Charly's Column – urlwatch

Some years ago, I reported on the Miniflux RSS feed aggregator [1] in this column, and I still use it. Miniflux is lean, fast, and easy to use. The media have been predicting the death of RSS feeds for what feels like an eternity, but it still has not happened. However, some websites simply don't offer feeds. I have to do something different here. What I need is a tool that alerts me when a particular website changes.

That's far more complicated than it sounds at first. Using a web service for this purpose (there are countless numbers of them) is out of the question for reasons of data economy. However, the biggest problem is something else. Things on websites that I don't find relevant are constantly changing. For example, a daily newspaper that I regularly read displays job ads that change with every reload. If I was notified every time, it would drive me crazy. There has to be a better way – and there is: urlwatch.

Written in Python 3, urlwatch is included in most popular distributions. If you want to know exactly if and which version of urlwatch is available in your favorite distro, you can find out on Repology.org [2]; DIY enthusiasts can use GitHub [3]. For example, I instructed urlwatch to keep an eye on the online news page for Linux Magazine (Listing 1) – pointlessly, because it actually still offers RSS.

01 $ urlwatch --add url=http://www.linux-magazine.com/Online/News,name=LinMag

In my home directory below .config/urlwatch/, urlwatch has now created a configuration file named urls.yaml (Listing 2). So far, so good – but I want to be sure that I am only notified when a new news ticker post is published. I want urlwatch to ignore any other changes to the website.

01 kind: url
02 name: LinMag
03 url: http://www.linux-magazine.com/Online/News

To do this, I briefly immersed myself in the website's HTML source code and discovered that every news ticker entry is introduced by a div tag that contains the specification "td_module_9 td_module_wrap" as its class specification. This prompted me to append the following line to the configuration in urls.yaml:

filter: element-by-id:td_module_9

Now urlwatch only alerts me when a new ticker entry appears on the website. There is a rich selection of alerting types; I opted for plain old email. All I have to do is enter the appropriate mail server, as well as the sender and recipient addresses, below .config/urlwatch/ in the urlwatch.yaml configuration file's report section. And, lo and behold, the electronic mailman was soon ringing the bell (Figure 1).

Figure 1: Urlwatch immediately notifies Charly by email when news is posted on his favorite websites.

The Author

Charly Kühnast manages Unix systems in a data center in the Lower Rhine region of Germany. His responsibilities include ensuring the security and availability of firewalls and the DMZ.