Ifconfig

Ifconfig is the command-line tool that every Windows admin wishes he had. You can both check and set your IP address quickly, which makes it one of my favorite programs.

ifconfig -a

Displays your current network information, the equivalent to "ipconfig /all"

ifconfig e0a

Displays the networking information for just interface e0a.

ifconfig e0a 192.168.1.9 netmask 255.255.255.0

Sets interface e0a to the specified network settings

It's important to note that the default gateway is not present in the NIC config, rather it's done through the route command. If you need to go back to DHCP, you actually just start up the DHCP client, like this:

dhclient e0a