How about this code that I pulled from the docs for PDF?
use PDF;
my $pdf=PDF->new($filename);
print "$filename is a PDF file\n" if ($pdf->IsaPDF);

[download]

Added: If a PDF contains no text, is it still a PDF? Of course.

Updated again: A PDF starts out with %PDF if it helps any...

D'oh! I totally misunderstood your question... I apologize.

In reply to Re: Detecting PDF content by Mr. Muskrat
in thread Detecting PDF content by Rich36

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