use vars qw/%extensions/;

# keep known extensions here.
%extensions = ();

sub assoc {
    my ($extension, $prog) = @_;
    $extensions{$extension} = $prog;
}

sub run_cmd {
    my $cmd = shift;
    my $ext = "";

    if ($cmd =~ /(\.\w+)$/) {
       $ext = $1;
    }

    # prepend interpreter for known extension
    if ($ext and exists $extensions{$ext}) {
        $cmd = "$extensions{$ext} $cmd";
    }

    return `$cmd`;
}