If you’ve never used sed, it’s only because you didn’t know you were using it. sed is used everywhere, by everything, for everything, and the only reason we don’t give it more credit is that it works so fast, clean and quiet that nobody realizes it’s there.
sed is one of those things that’s so quick and powerful that it looks very plain and boring — and then turns out being a wicked sharp tool. It takes almost no effort to get started, but once you start, tinkering with patterns and sequences can get addictive.
The fun thing, to me, about sed is that it occasionally can take the place of a trip through a text editor. Rather than wrangle with vim or emacs and their respective psychoses, sed can do a lot of simple text manipulation right there in front of your face.
I wouldn’t dream of trying to explain all its intricacies here, so I’ll point you in the direction of Bruce Barnett’s tutorial, which is where I cut my teeth on sed, oh-so-long-ago.
Now go forth and sedify. 😕