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HOW TO

This part will explain on how to edit your own LiveCD NOTW: we will take mit-linux.iso as the name of ISO use. Change it with whatever file name you are using

Create a folder and mount the iso

For doing so, we will execute the following command

mkdir mnt
sudo mount -o loop mit-linux.iso mnt

Copy the contents to another folder

Here, we will copy the contents to another folder named extraxt to use for editing

mkdir extract
sudo rsync --exclude=/casper/filesystem.squashfs -a mnt/ extract

Extract and copy the file system

We will need to extract the filesystem to use as environment for editing

sudo unsquashfs mnt/casper/filesystem.squashfs
sudo mv squashfs-root edit

Enable internet access

We will need internet connection for various file transfers and installations for that, we need to copy /etc/resolv.conf and mount /dev

sudo cp /etc/resolv.conf edit/etc/
sudo mount --bind /dev/ edit/dev

Create chroot environment

A chroot environment is where all the magic happens. You can boot into filesystem and modify using command line

sudo chroot edit

Mount important directories

Without saying, you will need these directories for proper functioning

mount -t proc none /proc
mount -t sysfs none /sys
mount -t devpts none /dev/pts
export HOME=/root
export LC_ALL=C
dbus-uuidgen > /var/lib/dbus/machine-id
dpkg-divert --local --rename --add /sbin/initctl
ln -s /bin/true /sbin/initctl

Do the magic

This is where all the magic happens. Install/remove apps, change setting, wallpapers, etc.

Cleanup

We now need to cleanup the temporary files created by the magic we did for doing so, following commands will help

apt-get autoremove && apt-get autoclean
rm -rf /tmp/* ~/.bash_history
rm /var/lib/dbus/machine-id
rm /sbin/initctl
dpkg-divert --rename --remove /sbin/initctl

Unmount directories

We will have to now unmount the directoried we previously mounted

umount /proc || umount -lf /proc
umount /sys
umount /dev/pts
exit

NOTE: the exit command exits you from the chroot environment

sudo umount edit/dev

Packing the filesystem

sudo chmod +w extract/casper/filesystem.manifest
sudo chroot edit dpkg-query -W --showformat='${Package} ${Version}\n' | sudo tee extract/casper/filesystem.manifest
sudo cp extract/casper/filesystem.manifest extract/casper/filesystem.manifest-desktop
sudo sed -i '/ubiquity/d' extract/casper/filesystem.manifest-desktop
sudo sed -i '/casper/d' extract/casper/filesystem.manifest-desktop
sudo mksquashfs edit extract/casper/filesystem.squashfs -b 1048576
printf $(sudo du -sx --block-size=1 edit | cut -f1) | sudo tee extract/casper/filesystem.size

NOTE: add -Xcompression-level # to for mksquashfs compression level. (1-9)

Generate md5sum and ISO

cd extract
sudo rm md5sum.txt
find -type f -print0 | sudo xargs -0 md5sum | grep -v isolinux/boot.cat | sudo tee md5sum.txt
sudo genisoimage -D -r -V "$IMAGE_NAME" -cache-inodes -J -l -b isolinux/isolinux.bin -c isolinux/boot.cat -no-emul-boot -boot-load-size 4 -boot-info-table -o ../mit-linux-generated.iso .
cd ..

Done

The new generated ISO will be named mit-linux-generated.iso