multiuser GRASS

Martin Schroeder emes at
Tue Aug 24 10:21:41 EDT 1993

In article <9308231655.AA12849 at> 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 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:

  Force programs to look for monitorcap in /tmp instead of $GISBASE/etc). 

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

   Insert the following lines just before 'trap "" 2 3' to create 
   individual monitorcap and fifos:

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

   # create fifo's
   if [ ! -p /tmp/'fifo_'$GUSER'' ]
     /etc/mknod /tmp/'fifo_'$GUSER'' p
     /etc/mknod /tmp/'fifo_'$GUSER'_x0.out' p 
     /etc/mknod /tmp/'fifo_'$GUSER'' p
     /etc/mknod /tmp/'fifo_'$GUSER'_x1.out' p 
     /etc/mknod /tmp/'fifo_'$GUSER'' p
     /etc/mknod /tmp/'fifo_'$GUSER'_cell.out' p
     chmod 0666 /tmp/fifo_$GUSER*
   At the end of 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   |      

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