bash match one word but exclude another

findipsubnetgateway

use double grep

command | grep 'what you want' | grep -v 'whatyoudontwant'

Or use awk

awk '/XXX/ && !/YYY/' file
     ^^^^^    ^^^^^^
I want it     I don't want it
You can even say something more complex. For example: I want those lines containing either XXX or YYY, but not ZZZ:

awk '(/XXX/ || /YYY/) && !/ZZZ/' file