Linux

This is a crash course in using Linux servers--anything more than a cursory look would require a dedicated class. There's a lot to learn here; you don't need to do it all at once, since this is mostly meant as a foundation for future lessons. Outside of what's mentioned in the study guide, you don't need to memorize specifics, but you should know what's possible and have a general idea of how to accomplish any reasonable shell task you're given.

Study guide

Know how to navigate a filesystem from the command line
Know the components of a file path including "." and ".."
Understand file ownership and permissions and how to change them with chown and chmod
Know how to redirect the stdin, stdout, and stderr of a command to and from files and other commands
Know how to use and set environment variables and how to make them available to child processes
Know how to use wildcards to select files based on a pattern
Know what aliases, functions, and scripts are and understand their comparative advantages
Know some of the most important shell commands like ls, cd, cp, mv, mkdir, and man
Know some of the most important environment variables like PATH and PWD
Become familiar enough with the shell to accomplish basic tasks there