++holli. That is the usually the best approach.

If needed, this also works (on Win32, and only tested with Acrobat 5.x).

use Win32::TieRegistry( Delimiter=>'/' );
my $key = 'Classes/Applications/AcroRd32.exe/shell/open/command';
my $command = $Registry->{$key}{'/'}
  or die "Can't read '$key': $^E\n";
$command =~ s{ "%1"$}{} or warn;
print $command;
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