# How to create custom Ubuntu live from scratch This procedure works and can create a bootable and installable Ubuntu Live (along with the automatic hardware detection and configuration) from scratch. ## Prerequisites (GNU/Linux Debian/Ubuntu) Install applications we need to build the environment. ``` sudo apt-get install \ debootstrap \ squashfs-tools \ xorriso \ grub-pc-bin \ grub-efi-amd64-bin \ mtools ``` ``` mkdir $HOME/live-ubuntu-from-scratch ``` ## Bootstrap and Configure Ubuntu * Checkout bootstrap ``` sudo debootstrap \ --arch=amd64 \ --variant=minbase \ bionic \ $HOME/live-ubuntu-from-scratch/chroot \ http://us.archive.ubuntu.com/ubuntu/ ``` > **debootstrap** is used to create a Debian base system from scratch, without requiring the availability of **dpkg** or **apt**. It does this by downloading .deb files from a mirror site, and carefully unpacking them into a directory which can eventually be **chrooted** into. * Configure external mount points ``` sudo mount --bind /dev $HOME/live-ubuntu-from-scratch/chroot/dev sudo mount --bind /run $HOME/live-ubuntu-from-scratch/chroot/run ``` As we will be updating and installing packages (among them grub), these mount points are necessary inside the chroot environment, so we can be able to finish the installations without errors. ## Define chroot environment *A chroot on Unix operating systems is an operation that changes the apparent root directory for the current running process and its children. A program that is run in such a modified environment cannot name (and therefore normally cannot access) files outside the designated directory tree. The term "chroot" may refer to the chroot(2) system call or the chroot(8) wrapper program. The modified environment is called a chroot jail.* > Reference: https://en.wikipedia.org/wiki/Chroot 1. Access chroot environment ``` sudo chroot $HOME/live-ubuntu-from-scratch/chroot ``` 2. **Configure mount points** ``` mount none -t proc /proc mount none -t sysfs /sys mount none -t devpts /dev/pts export HOME=/root export LC_ALL=C ``` 3. **Set a custom hostname** ``` echo "ubuntu-live" > /etc/hostname ``` 4. **Configure apt sources.list** ``` cat < /etc/apt/sources.list deb http://us.archive.ubuntu.com/ubuntu/ bionic main restricted universe multiverse deb-src http://us.archive.ubuntu.com/ubuntu/ bionic main restricted universe multiverse deb http://us.archive.ubuntu.com/ubuntu/ bionic-security main restricted universe multiverse deb-src http://us.archive.ubuntu.com/ubuntu/ bionic-security main restricted universe multiverse deb http://us.archive.ubuntu.com/ubuntu/ bionic-updates main restricted universe multiverse deb-src http://us.archive.ubuntu.com/ubuntu/ bionic-updates main restricted universe multiverse EOF ``` 4. **Update indexes packages** ``` apt-get update ``` 5. **Install systemd** ``` apt-get install -y systemd-sysv ``` > **systemd** is a system and service manager for Linux. It provides aggressive parallelization capabilities, uses socket and D-Bus activation for starting services, offers on-demand starting of daemons, keeps track of processes using Linux control groups, maintains mount and automount points and implements an elaborate transactional dependency-based service control logic. 5. **Configure machine-id and divert** ``` dbus-uuidgen > /var/lib/dbus/machine-id ln -fs /var/lib/dbus/machine-id /etc/machine-id ``` > The `/etc/machine-id` file contains the unique machine ID of the local system that is set during installation or boot. The machine ID is a single newline-terminated, hexadecimal, 32-character, lowercase ID. When decoded from hexadecimal, this corresponds to a 16-byte/128-bit value. This ID may not be all zeros. ``` dpkg-divert --local --rename --add /sbin/initctl ln -s /bin/true /sbin/initctl ``` > **dpkg-divert** is the utility used to set up and update the list of diversions. 6. **Install packages needed for Live System** ``` apt-get install -y \ ubuntu-standard \ casper \ lupin-casper \ discover \ laptop-detect \ os-prober \ network-manager \ resolvconf \ net-tools \ wireless-tools \ wpagui \ locales \ linux-generic ``` 7. **Graphical installer** ``` apt-get install -y \ ubiquity \ ubiquity-casper \ ubiquity-frontend-gtk \ ubiquity-slideshow-ubuntu \ ubiquity-ubuntu-artwork ``` 8. **Install window manager** ``` apt-get install -y \ plymouth-theme-ubuntu-logo \ ubuntu-gnome-desktop \ ubuntu-gnome-wallpapers ``` 9. **Install useful applications** ``` apt-get install -y \ clamav-daemon \ terminator \ apt-transport-https \ curl \ vim \ nano ``` 10. **Install Visual Studio Code** 1. Download and install the key ``` curl https://packages.microsoft.com/keys/microsoft.asc | gpg --dearmor > microsoft.gpg install -o root -g root -m 644 microsoft.gpg /etc/apt/trusted.gpg.d/ echo "deb [arch=amd64] https://packages.microsoft.com/repos/vscode stable main" > /etc/apt/sources.list.d/vscode.list rm microsoft.gpg ``` 2. Then update the package cache and install the package using ``` apt-get update apt-get install -y code ``` 11. **Install Google Chrome** 1. Download and install the key ``` wget -q -O - https://dl-ssl.google.com/linux/linux_signing_key.pub | sudo apt-key add - echo "deb http://dl.google.com/linux/chrome/deb/ stable main" > /etc/apt/sources.list.d/google-chrome.list ``` 2. Then update the package cache and install the package using ``` apt-get update apt-get install google-chrome-stable ``` 12. **Install Java JDK 8** ``` apt-get install -y \ openjdk-8-jdk \ openjdk-8-jre ``` 13. **Remove unused applications** ``` apt-get purge -y \ transmission-gtk \ transmission-common \ gnome-mahjongg \ gnome-mines \ gnome-sudoku \ aisleriot \ hitori ``` 14. **Remove unused packages** ``` apt-get autoremove -y ``` 15. **Reconfigure packages** 1. **Generate locales** ``` dpkg-reconfigure locales ``` 1. Select locales

2. Select default locale

2. **Reconfigure resolvconf** ``` dpkg-reconfigure resolvconf ``` 1. Confirm changes

3. **Configure network-manager** ``` cat < /etc/NetworkManager/NetworkManager.conf [main] rc-manager=resolvconf plugins=ifupdown,keyfile dns=dnsmasq [ifupdown] managed=false EOF ``` 4. **Reconfigure network-manager** ``` dpkg-reconfigure network-manager ``` 15. **Cleanup the chroot environment** 1. If you installed software, be sure to run ``` rm /var/lib/dbus/machine-id ``` 2. Remove the diversion ``` rm /sbin/initctl dpkg-divert --rename --remove /sbin/initctl ``` 3. Clean up ``` apt-get clean rm -rf /tmp/* ~/.bash_history umount /proc umount /sys umount /dev/pts export HISTSIZE=0 exit ``` ## Unbind mount points ``` sudo umount $HOME/live-ubuntu-from-scratch/chroot/dev sudo umount $HOME/live-ubuntu-from-scratch/chroot/run ``` ## Create the CD image directory and populate it 1. Access build directory ``` cd $HOME/live-ubuntu-from-scratch ``` 2. Create directories ``` mkdir -p image/{casper,isolinux,install} ``` 2. Copy kernel images ``` sudo cp chroot/boot/vmlinuz-**-**-generic image/casper/vmlinuz sudo cp chroot/boot/initrd.img-**-**-generic image/casper/initrd ``` 3. Copy memtest binary ``` sudo cp chroot/boot/memtest86+.bin image/install/memtest ``` ## Grub configuration 1. Access build directory ``` cd $HOME/live-ubuntu-from-scratch ``` 2. Create image/isolinux/grub.cfg ``` cat < image/isolinux/grub.cfg search --set=root --file /ubuntu insmod all_video set default="0" set timeout=30 menuentry "Try Ubuntu without installing" { linux /casper/vmlinuz boot=casper quiet splash --- initrd /casper/initrd } menuentry "Install Ubuntu" { linux /casper/vmlinuz boot=casper only-ubiquity quiet splash --- initrd /casper/initrd } menuentry "Check disc for defects" { linux /casper/vmlinuz boot=casper integrity-check quiet splash --- initrd /casper/initrd } menuentry "Test memory" { linux /install/memtest } EOF ``` ## Create manifest 1. Access build directory ``` cd $HOME/live-ubuntu-from-scratch ``` 2. Generate manifest ``` sudo chroot chroot dpkg-query -W --showformat='${Package} ${Version}\n' | sudo tee image/casper/filesystem.manifest sudo cp -v image/casper/filesystem.manifest image/casper/filesystem.manifest-desktop sudo sed -i '/ubiquity/d' image/casper/filesystem.manifest-desktop sudo sed -i '/casper/d' image/casper/filesystem.manifest-desktop sudo sed -i '/discover/d' image/casper/filesystem.manifest-desktop sudo sed -i '/laptop-detect/d' image/casper/filesystem.manifest-desktop sudo sed -i '/os-prober/d' image/casper/filesystem.manifest-desktop ``` ## Compress the chroot 1. Access build directory ``` cd $HOME/live-ubuntu-from-scratch ``` 2. Create squashfs ``` sudo mksquashfs chroot image/casper/filesystem.squashfs ``` 3. Write the filesystem.size ``` printf $(sudo du -sx --block-size=1 chroot | cut -f1) > image/casper/filesystem.size ``` ## Create diskdefines 1. Access build directory ``` cd $HOME/live-ubuntu-from-scratch ``` 2. Create file image/README.diskdefines ``` cat < image/README.diskdefines #define DISKNAME Ubuntu from scratch #define TYPE binary #define TYPEbinary 1 #define ARCH amd64 #define ARCHamd64 1 #define DISKNUM 1 #define DISKNUM1 1 #define TOTALNUM 0 #define TOTALNUM0 1 EOF ``` ## Recognition as an Ubuntu from scratch 1. Access build directory ``` cd $HOME/live-ubuntu-from-scratch ``` 2. Create an empty file named "ubuntu" and a hidden ".disk" folder. ``` touch image/ubuntu mkdir image/.disk ``` ## Create ISO Image for a LiveCD (BIOS + UEFI) 1. Access image directory ``` cd $HOME/live-ubuntu-from-scratch/image ``` 2. Create a grub UEFI image ``` grub-mkstandalone \ --format=x86_64-efi \ --output=isolinux/bootx64.efi \ --locales="" \ --fonts="" \ "boot/grub/grub.cfg=isolinux/grub.cfg" ``` 4. Create a FAT16 UEFI boot disk image containing the EFI bootloader ``` ( cd isolinux && \ dd if=/dev/zero of=efiboot.img bs=1M count=10 && \ sudo mkfs.vfat efiboot.img && \ mmd -i efiboot.img efi efi/boot && \ mcopy -i efiboot.img ./bootx64.efi ::efi/boot/ ) ``` 5. Create a grub BIOS image ``` grub-mkstandalone \ --format=i386-pc \ --output=isolinux/core.img \ --install-modules="linux normal iso9660 biosdisk memdisk search tar ls" \ --modules="linux normal iso9660 biosdisk search" \ --locales="" \ --fonts="" \ "boot/grub/grub.cfg=isolinux/grub.cfg" ``` 6. Combine a bootable Grub cdboot.img ``` cat /usr/lib/grub/i386-pc/cdboot.img isolinux/core.img > isolinux/bios.img ``` 7. Generate sha256sum.txt ``` sudo /bin/bash -c "(find . -type f -print0 | xargs -0 sha256sum | grep -v "\./sha256sum.txt" > sha256sum.txt)" ``` 7. Create iso from the image directory using the command-line ``` sudo xorriso \ -as mkisofs \ -iso-level 3 \ -full-iso9660-filenames \ -volid "Ubuntu from scratch" \ -eltorito-boot \ boot/grub/bios.img \ -no-emul-boot \ -boot-load-size 4 \ -boot-info-table \ --eltorito-catalog boot/grub/boot.cat \ --grub2-boot-info \ --grub2-mbr /usr/lib/grub/i386-pc/boot_hybrid.img \ -eltorito-alt-boot \ -e EFI/efiboot.img \ -no-emul-boot \ -append_partition 2 0xef isolinux/efiboot.img \ -output "../ubuntu-from-scratch.iso" \ -graft-points \ "." \ /boot/grub/bios.img=isolinux/bios.img \ /EFI/efiboot.img=isolinux/efiboot.img ```