Create iso file from CD/DVD using Linux dd command

# isoinfo -d -i /dev/cdrom | grep -i -E 'block size|volume size'
Logical block size is: 2048
Volume size is: 327867

# dd if=/dev/cdrom of=/path/to/my.iso bs=<block size from above> count=<volume size from above>

Source: https://www.thomas-krenn.com/en/wiki/Create_an_ISO_Image_from_a_source_CD_or_DVD_under_Linux