cluster.sh breaks on first run when no vault PID is found

[aeliton]

OS: Debian/bullseye

I'm following raft-ha-storage tutorial and found that the ./cluster.sh setup vault_1 command fails because it uses the following line to kill previous vault instances, but it fails if none is found.

ps aux | grep "vault server" | grep -v grep | awk '{print $2}' | xargs kill

The output is:

➜  new_cluster git:(master) ✗ ./cluster.sh setup vault_1
+ ps aux
+ grep 'vault server'
+ grep -v grep
+ xargs kill
+ awk '{print $2}'

Usage:
 kill [options] <pid> [...]

Options:
 <pid> [...]            send signal to every <pid> listed
 -<signal>, -s, --signal <signal>
                        specify the <signal> to be sent
 -l, --list=[<signal>]  list all signal names, or convert one to a name
 -L, --table            list all signal names in a nice table

 -h, --help     display this help and exit
 -V, --version  output version information and exit

For more details see kill(1).