====== Create An ISO File From a CD or DVD-ROM Using the Terminal ======
(Tested in Linux Mint.)

Insert the CD/DVD in the drive.

Open a terminal.

Install dcfldd, if it isn’t already:

<code bash>sudo apt-get install dcfldd</code>

Figure out where your CD/DVD is mounted:

<code bash>mount</code>

(On my system it’s mounted as /dev/sr0)

Unmount it:

<code bash>umount /dev/sr0</code>

Create the ISO image:

<code bash>dcfldd if=/dev/sr0 of=image.iso</code>

In the example above, “image.iso” will be created in the current directory.  You can change the “of” argument to whatever you want, e.g., different name, full path, etc.