For the longest time, I would run
kill -s9 to send
SIGKILL to the process, now it seems it doesn't work on Debian Testing,
$ kill -s 9 988224 kill: unknown signal: SIG9 kill: type kill -l for a list of signals
Moreover, it seems as if it's still documented to work,
-<signal> -s <signal> --signal <signal> Specify the signal to be sent. The signal can be specified by using name or number. The behavior of signals is explained in signal(7) manual page.
kill -9 works. Why did the
-s9 usage stop working?