QGIS provides the option to perform an action based on the attributes of a feature. This is useful if you want to run an external application or view a web page based on one or more values in your vector layer. How to define and run an action is explained in the user guide (http://download.osgeo.org/qgis/doc/manual/qgis-1.6.0_user_guide_en.pdf), check the section on ‘Action tab’.
I needed this feature to extract information from a vegetation map for Tanzania I am working on. The layer has fields for the vegetation type and an unique ID. I want list both the ID and name of the vegetation type for a number of polygons and export them to a text file. Following the user guide I tried:
bash -c "echo \"%cat %PNVs2\" >> /home/paulo/output.txt"
Unfortunately nothing was written to the file ‘output.txt’. After trying different options, I found out that the following syntax does work.
bash -c "echo '%cat %PNVs2' >> /home/paulo/output.txt"
I am not terribly familiar with bash syntax (OK, make that a not at all), but it seems things might work slightly different depending on the system you are working on (I am for example working on Ubuntu).