Practical articles on AI, DevOps, Cloud, Linux, and infrastructure engineering.
A field-tested workflow for diagnosing why a systemd unit refuses to start, from status output to exit codes to the usual root causes.
When a Linux box misbehaves, the same dozen problems come up again and again. This is the map: what each symptom means and the fast path to the fix.
A likelihood-ordered checklist for tracing "Permission denied" on Linux through mode bits, ownership, ACLs, SELinux, and mount options.
The kernel killed your process to save the box, and the log looks like noise until you know exactly which fields to read.
A field-tested workflow for finding which process burns your CPU and whether the time is user, system, or iowait.
A practical method for reading free, top, and ps correctly so you attribute Linux memory to a real cause instead of guessing.
Load average counts more than CPU demand, so a high number needs a diagnostic path before you reach for a fix.
Track down what owns a busy port, decide whether to kill it or rebind, and stop TIME_WAIT from blocking your restart.
When a process hits its file descriptor ceiling everything breaks at once; here is how to find the real limit and raise it correctly.
A field guide to reclaiming Linux disk space when df reports full but du can't find where the bytes actually went.
We had 140 engineers with 300 static public keys scattered across authorized_keys files nobody could audit. Moving to SSH certificates with short TTLs made access reviewable again.
Our proxy topped out at 40k connections while the CPU sat half-idle. The bottleneck was kernel defaults tuned for 2009, not the hardware.
