I was just curious why you would do this:

@files = reverse (sort { $files{$a} <=> $files{$b} } keys %files);
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instead of this:

@files = sort { $files{$b} <=> $files{$a} } keys %files;
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As for the "2A" example, you could simplify that to a single system call:

my $redirect = ( $TRACE < 2 ) ?  '>' : '| tee';

system( "sed s/{author}.*//g <$file $redirect ${file}1.txt";
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The trick there is that when you pipe to "tee filename", output is written to both stdout and to filename; and the stdout from "system()" is the same as the perl script's STDOUT, so you'll see it.