Is there a way to insert (at line head) and / or append (to line tail) arbitrary text strings to a selection? I've used another editor with that feature and it's pretty handy. If not, is there a way to pass values to a custom format command? I have a shell script that could be invoked, but I don't see a way to enter the pre / post text.

Maybe I just need to come up with a regex to do it...

Thanks.