pass the name of the python interpreter compatible with the python package to 'make install-python'

lib/python/Makefile.lammps

@@ -1,6 +1,7 @@
 # Settings that the LAMMPS build will import when this package library is used
 # See the README file for more explanation
 
-python_SYSINC = $(shell which python2-config > /dev/null 2>&1 && python2-config --includes || python-config --includes )
+python_SYSINC = $(shell which python-config > /dev/null 2>&1 && python-config --includes || :)
-python_SYSLIB = $(shell which python2-config > /dev/null 2>&1 && python2-config --ldflags || python-config --ldflags)
+python_SYSLIB = $(shell which python-config > /dev/null 2>&1 && python-config --ldflags || :)
 python_SYSPATH =
+PYTHON=python

lib/python/Makefile.lammps.python2

@@ -1,6 +1,7 @@
 # Settings that the LAMMPS build will import when this package library is used
 # See the README file for more explanation
 
-python_SYSINC = $(shell which python2-config > /dev/null 2>&1 && python2-config --includes || python-config --includes )
+python_SYSINC = $(shell which python2-config > /dev/null 2>&1 && python2-config --includes || which python-config > /dev/null 2>&1 && python-config --includes || :)
-python_SYSLIB = $(shell which python2-config > /dev/null 2>&1 && python2-config --ldflags || python-config --ldflags)
+python_SYSLIB = $(shell which python2-config > /dev/null 2>&1 && python2-config --ldflags || which python-config > /dev/null 2>&1 && python-config --ldflags || :)
 python_SYSPATH =
+PYTHON=$(shell which python2 > /dev/null 2>&1 && echo python2 || echo python)

lib/python/Makefile.lammps.python2.7

@@ -4,3 +4,4 @@
 python_SYSINC = -I/usr/local/include/python2.7
 python_SYSLIB = -lpython2.7 -lnsl -ldl -lreadline -ltermcap -lpthread -lutil -lm -Xlinker -export-dynamic
 python_SYSPATH = 
+PYTHON=python2.7

lib/python/Makefile.lammps.python3

@@ -1,6 +1,7 @@
 # Settings that the LAMMPS build will import when this package library is used
 # See the README file for more explanation
 
-python_SYSINC = $(shell which python3-config > /dev/null 2>&1 && python3-config --includes || python-config --includes )
+python_SYSINC = $(shell which python3-config > /dev/null 2>&1 && python3-config --includes || which python-config > /dev/null 2>&1 && python-config --includes || :)
-python_SYSLIB = $(shell which python3-config > /dev/null 2>&1 && python3-config --ldflags || python-config --ldflags)
+python_SYSLIB = $(shell which python3-config > /dev/null 2>&1 && python3-config --ldflags || which python-config > /dev/null 2>&1 && python-config --ldflags || : )
 python_SYSPATH =
+PYTHON=$(shell which python3 > /dev/null 2>&1 && echo python3 || echo python)

lib/python/README

@@ -1,22 +1,26 @@
 The Makefile.lammps file in this directory is used when building
 LAMMPS with its PYTHON package installed.  The file has several
 settings needed to compile and link LAMMPS with the Python library.
-You should choose a Makefile.lammps.* file compatible with your system
-and your version of Python, and copy it to Makefile.lammps before
-building LAMMPS itself.  You may need to edit one of the provided
-files to match your system.
 
-If you create a new Makefile.lammps file suitable for some version of
+The default Makefile.lammps will automatically choose the default
-Python on some system, that is not a match to one of the provided
+python interpreter of your system and will infer the flags from
-Makefile.lammps.* files, you can send it to the developers, and we can
+the python-config utility, that is usually bundled with the python
-include it in the distribution for others to use.
+installation. If needed, you can copy one of the other provided
+Makefile.lammps.* files to to Makefile.lammps before building
+LAMMPS itself.
 
-To illustrate, these are example settings from the
+The files Makefile.lammps.python2 and Makefile.lammps.python3 are
-Makefile.lammps.python2.7 file:
+similar to the default file, but meant for the case that both,
+python 2 and python 3, are installed simultaneously and you want
+to prefer one over the other. If neither of these files work, you
+may have to create a custom Makefile.lammps file suitable for
+the version of Python on your system.  To illustrate, these are
+example settings from the Makefile.lammps.python2.7 file:
 
 python_SYSINC = -I/usr/local/include/python2.7
 python_SYSLIB = -lpython2.7 -lnsl -ldl -lreadline -ltermcap -lpthread -lutil -lm
 python_SYSPATH =
+PYTHON=python2.7
 
 python_SYSINC refers to the directory where Python's Python.h file is
 found.  LAMMPS includes this file.
@@ -26,10 +30,13 @@ application (LAMMPS in this case) to "embed" Python in the
 application.  The Python library itself is listed (-lpython2.7) are
 are several system libraries needed by Python.
 
-python_SYSPATH = refers to the path (e.g. -L/usr/local/lib) where the
+python_SYSPATH refers to the path (e.g. -L/usr/local/lib) where the
 Python library can be found.  You may not need this setting if the
 path is already included in your LD_LIBRARY_PATH environment variable.
 
+PYTHON is the name of the python interpreter. It is used for
+installing the LAMMPS python module with "make install-python"
+
 -------------------------
 
 Note that the trickiest issue to figure out for inclusion in

src/Makefile

@@ -224,7 +224,8 @@ mpi-stubs:
 	@cd STUBS; $(MAKE) clean; $(MAKE)
 
 # install LAMMPS shared lib and Python wrapper for Python usage
-
+# include python package settings to automatically adapt name of python interpreter
+sinclude ../lib/python/Makefile.lammps
 install-python:
 	@$(PYTHON) ../python/install.py