#squashfs

You want to do something inside a squashfs, as a user?

EDIT: Updated Jan 3, 2014.Thank you for your interest in JustBrowsing LiveCD.

Layers of a LiveCD

I have not gotten around to packaging all the components to be built from scratch, however I did write some scripts to make it easy to remaster the existing ISO.

Quick video tutorial

The following will guide you step-by-step from within an existing Linux install (preferably ArchLinux):

Download the ISO

$ ls ~/Downloads/justbrowsing_20131225.iso

Create a new Firefox profile (or use an existing one) and customize it as desired. I highly recommend you use my provided profile as a template:

TERMINAL #1$ git clone https://github.com/justbrowsing/justbrowsing-firefox-profile $ cd justbrowsing-firefox-profileCopy Firefox profile to system$ cp -r oknp3n8p.default/  ~/.mozilla/firefox$ mv ~/.mozilla/firefox/profiles.ini{,.restore}$ cp profiles.ini  ~/.mozilla/firefox/profiles.iniCustomize as desired$ firefox --no-remote -P defaultOptional: vacuum sqlite DBs$ profile-cleaner fRestore system profiles.ini$ cp ~/.mozilla/firefox/profiles.ini.restore ~/.mozilla/firefox/profiles.ini

Download the remaster tools

TERMINAL #2$ git clone https://github.com/justbrowsing/justbrowsing-remaster$ cd justbrowsing-remaster

Install build dependencies: cdrtools squashfs-tools syslinux

Extract the ISO

TERMINAL #2$ sudo ./extract-iso ~/Downloads/justbrowsing_20131225.iso

Replace Firefox profile

TERMINAL #1$ sudo rm -rf /media/jb-iso/home/user/.mozilla/firefox/oknp3n8p.justbrowsing$ sudo cp -r ~/.mozilla/firefox/oknp3n8p.default  /media/jb-iso/home/user/.mozilla/firefox/oknp3n8p.justbrowsing

Re-pack the ISO

TERMINAL #2==> Repack image (y/N): y==> Cleanup (y/N): y

Boot the ISO: /opt/jb-build/justbrowsing_YYYYMMDD.iso

If you're trying to extract a [Squashfs](http://squashfs.sourceforge.net/) and get a zlib::uncompress failed, unknown error -3 error, you may be running into an unsupported compression type as I did recently. Ultimately, I discovered the compression used on my Squashfs was [LZMA](http://en.wikipedia.org/wiki/Lempel%E2%80%93Ziv%E2%80%93Markov_chain_algorithm). I wanted to share just how I was able to decompress the LZMA-compressed Squashfs. Here is the superblock info for our Squashfs:

# unsquashfs -s 12C8E6.squashfs Found a valid SQUASHFS 4:0 superblock on 12C8E6.squashfs. Creation or last append time Thu Aug 16 05:41:34 2012 Filesystem is exportable via NFS Inodes are compressed Data is compressed Fragments are compressed Check data is not present in the filesystem Fragments are present in the filesystem Always_use_fragments option is not specified Duplicates are removed Filesystem size 5209.19 Kbytes (5.09 Mbytes) Block size 131072 Number of fragments 64 Number of inodes 1199 Number of ids 1

Everything looks good. Let’s try extracting it:

# unsquashfs -d squash-root1 12C8E6.squashfs Parallel unsquashfs: Using 2 processors zlib::uncompress failed, unknown error -3 read_block: failed to read block @0x515a42 read_fragment_table: failed to read fragment table index FATAL ERROR aborting: failed to read fragment table

Ruh roh; zlib is failing and returning an unknown error. Let’s try grabbing a newer version of [squashfs-tools](http://sourceforge.net/projects/squashfs/files/squashfs/squashfs4.2/). Once we have downloaded and extracted the tarball, we'll need to compile the new squashfs-tools using [Make](https://www.gnu.org/software/make/):

squashfs4.2/squashfs-tools# make

Next, we grab the superblock info using the newly compiled version of unsquashfs:

# ./squashfs4.2/squashfs-tools/unsquashfs -s 12C8E6.squashfs Found a valid SQUASHFS 4:0 superblock on 12C8E6.squashfs. Creation or last append time Thu Aug 16 05:41:34 2012 Filesystem size 5209.19 Kbytes (5.09 Mbytes) Compression LZMA Block size 131072 Filesystem is exportable via NFS Inodes are compressed Data is compressed Fragments are compressed Always_use_fragments option is not specified Xattrs are compressed Duplicates are removed Number of fragments 64 Number of inodes 1199 Number of ids 1

The new unsquashfs indicates that the compression type is LZMA. Let’s attempt to decompress the filesystem with the new unsquashfs:

# squashfs4.2/squashfs-tools/unsquashfs 12C8E6.squashfs Filesystem uses lzma compression, this is unsupported by this version Decompressors available: gzip lzo xz

It looks like we're missing LZMA from our decompressors. We'll need to download and extract the LZMA SDK 4.65 [from SourceForge](http://sourceforge.net/projects/sevenzip/files/LZMA%20SDK/4.65/). We need to modify squashfs4.2/squashfs-tools/Makefile to add LZMA support by uncommenting the LZMA_SUPPORT and LZMA_DIR options and pointing to our LZMA SDK download:

LZMA_SUPPORT = 1 LZMA_DIR = ../../lzma465

Now we have to recompile our squashfs-tools with the new options:

# make clean && make

Let’s attempt that decompression again:

# ./squashfs4.2/squashfs-tools/unsquashfs 12C8E6.squashfs Parallel unsquashfs: Using 2 processors 1138 inodes (1200 blocks) to write [=========================================================================================================================================================================================================================|] 1200/1200 100% created 910 files created 61 directories created 228 symlinks created 0 devices created 0 fifes

Recently I was thinking, what will happen if my laptop which is installed with ubuntu crashes. I've made lot of customization in it and don't want to do that all over again. I was searching for a tool which can backup all my current configuration and burn that to a DVD/CD, so that I can install from it straight away. The research ended up with Remastersys.

Its a beautiful tool, and you can do the install from Synaptic Package Manager.

Now you might be confused with the option you need to select for creating the backup, the options I chose was the second

Another thing you need to note is that you need to omit the data folders and files which are large in size. There is an option named modify where you can specify them.

Another interesting I've learned is the compressed filesystem called squashfs which has a greater compressing power that tar and gz.  This is used by remastersys while taking backup.

Remember to unmount any other windows partitions if you are using a dual OS on your machine.

Now the backup is complete and you can see your iso file in /home/remastersys/remastersys folder

Burn this ISO file to a DVD using gnomebaker, for that you should use the option Tools > Burn to DVD.