Live-System - Usage

Quick start

Prepare a system

• Bootstrap an Arch Linux system:

mkdir system
pacstrap system base linux sudo xorg xfce4 lightdm-gtk-greeter network-manager-applet chromium #...
chroot system pacman -Scc
chroot system systemctl enable lightdm
chroot system systemctl enable NetworkManager
chroot system useradd -m -g users -G wheel linomad
echo -e "root:root
linomad:linomad" | chroot system chpasswd
sed 's/# \(%wheel ALL=(ALL)\)/\1/' -i system/etc/sudoers

• Or, a Slackware one :

mkdir system
mount -o loop path/to/slackware64-current.iso /mnt
installpkg --terse --root system /mnt/slackware64/{a,ap,d,l,n,x,xap,xfce}/*.t?z
umount /mnt
ln -sf xinitrc.xfce system/etc/X11/xinit/xinitrc
sed 's/^id:3:initdefault:$/id:4:initdefault:/' -i system/etc/inittab
chmod +x system/etc/rc.d/rc.networkmanager
chroot system useradd -m -g users -G wheel,audio,video,plugdev linomad
echo -e "root:root
linomad:linomad" | chroot system chpasswd
sed 's/# \(%wheel ALL=(ALL:ALL)\)/\1/' -i system/etc/sudoers

• Or, an Ubuntu one :

mkdir system
debootstrap --include ubuntu-minimal focal system http://archive.ubuntu.com/ubuntu
cp -a /etc/apt/* system/etc/apt/
for d in sys proc dev dev/pts; do sudo mount --bind /$d system/$d; done
chroot system apt update
chroot system apt upgrade
apt-mark showmanual > packages.lst
chroot system apt install $(cat packages.lst)
chroot system locale-gen
chroot system useradd -g users -G adm,cdrom,sudo,plugdev,lpadmin -m -s /bin/bash linomad
echo "linomad:linomad" | chroot chpasswd
chroot system systemctl disable apparmor.service
for d in dev/pts dev proc sys; do sudo umount system/$d; done

Make it live

• Setup kernel, initRamFs, GRUB EFI image and configuration file:

build-live-system.sh --init system live

• Create a SquashFS module of the system:

build-live-system.sh --module system live 0-base-xfce

• According to your needs, generate an ISO 9960 of the live DVD (and possibly test it with Qemu):

build-live-system.sh --iso live live-system.iso
qemu-system-x86_64 -enable-kvm -m 2048 -cdrom live-system.iso

• Or copy the live system to an USB stick; warning: this will destroy the data on the USB device:

build-live-system.sh --usb live /dev/sdx

Build script usage - live-system generation

Variables influencing the script behavior

There are some environment variables that can customize live-system generation:

• LIVELABEL (LiveSystem by default): the live-system filesystem label,
• LIVEDIR (linomad by default): the live-system directory name,
• HOMELABEL (LiveData by default): the persistent data filesystem label,
• and IMGSIZE (7680 MiB by default): the size of the disk image for a USB drive.

They should be set before running any of the --init, --module, --usb --img or --iso actions:

HOMELABEL="home-rw"
LIVELABEL="system-ro"
build-live-system.sh --init system live
#...

Setup kernel, initRamFs, GRUB EFI image and configuration file

Usage

build-live-system.sh --init root_dir live_dir [additional:modules]

Generates: live_dir/efi/boot/{bootx64.efi,grub.cfg} and live_dir/linomad/{vmlinuz,initrd.gz}. Included kernel modules (unless builtin and with their dependencies) are:

• keyboard support (Busybox console): atkbd, i8042
• P/S-ATA & CD-ROM support: atapiix, srmod
• USB support: xhci-pci, ehci-pci, usb-storage
• live filesystems: nls-iso8859-1, isofs, nls-cp437, vfat, ext4, loop, overlay, squashfs

Usually additional modules are NFS and ethernet drivers needed to boot over NFS.

Examples

build-live-system.sh --init system live
build-live-system.sh --init system live nfsv3:e1000e:8139too:atl1c:alx

Create a SquashFS module for the system

Usage

build-live-system.sh --module root_dir live_dir module_file [-gzip|-lza|-lzma|-lzo|-xz|-zstd]

All root_dir subdirectories but /sys, /proc, /dev and /tmp are included. Generates: live_dir/linomad/modules/module_file.

The compression option has an impact on media size and speed; zstd is the default.

The system can be divided into multiple modules (example: “1-core”, “2-gui”, …) that are loaded in alphabetical order; if a file is present in several modules, the one taken from the last loaded module is used.

Example

build-live-system.sh --module system live 0-main

Copy live system to USB device

Warning: this operation can destroy USB device data.

Usage

build-live-system.sh --usb live_dir device [systemsize]

This action triggers two different behaviors:

• if systemsize is not specified and if the device already contains a live-system (ie $LIVELABEL is found on device), an update is performed:
  • fsck is run on system and data partitions,
  • extra storage and persistent data are kept,
  • existing efi and $LIVEDIR are overwritten with their new versions.
• in the other cases, the device is wiped, permanently destroying all its data:
  • device is partitionned using GPT (GUID Partition Table - see table below),
  • live-system and persistent data partitions are formatted,
  • live-system files are copied.

• when partitioning, if systemsize is not specified, its size will be adjusted according to that of the system. For example, if the system size is 1.5 GiB, the systemsize will be calculated as 1.5 x 2 (for live updates), rounded to the nearest multiple of 2, resulting in 4 GiB.

Examples

build-live-system.sh --usb live /dev/sdx 8192   #install (systemsize is specified)
build-live-system.sh --usb live /dev/sdx        #install or update (`$LIVELABEL` found)

Create ISO or disk image

These operations are useful for distributing the live system. ISO images are intended for DVDs, while disk images are for USB devices, allowing data persistence. *USB Flashing is slower than partitionning, formatting and copying *

Usage

build-live-system.sh --img live_dir img_file_name
build-live-system.sh --iso live_dir iso_file_name

The disk image will, by default, have a size of 7.5 GiB (less than 8 GB for compatibility) and will be compressed with zstd.

Example

build-live-system.sh --img live live.img
build-live-system.sh --iso live live.iso

Flash disk image to USB device

Warning: this operation destroys USB device data.

Usage

zstd -d compressed_img_file_name -o device

The device must have a minimum size of IMGSIZE (8 GB by default).

Example

zstd -d live.img.zst -o /dev/sdx

It is then recommended to resize the LiveData partition and optionnally create an additionnal exFAT one, to share data between systems. Use a GParted like partition editor, or the command line:

• option 1: use all available space for the LiveData partition:

sgdisk -d 2 -n 2:0:0 /dev/sdx
resize2fs /dev/sdx2

• option 2: resize the LiveData partition (to 8 GiB in this example) and add another shared one:

sgdisk -d 2 -n 2:0:+8G -n 3:0:0 -t 3:0700 /dev/sdx
partprobe /dev/sdx
resize2fs /dev/sdx2
mkfs.exfat [-L "Shared Data / Anything"] /dev/sdx3

Boot parameters

System language and keymap layout

• locale: system language; example: locale=fr_FR.UTF-8
• keymap: keymap layout; example: keymap=fr; the first two caracters are used for Xorg keymap layout
• tz: timezone; example: tz=Europe/Paris (value must be a valid path from /usr/share/zoneinfo)
• hwc: hardware clock: UTC or localtime

Misc

• home=label, home=UUID or home=IP:path (NFS): specify persistent home location (defaults to LiveData);
• sys=label:path, sys=UUID:path or sys=IP:path (NFS): specify live system location (defaults to LiveSystem:linomad)
• exclude=module1:module2: to prevent loading of specified modules
• mode=busybox: to boot into a Busybox console (instead of the live system)

Live system installation

The live system can be installed into a hard disk partition; the result should be the same as a clean installation following the distribution regular install procedure. Both BIOS and UEFI firmwares are supported.

Install system and GRUB boot loader

Warning: this operation destroys all data on the install partition.

Usage

build-live-system.sh --install root_dir partition

Example

From a running live-system:

build-live-system.sh --install /live/system /dev/sdx2

Setup /home, user login and password

After installation, it is recommended to add a “normal” (non “root”) user and use a separate partition to store users files (/home).

Usage

build-live-system.sh --home install_part home_part login password

Example

build-live-system.sh --home /dev/sdx2 /dev/sdx4 linomad P@ssw0rd

GRUB installation and configuration

To boot the installed system, a boot loader (eg. GRUB) must be installed and configured.

Usage

build-live-system.sh --grub partition

Example

build-live-system.sh --grub /dev/sdx2