Howto bake Persistent Live USB – Debian Way (live-build)

Hey guys!! wish you happy festive days!!

For long time I was thinking about creating my own system. Recently, during my experiment with ‘mic2’, I came to know about ‘live-build’ package.

‘mic2’ is a package which contains tools to create Meego images. I’m yet to create my Meego Image. During Meego image creation, I had lot to do with my USB pendrive. My pendrive previously had puppy for system rescue purpose. After spending much time with Meego without any success, I thought of creating my rescue USB by downloading puppy. But decided to give ‘live-build’ a try.

First we need to install ‘live-build’

sudo apt-get install live-build cdebootstrap

‘live-build’ is a set of scripts to build customized debian iso/usb-hdd images. I’m not going to explain each scripts, instead, just lets start building a Debian Persistant Live USB with ‘rescue’ packages from ‘Testing’ repository for ‘i386’ architecture. My host system is ‘Debian Testing (amd64)’ Here is the steps,

Create a directory and go inside

mkdir live-build-base && cd live-build-base

Execute below command

sudo lb config --architecture i386 --binary-images usb-hdd --binary-filesystem fat32 --bootappend-live 'persistent' --bootstrap cdebootstrap --distribution testing --mirror-binary --packages 'usb-modeswitch' --packages-lists 'rescue'

This tells ‘–architecture’ for the live system should be ‘i386’, you can give any of debian ports like ‘amd64’, ‘sparc’, ‘powerpc’, ‘armel’, ‘hurd-i386’, ‘kfreebsd-gnu’ etc., to this option. But careful, we are not using qemu to build the image. we are using cdebootstrap, thus, an ‘amd64’ host system can bake ‘amd64’, ‘i386’, ‘hurd-i386’, ‘kfreebsd-gnu’ images, but it cannot bake ‘armel’, ‘sparc’ or ‘powerpc’.

The next option ‘–binary-images’ tells what kind of image to create, like ‘iso’ or ‘iso-hybrid’ or ‘usb-hdd’ etc., (see ‘man lb_config’). Next option ‘–binary-filesystem’ tells the format of the final root filesystem.

Next one ‘–bootappend-live’ passes options to ‘live-initramfs’ which is the main tool to create live debian system, see ‘man live-initramfs’ to know about its options. ‘persistent’ informs ‘live-initramfs’ to generate ‘initrd’ image which will search for partitions with label ‘live-rw’ or ‘home-rw’ at boot time, if ‘initrd’ finds, it will instruct ‘aufs’ to stage that partition as a rw layer for root filesystem.

‘–bootstrap cdebootstrap’ will use ‘cdebootstrap’ while creating the image. you should install ‘cdebootstrap’ in your host system first.

‘–distribution testing’ indicates which repo to download packages, you can give ‘stable’, ‘unstable’, ‘testing’, ‘experimental’, ‘lenny’, ‘squeeze’, ‘sid’ and ‘wheezy’.

‘–mirror-binary’ points to the repo URL

‘–packages usb-modeswitch’ will additionally install ‘usb-modeswitch’ package. I need this, because I’m using a netconnect datacard for internet access.

‘–packages-list rescue’ will get packages from /usr/share/live/build/lists/rescue file. This file is preconfigured to install specific packages for specific purpose, we can give ‘rescue’, ‘gnome’, ‘kde’, ‘gnustep’, ‘lxde’, ‘studio’ etc., each have a corresponding file inside /usr/share/live/build/lists directory in your host system.

Above options prepares ‘live-build-base’ directory to build your customized debian. Now, its time to build, execute the below command,

sudo lb build

Once started, ‘lb build’ will take some time to bake the required image. Finally, you will get ‘build.img’ with all your customized packages installed. Next step should be dd-ing the image to your USB pendrive. Insert it, and execute the following command,

sudo dd if=build.img of=/dev/sdX bs=4096

Here, ‘/dev/sdX’ indicates your loaded pendrive name, it may be ‘/dev/sdb’ or ‘/dev/sdc’. Once ‘dd’ finishes, reboot your system and boot from your USB pendrive. You will be inside ‘Debian Live’ !!!!

Next, we need to create ‘live-rw’ partition in your pendrive for persistent storage (means automatically saving the changes you do in your live system). Just create a partition with label as ‘live-rw’ from the free space left in your pendrive using ‘gparted’ or ‘fdisk’. Then boot your machine from USB drive, once you are inside ‘Debian Live’, you can see the new partition mounded as ‘aufs’ rw layer for root filesystem in /live/cow.

During ‘lb build’ phase, if any error occurs, or you decide to change your configuration, remove all directories except ‘cache’ from ‘live-build-base’ directory. Then remove ‘.stage’ directory and start ‘lb config’ with your options again from ‘live-build-base’ directory. This will reduce package download time, but if you are building for different architecture, then its better to delete ‘cache’ also. Here is the screenshot of my image running under QEMU,

Thats it!! hope you will bake a better ‘Debian Live cake’ than me!!!