access to PERMANENT (w/code)

Malcolm Williamson malcolm at
Thu Aug 19 18:33:24 EDT 1993

> I don't suggest that users share access to PERMANENT.   Instead, you can make
> copies of the few (and small) files that a user needs as a local PERMANENT, and
> then use soft UNIX links (ln -s) to provide read access to these databases.  I
> have included a perl script that I have built for local use which builds a
> GRASS database for a new user in dir grass_mapsets, adds 3 locations 
> ("us.albers", "us.latlong", "world.latlong") to which centralized, shared
> mapsets are then soft linked (but note that the PERMANENT mapset is copied, not
> linked--these PERMANENT files are bare bones and do not contain vector, site, or
> raster data), and additionally builds the location spearfish.  For spearfish,
> only 4 essential files are copied to a locally owned PERMANENT.  Then the 
> original PERMANENT is linked to the spearfish LOCATION as the spearfish MAPSET.
> This hack provides full access to shared data, both local databases and OGI
> supplied (like spearfish), without the hassle of potential database corruption.
> I'd welcome comments.
> greg

I'm missing something here. Why do you want multiple locations with access to
spearfish data? Do you not have centrally accessible data? We use traditional
GRASS directory structures, with a single location for a given projection /
geographic region. PERMANENT is writable by owner, readable by all. Each user
creates a new mapset owned by him/herself, with potential read access to all
other mapsets. Reclasses and custom color tables can be performed on maps in 
other mapsets without the need to duplicate teh data. When necessary, maps can
be copied to individual mapsets. 

I suspect that you have some special needs that you haven't mentioned, because
the traditional structure seems to meet most of ours. comments?


Malcolm D. Williamson - Research Assistant       E-mail: malcolm at
Center for Advanced Spatial Technologies      Telephone: (501) 575-6159
Ozark Rm. 12                                        Fax: (501) 575-3846 
University of Arkansas              
Fayetteville, AR 72701

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