How to Create ISO Images from Command-Line

For this tutorial we’ll use the genisoimage utility, developed as part of the cdrkit project. genisoimage is a command-line tool for creating ISO 9660 filesystem images, which can be burnt after to a CD or DVD using some other burning tool. To install it open a terminal and type the following as root:

Ubuntu and Debain
$ sudo apt-get install genisoimage (for Centos and redhat )

For Redhat and Centos
$ yum -y install genisoimage
Now, let’s use the simplest syntax to create an ISO image out of a directory and its contents:

$ genisoimage -o output_image.iso directory_name

The image, called output_image.iso, will have the directory_name as the root folder. In order to create an image out of several files and folders and without a root directory, use this command:

$ genisoimage -o output_image.iso file1 file2 file3

This command will create an image which will contain the files file1, file2 and file3 and will have no root directory.

Another useful switch to genisoimage is -R, which uses the Rock Ridge protocol to preserve ownership and permission records, enable longer filenames and support symbolic links and device files:

$ genisoimage -R -o output_image.iso file1 file2 file3

Creating ISO Images from CDs/DVDs

For this we will use the dd tool, used to create or copy files formatting them using the specified filesystem. First, unmount the device if it is already mounted:

# umount /dev/cdrom

Your device may have a different name (e.g. /dev/cdrw, /dev/scd0 or such, so replace accordingly). The command to create an image is the following:

$ dd if=/dev/cdrom of=~/cd_image.iso

Where if and of mean input file and output file, respectively and ~ is your home directory.

Additionally, you can create an image from an audio CD with the following command:

cat /dev/scd0 > ~/audio_image.iso