Mention grep -P to get things like \d

[NicMcPhee]

The grep -P flag enables Perl regex syntax, which includes a lot of useful things like \d for digits. Running man pcresyntax will give them a list of all the nifty things that this includes.

This won't work on the default MacOS (BSD) version of grep, so folks on a Mac do need to make sure they've installed and am using the GNU versions of these tools.