You can just pipe the output from tail -f to perl: tail -f /var/log/apache2/access.log | perl -pe 's/ /\t/g'

This tail -f's the apache log file, and replaces each space with a tab (useless, but it shows how you can do it).

And of course there's File::Tail on CPAN:

In reply to Re: using perl to format tail -f by moritz
in thread using perl to format tail -f by danmcb

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