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.
Create and manage users and groups, and check who you are and who's logged in.
useraddCreate a user accountBeginnerusermodChange an existing user accountBeginneruserdelDelete a user accountBeginnerpasswdSet or change a user's passwordBeginnergroupaddCreate a groupBeginneridShow user and group identityBeginnerwhoList logged-in usersBeginnerwShow who is logged in and what they're doingBeginnergroupsList the groups a user belongs toBeginnerchageManage password aging and account expiryIntermediatesuSwitch to another userIntermediate