Submit a patch

Unpack the latest tarball (download) which creates a tree with e.g. the top-level directory plplot-5.9.0

cp -a plplot-5.9.0 plplot-5.9.0new

Make your changes in the correct location in plplot-5.9.0new overwriting some of the files and adding new files in some cases. You should not compile anything in either plplot-5.9.0 or plplot-5.9.0new. That is, both should be clean directory trees. In order to test your changes make sure you configure plplot with CMake out-of-source. E.g.

cd plplot-5.9.0new
mkdir build
cd build
cmake ..
make

Remove the build directory after you tested your changes.

cd ..
rm -rf build
cd ..

To produce the patch from the two clean directory trees (don't forget to remove the CMake build directory) set up above do the following:

diff -Naur plplot-5.9.0 plplot-5.9.0new >plplot-5.9.0.patch

Please review plplot-5.9.0.patch to make sure those are the exact changes to the main tree that you require and nothing extra. Afterwards do the following:

gzip plplot-5.9.0.patch

Send plplot-5.9.0.patch.gz (the file created by gzip) to the the devel list.