[0] RHCSA & RHCE Training and Exam Preparation Guide by Asghar Ghori. This book will help insure you know your stuff as your system engineer/administrator wise.
[1] A Practical Guide to Linux Commands, Editor and Shell Programming Third Edition. This book will cover the majority of what you would need and want to know when connecting to a remote linux system over ssh.
If you want to get under the hood and become an expert, the following books should help get you started:
[2] Advanced Programming in the UNIX Environment
[3] The Linux Programming Interface: A Linux and UNIX System Programming Handbook
[4] Linux Kernel Development 3rd Edition
To get a nice general overview and get up and going quickly:
[5] How Linux works: What every superuser should know
[6] The Linux Command Line
[7] Python Crash Course
[8] Automate the boring stuff with Python. This is a great book to help you think about how to automate most of the repetitive things you will end up doing on a regular basis.
[0] https://www.amazon.com/RHCSA-RHCE-Red-Enterprise-Linux/dp/14...
[1] https://www.amazon.com/Practical-Guide-Commands-Editors-Prog...
[2] https://www.amazon.com/Advanced-Programming-UNIX-Environment...
[3] https://www.amazon.com/Linux-Programming-Interface-System-Ha...
[4] https://www.amazon.com/Linux-Kernel-Development-Robert-Love/...
[5] https://www.amazon.com/How-Linux-Works-Superuser-Should/dp/1...
[6] https://www.amazon.com/Linux-Command-Line-Complete-Introduct...
[7] https://www.amazon.com/Python-Crash-Course-Hands-Project-Bas...
[8] https://www.amazon.com/Automate-Boring-Stuff-Python-Programm...
http://www.amazon.com/The-Linux-Command-Line-Introduction/dp...
I agree with this.
Anyone interested in command line hacking can find everything nelsonmarcus recommends (and a bit more) in this very readable book: The Linux Command Line A complete Introduction By Shotts https://www.amazon.com/Linux-Command-Line-Complete-Introduct...