I have installed Ubuntu 18.04.1 LTS, and I need to add some routes. Which command shall I use?
ifup was deprecated?
You can inject temporary netplan configuration by writing config files under /run/netplan and running
netplan apply. However, if these are temporary routes, there's no reason you can't continue to use the commands you're familiar with to configure these directly in the kernel ('ip route add', 'route add').