Best Way To Start Learning Shell Commands in Terminal? [closed]

What's the best way to learn how to use System Administration / using shell-commands in the Terminal?

There is a nice manual in the community wiki, it can be found here. You have all you need to start there

My solution to this was to pick up a task that I needed to do, and start to do it terminal only, after that I tried to optimise the solution. Once you see the benefits you will create a virtous circle which will motivate you from then and onwards.

Example: remove empty spaces in a file (at that time a classmate was feeding me with source code with loads of this). Say this is an awk/perl one liner. At some point we have the file we want to fix. After that I substituted the file with a variable, encapsulated in a bash script. Bang! (now by automating that to parse all files in a folder, I could easily accept 100 files having both parties happy).