A simple script to turn on/off systemd-resolved.service from /etc/openvpn/update-resolv-conf.

systemd-resolved-switch.sh

#!/usr/bin/env bash

STATUS="$(sudo systemctl status systemd-resolved.service)"

# Stops the service if systemd-resolv.service is running.
if echo "${STATUS}" | grep -q "running"
then
    sudo systemctl stop systemd-resolved.service > /dev/null 2>&1
    if sudo systemctl status systemd-resolved.service | grep -q "inactive"
    then
        echo -e "\e[44mThe systemd-resolved.service has been stopped.\e[0m" && exit 0
    else
        echo -e "\e[41mThe service is still running.\e[0m" && exit 1
    fi
fi

# Starts the service if systemd-resolv.service is not running.
if echo "${STATUS}" | grep -q "inactive"
then
    sudo systemctl start systemd-resolved.service > /dev/null 2>&1
    if sudo systemctl status systemd-resolved.service | grep -q "running"
    then
        echo -e "\e[42mThe systemd-resolved.service has been launched.\e[0m" && exit 0
    else
        echo -e "\e[41mThe service is still inactive.\e[0m" && exit 1
    fi
fi