[GRASS-dev] How to use a rules file in add-on script without hardcoding the path

[Robin Wilson]

Hi all,

I'm fairly new to GRASS, so I apologise if this is a silly question - but I couldn't find the answer anywhere in either the User or Developer Wikis. I have written a (very simple) Python add-on which uses the r.reclass tool. Of course, to use this tool I need to provide a file with the reclass details in it. I am currently having issues getting GRASS to find this file when I run the script and I would like it to do this without hard-coding the script path - ie. by using relative paths. I have two questions:

1. If I am running this script from somewhere outside of the GRASS scripts directory (eg. from somewhere in my home directory), how should I write my script so that it simply uses the reclass file in the same directory as the script? Currently my script contains the line:

grass.run_command("r.reclass", input = options['input'], output = options['output'], rules = "./zerotonull.rules")

where zerotonull.rules is the file that contains the declass rules, but this always gives an error saying it can't find that file.

2. If I want to distribute this script (either just to friends/colleagues or by adding it to the GRASS add-on repository), how should I set up my Makefile so that the reclass rules file gets put in the right place, and the script can then find it?

I hope this is the right place to ask this - if not, please accept my apologies.

Best regards,

Robin