GRASS plugin mapset permission blocks use if user doesn't own PERMANENT

[hamish]

[fwd from the live-demo@osgeo list, where it breaks the QGIS-GRASS plugin completely] :-(

Massimo Di Stefano wrote:

Download a new spearfish.tar.gz in the download directory

(better: just copy -r from /usr/local/share/...)

and tring to load grass file from qgis opening this "new" spearfish directory i have no problem to dispay grass data inside qgis.

I get the same. (see comments in my 4.0rc6 error summary from some days ago where I cover this)

hence, it is a permision problem in the grass locations

exec summary: the problem is a bug in qgis 1.5.0 [...]. I don't think we can work around it for this release of the live DVD and the best solution for now is to add a note in the qgis quickstart that you should copy the spearfish dataset to the home dir before starting if you want to use the grass toolbox. [n.b. to date we have no qgis quickstart!]

longer version: GRASS was designed to be (optionally) used on a server/mainframe by a team/class all working on the same project, with the data held on the central server or mounted via NFS. (this is why the spearfish dataset's working mapset is called "user1" btw) To avoid mass confusion you may only write to your own mapsets, but you may read from (and include in your map search path) any of your teammates mapsets, and everyone on the team can read from the PERMANENT mapset which typically holds core base maps. The team leader controls the PERMANENT mapset. Individual users can also make their own mapsets public or private via the g.access module if they like. For many years it has been like this, all(?) bugs squashed long ago, and all has been well. (of course on the Windows build UAC is a total mess, but that's not really our fault)

So the rule is that your user account must own the mapset in the filesystem in order to make that the current one. and that's the way GRASS is set up on the livedvd, with an empty skeleton mapset in /home/, and read-only data mapsets owned by root.

QGIS is respecting this, but it is taking it too far enforcing that the PERMANENT mapset must be owned by the user too. or maybe it is trying to temporarily open the PERMANENT mapset even if you didn't request it? (eg to grab the common map projection info)

Hamish

ps- rpy2 addition may now fix habitat plugin removed in the livedvd install script. pls check