Beyond kill.
WHAT A SIGNAL IS
A notification sent to a process.
WHAT THE COMMON ONES ARE
Terminate, asking it to stop cleanly Interrupt, what a keyboard interrupt sends Hang-up, which many services treat as reload Kill, which cannot be caught Stop and continue, pausing and resuming
WHY HANG-UP IS USEFUL
Many services reload configuration on it without dropping connections.
WHAT CANNOT BE CAUGHT
Kill and stop.
WHY THAT MATTERS
A process ignoring everything else can still be stopped, but with no cleanup.
WHAT PAUSING A PROCESS ACHIEVES
Freezing something consuming resources without losing it.
WHERE THAT HELPS
Suspending a runaway job while you decide what to do.
HOW TO SEND ONE
kill with the signal named or numbered.
WHAT TO DO WHEN A PROCESS WILL NOT STOP
Try terminate, wait, then escalate.
WHY WAIT
Clean shutdown can take time, particularly for databases.
WHAT A PROCESS STUCK IN UNINTERRUPTIBLE SLEEP MEANS
It is waiting on hardware or a network file system.
WHY THAT MATTERS
It cannot be killed at all until that completes.
WHAT TO INVESTIGATE THEN
The storage or network mount it is waiting on.
WHAT TO TRAP IN SCRIPTS
Interrupt and terminate, to clean up temporary files.
