test-your-sysadmin-skills

<p align="center"> <a href="https://github.com/trimstray/test-your-sysadmin-skills"> <img src="https://github.com/trimstray/test-your-sysadmin-skills/blob/master/static/img/sysadmin_preview.png" alt="Master"> </a> </p> <br> <p align="center">:star:</p> <p align="center">"<i>A great Admin doesn't need to know everything, but they should be able to come up with amazing solutions to impossible projects.</i>" - cwheeler33 (ServerFault)</p> <p align="center">:star:</p> <p align="center">"<i>My skills are making things work, not knowing a billion facts. [...] If I need to fix a system I’ll identify the problem, check the logs and look up the errors. If I need to implement a solution I’ll research the right solution, implement and document it, the later on only really have a general idea of how it works unless I interact with it frequently... it’s why it’s documented.</i>" - Sparcrypt (Reddit)</p> <br> <p align="center"> <a href="https://github.com/trimstray/test-your-sysadmin-skills/pulls"> <img src="https://img.shields.io/badge/PRs-welcome-brightgreen.svg?longCache=true" alt="Pull Requests"> </a> <a href="LICENSE.md"> <img src="https://img.shields.io/badge/License-MIT-lightgrey.svg?longCache=true" alt="MIT License"> </a> </p> <p align="center"> <a href="https://twitter.com/trimstray" target="_blank"> <img src="https://img.shields.io/twitter/follow/trimstray.svg?logo=twitter"> </a> </p> <div align="center"> <sub>Created by <a href="https://twitter.com/trimstray">trimstray</a> and <a href="https://github.com/trimstray/test-your-sysadmin-skills/graphs/contributors">contributors</a> </div> <br>

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:information_source:  This project contains 284 test questions and answers that can be used as a test your knowledge or during an interview/exam for position such as Linux (*nix) System Administrator.

:heavy_check_mark:  The answers are only examples and do not exhaust the whole topic. Most of them contains useful resources for a deeper understanding.

:warning:  Questions marked *** don't have answer yet or answer is incomplete - make a pull request to add them!

:traffic_light:  If you find something which doesn't make sense, or something doesn't seem right, please make a pull request and please add valid and well-reasoned explanations about your changes or comments.

:books:  In order to improve your knowledge/skills please see devops-interview-questions. It looks really interesting.

<br> <p align="center"> » <b><code><a href="https://github.com/trimstray/test-your-sysadmin-skills/issues">All suggestions are welcome</a></code></b> « </p> <br>

Table of Contents

<b><u>The type of chapter</u></b>	<b><u>Number of questions</u></b>	<b><u>Short description</u></b>
<b>Introduction</b>
:small_orange_diamond: Simple Questions	14 questions	Relaxed, fun and simple - are great for starting everything.
<b>General Knowledge</b>
:small_orange_diamond: Junior Sysadmin	65 questions	Reasonably simple and straight based on basic knowledge.
:small_orange_diamond: Regular Sysadmin	94 questions	The mid level of questions if that you have sound knowledge.
:small_orange_diamond: Senior Sysadmin	99 questions	Hard questions and riddles. Check it if you want to be good.
<b>Secret Knowledge</b>
:small_orange_diamond: Guru Sysadmin	12 questions	Really deep questions are to get to know Guru Sysadmin.

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<a name="introduction">Introduction</a>

:diamond_shape_with_a_dot_inside: <a name="simple-questions">Simple Questions</a>

• <b>What did you learn this week?</b>
• <b>What excites or interests you about the sysadmin world?</b>
• <b>What is a recent technical challenge you experienced and how did you solve it?</b>
• <b>Tell me about the last major project you finished.</b>
• <b>Do you contribute to any open source projects?</b>
• <b>Describe the setup of your homelab.</b>
• <b>What personal achievement are you most proud of?</b>
• <b>Tell me about the biggest mistake you've made. How would you do it differently today?</b>
• <b>What software tools are you going to install on the first day at a new job?</b>
• <b>Tell me about how you manage your knowledge database (e.g. wikis, files, portals).</b>
• <b>What news sources do you check daily? (sysadmin, security-related or other)</b>
• <b>Your NOC team has a new budget for sysadmin certifications. What certificate would you like and why?</b>
• <b>How do you interact with developers: us vs. them or all pulling together with a different approach?</b>
• <b>Which sysadmin question would you ask, if you were interviewing me, to know, how good I'm with non-standard situations?</b>

<a name="general-knowledge">General Knowledge</a>

:diamond_shape_with_a_dot_inside: <a name="junior-sysadmin">Junior Sysadmin</a>

System Questions (37)

<details> <summary><b>Give some examples of Linux distribution. What is your favorite distro and why?</b></summary><br> - Red Hat Enterprise Linux - Fedora - CentOS - Debian - Ubuntu - Mint - SUSE Linux Enterprise Server (SLES) - SUSE Linux Enterprise Desktop (SLED) - Slackware - Arch - Kali - Backbox

My favorite Linux distribution:

• Arch Linux, which offers a nice minimalist base system on which one can build a custom operating system. The beauty of it too is that it has the Arch User Repository (AUR), which when combined with its official binary repositories allows it to probably have the largest repositories of any distribution. Its packaging process is also very simple, which means if one wants a package not in its official repositories or the AUR, it should be easy to make it for oneself.
• Linux Mint, which is also built from Ubuntu LTS releases, but features editions featuring a few different desktop environments, including Cinnamon, MATE and Xfce. Mint is quite polished and its aesthetics are rather appealing, I especially like its new icon theme, although I do quite dislike its GTK+ theme (too bland to my taste). I’ve also found a bug in its latest release Mint 19, that is getting quite irritating as I asked for with it over a fortnight ago on their forums and I have received no replies so far and it is a bug that makes my life on it more difficult.
• Kali Linux, is a Debian-based Linux distribution aimed at advanced Penetration Testing and Security Auditing. Kali contains several hundred tools which are geared towards various information security tasks, such as Penetration Testing, Security research, Computer Forensics and Reverse Engineering.

Useful resources:

• List of Linux distributions
• What is your favorite Linux distro and why?

</details> <details> <summary><b>What are the differences between Unix, Linux, BSD, and GNU?</b></summary><br>

GNU isn't really an OS. It's more of a set of rules or philosophies that govern free software, that at the same time gave birth to a bunch of tools while trying to create an OS. So GNU tools are basically open versions of tools that already existed, but were reimplemented to conform to principals of open software. GNU/Linux is a mesh of those tools and the Linux kernel to form a complete OS, but there are other GNUs, e.g. GNU/Hurd.

Unix and BSD are "older" implementations of POSIX that are various levels of "closed source". Unix is usually totally closed source, but there are as many flavors of Unix as there are Linux (if not more). BSD is not usually considered "open", but it was considered to be very open when it was released. Its licensing also allowed for commercial use with far fewer restrictions than the more "open" licenses of the time allowed.

Linux is the newest of the four. Strictly speaking, it's "just a kernel"; however, in general, it's thought of as a full OS when combined with GNU Tools and several other core components.

The main governing differences between these are their ideals. Unix, Linux, and BSD have different ideals that they implement. They are all POSIX, and are all basically interchangeable. They do solve some of the same problems in different ways. So other then ideals and how they choose to implement POSIX standards, there is little difference.

For more info I suggest your read a brief article on the creation of GNU, OSS, Linux, BSD, and UNIX. They will be slanted towards their individual ideas, but those articles should give you a better idea of the differences.

Useful resources:

• What is the difference between Unix, Linux, BSD and GNU? (original)
• The Great Debate: Is it Linux or GNU/Linux?

</details> <details> <summary><b>What is a CLI? Tell me about your favorite CLI tools, tips, and hacks.</b></summary><br>

CLI is an acronym for Command Line Interface or Command Language Interpreter. The command line is one of the most powerful ways to control your system/computer.

In Unix like systems, CLI is the interface by which a user can type commands for the system to execute. The CLI is very powerful, but is not very error-tolerant.

The CLI allows you to do manipulations with your system’s internals and with code in a much more fine-tuned way. It offers greater flexibility and control than a GUI regardless of what OS is used. Many programs that you might want to use in your software that are hosted on say Github also require running some commands on the CLI in order to get them running.

My favorite tools

• screen - free terminal multiplexer, I can start a session and My terminals will be saved even when you connection is lost, so you can resume later or from home
• ssh - the most valuable over-all command to learn, I can use it to do some amazing things:
  • mount a file system over the internet with sshfs
  • forward commands: runs against a rsync server with no rsync deamon by starting one itself via ssh
  • run in batch files: I can redirect the output from the remote command and use it within local batch file
• vi/vim - is the most popular and powerful text editor, it's universal, it's work very fast, even on large files
• bash-completion - contains a number of predefined completion rules for shell

Tips & Hacks

• searches the command history with CTRL + R
• popd/pushd and other shell builtins which allow you manipulate the directory stack
• editing keyboard shortcuts like a CTRL + U, CTRL + E
• combinations will be auto-expanded:
  • !* - all arguments of last command
  • !! - the whole of last command
  • !ssh - last command starting with ssh

Useful resources:

• Command Line Interface Definition
• What is your single most favorite command-line trick using Bash?
• What are your favorite command line features or tricks?

</details> <details> <summary><b>What is your favorite shell and why?</b></summary><br>

BASH is my favorite. It’s really a preferential kind of thing, where I love the syntax and it just "clicks" for me. The input/output redirection syntax (>>, << 2>&1, 2>, 1>, etc) is similar to C++ which makes it easier for me to recognize.

I also like the ZSH shell, because is much more customizable than BASH. It has the Oh-My-Zsh framework, powerful context based tab completion, pattern matching/globbing on steroids, loadable modules and more.

Useful resources:

• Comparison of command shells

</details> <details> <summary><b>How do you get help on the command line? ***</b></summary><br>

• man [commandname] can be used to see a description of a command (ex.: man less, man cat)

• -h or --help some programs will implement printing instructions when passed this parameter (ex.: python -h and python --help)

</details> <details> <summary><b>Your first 5 commands on a *nix server after login.</b></summary><br>

• w - a lot of great information in there with the server uptime
• top - you can see all running processes, then order them by CPU, memory utilization and more
• netstat - to know on what port and IP your server is listening on and what processes are using those
• df - reports the amount of available disk space being used by file systems
• history - tell you what was previously run by the user you are currently connected to

Useful resources:

• First 5 Commands When I Connect on a Linux Server (original)

</details> <details> <summary><b>What do the fields in <code>ls -al</code> output mean?</b></summary><br>

In the order of output:

-rwxrw-r--    1    root   root 2048    Jan 13 07:11 db.dump

• file permissions,
• number of links,
• owner name,
• owner group,
• file size,
• time of last modification,
• file/directory name

File permissions is displayed as following:

• first character is - or l or d, d indicates a directory, a - represents a file, l is a symlink (or soft link) - special type of file
• three sets of characters, three times, indicating permissions for owner, group and other:
  • r = readable
  • w = writable
  • x = executable

In your example -rwxrw-r--, this means the line displayed is:

• a regular file (displayed as -)
• readable, writable and executable by owner (rwx)
• readable, writable, but not executable by group (rw-)
• readable but not writable or executable by other (r--)

Useful resources:

• What do the fields in ls -al output mean? (original)

</details> <details> <summary><b>How do you get a list of logged-in users?</b></summary><br>

For a summary of logged-in users, including each login of a username, the terminal users are attached to, the date/time they logged in, and possibly the computer from which they are making the connection, enter:

# It uses /var/run/utmp and /var/log/wtmp files to get the details.
who

For extensive information, including username, terminal, IP number of the source computer, the time the login began, any idle time, process CPU cycles, job CPU cycles, and the currently running command, enter:

# It uses /var/run/utmp, and their processes /proc.
w

Also important for displays a list of last logged in users, enter:

# It uses /var/log/wtmp.
last

Useful resources:

• 4 Ways to Identify Who is Logged-In on Your Linux System

</details> <details> <summary><b>What is the advantage of executing the running processes in the background? How can you do that?</b></summary><br>

The most significant advantage of executing the running process in the background is that you can do any other task simultaneously while other processes are running in the background. So, more processes can be completed in the background while you are working on different processes. It can be achieved by adding a special character & at the end of the command.

Generally applications that take too long to execute and doesn't require user interaction are sent to background so that we