Category Archives: Linux

Installing Java 7 on Debian Squeeze

For all of my servers I use Debian, however that distribution has a few problems, mainly the packages can be a bit behind the cutting edge.

Now this is usually a good thing if you are looking for stability – cutting edge software can have issues, especially from new features etc, so for a live environment you want something thats stable.

However, there does come a time when this can bite back. You either need a feature thats not in the standard repositories or in this case the version is now unsupported.

In Debian Squeeze it has Java 6 – but that was EOL’d a couple of months ago so is no longer supported by Oracle. The current version is Java 7 update 17.

So how do we get Java 7 installed?

Well it’s pretty easy to do, we just need to add another repository into apt and install it.

First the repository:

sudo su -
echo "deb http://ppa.launchpad.net/webupd8team/java/ubuntu precise main" | tee -a /etc/apt/sources.list
echo "deb-src http://ppa.launchpad.net/webupd8team/java/ubuntu precise main" | tee -a /etc/apt/sources.list
apt-key adv --keyserver keyserver.ubuntu.com --recv-keys EEA14886
apt-get update
exit

What that does is to install the ubuntu ppa repository into apt, setup the public keys and then load the package lists.

Next we need to install it:

sudo apt-get install oracle-java7-installer

This will now download Oracle Java 7 and present you with a couple of screens about licensing. Just ok and accept it and it will now install.

That’s it. You now have Java 7 installed – but it’s not the default JDK (if you already had Java 6 installed). If you want it to be the default then there’s just one more thing to do:

sudo apt-get install oracle-java7-set-default

That’s a dummy package but it will make Java 7 the default on that machine. If you want to check then you can check:

peter@titan ~ $ java -version
java version "1.7.0_17"
Java(TM) SE Runtime Environment (build 1.7.0_17-b02)
Java HotSpot(TM) 64-Bit Server VM (build 23.7-b01, mixed mode)
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Setting up a Linux Weather WebCam

The weather effects our lives everyday and weather websites are among the most heavily trafficked on the web. They tell us whether we will need an umbrella today or what to pack for a trip across the country.

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.

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Formatting xml in emacs

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="test1@temp.retep.org/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="test1@temp.retep.org/client" id="iq_257" to="service.retep.org" type="get">
    <query xmlns="some:namespace"/>
  </iq>
</xml>
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