Watch each command run in a real-looking terminal, see what every part of it means, then try it yourself with practice tasks. From ls to kubectl.
The first three commands on any server: where am I, what's here, and how full is the disk.
Variables, PATH, aliases, history and sourcing: how your shell is configured.
envShow the environment, or run a command with a changed oneBeginnerexportPass variables to the programs you startBeginneraliasCreate shortcuts for commands you type all the timeBeginnerhistorySearch, reuse and clean your command historyBeginnersourceRun a file's commands in the current shellBeginnerechoPrint text and variables (and its quoting traps)BeginnersetShell options: set -euo pipefail, set -x and friendsIntermediateunsetRemove variables and functions from the shellBeginnerwhichFind which executable runs for a command nameBeginnertypeSee exactly what the shell will run for a nameIntermediate