12 Essential System Administration Cheatsheets

Albert Einstein, a man not known for his lack of learning, once said that we should never learn what we can look up in a book.
While it’s often efficient to have all the commands and options we need at our fingertips, sometimes the effort of cramming all that arcana into our brains isn’t worth the time when everything we need is a quick Google away.
System administrators have to get to grips with an enormous body of knowledge if they’re going to effectively manage servers and all the multitude of different applications that they run. They’re masters of the minutia, but even system administrators can’t hope to remember everything that they’ll need day-to-day, never mind committing the commands they use rarely but regularly to memory.
The cheat sheet is one of the secret weapons of system administrators everywhere. These concise collections of commands and options mean that so long as you have a good understanding of what’s possible and which tools have what capabilities, it’s fine if the precise details escape you now and then.
Here are 12 cheat sheets that every system administrator should have bookmarked for easy reference.

1. Basic Command Line Tools
   This is a simple guide to the most common commands of the most used tools on the Linux command line.
2. OpenSSH
   SSH is a crucial tool for system administrators, allowing them to securely access servers. This cheat sheet details the most pertinent configuration options for the SSH server, the most commonly used client options, and how to use public key authentication with SSH
3. Bash
   Everything you need to know about everyone’s favorite shell (well, almost everyone).
4. Vim Commands
   While not always everyone’s favorite editor, once you have Vim’s commands down, it’s very efficient and you’ll find it on almost every Linux box.
5. MySQL
   Still the world’s most popular open source SQL database, MySQL knowledge is a must for sys admins. These cheat sheets detail MySQL functions, data types, and provide sample queries.
6. The Find Command
   Find is an extraordinarily powerful tool, but if you’re anything like me, keeping track of all of the options doesn’t come naturally.
7. Regular Expressions
   If you’re going to find what you’re looking for, either on the command line or in text files, an understanding of regular expressions is vital.
8. IPv6
   Most of us have IPv4 subnetting down, but we can use a brush up on its younger sibling’s construction.
9. Ports
   It’s always useful to have a complete guide to what the most common ports are reserved for.
10. RAID
    Get your RAIDs muddled up? Not any more! This cheat sheet details the drive counts and benefits of each of the RAID types.
11. .htaccess
    A handy outlining of the configuration options most commonly used to control the behavior of the Apache web server.
12. Netcat
    Netcat is a vital tool for diagnosing networking problems.

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