How to plumb up a new IP interface

e.g. e1000g0

# ifconfig e1000g0 plumb up

# ifconfig e1000g0 192.168.0.1 netmask 255.255.255.0

# vi /etc/hostname.e1000g0

enter the hostname for that interface eg. server-e1000g0

enter the IP address for this hostname in /etc/hosts

# vi /etc/hosts

192.168.0.1 server-e1000g0