DD

The DD command is typically used to create a compressed ISO or IMG file that contains one or more files.In this example, the files at /home/user1/Documents/ are at /media/storage/documents.img.gz.

dd if=/home/user1/Documents/* conv=sync,noerror bs=64K | gzip -c  > /media/storage/documents.img.gz

Note:The new file can have either the .img or .iso extension.

MKISOFS

Mkisofs does the same. In this example, this command creates an .iso file named example.iso. The .iso file contains the contents of the /data directory.

[root@server1 ]# mkisofs -RJ -o example.iso /data

After creating the .iso file, let's make sure the .iso file contains the data we expect it to contain. Let's create a directory to mount the .iso file.

[root@server1 ]# mkdir /home/<username>/test

Mount the .iso file:

[root@server1 ]# mount -o loop example.iso /home/<username>/test

You can now enter the new directory, and the contents of the .iso will be listed.

[root@server1 ]# ls /home/<username>/test