How to create an ISO disk image of a CD or DVD from command line

The attempt to copy the entire disk image using cp may omit the final block if it is an unexpected length; dd will always complete the copy if possible.
We can use the dd command to create an ISO disk image of a CD or DVD.

dd if=/dev/cdrom of=/home/dipin/mydisk.iso bs=2048 conv=sync,notrunc

change /dev/cdrom and /home/dipin/mydisk.iso as per your needs.

The attempt to copy the entire disk image using cp may omit the final block if it is an unexpected length; dd will always complete the copy if possible.
Note that notrunc means do not truncate the output file.