๐Ÿ“ก Linux Process & Signal Reference

Complete reference of Linux signals, process states, and process management commands with examples

Process States
RRunning / Runnable
SSleeping (interruptible)
DDisk sleep (uninterruptible)
ZZombie (defunct)
TStopped / Traced
IIdle (kernel thread)

Kill Hierarchy
1. Try SIGTERM (15) first โ€” graceful
2. Wait a few seconds
3. Try SIGINT (2) โ€” interrupt
4. Last resort: SIGKILL (9) โ€” force

Never kill PID 1 (init/systemd)
Never kill D-state processes (I/O wait)

Quick Commands
kill -l โ€” list all signals
ps aux --sort=-%mem โ€” by memory
pgrep -f pattern โ€” find by name
pstree -p โ€” process tree