[GRASS-user] How to sum a hundred of raster maps using r.mapcalc

[Vaclav Petras]

On Fri, Sep 9, 2016 at 12:18 PM, Miguel Carrero <
miguel.carrero.pazos at gmail.com> wrote:

> I’ve tried with g.list, and pass a file with all map names in r.mapcalp,
> but realised that there is a limit on space to sum a high number of maps at
> the same time.


If you are using the file input instead of the command line and still
hitting some limit, you can check if it is system open files limit [1]. On
Linux, you can check soft limit with [2]:

ulimit -a

which gives 1024 on my system. And check also the hard limit with:

ulimit -aH

which gives 65536 on my system. And then increase the soft limit with:

ulimit -n number

Also, try it with some smaller amount of maps (like 10) to check that the
issue is really in the open file limit (or command line length) not, for
example, in the syntax.

Vaclav

[1]
https://grasswiki.osgeo.org/wiki/Large_raster_data_processing#Number_of_open_files_limitation
[2] https://lists.osgeo.org/pipermail/grass-dev/2014-April/068368.html
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