in reply to Need to change, oh, every file at once?
Congratulations, you can make toast!
Not to discourage you in anyway, but this is a very well-known idiom. Very cool, and also one of the things I enjoyed when I first encountered perl. Something that might come in handy with this if you have not yet seen it is File::Find
--
perl -pe "s/\b;([st])/'\1/mg"
In Section
Cool Uses for Perl