upgrade Linux to the latest OS
Learn about logrotate and deal with the 'can not rotate log files' error
Learn how to use the update-alternatives command
Learn about gpg and encrypting and decrypting files and key value pairs
Figure out if anyone is logged into your system or accessing applications on your server
Learn how to use rsync to transfer files between servers
Learn how to create ssh keys
5 practical examples of using the find command
Secure Copy. Learn how to use Secure Copy to transfer files between servers
Learn the difference between .profile and .bashrc and how to use them to add paths to your system