[GRASS-dev] [GRASS GIS] #3857: r.mapcalc unable to rename null and cell files

[GRASS GIS]

#3857: r.mapcalc unable to rename null and cell files
----------------------+-------------------------
  Reporter:  Hygsson  |      Owner:  grass-dev@…
      Type:  defect   |     Status:  new
  Priority:  major    |  Milestone:  7.6.2
 Component:  Raster   |    Version:  unspecified
Resolution:           |   Keywords:  r.mapcalc
       CPU:  x86-64   |   Platform:  MSWindows 7
----------------------+-------------------------

Comment (by hellik):

 Replying to [ticket:3857 Hygsson]:
 > **Note:** This works on Ubuntu without any problems.
 >
 > While using GRASS GIS 7.6.1 on 64-bit Windows 7, I encountered a problem
 with r.mapcalc. For a simple stochastic simulation of watershed, I used a
 following script (here it is recreated for Spearfish dataset).
 >
 > {{{
 > g.region raster=elevation.dem at PERMANENT
 > r.surf.random --overwrite output=frequency min=0 max=0
 > for (( n=1 ; n<21 ; n=$n+1 ))
 > do
 >       r.surf.random --overwrite output=errors min=-15 max=15
 >       r.mapcalc "terrain = elevation.dem at PERMANENT + errors at PERMANENT"
 --overwrite
 >       r.watershed --overwrite elevation=terrain at PERMANENT
 accumulation=accum$n
 >       r.reclass --overwrite input=accum$n at PERMANENT output=flow$n
 rules=C:/Users/Hygsson/Desktop/test/reclass.rules
 >       r.mapcalc "frequency = flow$n + frequency" --overwrite
 > done
 > }}}
 >
 > reclass.rules file has a following content:
 >
 > {{{
 > -500 thru 654 = 0
 > * = 1
 > }}}
 >
 > I tried to do it step by step without using the script. **The problem
 arises with this step:**
 >
 > {{{
 > r.mapcalc "frequency = flow$n + frequency" --overwrite
 > }}}
 >
 > I get this output for each iteration of the loop. Only numbers behind
 'unknown/' are different.
 >
 > {{{
 > WARNING: Unable to rename null file
 >
 'C:\Users\Hygsson\Documents\grassdata\Spearfish60_grass7\PERMANENT\.tmp/unknown\22368.1'
 >             to
 >
 'C:\Users\Hygsson\Documents\grassdata\Spearfish60_grass7\PERMANENT\cell_misc\frequency\nullcmpr':
 >             File exists
 > WARNING: Unable to rename cell file
 >
 'C:\Users\Hygsson\Documents\grassdata\Spearfish60_grass7\PERMANENT\.tmp/unknown\22368.0'
 >             to
 >
 'C:\Users\Hygsson\Documents\grassdata\Spearfish60_grass7\PERMANENT\fcell\frequency':
 >             File exists
 > }}}
 >
 > The desired 'frequency' raster is created, but obviously in a wrong
 manner, having only one value.


 {{{
 r.mapcalc "frequency = flow$n + frequency" --overwrite
 }}}

 it is an operating system issue/feature/limitation of MS windows, that you
 are not able to read and write the same file at the same time.

 therefore it's not a winGRASS bug.

 as Vaclav already mentioned, it may work in linux, but it's not garanteed
 that it always work in every linux.

 so I tend to a ''won't fix'' of the ticket.

-- 
Ticket URL: <https://trac.osgeo.org/grass/ticket/3857#comment:2>
GRASS GIS <https://grass.osgeo.org>