From TecMint comes this series of articles…

Linux command line attracts most of the Linux Enthusiastic. A normal Linux user generally posses a vocabulary of roughly 50-60 commands to carry out their day-to-day task. Linux commands and their switches remains the most valuable treasure for a Linux-user, Shell-script programmer and Administrator. There are some Linux Commands which are lesser Known, yet very useful and handy irrespective of the fact whether you are a Novice or an Advanced User.

Now, we personally prefer to do as much as possible in a GUI, but for those of you that prefer the command line, this series is for you:

11 Lesser Known Useful Linux Commands – Part I
10 Lesser Known Linux Commands – Part 2
10 Lesser Known Commands for Linux – Part 3