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.
Trace system calls, list open files, read kernel messages and profile hot paths.
straceTrace the system calls a process makesIntermediateltraceTrace the library calls a program makesAdvancedlsofList open files, sockets and the processes holding themIntermediatedmesgRead the kernel's message logBeginnerperfProfile where CPU time goes, kernel and user spaceAdvancedgdbDebug crashes, core dumps and hung processesAdvancedcoredumpctlFind and open core dumps captured by systemdIntermediate