Change IP and Gateway from Shell

Change IP

ifconfig <interface_name> <ip_address> netmask <netmask_address>

Change Gateway

sudo route add default gw <gateway_ip_address> <interface_name>

Example

sudo ifconfig Ethernet 10.0.100.27 netmask 255.255.255.0

sudo route add default gw 10.0.100.1 eth0