Barry outlined UnderDog in http://barryk.org/puppylinux/developmen ... works.html ... extracts of which follow :
An exciting alternative to the squashfs extensions is to use an existing installed Linux distro as the bottom layer:
But noted in http://barryk.org/blog/?viewDetailed=02668What the above diagram is intended to convey is that the bottom layer is a partition, not the "underdog.lnx" file itself. File underdog.lnx is just a text file, containing the name of a partition, for example "hda1".
At bootup Puppy will read underdog.lnx and will mount the partition as the bottom layer. If that partition happens to have a Linux distro installed in it, then the entire distro filesystem will "show through" on the top layer of Puppy's unionfs.
The image file available here is a form of Debian Jessie LXDE/Openbox (64 bit) UnderDog (of sorts, there's no underdog.lnx file involved as initrd and vmlinuz are as provided by Debian).There are possible problems, mostly to do with mismatched libraries. The Puppy libraries would be in a higher layer, which might mean that an application that you want to run in the Underdog Linux layer might not work. With some care though, it should be ok, for example with Wary/Racy, use an older version of Ubuntu not the latest as the Underdog. Or, better, use a matching distro, example Slacko and Slackware 13.37.
Its a xz compressed image file (1.3GB that expands to a 16GB USB image) so you'll need a USB of a least 16GB and a means to install the image to that USB http://barryk.org/news/?viewDetailed=00330 and have your PC set up so that it can boot that USB http://barryk.org/quirky/uefi.htm. For Linux users, you can use dd to write the image to USB :
Be careful, write to entire drive, for example 'sdf', not to a partition, example 'sdf1'.
Make sure that the drive is unmounted, as some Linux distros will auto-mount it as soon as it is plugged in.
Also be extra careful that it is the desired USB drive you are writing to, not your main hard drive!
Code: Select all
xz --decompress --stdout jessie-usb.img.xz | dd of=/dev/sdf bs=4M conv=fsync
BOOT CHOICES
1.
Boot loader → vmlinuz → initrd → Debian Jessie bottom layer + main sfs (empty by default) + additional sfs's/.dir/.ext layers if added.
Changes stored in ram, which can be flushed to the bottom (persistent) layer using flush2disk (2nd icon on panel), or are lost at shutdown/reboot.
Layering achieved by using persistence persistence-read-only boot parameters
2.
Boot loader → Debian Boot loader → vmlinuz → initrd → Debian Jessie
Changes stored as and when they occur. Comparable to a Debian full install.
Same vmlinuz and initrd in both cases, as supplied by Debian
Benefits of type 1 is that it largely circumvents that USB's are slow to write to and their life can be reduced by excessive/repeated writes. Another benefit is that changes can be 'undone' simply by rebooting without saving (handy for trying out things). Disadvantage is that as changes are stored in memory (with option to flush those changes to disk upon demand) which tends to be more limited compared to free disk space.
Type 2 in writing changes to disk as and when they occur is constrained to the number of changes only by available free disk space. Disadvantage is that it runs slower than type 1 that records changes in memory and that all changes are preserved no matter what.
By default auto logs into desktop as user
Passwords :
user = live
root = me
Note that pcmanfm (file manager) has a right click option to open a window as root (right click on folder, select "SU file manager" and that window opens under root userid).
If you only install programs from Debian, using apt-get (text) or Synaptic (gui), then you partake in a large central system of stable programs that work well with each other. Security issues/updates from Debian tend to be quickly addressed/applied/distributed, and provided you update periodically then over time you'll automatically be migrated onto later releases/versions.
The img does contain non-free software/firmware, so please inspect and confirm whether or not it is ok for you to use such software in your country/region. Downloading and usage is on the basis that you acknowledge, respect and honour each individual components Copyright and Conditions of Use.
With thanks and greatest appreciation going out to Barry without whom such projects would never have seen light. And of course to Linus Torvalds. And also to the extensive Debian team who tirelessly develop and maintain Debian. Thanks also to all those who helped to develop, maintain and enhance snapmergepuppy/save2flash (and to Fred who helped me fork that for this particular project). Thanks also go out to all those others such as the LXDE and Openbox teams ... amongst many others, who have helped make Linux what it is today.