I've used perl -pi -e 's/connexion/connection/g' `find . -name "*"` for that (note that this isn't optimal as it spits out some warning for directories, but it works)
I've used perl -pi -e 's/connexion/ connection/ g' `find . -name "*"` for that (note that this isn't optimal as it spits out some warning for directories, but it works)