This is answered in perlfaq5, specifically How do I do a tail -f in perl?. The seek-based solution there may work better than the filehandle read, depending on if the external program adds line endings.

The requisite module is probably File::Tail.

Update: Fixed the link, thanks to Albannach.

In reply to Re: printing lines of a changing document by chromatic
in thread printing lines of a changing document by Anonymous Monk

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