Good News Everyone!
I have just released the 5th Internet edition of my book, The Linux Command Line. This new edition contains hundreds of language refinements and modernizations including updated screenshots and diagrams.
You can download the new version here:
https://sourceforge.net/projects/linuxcommand/files/TLCL/19.01/TLCL-19.01.pdf/download
Be sure to download the file named TLCL-19.01.pdf
Enjoy!