Different users on the same mapset

[Conn Copas]

Luca Palmeri <lpalmeri at ux1.unipd.it> writes:

> Ok now I understand. Each user has his own mapset and can work only on
> that.

Last time I looked (which is a couple of releases ago) users may only _write_ to 
their own mapsets. They typically can _read_ both the PERMANENT mapset, and 
other users' mapsets in the same location, unless those users have explicitly 
blocked read access. See the docs for g.access and g.mapsets.

> My concern was on using multiple grass shells on different mapsets at
> the
> same time from different machines in NFS. Given that grass do not allow
> the same
> user to run multiple session I was thinking that one solution was to use
> different users in the same location, all accessing to the same mapsets.

That restriction on multiple sessions can be bypassed by a simple edit of 
etc/GIS.sh, by removing all the locking code. Alternatively, bypass that 
front-end file completely by simply issuing Grass commands at the Unix prompt 
(but you need to set a few environment variables in order to be able to do 
this).

Obviously, if you are attempting to create some generic Grass user in a 
distributed environment, then users will potentially be able to corrupt each 
others' files, as well as a few other problems to do with maintaining consistent 
regions and monitor selections. 
 
--
Conn V Copas
Information Technology Division
Defence Science and Technology Organisation
PO Box 1500
Salisbury            tel: +61 (0)8 825 95349
SA  5108             fax: +61 (0)8 825 95589
Australia       e-mail: Conn.Copas at dsto.defence.gov.au
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