I wish this was homework. I've been out of school for enough years not to get upset by the word "homework" anymore :). The "enough memory" solution I know, but I would rather avoid. I've learned the lesson "64k should be enough for everybody" soon after is was said :), so I am trying to avoid getting my head into this gutter.

The real application for this is messing with /etc/fstab file and changing the location where some partitions are mounted (i.e., flip two partitions). I made up the Name-Address simplified example so the discussions won't get off track and discuss the Unix problem rather than my Perl question.

Thanks for your suggestion, I'll look at that link!