Provision the Raspberry PI with Arch Linux

I am primarily writing this article for the Raspberry PI A/A+ but this guide also applies to any of the other models. The PI A+ is a very cheap and powerful model and for some the most important factor is its low power consumption. Perhaps you have an original model A or are interested in a cheap second PI - they can be found for around £15 new including postage.

Arch Linux is a great alternative to the Raspbian distribution for power users and those who want a minimal base system. The boot-up time really is impressive and it's one of the main reasons I use it for my robots.
Unfortunately as of early 2014 the distribution maintainers no longer provide a downloadable disk image. They do provide an archive of a base image which can be installed on an SD card to make it bootable.

Getting started

We first want to go over to the homepage of the Arch Linux ARM page (ALARM) and click 'Installation Instructions':

For PI A+/A/B/B+
http://archlinuxarm.org/platforms/armv6/raspberry-pi

For PI Model B 2
http://archlinuxarm.org/platforms/armv7/broadcom/raspberry-pi-2

An overview of the steps you will take:

  • Use wget to pull down the latest base system archive
  • Clear out the SD card with fdisk
  • Create a boot partition with dos format and a ext4 for the rest of the space
  • Create file systems on the partitions
  • Mount the new partitions and expand the files
  • Don't forget to populate the boot partition and type sync to complete the process.

At this point you could eject the SD card and boot the system - but you will find a problem arises when you try to connect to the network. There is no ethernet connection and you have no packages in the base system to configure wi-fi. Arch's base image really is minimal.

  • Download the following packages from the Arch mirror (i.e. http://de4.mirror.archlinuxarm.org/arm/core/) and copy them to the SD card in /root/temp.
    • dialog, libnl, wpa_supplicant, wpa_actiond
  • While you are here - get a USB hub ready because you will need to use a keyboard at the same time as your wi-fi dongle to authenticate to your router/access point.
  • Optionally edit /etc/hostname before booting the system

Plug everything in and log in with the default username/password. Type pacman -U /root/temp/*.xz and let the packages get installed.

To connect to the network wifi-menu and select to your access point.

You would think that the wifi will start on the next boot -- but it won't so we can't go 'headless' yet. Type netctl list - find your network and type in netctl enable network_name.

Find your IP address with ipconfig and then check sshd is enabled and running with systemctl enable sshd followed by going to another machine and attempting to connect in. systemctl enable ensures the service will be active on next boot.

Before unplugging everything it is worth doing a quick reboot to make sure your wi-fi network profile started automatically.

Headless

Now that you have headless operation in place install your favourite tools and packages with: pacman -Sy package_name and probably once per week do a full update with pacman -Syu - while it is possible to leave this longer it is not advisable due to the sheer amount of updates that are released.

Tasks for your PI/node

  • Ambient temperature logging - through 1 wire Dallas sensor
  • PIR motion sensing combined with a python script and RPi.GPIO library
  • Logging of ambient temperature
  • Add a USB hub and some USB disks/drives
  • Run a small website with node.js or a microframework such as Python Flask
  • Monitor the soil moisture levels of a plant in your house
  • Database server, perhaps MongoDB if you are running a PI 2.

There are countless other possiblities - Google, Instructables and the Raspberry PI forum are all good places to browse for ideas.

Packages I like to install

  • nodejs and npm
  • python and python-setuptools
  • base-devel - development tools
  • curl and wget
  • cronie (cron) for scheduling tasks
  • nginx to set up a quick web site

I would advise buying a small case and then you can find a permanent home for the PI - hidden away behind the TV, by your internet router or perhaps in your attic?

Any questions - let me know in the comments.

Alex Ellis

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United Kingdom http://alexellis.io/

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