Installation Chroot

This article will detail the installation of Arch Linux from another GNU/Linux (kernel >= 2.6.27) with a chroot.

This article was originally published in the ArchLinux.fr wiki. A script doing all the steps described in this page is available at: install-chroot.sh
It is recommended to read the article.

Requirement

To install ArchLinux you need some data :

Variable	Description	Example
install_path	You have to mount in this directory all the partitions that will be part of your system	/mnt/newarch
arch	Architecture of the system: (we can only install i686 from a i686 system)	i686 or x86_64
mirror	Miror of download: the list is available here	http://mir.archlinux.fr
pacman_mirrorlist_ver	Actual version of pacman-mirrorlist, see here.	20110703-1

You also need a minimal chroot. You can find an archive matching your achitecture here.

You can export variable with this command, for example :

export install_path="/mnt/newarch"

Warning: This method works only to install a system with the same architecture as the host system or to install a 32 bits system with a 64 bits host system.

Before we begin, we will create the tmp directory in the new architecture in order to put it temporary files. In $install_path:

mkdir tmp
chmod 1777 tmp

Base system creation

We need to download the archive and the package pacman-mirrorlist:

cd "$install_path"/tmp
wget "$mirror/core/os/$arch/pacman-mirrorlist-$pacman_mirrorlist_ver-any.pkg.tar.xz"
wget "http://mir.archlinux.fr/~tuxce/chroot/archlinux.chroot.$arch.tgz"
cd ..
tar xvf tmp/pacman-mirrorlist-$pacman_mirrorlist_ver-any.pkg.tar.xz
tar xvf tmp/archlinux.chroot.$arch.tgz

The mirror configuration file (etc/pacman.d/mirrorlist) has all its lines commented, you have to uncomment at least one line, for example :

Server = http://mir.archlinux.fr/$repo/os/$arch

Chroot preparation

The network

In order to have dns resolution, copy your /etc/resolv.conf from the host system to the chroot :

cp /etc/resolv.conf etc/resolv.conf

Mount special file

We need to mount the special file system /dev, /proc and /sys :

mount -o bind /proc "$install_path"/proc
mount -o bind /dev "$install_path"/dev
mount -o bind /sys "$install_path"/sys

Register the mount partitions

Mount partition are list in /etc/mtab, we need to copy it contents :

grep -v rootfs /proc/mounts > etc/mtab

In the chroot

The chroot is ready, enter it :

chroot "$install_path" /bin/bash

Base system installation

pacman -Syf base

Configure the new system

Configure /etc/rc.conf

One of the central file in the ArchLinux system. You'll find everything you need here. The current default rc.conf is here

Partition configuration

To specify what partitions will be used by your operating system you need to edit the /etc/fstab file. This file lists the partitions, where they will be mounted, the type of the file system and some other options. Be sure to check this page for more information. Here is a quick example of the /etc/fstab file:

#
# /etc/fstab: static file system information
#
# <file system>    <dir>         <type>    <options>          <dump> <pass>
devpts             /dev/pts      devpts    defaults            0      0
shm                /dev/shm      tmpfs     nodev,nosuid        0      0

/dev/sda5          swap          swap      defaults            0      0
/dev/sda6          /             ext4      defaults            0      1
/dev/sda7          /home         ext4      defaults            0      2

To see the list of partitions on your hard disk run the command fdisk -l (l is a lowercase L, NOT the digit) as root.

Grub

Perhaps you'll need GRUB now. You'll find information here

Users

Root password

The root password is empty by default, you may want to set one :

passwd root

Main user

A basic configuration is :

useradd -G wheel,audio,optical,storage,video,power -m nom_utilisateur
passwd nom_utilisateur

You'll find more information here

sudo configuration

See here.