Check if your target system is Ubuntu 16.04 (this procedure may work with other versions as well but not newer versions (18.04+) that use something called Netplan):
cat /etc/issue
If you want to add a static IP address, do the following:
vi /etc/network/interface
Example configuration:
auto eth0 iface eth0 inet static address 192.168.1.20 netmask 255.255.255.0 network 192.168.1.0 broadcast 192.168.1.255 gateway 192.168.1.1 dns-nameservers 1.1.1.1 8.8.4.4
To test:
ip addr