I needed to view a single frame of a m2v file that had been encoded by our designers for playing out on TV. The file name was .mpg but in actuality it was a single .m2v frame renamed to be a .mpg. Windows Media Player classic used to display the frame fine when I opened the file normally, under Windows XP. However now I have switched to a Mac, I have found that Quicktime and VLC refused to display the single frame. I couldn’t find a video player that would open the single frame. So I resorted to the command line version of ffmpeg, which I installed via macports, to convert this single frame to a jpg file to view as normal. This line worked a treat: ...

After I wrote a Java application in JDK 1.6, I was stuck for a while when I realised that the target deployment machine was Red Hat Enterprise Linux 4. RHEL4 does not support Java 1.6 in its default configuration. Luckily I found this article on the CentOS wiki which included instructions on how to install Java 1.6 on CentOS 4. Remembering that RHEL4 and CentOS 4 are almost identical, I tried the method supplied, and it worked. This is the page with the method: ...

Nagios can be seen as a automated test tool for systems, just as you would have automated tests for software projects. In test driven development (TDD), you write the tests first, and then use those tests to build up a software project that you can have confidence that it works. We can use this method to build up systems, or networks of systems. Plan out which services and processes should be running on your new systems, and then implement Nagios tests for every one. You can check the progress of your build by checking Nagios. I have been doing this at the BBC. It is a simple idea but one that seems to work.

I’m currently in the process of writing a web scraper for the forums on Gaia Online . Previously, I used to use Python to develop web scrapers, with the very handy Python library BeautifulSoup . Java has an equivalent called JSoup. Here I have written a class which is extended by each class in my project that wants to scrape HTML. This ‘Scraper’ class deals with the fetching of the HTML and converting it into a JSoup tree to be navigated and have the data picked out of. It advertises itself as a ‘web spider’ type of web agent and also adds a 0-7 second random wait before fetching the page to make sure it isn’t used to overload a web server. It also converts the entire page to ASCII, which may not be the best thing to do for multi-language web pages, but certainly has made the scraping of the English language site Gaia Online much easier. ...

At work, I still have to use Windows XP and Outlook 2003. I don’t particually mind this, except when I draft an email to someone and accidently I press Control-B instead of Control-V. Control-B will go ahead and send your partially composed email, resulting in some embarassment as you have to tell everyone to disregard it. So I wanted to remove the ‘send email’ shortcut keys in Outlook 2003. There are two ways of doing this, one involves editing your group policy, which is something only my IT administration team can do, and I didn’t want to have to involve them. The other way is by making a change to your registry, which I will describe here. ...

There is a problem I frequently encouter on Redhat/Fedora/CentOS systems with the output of the ls command. Under those distributions, the default setup is to display directories in a very dark colour. If you usually use a white foreground and a black background on your terminal client (such as Putty) then you will struggle to read the names of the directories under Redhat-based distributions. There are two soloutions that I have used: ...

I am moving to Manchester soon, and so I thought I’d get an idea of the housing market there by scraping all the Manchester Gumtree property adverts into a MySQL database. Once in the database, I could do things like find the average monthly price for a 2 bedroom flat in an area, and spot bargains through using standard deviation from the mean on the price through using simple SQL queries via phpMyAdmin . ...

REST (Representational State Transfer) is a way of delivering web services. When a web service conforms to REST, it is known as RESTful. The largest RESTful web service is the Hypertext Transfer Protocol (HTTP) which you use every day to send and receive information from web servers while browsing the internet. To implement RESTful web services, you should implement four methods: GET, PUT, POST and DELETE. Resources on RESTful web services are typically defined as collections of elements. The REST methods can either act on a whole collection, or a specific element in a collection. ...

The BBC provide 3 day weather RSS feeds for most locations in the UK. I thought it would be interesting to create a web service to turn the weather feed into calendar feed format, so I could have a constantly updated forecast of the next 3 days of weather mapped on to my iPhone’s calendar. Here it is on my iPhone: Overview The service is separated into five files: ical.php – this contains the class ical which corresponds to a single calendar feed. A method called ‘addevent’ allows you to add new events to the calendar, and a method called ‘returncal’ redirects the resulting calendar file to the browser so people can subscribe to it using their calendar application. forecast.php – this file contains the class forecast, which has properties for all aspects that we want to record for each day’s forecast, ie: Wind Speed and Humidity. It also contains the forecast set, which is a collection of forecast objects. The set class is serializable, which means each forecast object can be stored in a text file, including the Wind Speed, Humidity and all other things we want to record for each day. scrape-weather.php – this file contains code that scrapes the weather feed, populates the forecast set with all the weather information for the next 3 days, and stores the result in a file called forecasts.ser. forecasts.ser – this is all the data for the three day weather forecast, in serialized format. It is automatically deleted and recreated when the scrape-weather.php script is run. reader.php – this file converts the forecasts.ser file into an iCal calendar, and outputs the iCal formatted result to the calendar application that accesses reader.php page. It uses two external libraries: ...

To quickly find large files to delete if you have filled your startup disk, enter this command on the OSX terminal: sudo find / -size +500000 -print This will find and print out file paths to files over 500MB. You can then go through them and delete them individually by typing rm “”, although there is no undelete so make sure you know you won’t miss them.