Add an address to an interface
ip address add ${address}/${mask} dev ${interface name}
Examples:
ip address add
192.0.2.10/27 dev eth0
You can add as many addresses as you want.
If you add more than one address, your machine will accept packets for all of them. The first address you added will be used as source address for outgoing traffic by default, it's referred to as primary address.
All additional addresses you set will become secondary addresses.