Archive for the Computing Category

Understanding Linux CPU Load – when should you be worried?.

Ubuntu 12.04 and Java

| November 24th, 2012

OpenJDK comes with 12.4, but Sun’s Java doesn’t due to licnecings issues

Default Java install with Ubuntu 12.04
$java -version
java version "1.6.0_24"
OpenJDK Runtime Environment (IcedTea6 1.11.5) (6b24-1.11.5-0ubuntu1~12.04.1)
OpenJDK Client VM (build 20.0-b12, mixed mode, sharing)

Run this

sudo rm /var/lib/dpkg/info/oracle-java7-installer*
sudo apt-get purge oracle-java7-installer*
sudo rm /etc/apt/sources.list.d/*java*
sudo apt-get update
sudo add-apt-repository ppa:webupd8team/java
sudo apt-get update
sudo apt-get install oracle-java7-installer

Then you will have new java

$java -version
java version "1.7.0_09"
Java(TM) SE Runtime Environment (build 1.7.0_09-b05)
Java HotSpot(TM) Client VM (build 23.5-b02, mixed mode)


Raspbmc Tweaks

| November 22nd, 2012

Cache Buffer Size
When raspbmc upgraded i found that I had some buffering problems with video’s hanging and waiting a long time for it to start playing again, after a few google searches I found you can change your buffer size.

Run this command

nano ~/.xbmc/userdata/advancedsettings.xml

And then add or modify the settings below (this will add 150Mb cache buffer to your pi)

Backup xmbc settings

Tar up your .xbmc settings

cd ~
tar -czf backup.tar.gz .xbmc/

Then copy this tar to another place, either via scp or sftp.

To restore run the following commands
sudo initctl stop xbmc; tar -xzf backup.tar.gz; rm backup.tar.gz; sudo initctl start xbmc

List users
Find out what users are on your system.
cat /etc/passwd |grep "/home" |cut -d: -f1

Find Raspbmc version
Usefull if you want to know if the auto update is working, or if your on the latest RC version.

cat /scripts/upd_hist/build_info

My output was:-

pi@raspbmc:~/.xbmc$ cat /scripts/upd_hist/build_info
Raspbmc Testing Branch, with Hard Floating Point
Release Candidate 5, Built: 20121107

: XBMC / Raspbmc kept buffering

| November 21st, 2012

: XBMC / Raspbmc kept buffering. Very handy post will try this fix when i get home, but after a reinstall it might have also fixed the issue

RISC OS for Raspberry Pi | Raspberry Pi. Well Risc OS is now released for the Pi, going to gets this installed and dig out my old A5000 to copy over my files, hopefully I can get ‘Ibex the Viking’ working on it. 🙂 Along with some other Acorn games I have and might even try and get my old BBS running too.. time to dig out my old 56k modem.. I knew there was a reason I was keeping hold of it 😉

Setting up Wifi on Wheezy

| July 29th, 2012

Plug in your USB wifi adaptor and then type this command


You should see a output of the listings such as this

Bus 001 Device 005: ID 0ace:1215 ZyDAS ZD1211B 802.11g

Now check the reposotiry to see if there is a driver for this chipset

$apt-cache search zd1211

zd1211-firmware - Firmware images for the zd1211rw wireless driver

Install the driver

$sudo apt-get install zd1211-firmware

Now you can install a wireless tool

$sudo apt-get install wicd-curses

Once this has installed you can then run the configuration tool which, and connect to your wifi network.


And you will see a interface like the one shown below

From here you can setup your wifi network