say "\tDone with source and sink files\n";

$/ = "\n";      # restore record separator


my @choroba = ('choroba my car -- a $car -- is $car_colour. Choroba-',
              'choroba my car2 is $car_colour $car.  Choroba-',
              'choroba my car3 is $car_colour $car Choroba-',
              'choroba my car4 is $car_colour and |secondinstance: $car_colour| |firstinstance:$car| Choroba-',
              );

for (@choroba) {
    if ( $_ =~ /choroba/ .. /Choroba-/ ) {
        s/choroba/ /;           # ...
        s/Choroba-/ /;          # or set record separator
        s/\$car_colour/red/g;   # yup, need the g
        s/\$car[^_]{1}/ford/;
        say $_;
    }
}