Weather webcams are always popular and it is easy and free to set one up yourself. This article will show how to setup a simple USB webcam to produce still images and serve them on a local apache webserver.
I had this problem of debugging some xml but when reading the output of some log4j it was almost impossible to read so I needed some way of prettifying the xml quickly.
For this example I have the following xml:
<?xml version="1.0"?><xml><iq xmlns="jabber:component:accept" from="email@example.com/client" id="iq_257" to="service.retep.org" type="get"><query xmlns="some:namespace"/></iq></xml>
So how do we pretify this in emacs?
Well the first thing to do is to write an extension function & place it into your ~/.emacs file. Placing it here means that when you open emacs the extension is available:
(defun xml-format () (interactive) (save-excursion (shell-command-on-region (mark) (point) "xmllint --format -" (buffer-name) t) ) )
Now this works by passing the buffer to the xmllint utility and replaces it with the output – in this case nicely formatted xml.
Now we need to install xmllint:
pi@lindesfarne: ~$ sudo apt-get install libxml2-utils
Ok so now open emacs and open the xml. To format first select the xml you want to format then Press Escape then x followed by xml-format & press return. You should then get the xml nicely formatted:
<?xml version="1.0"?> <xml> <iq xmlns="jabber:component:accept" from="firstname.lastname@example.org/client" id="iq_257" to="service.retep.org" type="get"> <query xmlns="some:namespace"/> </iq> </xml>
The reason I had to do this was because I needed video4linux to get a webcam working for a forcoming series of posts connecting a telescope to the pi. Although the connection to the telescope wasn’t a problem, the customized webcam I have needed it.
Here I compile the kernel on a more powerful linux box to save time then transfer the kernel over to the PI.
Also this article is mainly my personal notes on compiling a new kernel rather than a tutorial on how to do it. Writing it here makes sense to keep things together & maybe it’s useful for anyone else.
These instructions are based on the RPI Kernel Compilation available at elinux.org.
Continue reading “Compiling a Kernel on the Raspberry PI”