open(my $in, "<", "./mod-recipes/intermediate.csv") or die "Can't open intermediates.csv";
open(my $out, ">", "./mod-recipes/output.csv") or die "Can't open output.csv";

while (<$in>) {
    @line = split(",", $_);
    if ($line[1] =~ /(iron|steel|copper|zinc|tungsten|titanium|tin|nickel|silver|platinum|manganese|lead|gold|aluminium)/) {
        $line[0] = 'metal'
    }
    my $lineout = join (',', @line);
    print $out "$lineout";
}
close $in or die "$in: $!";
close $out or die "$out: $!";