One other way to do it would be the following

$example = "This is an example";

while(<DATA>)
{
        chomp;
        s/^\$//;
        print $$_;
}

__DATA__
$example
[download]

Of course, when using the method, it would be even simpler if your file contained variable names without the '$', allowing to remove the substitution code line.

HTH

-- zejames