The best "linux sysops handbook" is the manual. Every one of these tools has a lengthy manual; read them in their entirety. Try out the options.<p>Not sure what commands there are or what they do? Try this out:<p><pre><code> zcat -f /usr/{,share/}man/man[18]/*.[18].gz | grep -A2 "\.SH NAME" | grep -v "^\.\|^$\|^--" | sed 's/\\//g' | sort -u | less
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Then read the manual for those tools that interest you. (learn how <i>man</i>, <i>info</i>, <i>less</i> and <i>more</i> work)<p>The source code is also free. Many of these tools come as part of a package of other tools and libraries. Find out what package the tools come from, find the source code, download it, peruse through it (even if you don't know the language). I guarantee you will find out new things you didn't know about how the system works.<p>You can also use debugging tools like strace, ltrace, gdb, lsof, etc to find out more about what these tools are doing. The more you understand what it's actually doing, the deeper your knowledge, and the less you need a handbook to tell you what to do.<p>Another way to play around with commands is to just run a Docker container like <i>docker run --rm -it ubuntu:18.04</i> and try anything you want in the container. On exit it will be destroyed. To play around with <i>systemd</i> tools, install Vagrant and spin up a mini Linux VM.