Chapter 2. Performing the pre-customization tasks

2.1. Working with ISO images

In this section, you will learn how to:

  • Extract a Red Hat ISO.
  • Create a new boot image containing your customizations.

2.2. Downloading RH boot images

Before you begin to customize the installer, download the Red Hat-provided boot images. You can obtain Red Hat Enterprise Linux 9 boot media from the Red Hat Customer Portal after login to your account.

  • Your account must have sufficient entitlements to download Red Hat Enterprise Linux  9 images.
  • You must download either the Binary DVD or Boot ISO image and can use any of the image variants (Server or ComputeNode).
  • You cannot customize the installer using the other available downloads, such as the KVM Guest Image or Supplementary DVD; other available downloads, such as the KVM Guest Image or Supplementary DVD.

For more information about the Binary DVD and Boot ISO downloads, see Red Hat Enterprise Linux 9 Performing an advanced RHEL 9 installation.

2.3. Extracting Red Hat Enterprise Linux boot images

Perform the following procedure to extract the contents of a boot image.


  1. Ensure that the directory /mnt/iso exists and nothing is currently mounted there.
  2. Mount the downloaded image.

    # mount -t iso9660 -o loop path/to/image.iso /mnt/iso

    Where path/to/image.iso is the path to the downloaded boot image.

  3. Create a working directory where you want to place the contents of the ISO image.

    $ mkdir /tmp/ISO
  4. Copy all contents of the mounted image to your new working directory. Make sure to use the -p option to preserve file and directory permissions and ownership.

    # cp -pRf /mnt/iso /tmp/ISO
  5. Unmount the image.

    # umount /mnt/iso

Additional resources