_Ass_uming safe input data here:

my $filename = $ARGV[0] or die "No filename given\n";
open INPUT, "<", $filename or die "could not open $filename\n";
while (<INPUT>) { print $_ };
close INPUT;
[download]

my ($file_without_path) = $filename =~ /^.*?\/(\w*?\w*?\.ext)$/;
[download]

Still, I don't see the point if you trust the filename as being safe, and just want to open it. (Since you will need the path anyway).

janx