Difference between revisions of "Install from existing Linux"

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[[zh-CN:Install from Existing Linux]]
 
[[zh-CN:Install from Existing Linux]]
 
[[zh-TW:Install from Existing Linux]]
 
[[zh-TW:Install from Existing Linux]]
{{Warning|This page is being worked on at the moment and should be stabilized by Oct. 18 2013 at 6pm EST}}
 
  
 
This document describes the bootstrapping process required to install Arch Linux from a running Linux host system.
 
This document describes the bootstrapping process required to install Arch Linux from a running Linux host system.
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Installing Arch Linux from a running Linux is useful for:
 
Installing Arch Linux from a running Linux is useful for:
 
* remotely installing Arch Linux, e.g. a (virtual) root server
 
* remotely installing Arch Linux, e.g. a (virtual) root server
 +
* replacing an existing Linux without a LiveCD (see [[#Replacing the Existing System without a LiveCD]])
 
* creating a new Linux distribution or LiveCD based on Arch Linux
 
* creating a new Linux distribution or LiveCD based on Arch Linux
 
* creating an Arch Linux chroot environment, e.g. for a Docker base container
 
* creating an Arch Linux chroot environment, e.g. for a Docker base container
 
* [[Diskless_network_boot_NFS_root|rootfs-over-NFS for diskless machines]]
 
* [[Diskless_network_boot_NFS_root|rootfs-over-NFS for diskless machines]]
  
==Bootstrapping Goal==
 
 
The goal of the bootstrapping procedure is to setup an environment from which {{Pkg|arch-install-scripts}} (such as {{ic|pacstrap}} and {{ic|arch-root}}) run.
 
The goal of the bootstrapping procedure is to setup an environment from which {{Pkg|arch-install-scripts}} (such as {{ic|pacstrap}} and {{ic|arch-root}}) run.
 
This goal is achieved by installing {{Pkg|arch-install-scripts}} natively on the host system, or setting up an Arch Linux-based chroot.
 
This goal is achieved by installing {{Pkg|arch-install-scripts}} natively on the host system, or setting up an Arch Linux-based chroot.
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If the host system runs Arch Linux, installing {{Pkg|arch-install-scripts}} is straightforward.
 
If the host system runs Arch Linux, installing {{Pkg|arch-install-scripts}} is straightforward.
  
On other distributions it is a more complicated process described in [[#Install pacstrap natively on non Arch Linux-based distributions (Advanced)]].
+
On other distributions, the process is more complicated (described in [[#Alternative: Install arch-install-scripts natively on non Arch distro]]).
For these distribution, it is recommended to set up a chroot instead.
+
For these distributions, it is recommended to set up a chroot instead.
  
 
{{Note|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.}}
 
{{Note|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.}}
  
==Setting up an Arch Linux-based chroot==
+
==Arch Linux-based chroot==
The Arch Linux chroot environment will be used to run {{ic|pacstrap}}.
+
The idea is to run an Arch system inside the host system.
{{ic|pacstrap}} will initiate the actual Arch Linux installation.
+
The actual installation is then executed from this Arch system.
There are different ways to setup the chroot explained below.
+
This nested system is contained inside a chroot.
 +
Three methods to setup and enter this chroot are presented below, from the easiest to the most complicated.
  
===Using the Bootstrap Image===
+
{{Note|Your host system must run Linux 2.6.32 or later.}}
  
* Extract this tarball. If you have enough memory, you can extract it into a tmpfs file system.
+
===Method 1: Using the Bootstrap Image===
   In the example below, we'll assume that it will be extracted to /tmp/root.x86_64/.
+
 
* Create your partitions and mount them under /tmp/root.x86_64/mnt/.
+
Download the bootstrap image from a [https://www.archlinux.org/download mirror]:
* If you have bash 4 or later installed, run
+
   curl -O http://www.gtlib.gatech.edu/pub/archlinux/iso/2013.10.01/archlinux-bootstrap-2013.10.01-x86_64.tar.gz
 +
Extract the tarball:
 +
  # cd /tmp
 +
  # tar xzf <path-to-bootstrap-image>/archlinux-bootstrap-2013.10.01-x86_64.tar.gz
 +
Select a repository server:
 +
  # nano /tmp/root.x86_64/etc/pacman.d/mirrorlist
 +
Enter the chroot
 +
* If you have bash 4 or later installed:
 
   # /tmp/root.x86_64/bin/arch-chroot /tmp/root.x86_64/
 
   # /tmp/root.x86_64/bin/arch-chroot /tmp/root.x86_64/
  If you don't have bash 4, run the following commands:
+
* Else run the following commands:
 
   # cp /etc/resolv.conf /tmp/root.x86_64/etc
 
   # cp /etc/resolv.conf /tmp/root.x86_64/etc
 
   # mount --rbind /proc /tmp/root.x86_64/proc
 
   # mount --rbind /proc /tmp/root.x86_64/proc
Line 51: Line 58:
 
     (assuming /run exists on your system)
 
     (assuming /run exists on your system)
 
   # chroot /tmp/root.x86_64/
 
   # chroot /tmp/root.x86_64/
* In the chroot, run
 
  # Create your partitions and mount them under /tmp/root.x86_64/mnt/.
 
  # pacman-key --init
 
  # pacman-key --populate archlinux
 
* Follow the Arch Linux installation guide
 
  https://wiki.archlinux.org/index.php/Installation_Guide#Install_the_base_system
 
  starting at the "Install the base system" step.
 
 
Download the bootstrap image which is a tarball containing the arch-install-scripts.
 
It is a smaller image.
 
Just expand the tarball into the directory of your choice (if sufficient RAM is available, to a directory in /tmp)
 
Use the included arch-chroot to chroot into your install "system".
 
* The root image can be found on one of the [https://www.archlinux.org/download mirrors] under either arch/x86_64/ or arch/i686/ depending on the desired architecture
 
  
===Using the LiveCD Image===
+
===Method 2: Using the LiveCD Image===
  
 
It is possible to mount the root image of the latest Arch Linux installation media 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.
 
It is possible to mount the root image of the latest Arch Linux installation media 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.
Line 94: Line 88:
 
{{bc|# chroot /arch bash}}
 
{{bc|# chroot /arch bash}}
  
===Assembling the chroot Manually (with a script)===
+
===Method 3: Assembling the chroot Manually (with a script)===
  
 
The script creates a directory called {{ic|archinstall-pkg}} and downloads the required packages in it. It then extracts them in the {{ic|archinstall-chroot}} directory. Finally, it prepares mount points, configures pacman and enters a chroot.
 
The script creates a directory called {{ic|archinstall-pkg}} and downloads the required packages in it. It then extracts them in the {{ic|archinstall-chroot}} directory. Finally, it prepares mount points, configures pacman and enters a chroot.
 
'''CHROOT_DIR=archinstall-chroot Must Change First, or you might ruin your /etc/'''
 
  
 
{{hc|archinstall-bootstrap.sh|<nowiki>
 
{{hc|archinstall-bootstrap.sh|<nowiki>
Line 148: Line 140:
 
</nowiki>}}
 
</nowiki>}}
  
==Install pacman and the arch-install-scripts natively on non Arch Linux-based distributions (Advanced)==
+
===Using the chroot Environment===
 +
 
 +
====Initializing pacman keyring====
 +
Before starting the installation, pacman keys need to be setup. Before running the following two commands read [[pacman-key#Initializing the keyring]] to understand the entropy requirements:
 +
{{bc|
 +
# pacman-key --init
 +
# pacman-key --populate archlinux
 +
}}
 +
 
 +
====Installation====
 +
Follow the [[Installation Guide#Mount the partitions|Mount the partitions]] and [[Installation Guide#Install the base system|Install the base system]] sections of the [[Installation Guide]].
 +
 
 +
=====Debian-based host=====
 +
On Debian-based host systems, {{ic|pacstrap}} produces the following error:
 +
# pacstrap /mnt base
 +
# ==> Creating install root at /mnt
 +
# mount: mount point /mnt/dev/shm is a symbolic link to nowhere
 +
# ==> ERROR: failed to setup API filesystems in new root
 +
 
 +
In Debian, /dev/shm points to /run/shm. However, in the Arch-based chroot, /run/shm does not exist and the link is broken. To correct this error, create a directory /run/shm:
 +
# mkdir /run/shm
 +
 
 +
====Configure the system====
 +
 
 +
From that point, simply follow the [[Installation Guide#Mount the partitions|Mount the partitions]] section of the [[Installation Guide]] and following sections.
 +
 
 +
==Alternative: Install arch-install-scripts natively on non Arch distro==
 +
{{Deletion|This method is overkill after Arch provide Bootstrap image.}}
 
{{Warning|This method is potentially difficult, your mileage may vary from distro to distro.}}
 
{{Warning|This method is potentially difficult, your mileage may vary from distro to distro.}}
  
Line 180: Line 199:
 
Another option is using the {{ic|alien}} tool to convert the {{ic|pacman-mirrorlist}} and {{ic|arch-install-scripts}} (but no {{ic|pacman}}) to native packages of your distro.
 
Another option is using the {{ic|alien}} tool to convert the {{ic|pacman-mirrorlist}} and {{ic|arch-install-scripts}} (but no {{ic|pacman}}) to native packages of your distro.
  
==Using the Bootstrapped Environment==
+
==Replacing the Existing System without a LiveCD==
 
+
Find ~500MB of free space somewhere on the disk, e.g. by partitioning a swap partition.
===Fix the pacman signature keyring===
+
Install the new Arch Linux system there, reboot into the newly created system, and [[Full_System_Backup_with_rsync#With_a_single_command|rsync the entire system]] to the primary partition.
 
+
Fix the bootloader configuration before rebooting.
This chroot is able to execute the arch install scripts. '''The destination partitions should be mounted under the {{ic|/mnt}} directory from this chroot'''. After that, continue with the next step, which is [[#Fix the Pacman Signature Keyring]].
+
 
+
This chroot is able to execute the arch install scripts. The destination partitions should be mounted under the {{ic|/mnt}} directory from this chroot.
+
 
+
when chrooting Debian based host systems the /dev/shm points to /run/shm . /run/shm does not exist in the chroot environment , the link is broken and pacstrap returns an error. create a directory /run/shm in the chroot environment when chrooting from debian based host systems
+
 
+
You might need to run these commands if you get key errors when you try to install packages:
+
{{bc|
+
# pacman-key --init
+
# pacman-key --populate archlinux
+
}}
+
 
+
 
+
It is necessary to initialize ''pacman's'' keyring for signature checking.
+
 
+
This is done using
+
# pacman-key --init # read the note below!
+
# pacman -S archlinux-keyring
+
# pacman-key --populate archlinux
+
 
+
'''However''', when connected via SSH you might run out of [http://en.wikipedia.org/wiki/Entropy_(computing) entropy]. In this case you can try something like
+
 
+
# cat /usr/bin/* > /dev/null &
+
# find / > /dev/null &
+
 
+
before executing {{ic|pacman-key --init}}.
+
 
+
It might take some time. If nevertheless all this does help install {{Pkg|haveged}} and run prior to {{ic|pacman-key --init}}
+
# /usr/sbin/haveged -w 1024 -v 1
+
 
+
===Setup the target system===
+
 
+
At this point, follow the normal steps of [[Installation Guide]]. Remember to mount the destination partition under the {{ic|/mnt}} of the chroot.
+
 
+
# pacstrap /mnt base base-devel
+
+
If you see this:
+
# pacstrap /mnt base base-devel
+
# ==> Creating install root at /mnt
+
# mount: mount point /mnt/dev/shm is a symbolic link to nowhere
+
# ==> ERROR: failed to setup API filesystems in new root
+
 
+
On a debian based host system /dev/shm points to /run/shm, but that directory doesn't exist in your chroot.
+
Log into your chroot, then do
+
# mkdir /run/shm
+
and you'll be fine.
+
 
+
Perhaps someone could add a check to the script to do this?
+
 
+
====Edit the fstab file====
+
 
+
Probably the {{ic|genfstab}} script won't work. In that case, you'll need to edit the {{ic|/mnt/etc/fstab}} file by hand.
+
You can use the content of {{ic|/etc/mtab}} as reference.
+
 
+
===Tips and tricks===
+
* In case you want to replace an existing system, but can for some reason not use a LiveCD, since, e.g., you have no physical access to the computer, the following tip might help: If you manage to get ~500MB of free space somewhere on the disk (e.g. by partitioning a swap partition) you can install the new Archlinux system there, reboot into the newly created system and [[Full_System_Backup_with_rsync#With_a_single_command|rsync the entire system]] to the primary partition. Finally don't forget to fix the bootloader configuration before rebooting.
+

Revision as of 01:13, 26 October 2013


This document describes the bootstrapping process required to install Arch Linux from a running Linux host system. After bootstrapping, the installation proceeds as described in the Installation Guide.

Installing Arch Linux from a running Linux is useful for:

The goal of the bootstrapping procedure is to setup an environment from which arch-install-scripts (such as pacstrap and arch-root) run. This goal is achieved by installing arch-install-scripts natively on the host system, or setting up an Arch Linux-based chroot.

If the host system runs Arch Linux, installing arch-install-scripts is straightforward.

On other distributions, the process is more complicated (described in #Alternative: Install arch-install-scripts natively on non Arch distro). For these distributions, it is recommended to set up a chroot instead.

Note: 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.

Arch Linux-based chroot

The idea is to run an Arch system inside the host system. The actual installation is then executed from this Arch system. This nested system is contained inside a chroot. Three methods to setup and enter this chroot are presented below, from the easiest to the most complicated.

Note: Your host system must run Linux 2.6.32 or later.

Method 1: Using the Bootstrap Image

Download the bootstrap image from a mirror:

 curl -O http://www.gtlib.gatech.edu/pub/archlinux/iso/2013.10.01/archlinux-bootstrap-2013.10.01-x86_64.tar.gz

Extract the tarball:

 # cd /tmp
 # tar xzf <path-to-bootstrap-image>/archlinux-bootstrap-2013.10.01-x86_64.tar.gz

Select a repository server:

 # nano /tmp/root.x86_64/etc/pacman.d/mirrorlist

Enter the chroot

  • If you have bash 4 or later installed:
  # /tmp/root.x86_64/bin/arch-chroot /tmp/root.x86_64/
  • Else run the following commands:
  # cp /etc/resolv.conf /tmp/root.x86_64/etc
  # mount --rbind /proc /tmp/root.x86_64/proc
  # mount --rbind /sys /tmp/root.x86_64/sys
  # mount --rbind /dev /tmp/root.x86_64/dev
  # mount --rbind /run /tmp/root.x86_64/run
    (assuming /run exists on your system)
  # chroot /tmp/root.x86_64/

Method 2: Using the LiveCD Image

It is possible to mount the root image of the latest Arch Linux installation media 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.

Note: Before proceeding, make sure the latest version of squashfs is installed on the host system. Otherwise you will get errors like: FATAL ERROR aborting: uncompress_inode_table: failed to read block.
  • The root image can be found on one of the mirrors under either arch/x86_64/ or arch/i686/ depending on the desired architecture. The squashfs format is not editable so we unsquash the root image and then mount it.
  • To unsquash the root image, run
# unsquashfs -d /squashfs-root root-image.fs.sfs
  • Now you can loop mount the root image
# mkdir /arch
# mount -o loop /squashfs-root/root-image.fs /arch
  • Before chrooting to it, we need to set up some mount points and copy the resolv.conf for networking.
# mount -t proc none /arch/proc
# mount -t sysfs none /arch/sys
# mount -o bind /dev /arch/dev
# mount -o bind /dev/pts /arch/dev/pts # important for pacman (for signature check)
# cp -L /etc/resolv.conf /arch/etc #this is needed to use networking within the chroot
  • Now everything is prepared to chroot into your newly installed Arch environment
# chroot /arch bash

Method 3: Assembling the chroot Manually (with a script)

The script creates a directory called archinstall-pkg and downloads the required packages in it. It then extracts them in the archinstall-chroot directory. Finally, it prepares mount points, configures pacman and enters a chroot.

archinstall-bootstrap.sh
#!/bin/bash
# This script is inspired on the archbootstrap script.

PACKAGES=(acl attr bzip2 curl expat glibc gpgme gnupg libarchive libassuan libgcrypt libgpg-error libssh2 lzo2 openssl pacman xz zlib pacman-mirrorlist coreutils bash grep gawk file filesystem tar ncurses readline libcap util-linux pcre arch-install-scripts)
# Change the mirror as necessary
MIRROR='http://mirrors.kernel.org/archlinux' 
# You can set the ARCH variable to i686 or x86_64
ARCH=`uname -m`
LIST=`mktemp`
CHROOT_DIR=archinstall-chroot
DIR=archinstall-pkg
mkdir -p "$DIR"
mkdir -p "$CHROOT_DIR"
# Create a list with urls for the arch packages
for REPO in core community extra; do  
        wget -q -O- "$MIRROR/$REPO/os/$ARCH/" |sed  -n "s|.*href=\"\\([^\"]*\\).*|$MIRROR\\/$REPO\\/os\\/$ARCH\\/\\1|p"|grep -v 'sig$'|uniq >> $LIST  
done
# Download and extract each package.
for PACKAGE in ${PACKAGES[*]}; do
        URL=`grep "$PACKAGE-[0-9]" $LIST|head -n1`
        FILE=`echo $URL|sed 's/.*\/\([^\/][^\/]*\)$/\1/'`
        wget "$URL" -c -O "$DIR/$FILE" 
        xz -dc "$DIR/$FILE" | tar x -k -C "$CHROOT_DIR"
done
# Create mount points
mkdir -p "$CHROOT_DIR/dev" "$CHROOT_DIR/proc" "$CHROOT_DIR/sys" "$CHROOT_DIR/mnt"
mount -t proc proc "$CHROOT_DIR/proc/"
mount -t sysfs sys "$CHROOT_DIR/sys/"
mount -o bind /dev "$CHROOT_DIR/dev/"
mkdir -p "$CHROOT_DIR/dev/pts"
mount -t devpts pts "$CHROOT_DIR/dev/pts/"

# Hash for empty password  Created by doing: openssl passwd -1 -salt ihlrowCo and entering an empty password (just press enter)
echo 'root:$1$ihlrowCo$sF0HjA9E8up9DYs258uDQ0:10063:0:99999:7:::' > "$CHROOT_DIR/etc/shadow"
echo "root:x:0:0:root:/root:/bin/bash" > "$CHROOT_DIR/etc/passwd" 
touch "$CHROOT_DIR/etc/group"
echo "myhost" > "$CHROOT_DIR/etc/hostname"
test -e "$CHROOT_DIR/etc/mtab" || echo "rootfs / rootfs rw 0 0" > "$CHROOT_DIR/etc/mtab"
[ -f "/etc/resolv.conf" ] && cp "/etc/resolv.conf" "$CHROOT_DIR/etc/"
sed -ni '/^[ \t]*CheckSpace/ !p' "$CHROOT_DIR/etc/pacman.conf"
sed -i "s/^[ \t]*SigLevel[ \t].*/SigLevel = Never/" "$CHROOT_DIR/etc/pacman.conf"
echo "Server = $MIRROR/\$repo/os/$ARCH" >> "$CHROOT_DIR/etc/pacman.d/mirrorlist"

chroot $CHROOT_DIR /usr/bin/pacman -Sy 
chroot $CHROOT_DIR /bin/bash

Using the chroot Environment

Initializing pacman keyring

Before starting the installation, pacman keys need to be setup. Before running the following two commands read pacman-key#Initializing the keyring to understand the entropy requirements:

# pacman-key --init
# pacman-key --populate archlinux

Installation

Follow the Mount the partitions and Install the base system sections of the Installation Guide.

Debian-based host

On Debian-based host systems, pacstrap produces the following error:

# pacstrap /mnt base
# ==> Creating install root at /mnt
# mount: mount point /mnt/dev/shm is a symbolic link to nowhere
# ==> ERROR: failed to setup API filesystems in new root

In Debian, /dev/shm points to /run/shm. However, in the Arch-based chroot, /run/shm does not exist and the link is broken. To correct this error, create a directory /run/shm:

# mkdir /run/shm

Configure the system

From that point, simply follow the Mount the partitions section of the Installation Guide and following sections.

Alternative: Install arch-install-scripts natively on non Arch distro

Tango-edit-cut.pngThis section is being considered for removal.Tango-edit-cut.png

Reason: This method is overkill after Arch provide Bootstrap image. (Discuss in Talk:Install from existing Linux#)
Warning: This method is potentially difficult, your mileage may vary from distro to distro.

Download pacman source code and pacman packages

Visit the pacman homepage: https://www.archlinux.org/pacman/#_releases and download the latest release.

Now, download the following packages:

Install dependencies

Using your distribution mechanisms, install the required packages for pacman and the arch install scripts. libcurl, libarchive, fakeroot, xz, asciidoc, wget, and sed are among them. Of course, gcc, make and maybe some other "devel" packages are necessary too.

Compile pacman

  • Decompress the pacman source code and cd inside.
  • Execute configure, adapting the paths as necessary:
     ./configure --prefix=/usr --sysconfdir=/etc --localstatedir=/var --enable-doc

If you get errors here, chances are you are missing dependencies, or your current libcurl, libarchive or others, are too old. Install the dependencies missing using your distro options, or if they are too old, compile them from source.

  • Compile
    make
  • If there were no errors, install the files
    make install
  • You may need to manually call ldconfig to make your distro detect libalpm.

Prepare configuration files

Now is time to extract the configuration files. Change the x86_64 as necessary.

  • Extract the pacman.conf and makepkg.conf files from the pacman package, and disable signature checking:
    tar xJvf pacman-*-x86_64.pkg.tar.xz etc -C / ; sed -i 's/SigLevel.*/SigLevel = Never/g' /etc/pacman.conf
  • Extract the mirror list:
    tar xJvf pacman-mirrorlist-*-any.pkg.tar.xz -C /
  • Enable some mirrors on /etc/pacman.d/mirrorlist
  • Extract the arch-install-scripts
    tar xJvf arch-install-scripts-*-any.pkg.tar.xz -C /

Another option is using the alien tool to convert the pacman-mirrorlist and arch-install-scripts (but no pacman) to native packages of your distro.

Replacing the Existing System without a LiveCD

Find ~500MB of free space somewhere on the disk, e.g. by partitioning a swap partition. Install the new Arch Linux system there, reboot into the newly created system, and rsync the entire system to the primary partition. Fix the bootloader configuration before rebooting.