environment variable doc updates

python/doc/usage/cluster_expansion.rst

@@ -31,12 +31,15 @@ The :func:`~libcasm.clexulator.make_cluster_expansion` method can be used to con
         export CASM_PREFIX=$(python -m libcasm.casmglobal --prefix)
 
 
-    In some cases, finer control of compilation and linking options may be necessary, which can be done as described in the :class:`~libcasm.clexulator.make_clexulator` documentation. For example, compiling and linking with gcc may require:
+    In some cases, finer control of compilation and linking options may be necessary, which can be done as described in the :class:`~libcasm.clexulator.make_clexulator` documentation. For example, compiling and linking on some Linux distros may require one or both of the "-D_GLIBCXX_USE_CXX11_ABI=0" and "--no-as-needed" flags. These can be set in the environment variables ``CASM_CXXFLAGS`` and ``CASM_SOFLAGS`` respectively:
 
     .. code-block:: bash
 
-        export CASM_SOFLAGS="-shared -Wl,--no-as-needed"
+        export CASM_CXXFLAGS="-O3 -Wall -fPIC --std=c++17 -D_GLIBCXX_USE_CXX11_ABI=0 "
+
+    .. code-block:: bash
 
+        export CASM_SOFLAGS="-shared -Wl,--no-as-needed"
 
 
 .. code-block:: Python

python/src/clexulator.cpp

@@ -1160,7 +1160,7 @@ PYBIND11_MODULE(_clexulator, m) {
       compile_options: str = None
           Options used to compile the Clexulator source file, if it is not yet
           compiled. Example: "g++ -O3 -Wall -fPIC --std=c++17 -I/path/to/include".
-          The default values can be configured with:
+          The default values can be configured by setting environment variables:
 
               CASM_CXX:
                   Set compiler; default="g++"
@@ -1177,7 +1177,7 @@ PYBIND11_MODULE(_clexulator, m) {
           Options used to compile the Clexulator shared object file, if it is not
           yet compiled. Example: "g++ -shared -L/path/to/lib -lcasm_clexulator "
 
-          The default values can be configured with:
+          The default values can be configured by setting environment variables:
 
               CASM_CXX:
                   Set compiler; default="g++"
@@ -1186,7 +1186,7 @@ PYBIND11_MODULE(_clexulator, m) {
               CASM_LIBDIR:
                   Set link search path, overriding CASM_PREFIX
               CASM_PREFIX:
-                  Set include search path to -L$CASM_PREFIX/lib; default
+                  Set library search path to -L$CASM_PREFIX/lib; default
                   tries to find "ccasm" or "casm" executables on PATH and
                   checks relative locations