[GRASS-user] r.patch number of input limitation?

[Markus Neteler]

On Wed, Sep 24, 2014 at 2:40 PM, Robert Kuszinger <kuszinger at giscom.hu> wrote:
>
> Hello!
>
>
> I'm trying to patch 1393 pieces of raster images with r.patch.
>
> before r.patch, the projection is set as follows:
>
>
> projection: 3 (Latitude-Longitude)
> zone:       0
> datum:      wgs84
> ellipsoid:  wgs84
> north:      33:00:00.5N
> south:      14:00:00.5S
> west:       75:59:59.5E
> east:       136:00:00.5E
> nsres:      0:01:00.000355
> ewres:      0:01:00.000278
> rows:       2820
> cols:       3600
> cells:      10152000
>
> As you see, the target mosaic is set to be a moderate resolution by setting
> es/nwres to 1 minute instead of seconds.
>
> I do then:
>
> GRASS 6.4.3 (wgs84pure):~/grassdata/import > MAPS=`g.mlist type=rast sep=,
> pat="AST*"`
> GRASS 6.4.3 (wgs84pure):~/grassdata/import > r.patch in=$MAPS out=mosaic
> WARNING: Unable to open raster map <ASTGTM2N31E096 at seasdem2>
> ERROR: One or more input raster maps not found
>
> How could it be? Is there a limitation on the string what r.patch is parsing
> from the command line?

It is indeed the operating system which limits the number of open
files. For Linux, it is likely 1024 files.
I have now added a note to the manual of r.patch (using those of r.series).

For a solution, see also

http://grasswiki.osgeo.org/wiki/Large_raster_data_processing#Number_of_open_files_limitation

You can increase this limit.

Hope this helps,
Markus