Is it possible to overwrite the raster generated using gdal_merge.py? When I ran the command:

% gdal_merge.py -init 255 -o out.tif in1.tif in2.tif

it works fine, but if I ran the same command and out.tif was already previously generated, it overwrites out.tif to a uniform raster (i.e., all values equal to 255).

  • What do mean by "to a wrong raster"?
    – user30184
    Feb 24, 2016 at 20:26
  • @user30184 I have updated the question to explain what I mean by wrong raster, thanks!
    – gcamargo
    Feb 24, 2016 at 21:21
  • By reading the documentation gdal.org/gdal_merge.html your command looks right.
    – user30184
    Feb 25, 2016 at 9:57
  • The command is correct, the issue is on the overwriting, or running the command twice.
    – gcamargo
    Feb 25, 2016 at 18:09

1 Answer 1


Old question, but for completeness here is an answer. You can't pass in an overwrite flag to gdal_merge.py as you can some other gdal functions. One workaround is to delete the file (if it exists) before you run gdal_merge.py:

import os
except OSError:

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