#linux

A one-liner with awk that counts running, paused, idle, and shut-off KVM guests from virsh list --all output. Quick health check on a busy hypervisor.

Intel's open-source ledmon lets you blink the LED on a specific drive in a server enclosure — handy when you need to physically locate a disk before pulling the wrong one.

System Activity Reports — using sar to investigate a sudden server crash. Where the data lives, how to generate plain-text reports, and a free chart tool to actually make sense of the numbers.

Quick reference for restricting access in Apache: the order/deny/allow syntax of 2.2 vs the Require syntax of 2.4 — almost the same problem, almost the same words, different config.

Reload Logstash pipeline config without restarting the service — just send SIGHUP to the running process and watch the log confirm the reload.

A scratchpad of one-liners I keep typing — find files older than N days, list IPs, and the others I'm too lazy to memorize properly.