You could skip both cat and grep and do it all in awk. Also if speed was an issue you would want to make sure LANG=C is set for grep. Edit: I see they did use

You could skip both cat and grep and do it all in awk. Also if speed was an issue you would want to make sure LANG=C is set for grep. Edit: I see they did use awk later in article, I should really read all of things before commenting.