kill

Stop a stuck program by its PID: the polite way first, kill -9 when it won't listen.

>_ Try it: a simulated Linux, right herenothing runs on your computer

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Examples

kill 4242 ask the report to stop
kill 5150 the frozen server ignores the polite request
ps aux | grep frozen still there
kill -9 5150 force it
kill -l every signal kill knows

How it works

Every running program is a process with a number, its PID. ps aux lists them; kill PID asks one to stop.

By default kill sends SIGTERM, a polite "please finish": the program can clean up. A frozen one may ignore it; kill -9 (SIGKILL) stops it at once, with no chance to save anything.

Syntax

kill [-SIGNAL] PID...

Options

Option	What it does
`PID`	the process number, from ps aux
`-15`	SIGTERM: ask it to stop (the default)
`-9`	SIGKILL: stop it now, no cleanup
`-l`	list the signal names

Good to know

Try plain kill first: -9 can leave half-written files behind.
pkill NAME stops processes by name instead of PID.