How do I become a valuable Unix/Linux System Administrator?

Ask my boss! Seriously, though, learn the fundamentals of Linux (cli commands, filesystem layout, networking, services) and learn them well.  If you're not running a Linux system of your own or spending a ton of time in the OS X Terminal, start now.  The better you know your tools, the better you'll be able to do your job. Learn how each layer of the Internet works.  When you type "http://www.google.com" into your browser, what happens?  What protocols are involved?  This is where Wireshark is invaluable: you'll learn tons about networking from examining packets. Set up your own network, even if it's just a bunch of virtual machines.  It's essential that you understand IP addressing backwards and forwards.  Know which protocols use which ports. Learn how to program.  Specifically, Bash.  Even if you don't write many shell scripts, you'll have to read them.  Learn SQL as well--you'll use it as much as you code.  Python is the next most common language you'll see, and it's much more powerful than Bash in many respects. Learn how to install and configure the most common servers: BIND, dhcpd, Apache, Postfix, Nginx, MySQL--they're not going away anytime soon! Learn the basics of source control--specifically git, GitHub/Bitbucket, and basic markdown syntax. Learn when not to write code--there's almost always tools already out there.  It sucks, but sometimes, it's better to do some things manually than to automate them.  I both love and hate the XKCD comic https://xkcd.com/1205/ -- it's a great way to figure out what you should script.  Trouble is, it's a great way to figure out what you shouldn't script as well. Finally, never stop learning!  The learning curve for sysadmins is particularly steep right now--you have to have programming knowledge to support programmers, but you still have to know all the fundamentals of Linux and the Internet.

One step you can do immediately is to start using Linux as your day-to-day operating system and modify it to satisfy your needs. Secondly, don't stop there: build a complete network, using various versions of Linux or BSD or Windows, and incorporating various servers into it such as DNS, NFS, SSH, and more. Go to school for system administration - the technical schools often teach this, and a degree is very important. Once you gain the proper knowledge, become certified: good certifications might be the Red Hat Certified Engineer (RHCE) or Linux+. If you expand your knowledge to Unix, get the Solaris Certified Administrator (SCA). One that I find critical is programming - learn one or more scripting languages such as Perl, Ruby, Python, and awk - and well. Learn the Korn shell - others will be either compatible or niche. Good luck!

I have been Linux system engineer for more than a decade now and supported both infrastructure, applications and high performance computing clusters. You need to understand the basics of Operating Systems to understand Linux. There are different routes to be a Linux system engineer. But foremost, you need to  have the passion to troubleshoot, spent hours in command line interface, write codes preferably in  bash and enjoy reading and writing documentations. Here are the different paths which are not in any order: Start with technology analyst/support positions  positions but start digging hard on Networking and operating systems. Go to school , have undergraduate in Computer Science - this will make a lot of differences in your professional career. Go for some certifications or focus on some online courses in system administration, database administration and programming. Here are interview questions ? 1. Can you list at-least one protocols in TCP/IP layer and how do you do end-to-end troubleshooting ? ( Hints: First part is straight forward , second part use divide and conquer algorithms , isolate network troubleshooting and OS /Application Troubleshooting)2. what distros of linux do you prefer and why ? what are the commands use to running processes?3. what is kernel space and user space ? Irrespective of the route you choose, the system administration role is changing dramatically because of cloud computing and big data. The concept of devops and devsecops are evolving that emphasizes on infrastructure as a code and security as a code ; Bottom line  you need to have reasonable programming experience in Shell and one high level programming language ( Ruby, Python.C etc) There are lot of opportunities in this role in the years to come. Most security engineers , who demand is very high are moving from system engineering roles.

IMHO, this is not quite the right question for an individual - maybe for a career counselor. Better to ask what problems you really like to solve and are really good at solving, then figure out where you can best do that for a living as you learn your trade. That way you can become really, really good at something, people will recognize your expertise, and you can do good while doing well.

I made a rubric that covers what I think demonstrates the abilities of a junior vs. mid-level vs. senior Dev Ops engineer. Note that this is not an all-or-nothing checklist where you need to check every box to be a senior engineer, but I hope this gives you a good idea: http://liquid.pch.com/engineering-rubrics/ (click the Dev Ops tab).

You need to solve problems and build systems and infrastructure. If you are looking for a start I suggest that you either attend University for Computer Science and/or obtain RHCSA/RHCE. Then work on actual issues. One way is to build for yourself a LAMP server or email server. Just be aware that answering questions on a test isn’t really enough you need to be able to resolve issues in the real world.