send email if an host is not pingable

ping_email.sh

#!/usr/bin/env bash
set -Eeuo pipefail

HOSTS_TO_CHECK=(
    127.0.0.1
    github.com
    test_invalid.com
)

test_host() {
    host=$1
    ping -W 1 -c 1 "$host" >/dev/null || return 1
}

send_email() {
    hosts_down=$@
    # echo "Those hosts are down: ${HOSTS_DOWN[*]}"
    raid_control --test-alert
}


HOSTS_DOWN=()

for host in "${HOSTS_TO_CHECK[@]}"; do
    if ! test_host "$host"; then
        HOSTS_DOWN+=("$host")
    fi
done

if (( "${#HOSTS_DOWN[*]}" != 0 )); then
    send_email "${HOSTS_DOWN[@]}"
fi