I’ve recently spent some time working with Pacemaker, and ended up with an interesting collection of XPath snippets that I am publishing here for your use and/or amusement.

Check if there are any inactive resources

pcs status xml |
  xmllint --xpath '//resource[@active="false"]' - >&/dev/null &&
  echo "There are inactive resources"

This selects any resource (//resource) in the output of pcs status xml that has the attribute active set to false. If there are no matches to this query, xmllint exits with an error code.

Recently, changes from the xmlgawk project have been integrated into GNU awk, and xmlgawk has been renamed to gawkextlib. With both a recent (post-4.0.70) gawk and gawkextlib built and installed correctly, you can write simple XML parsing scripts using gawk.

For example, let’s say you would like to generate a list of disk image files associated with a KVM virtual instance. You can use the virsh dumpxml command to get output like the following:

The MBTA has a trial web service interface that provides access to realtime location information for select MBTA buses, as well as access to route information, arrival prediction, and other features. More information can be found here:

http://www.eot.state.ma.us/developers/realtime/

The service is provided by NextBus, which specializes in real-time location information for public transit organizations. The API (sorry, PDF) is very simple and does not require any sort of advance registration.

At the moment, the service only provides coverage for a small number of routes (39, 111, 114, 116, 117). I hope they expand the coverage of this service in the near future!