gdal_merge.py can't find libgdal.so.20

Question

I am having some trouble with GDAL (v2.1-dev). I build it from source today using Poppler and OpenJPEG. All the command line utilities work fine, but none of the Python plugins work at all, producing this error message:

Traceback (most recent call last):
  File "/usr/local/bin/gdal_merge.py", line 37, in <module>
import gdal
  File "/usr/local/lib/python2.7/dist-packages/gdal.py", line 2, in <module>
from osgeo.gdal import deprecation_warn
  File "/usr/local/lib/python2.7/dist-packages/osgeo/__init__.py", line 21, in <module>
_gdal = swig_import_helper()
  File "/usr/local/lib/python2.7/dist-packages/osgeo/__init__.py", line 17, in swig_import_helper
_mod = imp.load_module('_gdal', fp, pathname, description)
ImportError: libgdal.so.20: cannot open shared object file: No such file or directory

Now, I've seen plenty of threads that say update LD_LIBRARY_PATH or include /usr/local/bin/ in my ld.so.conf file. I've done both of those things and they don't help. Furthermore, those posts all refer to libgdal.so.1 not being found. So, I added the location of libgdal.so.20 to ld.so.conf and still no dice.

Any recommendations?

Update (11/2/15)
I am running Ubuntu 14.04.03 32bit, cleanly installed just a few days ago.
I followed these instructions to download, make, and install GDAL and OpenJPEG in a folder I made called /home/ronn4031/src/.

Answer 1

Did you do ldconfig to be sure that your changes to LD_LIBRARY_PATH are really applied?

Where is your libgdal.so.20 file?

Did you look at the GDAL .travis.yml file? A Travis file instructs how you can compile, deploy code for testing. It's firstly for testing code purpose but you can also use it to find out if you didn't miss a point when compiling.

Edit

It seems that you are missing parts otherwise, it would works. You will find below what I tried to make things work on an Ubuntu box 14.04 (mainly extracted from the .travis.yml file)

wget http://s3.amazonaws.com/etc-data.koordinates.com/gdal-travisci/install-openjpeg-2.0.0-ubuntu12.04-64bit.tar.gz
tar xzf install-openjpeg-2.0.0-ubuntu12.04-64bit.tar.gz
sudo cp -r install-openjpeg/include/* /usr/local/include
sudo cp -r install-openjpeg/lib/* /usr/local/lib

cd ~/$HOME
git clone https://github.com/OSGeo/gdal.git
cd gdal/gdal
./autogen.sh
# I use a prefix because I don't want to mix this compiled version with my already GDAL versions installed 
./configure --with-python --with-poppler --with-openjpeg=/usr/local --prefix=/usr/local/gdal
make
make install
ldconfig

# Temporary: you have to make them persistent or remove the prefix option in configure I used
export LD_LIBRARY_PATH="/usr/local/gdal/lib:$LD_LIBRARY_PATH"
export PATH="/usr/local/gdal/bin:$PATH"
export PYTHONPATH="/usr/local/gdal/lib/python2.7/site-packages/:$PYTHONPATH"

Launch Python with python and do the following to try if it's working:

from osgeo import gdal
print gdal.VersionInfo() # Should return 2010000 currently (may change with time)

I also tried gdal_merge.py and it works too (the initial issue you raised)

Answer 2

I had the same problem on Ubuntu 14.04 LTS with python 3.5.2 |Anaconda after installing via "conda install gdal". I searched for libgdal.so.20 on my computer, but it was nowhere. I then first did a "conda install libgdal" and then "conda install gdal". This fixed the problem for me.