Yep, I was just able to do it only with cat, grep, sed, and head.

I think I would have found it painful without join and sort, though (which, also in that list).

I rarely use join and it never occurred to me. For combining the one file that had records spanning several lines, I used awk instead of grep -A as the hints suggest. Where the hints suggest a head/tail combination, I used sed. I also used sort piped to uniq in one case; combinations of those two are very often useful.

Thanks! I'll be checking this out then.

cd, cat, ls, head, tail, grep