[GRASS-user] user/group permissions for accessing data on mounted drive

[Glynn Clements]

Tim Michelsen wrote:

> I have a question on the requirements GRASS has towards user/group 
> permissions on linux:
> 
> My data is stored on a vfat partition mounted by a Ubuntu Linux.
> The corresponding entry in the mount configuration file (/etc/fstab) goes:
> 
> UUID=44FC-A7FD /media/daten vfat 
> defaults,utf8,gid=46,fmask=111,umask=000   0   0
> 
> group id 46 belongs to plugdev which contains all users that can mount 
> drives.
> 
> The rights shown by ls -l look like:
> drwxrwxrwx  5 root plugdev  32K 2009-03-02 20:01 transfer
> -rwxrwxrwx  1 root plugdev    0 2009-07-07 23:11 video.flv
> 
> When I start GRASS trying to access the GRASS data base at 
> /media/daten/grassdata it says "ERROR: MAPSET PERMANENT - permission 
> denied" and the GUI would abort.
> 
> Please inicate me how I need to set my permissions on the mounted drive 
> that GRASS can use the data.

You must be the owner of the directory selected as the current mapset. 
A FAT/VFAT partition mounted by root must be mounted with the uid=
option to set the owner.

Alternatively, you can disable the checks in the source code and
re-compile. The checks are in G__mapset_permissions and
G__mapset_permissions2 in lib/gis/mapset_msc.c. This isn't recommended
on a multi-user system, as it can result in a user inadvertently
creating directories which the mapset's owner cannot delete or rename.

-- 
Glynn Clements <glynn at gclements.plus.com>