Setup is Ubuntu 14.04.1 LTS or Debian 7.
I can assign bound IPs to network interfaces without network downtime with ifconfig, but it doesn't persist across restarts (unless you use rc.local, which apparently isn't recommended), with:
sudo ifconfig eth0:x <bound IP here>
What is the "preferred" way to do this that doesn't involve any network downtime (e.g. no ifup/ifdown)?