Create Ubuntu Live CD From Scratch

I. Setup Host

1. Install tools

sudo apt-get install binutils debootstrap squashfs-tools xorriso grub-pc-bin grub-efi-amd64-bin mtools schroot 

2. Cấu hình Ubuntu sử dụng debootstrap

export HOME=/home/phong/
mkdir $HOME/customize-live-ubuntu-cd
// cat /etc/os-release bionic
sudo debootstrap --arch=amd64 --variant=minbase bionic $HOME/customize-live-ubuntu-cd/chroot http://vn.archive.ubuntu.com/ubuntu/

sudo mount --bind /dev $HOME/customize-live-ubuntu-cd/chroot/dev
sudo mount --bind /run $HOME/customize-live-ubuntu-cd/chroot/run

   
- Debootstrap là công cụ được sử dụng để tạo ra hệ thống Debian từ ban đầu mà không yêu cầu dpkg hoặc apt. 
Debootstrap sẽ thực hiện download bản sao từ upstream và giải nén về local.
- Sau khi có được bản sao Debian. Chúng ta sẽ thực hiện chạy nó trong môi trường chroot.
Ta có thể coi chroot như là một Virtual Machine tuy nhiên nó nhẹ hơn và không yêu cầu cài đặt kernel để có thể chạy. 
Host sẽ chia sẻ nhân kernel với chroot.

II. Basic configuration for chroot

1. Đăng nhập vào chroot

sudo chroot $HOME/customize-live-ubuntu-cd/chroot

mount none -t proc /proc
mount none -t sysfs /sys
mount none -t devpts /dev/pts
export HOME=/root
export LC_ALL=C

The none just means that there is no physical disk partition linked to the mount point you see when issuing the mount command. 
It is used for virtual filesystems like shm, ramfs, proc and tmpfs.

2. Update hostname

echo "slayder" > /etc/hostname	

3. Update apt/source.list

// update apt source-list
cat <<EOF > /etc/apt/sources.list
deb http://vn.archive.ubuntu.com/ubuntu/ bionic main restricted
deb http://vn.archive.ubuntu.com/ubuntu/ bionic-updates main restricted
deb http://vn.archive.ubuntu.com/ubuntu/ bionic universe
deb http://vn.archive.ubuntu.com/ubuntu/ bionic-updates universe
deb http://vn.archive.ubuntu.com/ubuntu/ bionic multiverse
deb http://vn.archive.ubuntu.com/ubuntu/ bionic-updates multiverse
deb http://vn.archive.ubuntu.com/ubuntu/ bionic-backports main restricted universe multiverse
deb http://security.ubuntu.com/ubuntu bionic-security main restricted
deb http://security.ubuntu.com/ubuntu bionic-security universe
deb http://security.ubuntu.com/ubuntu bionic-security multiverse
EOF

// update
apt-get update

4. install systemD service

SystemV is older, and goes all the way back to original Unix.
SystemD is the new system that many distros are moving to.
SystemD was designed to provide faster booting, better dependency management, and much more.
SystemD handles startup processes through .service files.
SystemV handles startup processes through shell scripts in /etc/init*.

// file /sbin/init
apt-get install -y libterm-readline-gnu-perl systemd-sysv	

5. Install packages necessary needed by system

apt-get install -y \
    sudo \
    ubuntu-standard \
    casper \
    lupin-casper \
    discover \
    laptop-detect \
    os-prober \
    network-manager \
    resolvconf \
    net-tools \
    wireless-tools \
    wpagui \
    locales \
    grub-common \
    grub-gfxpayload-lists \
    grub-pc \
    grub-pc-bin \
    grub2-common \

apt-get install -y --no-install-recommends linux-generic

6. Graphic Installer

apt-get install -y \
ubiquity \
ubiquity-casper \
ubiquity-frontend-gtk \
ubiquity-slideshow-ubuntu \
ubiquity-ubuntu-artwork

7. Install window manager

apt-get install -y \
	plymouth-theme-ubuntu-logo \
	ubuntu-gnome-desktop \
	ubuntu-gnome-wallpapers

8. Generate locales

dpkg-reconfigure locales

9. Reconfigure resolvconf

dpkg-reconfigure resolvconf

III. Starting customize

1. Install Packages

apt-get install -y \
	clamav-daemon \
	terminator \
	apt-transport-https \
	software-properties-common \
	wget \
	curl \
	vim \
	nano \
	less \
	ibus-unikey

2. Install Applications

// visual code
sudo apt update && sudo apt upgrade -y
wget -q https://packages.microsoft.com/keys/microsoft.asc -O- | sudo apt-key add -
sudo add-apt-repository "deb [arch=amd64] https://packages.microsoft.com/repos/vscode stable main"
sudo apt install code

// chrome
sudo apt-get install libxss1 libappindicator1 libindicator7
wget https://dl.google.com/linux/direct/google-chrome-stable_current_amd64.deb
sudo apt install ./google-chrome*.deb

// gparted
sudo apt-get install gparted

// beyond compare
sudo dpkg --add-architecture i386
sudo apt update
sudo apt install ./bcompare-4.4.2.26348_amd64.deb

// notepad++
sudo apt-get install snapd snapd-xdg-open

3. Remove unnecessary packages

3.1 Remove apps

sudo apt-get remove package-name
	<Any of the above commands will remove the specified package, but they will leave behind configuration files, 
	and in some cases, other files that were associated with the package.>
sudo apt-get purge package-name

// remove firefox
sudo apt-get purge firefox

// remove gnome-games and non-language
sudo apt-get remove --purge gnome-games*
sudo apt-get remove --purge `dpkg-query -W --showformat='${Package}\n' | grep language-pack | egrep -v '\-en'`

// show pakages
dpkg-query -W --showformat='${Package}\n | less

3.2 Remove unused package

apt-get autoremove -y

autoremove is used to remove packages that were automatically
installed to satisfy dependencies for other packages and are now no
longer needed.

4. Clean tempotary files and quit

apt-get clean
rm -rf /tmp/* ~/.bash_history
umount /proc
umount /sys
umount /dev/pts
exit	

sudo umount $HOME/customize-live-ubuntu-cd/chroot/dev
sudo umount $HOME/customize-live-ubuntu-cd/chroot/run

IV. Create LiveCD

1. mout iSO image to customize-live-ubuntu-cd/livecd

mkdir /tmp/livecd
sudo mount -o loop ubuntu-18.04.6-desktop-amd64.iso /tmp/livecd 

3. Remove rootfs file

mkdir livecd
sudo cp -rf /tmp/livecd/* livecd && sync
sudo rm -rf livecd/casper/filesystem.squashfs

4. Compress chroot -> filesystem.squashfs

sudo mksquashfs chroot livecd/casper/filesystem.squashfs

5. Copy linux -> livecd/casper/

sudo cp -rf chroot/boot/vmlinuz-4.15.0-180-generic livecd/casper/vmlinuz
sudo cp -rf chroot/boot/initrd.img-4.15.0-180-generic livecd/casper/initrd

6. Recreate manifest file

sudo chroot chroot/ dpkg-query -W --showformat='${Package} ${Version}\n' | sudo tee livecd/casper/filesystem.manifest

7. Write the filesystem.size

printf $(sudo du -sx --block-size=1 chroot | cut -f1) > filesystem.size && sudo cp -f filesystem.size livecd/casper/

8. Recreate md5 checksum

find livecd -type f -print0 | xargs -0 md5sum > /tmp/md5sum.txt && cp -f /tmp/md5sum.txt livecd

9. Create ISO image

cd livecd && sudo mkisofs -r -V "phonglt15-Ubuntu-Live-Custom" -b isolinux/isolinux.bin -c isolinux/boot.cat -cache-inodes -J -l -no-emul-boot \
-boot-load-size 4 -boot-info-table -o ../phonglt15-Ubuntu-Live-Custom.iso .