LiveSystem helpers

Scripts and configs to allow creation and use of non-persistent Ubuntu system.

Creation script

Shell functions in mklive.sh are used to create a squashfs image and prepare USB media for live system booting.

To show available operations call script without arguments.

Image creation

The create operation builds a squashfs image (filesystem.squashfs) and additional package info from a system root directory.

The /boot/grub directory and initrd images are excluded from squashfs image to save space. The default kernel (vmlinuz) and initrd (initrd.img) are copied to the output directory.

Cleanup and package functions are designed for Debian/Ubuntu type systems.

Required packages:

• squashfs-tools: creating compressed image file
• dpkg: listing installed packages

Disk partitioning

Create a single new partition spanning the whole disk by calling new on a USB flash device (WARNING: check for correct target device!)

Boot code creation

Matching GRUB2 boot code is written to a target device with the grub option. Examples for grub configuratiuons can be found in grub.cfg.

A minimal module set (working for my grub2 version!) is listed in grub_minimal.txt. The listed files must be present in the GRUB module folder on the live media device.

#!/bin/sh
for m in `cat grub_minimal.txt`; do \
    cp -a "${grub_base}/$m" "${live_grub_moduledir}"
done

Live USB creation

Use install operation to copy live data to stick and create and write boot code.

Try to hide live system directory via FAT file system attributes.

Disk image mounting

A shortcut to mount the first partition of a disk image at sector 2048 (or 512 on 4k) is provided by the mount operation.

Live system update

By calling update on a directory containing a complete deb-based distribution the script uses chroot to load and apply updates to the system in this directory.

A combination of mount and update can be used to avoid starting a VM instance to apply updates to a system image but both operations require root priviledges on host machine.

File system relabel

A file system label can be changed by the scripts label operation. Detection and call for FAT, ExFAT and NTFS label commands is implemented. Required program to change label must be installed.

VM runtime support

The alias/script file aliases.sh may be copied into the live system base VM image to supply a shortcut for image creation from within a running QEMU instance.

Casper Configuration

Scripts for live system modification using casper must be copied to /usr/share/initramfs-tools/scripts/casper-bottom in the live system base directory.

Required packages:

• casper: Ubuntu live image runtime

Insert additional data

To add data to the live system ramdisk the script 27livedata searches for archives and extracts them to locations according to their name.

Change system setup

The script 27livemod can change mount flags (live-rw) and add the live user to the fuse group (live-fuse). The second option also creates the directory /remote to be used by the live system user for fuse mounts. Both options are enabled in supplied grub.cfg.

Documentation Shell Interface

To access documentation via a command line Interface doc.py displays availabel elements or opens selected content. Documentation entries are loaded from files matching DOC_LOAD environment variable (e.g. "/doc/*/*.conf:~/.mydoc/*.conf").

The config files are in standard desktop entry format, localization is taken from environment. Only simple CC locale is supported.