That's one of my favorite ways to do it. You may want to adopt perl 5.6+ notation for piped open, use a lexical file handle, and keep the child pid,

{
    my $cpid = open my $fd, '-|', 'a' or die $!;
    print while <$fd>;
}
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The three-arg form of open is preferred because it separates the open mode from the file name, and it can take modifiers like ':raw' to activate IO layers, remove the need for binmode, etc.

Your app could have done this with backticks, but not so well.