[CentOS] Modifying a netinstall ISO image

Fri Jul 27 18:59:36 UTC 2012
Alfred von Campe <alfred at von-campe.com>

I want to make a very minor change to the netinstall ISO image, namely adding a few parameters to the boot line to automatically kick off a kickstart installation.  Here is my approach:

  mount -o loop CentOS-6.2-i386-netinstall.iso /mnt
  cp -pr /mnt /tmp
  cd /tmp/mnt
  vi isolinux/isolinux.cfg  # Add some stuff to the default append line and reduce timeout
  mkisofs -o /tmp/CentOS-6.2-i386-netinstall-ks.iso -b isolinux/isolinux.bin -c isolinux/boot.cat -no-emul-boot -boot-load-size 4 -boot-info-table -R -J -v -T .

I got the mkisofs command line from http://www.centos.org/docs/5/html/5.2/Installation_Guide/s2-steps-make-cd.html (I couldn't find anything similar in the CentOS/RHEL 6.X documentation).

This appears to work just fine, but the resulting ISO image is about 20% bigger (194M vs. 162M) and has an extra TRANS.TBL file at the top level.  Any ideas what is causing this?  It's no big deal as I've got things working, but I'm curious nonetheless...