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
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.
You know I’ve known for decades that -9 is basically “nuke it from orbit”, but does anyone know what the “9” actually means or where it came from?
It’s the number of the signal sent,
9is forSIGKILL. 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,SIGKILLcan’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
Thank you! That’s what I was looking for.
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.
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.