Interrupts on the PiFace

Mon 05 August 2013 by Lars Kellogg-Stedman Tags raspberrypi python piface

I recently acquired both a Raspberry Pi and a PiFace IO board. I had a rough time finding examples of how to read the input ports via interrupts (rather than periodically polling for values), especially for the newer versions of the PiFace python libraries.

After a little research, here's some …

read more

Generating a memberOf attribute for posixGroups

Mon 22 July 2013 by Lars Kellogg-Stedman Tags ldap

This showed up on #openstack earlier today:

2013-07-22T13:56:10  <m0zes> hello, all. I am looking to
setup keystone with an ldap backend. I need to filter
users based on group membership, in this case a
non-rfc2307 posixGroup. This means that memberOf doesn't
show up, and that the memberUid in the group is not a
dn. any thoughts on how to accomplish this?

It turns out that this is a not uncommon question, so I spent some time today working out a solution using the dynlist overlay for OpenLDAP.

read more

Split concatenated certificates with awk

Tue 16 July 2013 by Lars Kellogg-Stedman Tags awk

This is a short script that takes a list of concatenated certificates as input (such as a collection of CA certificates) and produces a collection of numbered files, each containing a single certificate.

#!/bin/awk -f

# This script expects a list of concatenated certificates on input and
# produces a collection …
read more

Did Arch Linux eat your KVM?

Mon 08 April 2013 by Lars Kellogg-Stedman Tags archlinux virtualization kvm

A recent update to Arch Linux replaced the qemu-kvm package with an updated version of qemu. A side effect of this change is that the qemu-kvm binary is no longer available, and any libvirt guests on your system utilizing that binary will no longer operate. As is typical with Arch …

read more

I2C on the Raspberry Pi

I've set up my Raspberry Pi to communicate with my Arduino via I2C. The Raspberry Pi is a 3.3v device and the Arduino is a 5v device. While in general this means that you need to use a level converter when connecting the two devices, you don't need to …

read more