Install from existing Linux

This guide is intended to combine and update the three previously existing and highly similar alternative install guides on this wiki. This guide is intended for anybody who wants to install Arch Linux from any other running Linux -- be it off a LiveCD or a pre-existing install of a different distro.

Overview

Arch Linux's pacman can be configured (-r) to perform operations in any directory you like, using that as the context of "root" while running.

This is useful for building up new Arch Linux systems from scratch from another distro's LiveCD or existing installation. It is also useful for creating new chroot environments on a "host" system, maintaining a "golden-master" for development & distribution, or other fun topics like rootfs-over-NFS for diskless machines.

This guide requires that the existing host system be able to execute the new target Arch Linux architecture programs. In the case of an x86_64 host, it is possible to use i686-pacman to build a 32-bit chroot environment. See Arch64 Install bundled 32bit system. However it is not so easy to build a 64-bit environment when the host only supports running 32-bit programs.

Throughout this guide, we will refer to partitions as /dev/sdxx. This refers to whatever dev entry you have on your system for the partition in question. The convention is:

Drive 1, Partition 1:  /dev/sda1
Drive 1, Partition 2:  /dev/sda2
Drive 2, Partition 1:  /dev/sdb1

etc...

We will refer to it as /dev/sdxx whenever possible.

In this article,

host

refers to the computer which is used to perform the installation.

target

refers to the computer where you want to install Arch.

These may be one and the same computer. The host does not need to be an Arch system -- it can be a Debian or Redhat system, for example. The section entitled "Setup the host system" explains how to install pacman on the host. The following section "Setup the target system" explains how to use pacman from the host system to install Arch on the target system. Therefore if the host system is already running Arch, you can skip to "Setup the target system".

Alternatively, if you have an Arch Linux Live CD, you can directly mount and use the root image in the Live CD as the host system with pacman and required libraries already installed. See section #Use Arch Linux Live CD Root Image as Host System

Setup the host system

You need to install the Arch Linux package manager, pacman, on your host Linux environment. In addition you will need a list of pacman mirror sites which is used to download data on available packages as well as the packages themselves. If you are already using Arch, skip this step and go to Install from Existing Linux#Setup the target system.

Get the required packages

Introduction

You need to get the required packages for your host Linux environment. The examples given here assume you are using an i686 environment. If you are running on a 64-bit Linux instead you should replace each occurrence of "i686" with "x86_64".

All version numbers given here may change. Please check the version numbers the packages are at first and note them down. The version numbers can be found at:

• pacman
• pacman-mirrorlist

Once you are sure of the version numbers, download the required packages (change the value of ARCH to either x86_64 or i686, see above):

ARCH=i686
base_chroot=/tmp
mkdir ${base_chroot}/archlinux
cd ${base_chroot}/archlinux

Download pacman's binaries and shared libraries

You want to install pacman in order to be able to install software in your new base directory. We first download the binaries for pacman, the Arch package manager.

• pacman: https://www.archlinux.org/packages/core/$ARCH/pacman/download/ . Change $ARCH according to your system.
• pacman-mirrorlist: https://www.archlinux.org/packages/core/any/pacman-mirrorlist/download/

Using wget to download

wget  https://www.archlinux.org/packages/core/$ARCH/pacman/download/ --no-check-certificate --trust-server-names
wget https://www.archlinux.org/packages/core/any/pacman-mirrorlist/download/ --no-check-certificate --trust-server-names

or this direct way (give attention to the date string in the file name, as it may need changing) :

wget http://mirrors.kernel.org/archlinux/core/os/i686/pacman-mirrorlist-20120626-1-any.pkg.tar.xz

See the man page and the official manual of wget for further details.

Using lftp to download

If you have issues with downloading pacman-mirrorlist use this direct way with lftp :

link_name=http://mirrors.kernel.org/archlinux/core/os/i686/
lftp -e "mget pacman-mirrorlist-*.tar.xz" "${link_name}"

Additional libraries

You may need additional libraries to make pacman work, for newer distributions:

for software_name in libarchive openssl xz expat ; do wget https://www.archlinux.org/packages/core/$ARCH/${software_name}/download/ --trust-server-names ; done

When using an older distribution to bootstrap, a few more libraries may be needed for it to work, for example :

for software_name in glibc gcc-libs binutils libssh2 curl gcc libarchive openssl xz expat ; do wget https://www.archlinux.org/packages/core/$ARCH/${software_name}/download/ --trust-server-names ; done

Also note that below when you set LD_LIBRARY_PATH you have to add /lib and /lib64:

export LD_LIBRARY_PATH=${base_chroot}/archlinux/usr/lib:${base_chroot}/archlinux/lib:${base_chroot}/archlinux/usr/lib64:$LD_LIBRARY_PATH

Unpack all needed packages:

for f in *.pkg.tar*; do tar xvf $f; done

To prepare for using pacman, do not forget to edit /tmp/archlinux/etc/pacman.conf to point to /tmp/archlinux/etc/pacman.d/mirrorlist and select your favorite mirror. For easier use (assuming you are using bash or zsh), you may set up an environment:

export PATH=${base_chroot}/archlinux/usr/bin:$PATH
export LD_LIBRARY_PATH=${base_chroot}/archlinux/usr/lib:$LD_LIBRARY_PATH
alias pacman="pacman --config ${base_chroot}/archlinux/etc/pacman.conf"

Install pacman on the host system

Note: (Issues while running pacman on 64-bit host) If while running pacman you end up with /tmp/archlinux/usr/bin/pacman: No such file or directory please symlink ld-linux-x86-64.so.2: ln -s /lib64/ld-linux-x86-64.so.2 /lib/

If you do not mind littering your install host, you can extract all the downloaded tar balls into your root directory by running as root:

Note: However, keep in mind that this operation could erase some of your files, and break your system.

cd /
for f in /tmp/archlinux/pacman-*pkg.tar.gz ; do
  tar xzf $f
done

1. If installing from Ubuntu 9.10's LiveCD (perhaps other versions), you will need more than just the pacman files (shared libs) to use pacman at all. Use Lucky's script described in [this thread] to get/install them for you!
2. Alternatively, you can instead turn these tarballs into packages for your distribution with the alien tool. See the man page of the tool for instructions. The packages created that way may be installed into your host distribution using the usual package management tools available there. This approach offers the best integration into the host Linux environment. For a Debian package based system this is done with the following commands:

   cd /tmp/archlinux
   alien -d pacman-*-i686.pkg.tar.xz
   alien -d pacman-mirrorlist-20120626-1-any.pkg.tar.xz
   

   RPM based systems will need to replace the parameter "-d" with "-r".

   These distribution packages can then get installed using the normal package management tools of the host Linux environment.

3. Under Fedora 12, I was not able to install pacman with any of the other methods, but with the nice script at https://bbs.archlinux.org/viewtopic.php?pid=734336#p734336 it will download and install it for you. Worked wonderfully for me.

4. On Gentoo: Just unmask pacman by adding sys-apps/pacman to /etc/portage/package.keywords. Now just run emerge -av pacman.

   There is also a more detailed tutorial.

Use Arch Linux Live CD Root Image as Host System

Alternatively, instead of installing pacman on your host system, you can mount the root image of an Arch Linux Live CD and then chroot into it. This method has the advantage of providing you with a working Arch Linux installation right within your host system without the need to prepare it by installing specific packages.

Unsquash the root image

The root image exists in squashfs format on the Live CD. The squashfs format is not editable as such. Hence, we unsquash the root image and then mount it.

To unsquash the root image, run

unsquashfs -d /squashfs-root root-image.sqfs

Mount root file system

Then, mount the unsquashed root file system to a suitable mount point. We shall mount it to /arch. You can mount it wherever you want.

livecd_arch=/arch
mount -B /squashfs-root ${livecd_arch}

Chroot into the Live CD root file system

Mount various file systems into the Live CD root file system:

mount -t proc /proc ${livecd_arch}/proc
mount -t sysfs /sys ${livecd_arch}/sys
mount -B /dev ${livecd_arch}/dev
mount -t devpts /dev/pts ${livecd_arch}/dev/pts

Then, chroot into the Live CD root file system:

chroot ${livecd_arch} /bin/bash

Configure the host system

The main goal of this operation is to make a proper configuration to pacman.

Configure your /etc/pacman.conf to your liking, and remove unnecessary mirrors from /etc/pacman.d/mirrorlist. Also, enabling at least a few mirrors might become necessary, as you may experience errors during syncing if you have no mirror set. You may want to manually resolve DNS in the /etc/pacman.d/mirrorlist, because pacman for i686 may not be able to get address information on x86_64 systems.

If you are installing from a LiveCD, and you have a system with a low amount of combined RAM and swap (< 1 GB), be sure to set the cachedir in /etc/pacman.conf to be in the new Arch partition (e.g. /newarch/var/cache/pacman/pkg). Otherwise you could exhaust memory between the overhead of the existing distro and downloading necessary packages to install.

Setup the target system

Prepare a partition for Arch

You do not have to install Arch on a separate partition. You could instead build up a root filesystem in a normal directory, and then create a master tarball from it, or transfer it across the network.

However, most users will want to be installing Arch onto its own partition.

Prepare any partitions and filesystems you need for your installation. If your host system has any GUI tools for this, such as gparted, cfdisk, or Mandrake's diskdrake, feel free to use them.

To format a partition as ext4, you run (where /dev/sdxx is the partition you want to setup):

mkfs.ext4 /dev/sdxx 

To format it as ext3 with journaling and dir_index:

mkfs.ext4 -j -O dir_index /dev/sdxx 

To format it as reiserfs:

mkreiserfs /dev/sdxx 

To format a partition as swap, and to start using it:

mkswap /dev/sdxx 
swapon /dev/sdxx

Most other filesystems can be setup with their own mkfs variant, take a look using tab completion. Available filesystems depend entirely on your host system.

Once you have your filesystems setup, mount them. Throughout this guide, we will refer to the new Arch root directory as /newarch, however you can put it wherever you like.

new_arch=/newarch
mkdir ${new_arch}
mount /dev/sdxx ${new_arch}

Install the core

Update pacman. You may have to create the /newarch/var/lib/pacman folder for it to work (see "Setup the host system" above):

mkdir -p ${new_arch}/var/lib/pacman 
pacman -Sy -r ${new_arch}

Install the 'base' group of packages and the Archlinux keyring:

mkdir -p ${new_arch}/var/cache/pacman/pkg
pacman  -S base archlinux-keyring --cachedir ${new_arch}/var/cache/pacman/pkg -r ${new_arch}

Prepare /dev nodes

First, ensure the correct /dev nodes have been made for udev:

ls -alF ${new_arch}/dev

This result in a list containing lines similar to the following (the dates will differ for you):

crw-------  1 root root 5, 1 2008-12-27 21:40 console
crw-rw-rw-  1 root root 1, 3 2008-12-27 21:42 null
crw-rw-rw-  1 root root 1, 5 2008-12-27 21:40 zero

Delete and recreate any device which has a different set of permissions (the crw-... stuff plus the two root entries) and major/minor numbers (the two before the date).

cd ${new_arch}/dev 
rm -f console ; mknod -m 600 console c 5 1 
rm -f null ; mknod -m 666 null c 1 3 
rm -f zero ; mknod -m 666 zero c 1 5

All device nodes should have been created for you already with the right permissions and you should not need to recreate any of them.

Chroot

Now we will chroot into the new Arch system.

In order for DNS to work properly you need to edit ${new_arch}/etc/resolv.conf or replace it with the resolv.conf from your running distribution

cp /etc/resolv.conf ${new_arch}/etc/ 

Also, you need to copy a correctly setup mirrorlist into the new system:

cp /etc/pacman.d/mirrorlist ${new_arch}/etc/pacman.d

Finally edit the pacman configuration file ${new_arch}/etc/pacman.conf setting "Architecture" so that it matches the one of the target system. The default of "auto" might fail if it is different from the host system.

Architecture = i686 or x86_64

Mount various filesystems into the new Arch system:

mount -t proc proc ${new_arch}/proc
mount -t sysfs sys ${new_arch}/sys
mount -o bind /dev ${new_arch}/dev
mount -t devpts pts ${new_arch}/dev/pts

If you have a separate /boot partition, you will probably need to mount that too. See Change Root for more details.

Warning: If you have a separate /boot partition and plan on using grub2, make sure to mount /boot after chrooting. If you mount the /boot partition before the chroot, grub2 will assume that /boot and root are on the same partition and will not update correctly.

When everything is prepared, chroot into the new filesystem:

chroot ${new_arch} /bin/bash

Then setup pacman-key and verify the Master keys:

pacman-key --init ; pacman-key --populate archlinux

Install the rest

Install your preferred kernel, and any other packages you may wish to install. For the default kernel (which is already installed!):

pacman -S --needed linux

If you wish to install extra packages now, you may do so with:

pacman -S packagename

Configure the target system

Edit your /etc/fstab, remembering to add /, swap and any other partitions you may wish to use.

Edit your /etc/rc.conf, /etc/hosts and /etc/mkinitcpio.conf to your needs. If you are installing Arch Linux to a USB flash drive, don't forget to add the usb hook to /etc/mkinitcpio.conf. Then, rebuild the initcpio image:

mkinitcpio -p linux

Edit /etc/locale.gen, uncommenting any locales you wish to have available, and build the locales:

locale-gen

Setup Grub

To use GRUB when chrooted, you need to ensure that /etc/mtab is up-to-date:

diff /etc/mtab /proc/mounts

If you get any output from the previous command, run:

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

You can now run:

grub-install /dev/sdx

If grub-install fails, you can manually install:

grub 
grub> find /boot/grub/stage1     (You should see some results here if you have done everything right so far.   If not, back up and retrace your steps.)
grub> root (hd0,X)    (Note that Grub 1 and Grub 2 differ in how they each handle partition numbering. See the GRUB articles for info.)
grub> setup (hd0) 
grub> quit 

Double-check your /boot/grub/menu.lst. Depending on the host, it could need correcting from hda to sda, and a prefix of /boot as well in the paths.

Manual recovery of GRUB libs

The *stage* files are expected to be in /boot/grub, which may not be the case if the bootloader was not installed during system installation or if the partition/filesystem was damaged, accidentally deleted, etc.

Manually copy the grub libs like so:

# cp -a /usr/lib/grub/i386-pc/* /boot/grub

Note: Do not forget to mount the system's boot partition if your setup uses a separate one! The above assumes that either the boot partition resides on the root filesystem or is mounted to /boot on the root file system!

Detailed instructions for GRUB, GRUB2, LILO, Burg and Syslinux are available; see also Category:Boot loaders.

Finishing touches

See Beginners Guide:Configure the system. You can ignore 2.11, but the rest of that guide should be of use to you in post-installation configuration of your system.

Exit your chroot:

exit
umount ${new_arch}/boot   # if you mounted this or any other separate partitions
umount ${new_arch}/{proc,sys,dev}
umount ${new_arch}

Reboot to your new Arch system!

An alternate, simpler installation method

This method is verified to be working as of 1-4-12. This works best if you are in a LiveCD environment (or, in the case of servers, a GNU/Linux-based rescue environment). Firstly, you need to mount the disk you want to use for the Archlinux installation at /mnt. In this example, /dev/sda1 is used.

mnt /dev/sda1 /mnt
cd ~
wget http://tokland.googlecode.com/svn/trunk/archlinux/arch-bootstrap.sh && chmod +x arch-bootstrap.sh

If you are wanting to install a 32-bit system:

./arch-bootstrap.sh -a i686 -r "ftp://ftp.hosteurope.de/mirror/ftp.archlinux.org" /mnt/

Or a 64-bit system:

./arch-bootstrap.sh -a x86_64 -r "ftp://ftp.hosteurope.de/mirror/ftp.archlinux.org" /mnt/

The bootstrapping will take 2-5 minutes depending on the speed of your system.

mount -t proc none /mnt/proc
mount -t sysfs none /mnt/sys
mount -o bind /dev /mnt/dev

Mounting these is essential for the installation of a bootloader later on.

If you have switched between architectures, pacman auto-detection might not work, in this case you need to edit /etc/pacman.conf to:

From 64-bit to a 32-bit system:

Architecture = i686

Or from 32-bit to a 64-bit system:

Architecture = x86_64

Now for the fun part, chroot into your newly installed Arch installation:

chroot /mnt bash
pacman -Sy base
mkinitcpio -p linux

Choose a bootloader. You can find the installation instructions on their own dedicated pages. (Syslinux, Grub, Grub2, etc.).

Remember: You will still need to do any final configuration touches as you would in a normal Arch install.

Credits to the Turkish site Raptiye for the original guide.