Hi Brian,
It’s normal I think…as network engineers, we don’t use regular expressions much. If you are into programming, you’ll use them quite a lot to match strings/numbers/etc… If you want to practice these, try a site like:
Paste in the output of a BGP table there and test it…it’s easier and quicker than testing regex on your router.
I wouldn’t worry about this too much though…when you need to use them for BGP, you can always look them up…test it, then apply it to your router. No need to memorize all the different options. When you need it, it’s probably a simple regex, nothing more.
The underscore works fine here btw? SHIFT + - (dash) does the job.
Rene