How to create an iso image on linux (dd/mkisofs)

# How to create the content of a directory into an iso image
## if you mount an unprotected DVD under /dev/disk2/
## Here how you can make an iso file from it.

dd if=/dev/disk2 of=FIRST_TRIP.iso bs=256k

or

cd /dev/disk2
mkisofs -r -o ~/FIRST_TRIP.iso .