A great blog that has interesting notes on solving different problems when working with Linux. For example, you might find useful the following posts:
- The Pinky Finger Habits Of Experienced Sysadmins
- Specialised Versus General Tools
- How To Kill A Process That Won't Respond To ctrl-C
- How To Debug Your WebServer From The Command Line
- How To Tell If Your Linux Server Has Been Compromised
Ten Things I Wish I’d Known About bash
Brendan Gregg (Netflix) is a true expert in monitoring, debugging and tunning of the systems. He has a great blog where he shares his knowledge. Some of the must-read posts:
Linux Journey is a site dedicated to making learning Linux fun and easy.
Julia Evans has a great blog where you can find a lot of really interesting posts on various Linux topics.
The Linux System Administrator's Guide
A lot of the material in this cheatsheet was taken from this guide, so it's definitely worth to check out.
A great style guide for Bash scripts from Google.