Linux distros: Ubuntu Server → Debian. (CentOS for educational purposes only.) Maybe Arch (or Gentoo) in the future.
Basic Path: Linux, Command-line & Shell scripting, Python programming, Security, Networking (Cisco, HP, Juniper), Virtualization, and High Availability. See IT Certification Roadmap.pdf for more info.
Programming Path: JS, Python, PHP, Ruby, C, C++, Go, Java, Swift, Rust, Scala, C#.
Certifications:
SysAdmin
- The Linux Foundation's LFCS → LFCE.
- Linux Professional Institute's Linux Essentials → LPIC - 1, 2 & 3.
- Red Hat's RHCSA → RHCE → RHCA.
Network
- Cisco's CCENT → CCNA → CCDA → CCNP → CCDP → CCIE → CCDE → CCAr.
Security
- GIAC's (at least) GISF → GSEC → GCWN & GCUX → GCIH → GCIA → GSE.
- Offensive Security's OSCP → OSWP → OSCE → OSEE → OSWE.
- Nginx HTTP Server (2015) by Clement Nedelcu
- Nginx: From Beginner to Pro (2016) by Rahul Soni
Mastering NGINX (2016) by Dimitri Aivaliotis- Nginx Essentials (2015) by Valery Kholodkov
- Nginx High Performance (2015) by Rahul Sharma
- Nginx Troubleshooting (2016) by Alex Kapranoff
- nginx: A Practical Guide to High Performance (2017) by Stephen Corona
Regexp Patterns (Regular-Expressions.info)
- Getting Started with Varnish Cache (2017) by Thijs Feryn
- Instant Varnish Cache How-to (2013) by Roberto Moutinho
- The Varnish Book (Official training material.)
Based on these search terms: ubuntu [server], linux [server], centos [server], linux command, shell script, sys admin, linux security, linux hardening.
- The Official Ubuntu Book by Matthew Helmke, Elizabeth K. Joseph, Jose Antonio Rey
- Ubuntu Unleashed by Matthew Helmke
- A Practical Guide to Ubuntu Linux by Mark G. Sobell
- Mastering Ubuntu Server by Jay LaCroix
- Ubuntu 16.04 LTS Server: Administration and Reference by Richard Petersen
- The Official Ubuntu Server Book by Kyle Rankin, Benjamin Mako Hill
- Ubuntu Server Cookbook by Uday R. Sawant
- Troubleshooting Ubuntu Server by Skanda Bhargav
- Ubuntu Linux Toolbox by Christopher Negus
- How Linux Works by Brian Ward
- Linux Bible by Christopher Negus
- Linux Administration: A Beginner’s Guide by Wale Soyinka
- Mastering CentOS 7 Linux Server by Mohamed Alibi, Bhaskarjyoti Roy
- CentOS 7 Linux Server Cookbook by Oliver Pelz, Jonathan Hobson
- Red Hat Enterprise Linux Server Cookbook by William Leemans
- CentOS High Availability by Mitja Resman
- CentOS High Performance by Gabriel Canepa
- Troubleshooting CentOS by Jonathan Hobson
- UNIX and Linux System Administration Handbook (5th Edition) by Evi Nemeth, Garth Snyder, Trent R. Hein, Ben Whaley, Dan Macklin
- The Linux Command Line by William E. Shotts Jr.
- Linux Command Line and Shell Scripting Bible by Richard Blum, Christine Bresnahan
- A Practical Guide to Linux Commands, Editors, and Shell Programming by Mark G. Sobell
- GitHub: awesome-shell, bash-handbook, the-art-of-command-line, bash-guide
- Linux Pocket Guide by Daniel J. Barrett
- Bash Pocket Reference by Arnold Robbins
- Shell Scripting by Jaosn Cannon
- Wicked Cool Shell Scripts by Dave Taylor, Brandon Perry
- Begin learning Python for sysadmin...
- Linux Hardening in Hostile Networks by Kyle Rankin
- Practical Linux Security Cookbook by Tajinder Kalsi
- Hardening Linux by James Turnbull
- Linux Security Cookbook by Daniel J. Barrett, Richard E. Silverman, Robert G. Byrnes
- Linux Forensics by Philip Polstra