even more advanced script
that creates a persistent disk.
with a few options:
I Home: use only your persistent home directory.
I System: replace the entire /ramdisk mountpoint with the persistent disk image.
I Overwrite: off by default, but it will replace the /etc directory on your persistent image if you also enable the System option. You might want to do this if your system-wide graphics or network settings from a previous machine interfere with your current one.
I Init: start any persistent init scripts.
If you don’t select any of these options, Knoppix will boot normally. It’s also possible that you might have multiple knoppix.img files on different drives (or multiple files on the same drive in different directories). This actually is a good way to create custom Knoppix settings that are stored in different directories on a USB key. Say I have a security-focused persis-tent image in the security directory on my USB key (which Knoppix detects as /dev/sda1), I could then boot Knoppix with the home=/dev/sda1/security/knoppix.img cheat code.
Tweak Boot Settings
The saveconfig and knoppix.sh tweaks provide a lot of functionality, but their main downside is that they execute at the end of the boot process. Sometimes you want to change Knoppix settings sooner than that—whether it’s the default screen you see at boot time or Knoppix’s default cheat codes. These options and more are stored in the boot/isolinux/ directory on the disc and can be changed without much effort. Below I cover some of the more important files and what you can change with them.
Boot messages: the boot.msg, f2 and f3 files are text files that define what shows up at the boot prompt, when you press F2 and F3, respectively. If you want to add special help or even change the text completely, you can do so in these files.
isolinux.cfg: this is one of the most useful files in this directory, as it defines all the different kernels that can be loaded, along with their default boot options. For instance, here is the section of the file that defines the default Knoppix settings and cheat codes if you let the boot prompt time out or just press Enter:
LABEL knoppix KERNEL linux
APPEND ramdisk_size=100000 init=/etc/init lang=us apm=power-off vga=791 initrd=m
inirt.gz nomce loglevel=0 quiet BOOT_IMAGE=knoppix
For instance, you can see here that the default language is English, but if you wanted to change it to Spanish, you would change lang=usto lang=es. If you scroll down farther in the file, you can not only see other Knoppix types you can boot, but also listings for memtest and dos.
Tweak initrd
Along with the other boot files, under boot/isolinux/ is the default Knoppix initrd file called minirt.gz. This file is the initial root image that Knoppix mounts. Within the image are essential files for the boot process, including the init executable, but the file of most interest to Knoppix hackers is the linuxrc file, which acts as Knoppix’s general startup script. First, make a copy of the minirt.gz file (in my example, I assume it was mounted under /cdrom), uncompress it and then mount the filesystem:
# cp /cdrom/boot/isolinux/minirt.gz .
# gunzip minirt.gz
# mkdir temp
# mount -t ext2 -o loop minirt ./temp
Now, if you look in the top-level directory of that mounted filesystem, you will see the linuxrc file. A lot of the script defines default settings, such as which filesystems are built in to Knoppix and the process Knoppix uses to mount them, but you also can see where Knoppix defines system-wide defaults and also allows you to override them. For instance, the follow-ing lines define the default Knoppix directory and cloop file and the ability to overwrite them via a cheat code:
KNOPPIX_DIR="KNOPPIX"
KNOPPIX_NAME="KNOPPIX"
case "$CMDLINE" in *knoppix_dir=*) KNOPPIX_DIR="$knoppix_dir"; ;; esac case "$CMDLINE" in *knoppix_name=*) KNOPPIX_NAME="$knoppix_name"; ;; esac
If you want to add some extra functions to the boot pro-cess, read through the script to identify where would be best.
For instance, at some points of the script, the KNOPPIX cloop filesystem isn’t loaded yet, nor are many common modules. If you aren’t sure where to add your changes, just add them to the end of the script before the comment #Give control to the init process. At that point, Knoppix should have major modules and filesystems loaded and mounted.
Once you are finished with your tweaks, unmount the minirt filesystem and recompress it. Then, you can overwrite the default version with your custom edition:
umount temp gzip -9 minirt
These are only a few examples of how to remaster Knoppix without remastering. One of the great things about these meth-ods is that they are typically easy to try, so if you make a mistake, you can fix it quickly. Plus, most of these methods lend themselves well to migration from one Knoppix disc to the next for when the next version of Knoppix is released. Finally, because most of your custom tweaks can be self-contained, if you want to share them with friends, you simply can share your knoppix.sh and configs.tbz files, for instance, instead of an entire ISO image.I
Kyle Rankin is a Senior Systems Administrator in the San Francisco Bay Area and the author of a number of books, including Knoppix Hacks and Ubuntu Hacks for O’Reilly Media. He is currently the president of the North Bay Linux Users’ Group.