• In more readable Perl:

        # Accept a number from the user
        print "maximum:";
        $maximum = <STDIN>;

        # Make an array of numbers
        @numbers = (2..$maximum);

        # Iterate through that array
        while ($prime = shift @numbers) {
            # Print the next prime
            print "$prime\n";
            # Remove multiples of that prime
            @numbers = grep {$_ % $prime} @numbers;
        }