multiuser GRASS

[Martin Schroeder]

In article <9308231655.AA12849 at hpc.lut.ac.uk> you wrote:

: _data_, but a comparatively weaker concept of multi-user _displays_. In the
: long-term, it would appear that user-specific monitors should be allocated on
: demand. Which raises the question of whether it is possible or sensible to
: write dynamically to the <etc/monitorcap> file at run-time?

This could be done in GIS.sh. For instance we changed this script in a
way, that each time a user starts GRASS, an individual monitorcap and
individual fifos will be created in /tmp. With changes in three (see below)
files it is possible to run GRASS by different users at the same time. 

In total we made the following changes:

src/libes/raster/parse_mon.c:
  Force programs to look for monitorcap in /tmp instead of $GISBASE/etc). 

etc/monitorcap:
  change the name of the fifos in a way, that makes it easier to be
  modified automaticaly. For example change the line
    /tmp/fifo_x0.in /tmp/fifo_x0.out \
               in
    /tmp/fifoxxxx_x0.in /tmp/fifoxxxx_x0.out \

etc/GIS.sh:
   Insert the following lines just before 'trap "" 2 3' to create 
   individual monitorcap and fifos:

   GUSER=`whoami`
   sed "s/fifoxxxx/fifo_$GUSER/g" $GISBASE/etc/monitorcap > /tmp/monitorcap_$GUSER

   # create fifo's
   if [ ! -p /tmp/'fifo_'$GUSER'_x0.in' ]
   then
     /etc/mknod /tmp/'fifo_'$GUSER'_x0.in' p
     /etc/mknod /tmp/'fifo_'$GUSER'_x0.out' p 
     /etc/mknod /tmp/'fifo_'$GUSER'_x1.in' p
     /etc/mknod /tmp/'fifo_'$GUSER'_x1.out' p 
     /etc/mknod /tmp/'fifo_'$GUSER'_cell.in' p
     /etc/mknod /tmp/'fifo_'$GUSER'_cell.out' p
     chmod 0666 /tmp/fifo_$GUSER*
   fi
   
   
   At the end of GIS.sh insert:
   
   rm /tmp/fifo_$GUSER*
   rm /tmp/monitorcap_$GUSER*
   
If there are any questions feel free to contact me.
M. Schroeder

*************************************************
|  Martin Schroeder                             |
|  Dept. of Geography                           |
|  University of Heidelberg, Germany            |    
|                                               |
|  Internet: emes at geo0.geog.uni-heidelberg.de   |      
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