How to use Unix

If you are using the school or research-group unix machines, you will have to interact with the unix ‘command line’ at some level.

Although most modern unix environments use windows and mice to interact with the system, the core interaction with the system is by typing commands at the command-line, and observing the textual responses.

Key points:

If you ssh to the machine, or if you open up a ‘shell’ (or ‘console’ or ‘terminal’) window, you are typing commands to this command-line.
Almost everyone will use the ‘bash’ shell (in some specialised cases you may be advised to use an alternate shell, usually ‘tcsh’, with a slightly different syntax).
Your ‘username’ in most cases is your GUID, and you will log on using your usual GUID password (there is a confusing range of usernames within the school, but most school unix resources use this username, specifically including the jupyterhub server and various teaching machines).
You have a ‘home directory’, which is the starting point for saving files. If you type ls after you log on, you'll see the files currently in this directory. This directory is shared across different school unix machines.

You can find multiple introductions to Unix on the web, but the following might be useful starting points.

A well-known introduction to Unix from the University of Sussex.
The Software Carpentry project has a good introduction to using the Unix shell for scripting, which is slightly more advanced, but gives a hint at how you can become more productive using the Unix shell.
(further suggestions for beginners' guides are very welcome)