In the office I use Red Hat quite often and one of the quicker ways to provision a Red Hat server is via kickstart. There are many ways to reach a kickstart file during initial install (NFS, HTTP, FTP) but one of the ways I commonly use is to put the file on the installation DVD itself.

The below steps are what I use to add a custom directory to the installation iso file.

Mount the official ISO as a directory

In order to access the contents of the ISO file we can mount it as a file system.

# mkdir -p /mnt/linux
# mount -o loop /tmp/linux-install.iso /mnt/linux

Copy the contents to a working directory

Since the ISO is read-only we will need to copy the contents into another directory that we can modify and add what we want.

# cd /mnt/
# tar -cvf - linux | (cd /var/tmp/ && tar -xf - )

Make your changes

At this point you can add to or modify any of the files and directories in the /var/tmp/linux directory.

Repackage the directory into a new ISO file

Once finished we will repackage the directory into a new boot-able ISO file.

# cd /var/tmp/linux
# mkisofs -o ../your-new.iso -b isolinux/isolinux.bin -c isolinux/ 
-no-emul-boot -boot-load-size 4 -boot-info-table -J -R -V Your Disk Name Here .