use -s for the kill signal

[engin]

Hello,

When using kill with shorthand signal like kill -HUP Debian bullseye gives error kill: invalid argument H

here is the prometheus systemd config:

ExecReload=/bin/kill -HUP $MAINPID

OS Version:

# lsb_release -a
No LSB modules are available.
Distributor ID:	Debian
Description:	Debian GNU/Linux 11 (bullseye)
Release:	11
Codename:	bullseye

systemd logs

Mar 27 15:03:23 prometheus systemd[1]: Reloading Prometheus.
Mar 27 15:03:23 prometheus prometheus[34185]: kill: invalid argument H
Mar 27 15:03:23 prometheus prometheus[34185]: Usage:
Mar 27 15:03:23 prometheus prometheus[34185]:  kill [options] <pid> [...]
Mar 27 15:03:23 prometheus prometheus[34185]: Options:
Mar 27 15:03:23 prometheus prometheus[34185]:  <pid> [...]            send signal to every <pid> listed
Mar 27 15:03:23 prometheus prometheus[34185]:  -<signal>, -s, --signal <signal>
Mar 27 15:03:23 prometheus prometheus[34185]:                         specify the <signal> to be sent
Mar 27 15:03:23 prometheus prometheus[34185]:  -q, --queue <value>    integer value to be sent with the signal
Mar 27 15:03:23 prometheus prometheus[34185]:  -l, --list=[<signal>]  list all signal names, or convert one to a name
Mar 27 15:03:23 prometheus prometheus[34185]:  -L, --table            list all signal names in a nice table
Mar 27 15:03:23 prometheus prometheus[34185]:  -h, --help     display this help and exit
Mar 27 15:03:23 prometheus prometheus[34185]:  -V, --version  output version information and exit
Mar 27 15:03:23 prometheus prometheus[34185]: For more details see kill(1).
Mar 27 15:03:23 prometheus systemd[1]: prometheus.service: Control process exited, code=exited, status=1/FAILURE
Mar 27 15:03:23 prometheus systemd[1]: Reload failed for Prometheus.

I think kill -s SIGHUP is more explicit usage.