Linux AdministrationNOTE_01
A practical sequence for checking service state, validating configuration, reading logs, and verifying recovery without restarting blindly.
systemdjournalctlincident response
Linux FundamentalsNOTE_02
A troubleshooting checklist for permission errors using user identity, group membership, directory traversal, ownership, and mode bits.
permissionsusers and groupschmodchown
NetworkingNOTE_03
A layered sequence for investigating address configuration, routing, DNS resolution, and application reachability on a Linux host.
TCP/IPDNSroutingconnectivity