How to get IP by command? (Linux)

 How to get IP by command? (Linux)

Ubuntu:

ip addr show | grep -o 'inet [0-9]\+\.[0-9]\+\.[0-9]\+\.[0-9]\+' | grep -o [0-9].*

Centos:

ifconfig | grep -o 'inet [0-9]\+\.[0-9]\+\.[0-9]\+\.[0-9]\+' | grep -o [0-9].*