It's the number of the signal sent, 9 is for SIGKILL. You can send various signals with kill, and depending on how application was made it may react on all signals with dying, or meaningfully process most of them. Afaik, SIGKILL can't be processed by the app, and it always means just that: "die already".

Checked in Wikipedia, that's about right but there are more details I left out, mostly because didn't know about them, too: POSIX signals

[–] ramble81@lemm.ee 4 points 1 month ago (1 children)

Thank you! That’s what I was looking for.

[–] jaybone@lemmy.world 7 points 1 month ago

In languages like C, your application code can register what is called a signal handler. These functions get called when the process receives a signal. You could do something like reload a config file for example, without the user needing to stop and restart the process.

[–] dohpaz42@lemmy.world 5 points 1 month ago* (last edited 1 month ago) (1 children)

You can use kill -l (lowercase L) to see a list of signals. But IIRC it’s the same as -KILL.

EDIT: fixed the signal name.

[–] southernbrewer@lemmy.world 4 points 1 month ago (1 children)

TERM is the default (15). 9 is KILL

[–] dohpaz42@lemmy.world 2 points 1 month ago

Thank you!