[GRASS-user] GRASS and reading mapsets on NTFS

[Hamish]

Patrick Giraudoux wrote:
> I have just migrated from a computer double boot
> (Windows/Ubuntu Hardy) with user data on a FAT32 partition
> to a new one with a NTFS partition instead. All went OK
> except that I can read mapsets only when grass (6.3) is
> started with sudo. If not, I can access locations in the
> grassdata folder but maptsets are not read. Googling a bit
> within the list I understand that grass can read only with
> owner rights (and not only read/write permission) and this
> explains the difference. I agree with comments that this it
> looks like a bit over the  top regarding security (I may be
> wrong...).

It is not really meant as a "security measure" in the modern sense, more
of ensuring sanity on a multi-user system when working on a collaborative
project. [an original design goal for GRASS; predates the advent of
single user "desktop GIS" (and probably the desktop PC revolution too,
depending on when you put the date for that)].

 
> Of course a solution would be to alvays work as "super
> user" (sudo) with grass on the NTFS partition, but this
> is obviously not safe and not in the spirit of Linux... On
> the other hand, I cannot move the data on the ext3 partition
> since it was not designated for that (space is limited) and
> more importantly I suppose this would make problem to read
> from Windows (e.g. from QGIS under windows - teaching
> purpose)....
> 
> I would really like to use the NTFS partition to get the
> data shared by the two systems.
> 
> As anyone an idea about a workaround ?

(re)mount the Windows partition with your user account as the owner.


the /etc/fstab entry might look like:

/dev/sda4    /mnt/dos   vfat   rw,user,gid=6,umask=007,quiet 0 2

or force mount as your user ID with the uid= option (see /etc/passwd for
your uid). see fstab and mount man pages. The above restricts mount to
group ID 6 ("disk" group from /etc/group)
the "user" option lets a regular user (non-root) mount it themselves.


see also the g.access help page,
 http://grass.osgeo.org/grass64/manuals/html64_user/g.access.html


(this should probably be a FAQ in the wiki...)

Hamish