Archiso

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Revision as of 14:43, 28 April 2013 by Lonaowna (Talk | contribs) (Setup)

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Archiso is a small set of bash scripts capable of building fully functional Arch Linux based live CD and USB images. It is a very generic tool, so it could potentially be used to generate anything from rescue systems, install disks, to special interest live CD/DVD/USB systems, and who knows what else. Simply put, if it involves Arch on a shiny coaster, it can do it. The heart and soul of Archiso is mkarchiso. All of its options are documented in its usage output, so its direct usage won't be covered here. Instead, this wiki article will act as a guide for rolling your own live media in no time!

Setup

Note: The script is to be used on an x86_64 machine.

Before we begin, we need to install archiso from the official repositories. Alternatively, archiso-gitAUR can be found in the AUR.

Create a directory to work within, this is where all the modifications to the live image will take place: ~/archlive should do fine.

$ mkdir ~/archlive

The archiso scripts that were installed to the host system earlier now need to be copied over into the newly created directory you will be working within. Archiso comes with two "profiles": releng and baseline. If you wish to create a fully customised live version of Arch Linux, pre-installed with all your favourite programs and configurations, use releng. If you just want to create the most basic live medium, with no pre-installed packages and a minimalistic configuration, use baseline.

So, depending on your needs, execute the following, replacing 'PROFILE' with either releng or baseline.

# cp -r /usr/share/archiso/configs/PROFILE/ ~USER/archlive

If you are using the releng profile to make a fully customised image, then you can proceed onto #Configure our live medium.

If you are using the baseline profile to create a bare image, then you won't be needing to do any customisations and can proceed onto #Build the ISO.

Configure our live medium

This section details configuring the image you will be creating, allowing you to define the packages and configurations you want your live image to contain.

Change into the directory we created earlier (~/archlive/releng/ if you have been following this guide), you will see a number of files and directories; we are only concerned with a few of these, mainly: packages.* - this is where you list, line by line, the packages you want to have installed, and the root-image directory - this directory acts as an overlay and it is where you make all the customisations.

Installing packages

You will want to create a list of packages you want installed on your live CD system. A file full of package names, one-per-line, is the format for this. This is great for special interest live CDs, just specify packages you want in packages.both and bake the image. The packages.i686 and packages.x86_64 files allow you to install software on just 32bit or 64bit, respectively.

Tip: You can also create a custom local repository for the purpose of preparing custom packages or packages from AUR/ABS. Just add your local repository at the first position (for top priority) of your build machine's pacman.conf and you are good to go!

I recommend installing "rsync" if you wish to install the system later on with no internet connection or skipping downloading it all over again. (#Installation)

Adding a user

There are two methods to creating a user: either by adding the relevant useradd command to rc.local, or by copying over (and modifying) /etc/shadow, /etc/passwd, and /etc/group. The latter method shall be discussed here.

Copy your /etc/shadow, /etc/passwd, and /etc/group from your host system to the /etc/ directory of the new live system (which should be ~/archlive/releng/root-image/etc) e.g.

# cp /etc/{shadow,passwd,group} ~/archlive/releng/root-image/etc/
Warning: The shadow file will contain your encrypted password. I recommend before you copy the shadow file over, you change the password of your host user to that which you want your live user to have, copy the shadow file over, and then change back your password.

Adding files to image

Note: You must be root to do this, do not change the ownership of any of the files you copy over, everything within the root-image directory must be root owned. Proper ownerships will be sorted out shortly.

The root-image directory acts as an overlay, think of it as root directory '/' on your current system, so any files you place within this directory will be copied over on boot-up.

So if you have a set of iptables scripts on your current system you want to be used on you live image, copy them over as such:

# cp -r /etc/iptables ~/archlive/releng/root-image/etc

Placing files in the users home directory is a little different. Do not place them within root-image/home, but instead create a skel directory within root-image/ and place them there. We will then add the relevant commands to the rc.local we are going to create to copy them over on boot and sort out the permissions.

First, create the skel directory; making sure you are within ~/archlive/releng/root-image/etc directory (if this is where you are working from):

# cd ~/archlive/releng/root-image/etc && mkdir skel

Now copy the 'home' files to the skel directory, again doing everything as root! e.g for .bashrc.

# cp ~/.bashrc ~/archlive/releng/root-image/etc/skel/

Inside the root-image/etc/ directory, create the rc.local file, and make sure you make it executable:

# cd ~/archlive/releng/root-image/etc && touch rc.local && chmod +x rc.local

Now add the all of following to rc.local, replacing 'youruser' with the user you specified earlier.

# Create the user directory for live session
if [ ! -d /home/youruser ]; then
    mkdir /home/youruser && chown youruser /home/youruser
fi
# Copy files over to home
su -c "cp -r /etc/skel/.* /home/youruser/" youruser

aitab

The default file should work fine, so you should not need to touch it.

The aitab file holds information about the filesystems images that must be created by mkarchiso and mounted at initramfs stage from the archiso hook. It consists of some fields which define the behaviour of images.

# <img>         <mnt>                 <arch>   <sfs_comp>  <fs_type>  <fs_size>
<img>
Image name without extension (.fs .fs.sfs .sfs).
<mnt>
Mount point.
<arch>
Architecture { i686 | x86_64 | any }.
<sfs_comp>
SquashFS compression type { gzip | lzo | xz }.
<fs_type>
Set the filesystem type of the image { ext4 | ext3 | ext2 | xfs }. A special value of "none" denotes no usage of a filesystem. In that case all files are pushed directly to SquashFS filesystem.
<fs_size>
An absolute value of file system image size in MiB (example: 100, 1000, 4096, etc) A relative value of file system free space [in percent] {1%..99%} (example 50%, 10%, 7%). This is an estimation, and calculated in a simple way. Space used + 10% (estimated for metadata overhead) + desired %
Note: Some combinations are invalid. Example both sfs_comp and fs_type are set to none

Boot Loader

The default file should work fine, so you should not need to touch it.

Due to the modular nature of isolinux, you are able to use lots of addons since all *.c32 files are copied and available to you. Take a look at the official syslinux site and the archiso git repo. Using said addons, it is possible to make visually attractive and complex menus. See here.

Login manager

Starting X at boot time was done by modifying inittab on sysvinit systems. On a systemd based system things are handled by enabling your login manager's service. If you know which .service file needs a softlink: Great. If not, you can easily find out in case you're using the same program on the system you build your iso on. Just use

# systemctl disable nameofyourloginmanager

to temporarily turn it of. Next type the same command again and replace "disable" with "enable" to activate it again. Systemctl prints information about softlink it creates. Now change to ~/archiso/releng/root-image/etc/systemd/system and create the same softlink there.

An example (make sure you're either in ~/archiso/releng/root-image/etc/systemd/system or add it to the command):

# ln -s /usr/lib/systemd/system/lxdm.service display-manager.service

This will enable LXDM at system start on your live system.

Build the ISO

Now you are ready to turn your files into the .iso which you can then burn to CD or USB: Inside the directory you are working with, either ~/archlive/releng, or ~/archlive/baseline, execute:

# ./build.sh -v

The script will now download and install the packages you specified to work/*/root-image, create the kernel and init images, apply your customizations and finally build the iso into out/.

Using the ISO

CD

Just burn the iso to a cd. You can follow CD Burning as you wish.

USB

You can now dd the iso file onto a USB using dd, an example of which:

# dd if=~/archlive/releng/out/*.iso of=/dev/sdx

You will have to adjust accordingly, and make sure you choose the right output file! A simple mistake here will destory data on your harddisk.

grub4dos

Grub4dos is a utility that can be used to create multiboot usbs, able to boot multiple linux distros from the same usb stick.

To boot the generated system on a usb with grub4dos already installed, loop mount the ISO and copy the entire /arch directory to the root of the usb. Then edit the menu.lst file from the grub4dos (it must be on the usb root) and add this lines:

title Archlinux x86_64
kernel /arch/boot/x86_64/vmlinuz archisolabel=<your usb label>
initrd /arch/boot/x86_64/archiso.img

Change the x86_64 part as necessary and put your real usb label there.

Installation

Boot the created CD/DVD/USB. If you wish to install the Archiso you created -as it is-, there are several ways to do this, but either way we're following the Beginners' Guide mostly.

If you don't have an internet connection on that PC, or if you don't want to download every packages you want again, follow the guide, and when you get to Beginners' Guide#Install_the_base_system, instead of downloading, use this: Full System Backup with rsync. (more info here: Talk:Archiso)

You can also try: Archboot, GUI installer.

See also