March 2009 Archives

30-03-2009 10:42

Some handy tips for Gimp

Some great little quick tips on how to use the Gimp to clean up those holiday picutres.

Posted by DaveQB | Permanent Link | Categories: IT

25-03-2009 16:18

Vertical alignment of text within div

Posted by Jon Jenson

If you want to align text at the bottom of a div, the best way is to make the div "position:relative;", and then put the text in a container (p or div or whatever) inside the aforementioned div and make it "position:absolute; bottom:0;"

Posted by DaveQB | Permanent Link | Categories: IT

24-03-2009 16:30

Remotely launching applications over ssh

I did this once and then could never remember how to do it again exactly. If you want to ssh to a box running a normal KDE or Gnome session, and launch an app onto their desktop you run this:

no hup <applications> --display :0 &

This will launch it and allow you to exit the ssh session and the app to keep running. Run a ps ax to check its launched successfully.

Posted by DaveQB | Permanent Link | Categories: IT

19-03-2009 07:22

"Firefox: "There was a problem printing because the paper size you specified is not supported by your printer."

Ever had this error when trying to print from Firefox? It's annoying as it pops this message up before even a printer selection or any printer dialog boxes appear, so you can't do much trouble shooting. The solution is below, taken from:


Next in the filter bar type

This filters out all but the entries that start with this string.

Find the following the following entrie
double click it and change the value to 279.40

Next find
And change this entry to Letter

Finally find
and change it to read 215.90

Close FireFox and re-open, you should now be able to print. 

I didn't need to close Firefox, worked straight away. I found the letter size was "na_letter" for me, so that's the one that did it for me, oh also margins were all 25 apart from bottom margin which was 56, so I made it 25 as well. One of those fixed it for me.

Posted by DaveQB | Permanent Link | Categories: IT

12-03-2009 17:06

CPU Quota and priority for Xen

xm sched-credit -d <domain> lists weight and cap
xm-sched-credit -d <domain> -w <weight> sets the weight
xm-sched-credit -d <domain> -c <cap> sets the cap


Each domain (including Host OS) is assigned a weight and a cap.


A domain with a weight of 512 will get twice as much CPU as a domain with a weight of 256 on a contended host. Legal weights range from 1 to 65535 and the default is 256.


The cap optionally fixes the maximum amount of CPU a domain will be able to consume, even if the host system has idle CPU cycles. The cap is expressed in percentage of one physical CPU: 100 is 1 physical CPU, 50 is half a CPU, 400 is 4 CPUs, etc... The default, 0, means there is no upper cap.

SMP load balancing

The credit scheduler automatically load balances guest VCPUs across all available physical CPUs on an SMP host. The administrator does not need to manually pin VCPUs to load balance the system. However, she can restrict which CPUs a particular VCPU may run on using the generic vcpu-pin interface.

All copied off the xensource wiki

Posted by DaveQB | Permanent Link | Categories: IT

12-03-2009 11:24

GNU Screen - what a wonderful app

Screen is one of the most handy applications out there. I sometimes need to run screen, and in that, ssh to another server and then run or join screen there. I have done this successfully before but never saved how. Here is a nice page that explains 2 tips with regards to this.

...if you ever need to ssh to another machine and run screen there while already in a screen session on the first (i.e., nested screens, if you will), you'll realize that CTRL+A can no longer be used as the 'magic' key for both screen sessions. fortunately, the 'magic' screen key can be changed on a session-by-session basis, and can be set to any reasonable value. for example, using

screen -e^Vv
to start your session will make CTRL-V the 'magic' key.

Posted by DaveQB | Permanent Link | Categories: IT

12-03-2009 11:13

Linux Virtualisation comparison table

A simple table to use to see the difference of all the virtualisation options for Linux.

Posted by DaveQB | Permanent Link | Categories: IT