Upgrading the Raspberry Pi 'Wheezy' OS

You can either download a fresh Raspberry Pi image from here: http://www.raspberrypi.org/downloads

or you can upgrade the OS software view running the following:

• Make sure the Raspberry Pi is looking to the correct place for the upgrade information:  sudo cat /etc/apt/sources.list.d/raspi.list  it should say:  deb http://archive.raspberrypi.org/debian/ wheezy main  if you want the latest, you could place the switch 'untested' at the end, ie:  deb http://archive.raspberrypi.org/debian/ wheezy main untested
• Next, do the following commands: 
  • sudo apt-get update 
  • sudo apt-get upgrade
  • sudo reboot

Note, you could run all of the above commands at once via a simple shell script, or from the CLI:  sudo apt-get update  && sudo apt-get upgrade && sudo reboot

I didn't time how long it took to run the upgrade as I was doing other things while the commands where running. Next time I will see how long it takes by pre-empting each command with 'time', ie:  time sudo apt-get update.  This will then report back how long the process took.  My upgrade took less than 1.5 hours.  Of course, the time will vary, depending on how much needs upgrading.  This upgrade needed an extra ~400MB, but had reclaimed back ~100M by the end.

You can check to see what version your running using this command:  uname -a

was: Linux raspberrypi 3.1.9+ #272 PREEMPT Tue Aug 7 22:51:44 BST 2012 armv6l GNU/Linux

and is now:  Linux raspberrypi 3.2.27+ #250 PREEMPT Thu Oct 18 19:03:02 BST 2012 armv6l GNU/Linux