diff --git a/packages/PyTrilinos/doc/DevelopersGuide/DevelopersGuide.html b/packages/PyTrilinos/doc/DevelopersGuide/DevelopersGuide.html
index ac8c64167bd5..b54b01e457c4 100644
--- a/packages/PyTrilinos/doc/DevelopersGuide/DevelopersGuide.html
+++ b/packages/PyTrilinos/doc/DevelopersGuide/DevelopersGuide.html
@@ -1325,7 +1325,7 @@ <h2><a class="toc-backref" href="#id26">Build System</a></h2>
 during the copy procedure.  For example, the first line of each test
 script source file is now:</p>
 <pre class="literal-block">
-#! ${PYTHON_EXECUTABLE}
+#! ${Python3_EXECUTABLE}
 </pre>
 <p>which means that the python executable that is recognized (and
 compiled against) by the CMake build system will also be the python
diff --git a/packages/PyTrilinos/doc/DevelopersGuide/Testing.txt b/packages/PyTrilinos/doc/DevelopersGuide/Testing.txt
index 089946e00b03..c98a32442662 100644
--- a/packages/PyTrilinos/doc/DevelopersGuide/Testing.txt
+++ b/packages/PyTrilinos/doc/DevelopersGuide/Testing.txt
@@ -44,7 +44,7 @@ reason for this is that CMake variable values can be substituted
 during the copy procedure.  For example, the first line of each test
 script source file is now::
 
-  #! ${PYTHON_EXECUTABLE}
+  #! ${Python3_EXECUTABLE}
 
 which means that the python executable that is recognized (and
 compiled against) by the CMake build system will also be the python
diff --git a/packages/PyTrilinos/doc/Doxygen/docstrings.py.in b/packages/PyTrilinos/doc/Doxygen/docstrings.py.in
index c0a537af9b29..ac59b6b38cd6 100755
--- a/packages/PyTrilinos/doc/Doxygen/docstrings.py.in
+++ b/packages/PyTrilinos/doc/Doxygen/docstrings.py.in
@@ -1,4 +1,4 @@
-#! ${PYTHON_EXECUTABLE}
+#! ${Python3_EXECUTABLE}
 
 # System includes
 from __future__ import print_function
diff --git a/packages/PyTrilinos/doc/Doxygen/doxy2swig.py.in b/packages/PyTrilinos/doc/Doxygen/doxy2swig.py.in
index ba7088ecc27e..878bd9721ffc 100755
--- a/packages/PyTrilinos/doc/Doxygen/doxy2swig.py.in
+++ b/packages/PyTrilinos/doc/Doxygen/doxy2swig.py.in
@@ -1,4 +1,4 @@
-#! ${PYTHON_EXECUTABLE}
+#! ${Python3_EXECUTABLE}
 """
 Doxygen XML to SWIG docstring converter.
 
diff --git a/packages/PyTrilinos/doc/Doxygen/makedeps.py.in b/packages/PyTrilinos/doc/Doxygen/makedeps.py.in
index e7c18c441311..3a94a5590bfc 100755
--- a/packages/PyTrilinos/doc/Doxygen/makedeps.py.in
+++ b/packages/PyTrilinos/doc/Doxygen/makedeps.py.in
@@ -1,4 +1,4 @@
-#! ${PYTHON_EXECUTABLE}
+#! ${Python3_EXECUTABLE}
 
 """
 Create a Makefile dependency file that includes all of the names of the source
diff --git a/packages/PyTrilinos/doc/UsersGuide/BuildingAndInstalling.txt b/packages/PyTrilinos/doc/UsersGuide/BuildingAndInstalling.txt
index 99b5ec781a64..0392cd4df3b2 100644
--- a/packages/PyTrilinos/doc/UsersGuide/BuildingAndInstalling.txt
+++ b/packages/PyTrilinos/doc/UsersGuide/BuildingAndInstalling.txt
@@ -62,7 +62,7 @@ Python and SWIG
 You may specify the python interpreter (and thus the version of the
 Python/C API) with the ``cmake`` option::
 
-    -D PYTHON_EXECUTABLE:FILEPATH=...
+    -D Python3_EXECUTABLE:FILEPATH=...
 
 If you do not specify this option, ``cmake`` actually looks for an
 executable named ``python2.7`` (and then ``python2.6``, etc., down to
diff --git a/packages/PyTrilinos/doc/UsersGuide/UsersGuide.html b/packages/PyTrilinos/doc/UsersGuide/UsersGuide.html
index 6a2425e34a7d..377b14dd0b58 100644
--- a/packages/PyTrilinos/doc/UsersGuide/UsersGuide.html
+++ b/packages/PyTrilinos/doc/UsersGuide/UsersGuide.html
@@ -427,7 +427,7 @@ <h2><a class="toc-backref" href="#id4">Python and SWIG</a></h2>
 <p>You may specify the python interpreter (and thus the version of the
 Python/C API) with the <tt class="docutils literal">cmake</tt> option:</p>
 <pre class="literal-block">
--D PYTHON_EXECUTABLE:FILEPATH=...
+-D Python3_EXECUTABLE:FILEPATH=...
 </pre>
 <p>If you do not specify this option, <tt class="docutils literal">cmake</tt> actually looks for an
 executable named <tt class="docutils literal">python2.7</tt> (and then <tt class="docutils literal">python2.6</tt>, etc., down to
diff --git a/packages/PyTrilinos/example/exAmesos_Factory.py.in b/packages/PyTrilinos/example/exAmesos_Factory.py.in
index 0e3d3481ea00..8b2279f78c26 100755
--- a/packages/PyTrilinos/example/exAmesos_Factory.py.in
+++ b/packages/PyTrilinos/example/exAmesos_Factory.py.in
@@ -1,4 +1,4 @@
-#! ${PYTHON_EXECUTABLE}
+#! ${Python3_EXECUTABLE}
 # -*- python -*-
 
 # @HEADER
diff --git a/packages/PyTrilinos/example/exAmesos_Solvers.py.in b/packages/PyTrilinos/example/exAmesos_Solvers.py.in
index c056d4341ebf..273200a054ff 100755
--- a/packages/PyTrilinos/example/exAmesos_Solvers.py.in
+++ b/packages/PyTrilinos/example/exAmesos_Solvers.py.in
@@ -1,4 +1,4 @@
-#! ${PYTHON_EXECUTABLE}
+#! ${Python3_EXECUTABLE}
 # -*- python -*-
 
 # @HEADER
diff --git a/packages/PyTrilinos/example/exAnasazi_BlockDavidson.py.in b/packages/PyTrilinos/example/exAnasazi_BlockDavidson.py.in
index 2de10323d03f..69a94881498f 100755
--- a/packages/PyTrilinos/example/exAnasazi_BlockDavidson.py.in
+++ b/packages/PyTrilinos/example/exAnasazi_BlockDavidson.py.in
@@ -1,4 +1,4 @@
-#! ${PYTHON_EXECUTABLE}
+#! ${Python3_EXECUTABLE}
 # -*- python -*-
 
 # @HEADER
diff --git a/packages/PyTrilinos/example/exAztecOO.py.in b/packages/PyTrilinos/example/exAztecOO.py.in
index 0c3f04afacc9..23d357963874 100755
--- a/packages/PyTrilinos/example/exAztecOO.py.in
+++ b/packages/PyTrilinos/example/exAztecOO.py.in
@@ -1,4 +1,4 @@
-#! ${PYTHON_EXECUTABLE}
+#! ${Python3_EXECUTABLE}
 # -*- python -*-
 
 # @HEADER
diff --git a/packages/PyTrilinos/example/exAztecOO_BasicRowMatrix.py.in b/packages/PyTrilinos/example/exAztecOO_BasicRowMatrix.py.in
index e52348c1a679..83a21b88c21d 100755
--- a/packages/PyTrilinos/example/exAztecOO_BasicRowMatrix.py.in
+++ b/packages/PyTrilinos/example/exAztecOO_BasicRowMatrix.py.in
@@ -1,4 +1,4 @@
-#! ${PYTHON_EXECUTABLE}
+#! ${Python3_EXECUTABLE}
 # -*- python -*-
 
 # @HEADER
diff --git a/packages/PyTrilinos/example/exAztecOO_Operator.py.in b/packages/PyTrilinos/example/exAztecOO_Operator.py.in
index 9ad6a7d25254..d1690befac1c 100755
--- a/packages/PyTrilinos/example/exAztecOO_Operator.py.in
+++ b/packages/PyTrilinos/example/exAztecOO_Operator.py.in
@@ -1,4 +1,4 @@
-#! ${PYTHON_EXECUTABLE}
+#! ${Python3_EXECUTABLE}
 # -*- python -*-
 
 # @HEADER
diff --git a/packages/PyTrilinos/example/exAztecOO_RowMatrix.py.in b/packages/PyTrilinos/example/exAztecOO_RowMatrix.py.in
index dcc4f8e83e39..f9a2e09b7f1e 100755
--- a/packages/PyTrilinos/example/exAztecOO_RowMatrix.py.in
+++ b/packages/PyTrilinos/example/exAztecOO_RowMatrix.py.in
@@ -1,4 +1,4 @@
-#! ${PYTHON_EXECUTABLE}
+#! ${Python3_EXECUTABLE}
 # -*- python -*-
 
 # @HEADER
diff --git a/packages/PyTrilinos/example/exDomi_Simple.py.in b/packages/PyTrilinos/example/exDomi_Simple.py.in
index 89b739d115a7..1bb1b0f340f2 100755
--- a/packages/PyTrilinos/example/exDomi_Simple.py.in
+++ b/packages/PyTrilinos/example/exDomi_Simple.py.in
@@ -1,4 +1,4 @@
-#! ${PYTHON_EXECUTABLE}
+#! ${Python3_EXECUTABLE}
 # -*- python -*-
 
 # @HEADER
diff --git a/packages/PyTrilinos/example/exEpetra.py.in b/packages/PyTrilinos/example/exEpetra.py.in
index f27b511520bb..49fcb6c0bee7 100755
--- a/packages/PyTrilinos/example/exEpetra.py.in
+++ b/packages/PyTrilinos/example/exEpetra.py.in
@@ -1,4 +1,4 @@
-#! ${PYTHON_EXECUTABLE}
+#! ${Python3_EXECUTABLE}
 # -*- python -*-
 
 # @HEADER
diff --git a/packages/PyTrilinos/example/exEpetraExt_IO_HDF5.py.in b/packages/PyTrilinos/example/exEpetraExt_IO_HDF5.py.in
index 3d90da47e640..d35f64db9cd6 100755
--- a/packages/PyTrilinos/example/exEpetraExt_IO_HDF5.py.in
+++ b/packages/PyTrilinos/example/exEpetraExt_IO_HDF5.py.in
@@ -1,4 +1,4 @@
-#! ${PYTHON_EXECUTABLE}
+#! ${Python3_EXECUTABLE}
 # -*- python -*-
 
 # @HEADER
diff --git a/packages/PyTrilinos/example/exEpetraExt_IO_MatrixMarket.py.in b/packages/PyTrilinos/example/exEpetraExt_IO_MatrixMarket.py.in
index 83e1df3fc8b3..fecc442d3b97 100755
--- a/packages/PyTrilinos/example/exEpetraExt_IO_MatrixMarket.py.in
+++ b/packages/PyTrilinos/example/exEpetraExt_IO_MatrixMarket.py.in
@@ -1,4 +1,4 @@
-#! ${PYTHON_EXECUTABLE}
+#! ${Python3_EXECUTABLE}
 # -*- python -*-
 
 # @HEADER
diff --git a/packages/PyTrilinos/example/exEpetraExt_IO_XML.py.in b/packages/PyTrilinos/example/exEpetraExt_IO_XML.py.in
index 4c338604eb51..b56c447cd88e 100755
--- a/packages/PyTrilinos/example/exEpetraExt_IO_XML.py.in
+++ b/packages/PyTrilinos/example/exEpetraExt_IO_XML.py.in
@@ -1,4 +1,4 @@
-#! ${PYTHON_EXECUTABLE}
+#! ${Python3_EXECUTABLE}
 # -*- python -*-
 
 # @HEADER
diff --git a/packages/PyTrilinos/example/exEpetraExt_MatrixMatrix.py.in b/packages/PyTrilinos/example/exEpetraExt_MatrixMatrix.py.in
index 4205551be1e0..d4fd5be9a91f 100755
--- a/packages/PyTrilinos/example/exEpetraExt_MatrixMatrix.py.in
+++ b/packages/PyTrilinos/example/exEpetraExt_MatrixMatrix.py.in
@@ -1,4 +1,4 @@
-#! ${PYTHON_EXECUTABLE}
+#! ${Python3_EXECUTABLE}
 # -*- python -*-
 
 # @HEADER
diff --git a/packages/PyTrilinos/example/exEpetra_Comm.py.in b/packages/PyTrilinos/example/exEpetra_Comm.py.in
index ec499a8c3522..4286f676cd99 100755
--- a/packages/PyTrilinos/example/exEpetra_Comm.py.in
+++ b/packages/PyTrilinos/example/exEpetra_Comm.py.in
@@ -1,4 +1,4 @@
-#! ${PYTHON_EXECUTABLE}
+#! ${Python3_EXECUTABLE}
 # -*- python -*-
 
 # @HEADER
diff --git a/packages/PyTrilinos/example/exEpetra_CrsMatrix_Easy.py.in b/packages/PyTrilinos/example/exEpetra_CrsMatrix_Easy.py.in
index 6abadf1e4338..ec6d02a78e13 100755
--- a/packages/PyTrilinos/example/exEpetra_CrsMatrix_Easy.py.in
+++ b/packages/PyTrilinos/example/exEpetra_CrsMatrix_Easy.py.in
@@ -1,4 +1,4 @@
-#! ${PYTHON_EXECUTABLE}
+#! ${Python3_EXECUTABLE}
 # -*- python -*-
 
 # @HEADER
diff --git a/packages/PyTrilinos/example/exEpetra_CrsMatrix_Efficient.py.in b/packages/PyTrilinos/example/exEpetra_CrsMatrix_Efficient.py.in
index bedee3eb2148..59feca1aab25 100755
--- a/packages/PyTrilinos/example/exEpetra_CrsMatrix_Efficient.py.in
+++ b/packages/PyTrilinos/example/exEpetra_CrsMatrix_Efficient.py.in
@@ -1,4 +1,4 @@
-#! ${PYTHON_EXECUTABLE}
+#! ${Python3_EXECUTABLE}
 # -*- python -*-
 
 # @HEADER
diff --git a/packages/PyTrilinos/example/exEpetra_DAP.py.in b/packages/PyTrilinos/example/exEpetra_DAP.py.in
index d112a8f45a05..a3a3fd165c43 100755
--- a/packages/PyTrilinos/example/exEpetra_DAP.py.in
+++ b/packages/PyTrilinos/example/exEpetra_DAP.py.in
@@ -1,4 +1,4 @@
-#! ${PYTHON_EXECUTABLE}
+#! ${Python3_EXECUTABLE}
 # -*- python -*-
 
 # @HEADER
diff --git a/packages/PyTrilinos/example/exEpetra_FECrsMatrix_Easy.py.in b/packages/PyTrilinos/example/exEpetra_FECrsMatrix_Easy.py.in
index 72b75666e425..9e0d4f064d35 100755
--- a/packages/PyTrilinos/example/exEpetra_FECrsMatrix_Easy.py.in
+++ b/packages/PyTrilinos/example/exEpetra_FECrsMatrix_Easy.py.in
@@ -1,4 +1,4 @@
-#! ${PYTHON_EXECUTABLE}
+#! ${Python3_EXECUTABLE}
 # -*- python -*-
 
 # @HEADER
diff --git a/packages/PyTrilinos/example/exEpetra_ImportExport.py.in b/packages/PyTrilinos/example/exEpetra_ImportExport.py.in
index 37b690100d76..3880f9377ccf 100755
--- a/packages/PyTrilinos/example/exEpetra_ImportExport.py.in
+++ b/packages/PyTrilinos/example/exEpetra_ImportExport.py.in
@@ -1,4 +1,4 @@
-#! ${PYTHON_EXECUTABLE}
+#! ${Python3_EXECUTABLE}
 # -*- python -*-
 
 # @HEADER
diff --git a/packages/PyTrilinos/example/exGaleri.py.in b/packages/PyTrilinos/example/exGaleri.py.in
index 4625ae8061eb..172437b804f9 100755
--- a/packages/PyTrilinos/example/exGaleri.py.in
+++ b/packages/PyTrilinos/example/exGaleri.py.in
@@ -1,4 +1,4 @@
-#! ${PYTHON_EXECUTABLE}
+#! ${Python3_EXECUTABLE}
 # -*- python -*-
 
 # @HEADER
diff --git a/packages/PyTrilinos/example/exGaleri_ReadHB.py.in b/packages/PyTrilinos/example/exGaleri_ReadHB.py.in
index d4d291c2a5db..ef3028537641 100755
--- a/packages/PyTrilinos/example/exGaleri_ReadHB.py.in
+++ b/packages/PyTrilinos/example/exGaleri_ReadHB.py.in
@@ -1,4 +1,4 @@
-#! ${PYTHON_EXECUTABLE}
+#! ${Python3_EXECUTABLE}
 # -*- python -*-
 
 # @HEADER
diff --git a/packages/PyTrilinos/example/exIFPACK.py.in b/packages/PyTrilinos/example/exIFPACK.py.in
index 85da04dfe92a..b8848fd4ca40 100755
--- a/packages/PyTrilinos/example/exIFPACK.py.in
+++ b/packages/PyTrilinos/example/exIFPACK.py.in
@@ -1,4 +1,4 @@
-#! ${PYTHON_EXECUTABLE}
+#! ${Python3_EXECUTABLE}
 # -*- python -*-
 
 # @HEADER
diff --git a/packages/PyTrilinos/example/exIsorropia.py.in b/packages/PyTrilinos/example/exIsorropia.py.in
index 846367e6b23f..911ef3c3b8b4 100755
--- a/packages/PyTrilinos/example/exIsorropia.py.in
+++ b/packages/PyTrilinos/example/exIsorropia.py.in
@@ -1,4 +1,4 @@
-#! ${PYTHON_EXECUTABLE}
+#! ${Python3_EXECUTABLE}
 # -*- python -*-
 
 # @HEADER
diff --git a/packages/PyTrilinos/example/exKomplex_Simple.py.in b/packages/PyTrilinos/example/exKomplex_Simple.py.in
index e3f4e98b36c0..1fc22a553020 100755
--- a/packages/PyTrilinos/example/exKomplex_Simple.py.in
+++ b/packages/PyTrilinos/example/exKomplex_Simple.py.in
@@ -1,4 +1,4 @@
-#! ${PYTHON_EXECUTABLE}
+#! ${Python3_EXECUTABLE}
 # -*- python -*-
 
 # @HEADER
diff --git a/packages/PyTrilinos/example/exLOCA_Chan.py.in b/packages/PyTrilinos/example/exLOCA_Chan.py.in
index 95a3efc5d4b3..a7e713957dd2 100755
--- a/packages/PyTrilinos/example/exLOCA_Chan.py.in
+++ b/packages/PyTrilinos/example/exLOCA_Chan.py.in
@@ -1,4 +1,4 @@
-#! ${PYTHON_EXECUTABLE}
+#! ${Python3_EXECUTABLE}
 # -*- python -*-
 
 # ************************************************************************
diff --git a/packages/PyTrilinos/example/exLOCA_Chan_Jac.py.in b/packages/PyTrilinos/example/exLOCA_Chan_Jac.py.in
index 874930734eb3..ac2b993e8044 100755
--- a/packages/PyTrilinos/example/exLOCA_Chan_Jac.py.in
+++ b/packages/PyTrilinos/example/exLOCA_Chan_Jac.py.in
@@ -1,4 +1,4 @@
-#! ${PYTHON_EXECUTABLE}
+#! ${Python3_EXECUTABLE}
 # -*- python -*-
 
 # ************************************************************************
diff --git a/packages/PyTrilinos/example/exMLAPI.py.in b/packages/PyTrilinos/example/exMLAPI.py.in
index 80710cee17f6..2143e440ac8b 100755
--- a/packages/PyTrilinos/example/exMLAPI.py.in
+++ b/packages/PyTrilinos/example/exMLAPI.py.in
@@ -1,4 +1,4 @@
-#! ${PYTHON_EXECUTABLE}
+#! ${Python3_EXECUTABLE}
 # -*- python -*-
 
 # @HEADER
diff --git a/packages/PyTrilinos/example/exMLAPI_AztecOO.py.in b/packages/PyTrilinos/example/exMLAPI_AztecOO.py.in
index ecee9419a9e9..a54438b4211a 100755
--- a/packages/PyTrilinos/example/exMLAPI_AztecOO.py.in
+++ b/packages/PyTrilinos/example/exMLAPI_AztecOO.py.in
@@ -1,4 +1,4 @@
-#! ${PYTHON_EXECUTABLE}
+#! ${Python3_EXECUTABLE}
 # -*- python -*-
 
 # @HEADER
diff --git a/packages/PyTrilinos/example/exMLAPI_Iterate.py.in b/packages/PyTrilinos/example/exMLAPI_Iterate.py.in
index 146efc841ba2..a2dd0c6d8658 100755
--- a/packages/PyTrilinos/example/exMLAPI_Iterate.py.in
+++ b/packages/PyTrilinos/example/exMLAPI_Iterate.py.in
@@ -1,4 +1,4 @@
-#! ${PYTHON_EXECUTABLE}
+#! ${Python3_EXECUTABLE}
 # -*- python -*-
 
 # @HEADER
diff --git a/packages/PyTrilinos/example/exMLAPI_PyMatrix.py.in b/packages/PyTrilinos/example/exMLAPI_PyMatrix.py.in
index 840f36179e63..c7762fe76f36 100755
--- a/packages/PyTrilinos/example/exMLAPI_PyMatrix.py.in
+++ b/packages/PyTrilinos/example/exMLAPI_PyMatrix.py.in
@@ -1,4 +1,4 @@
-#! ${PYTHON_EXECUTABLE}
+#! ${Python3_EXECUTABLE}
 # -*- python -*-
 
 # @HEADER
diff --git a/packages/PyTrilinos/example/exMLAPI_Simple.py.in b/packages/PyTrilinos/example/exMLAPI_Simple.py.in
index aaef201b7f27..004b6d09f62a 100755
--- a/packages/PyTrilinos/example/exMLAPI_Simple.py.in
+++ b/packages/PyTrilinos/example/exMLAPI_Simple.py.in
@@ -1,4 +1,4 @@
-#! ${PYTHON_EXECUTABLE}
+#! ${Python3_EXECUTABLE}
 # -*- python -*-
 
 # @HEADER
diff --git a/packages/PyTrilinos/example/exMLAPI_Smoother.py.in b/packages/PyTrilinos/example/exMLAPI_Smoother.py.in
index ef3c891d3bcc..49e96dbeeec4 100755
--- a/packages/PyTrilinos/example/exMLAPI_Smoother.py.in
+++ b/packages/PyTrilinos/example/exMLAPI_Smoother.py.in
@@ -1,4 +1,4 @@
-#! ${PYTHON_EXECUTABLE}
+#! ${Python3_EXECUTABLE}
 # -*- python -*-
 
 # @HEADER
diff --git a/packages/PyTrilinos/example/exMPI_Init.py.in b/packages/PyTrilinos/example/exMPI_Init.py.in
index 50734b6d7764..2de079f7340f 100755
--- a/packages/PyTrilinos/example/exMPI_Init.py.in
+++ b/packages/PyTrilinos/example/exMPI_Init.py.in
@@ -1,4 +1,4 @@
-#! ${PYTHON_EXECUTABLE}
+#! ${Python3_EXECUTABLE}
 # -*- python -*-
 
 # @HEADER
diff --git a/packages/PyTrilinos/example/exNOXEpetraExt_2DSim.py.in b/packages/PyTrilinos/example/exNOXEpetraExt_2DSim.py.in
index b138a090d67d..e4d7e73ea745 100755
--- a/packages/PyTrilinos/example/exNOXEpetraExt_2DSim.py.in
+++ b/packages/PyTrilinos/example/exNOXEpetraExt_2DSim.py.in
@@ -1,4 +1,4 @@
-#! ${PYTHON_EXECUTABLE}
+#! ${Python3_EXECUTABLE}
 # -*- python -*-
 
 # @HEADER
diff --git a/packages/PyTrilinos/example/exNOX_1Dfdm.py.in b/packages/PyTrilinos/example/exNOX_1Dfdm.py.in
index 44a3ff9563d1..aecd4893dff2 100755
--- a/packages/PyTrilinos/example/exNOX_1Dfdm.py.in
+++ b/packages/PyTrilinos/example/exNOX_1Dfdm.py.in
@@ -1,4 +1,4 @@
-#! ${PYTHON_EXECUTABLE}
+#! ${Python3_EXECUTABLE}
 # -*- python -*-
 
 # @HEADER
diff --git a/packages/PyTrilinos/example/exNOX_2DSim.py.in b/packages/PyTrilinos/example/exNOX_2DSim.py.in
index 4b79e9a051ba..c388b9e01dd3 100755
--- a/packages/PyTrilinos/example/exNOX_2DSim.py.in
+++ b/packages/PyTrilinos/example/exNOX_2DSim.py.in
@@ -1,4 +1,4 @@
-#! ${PYTHON_EXECUTABLE}
+#! ${Python3_EXECUTABLE}
 # -*- python -*-
 
 # @HEADER
diff --git a/packages/PyTrilinos/example/exTeuchos.py.in b/packages/PyTrilinos/example/exTeuchos.py.in
index 7a0075568952..2418b35dfc37 100755
--- a/packages/PyTrilinos/example/exTeuchos.py.in
+++ b/packages/PyTrilinos/example/exTeuchos.py.in
@@ -1,4 +1,4 @@
-#! ${PYTHON_EXECUTABLE}
+#! ${Python3_EXECUTABLE}
 # -*- python -*-
 
 # @HEADER
diff --git a/packages/PyTrilinos/example/exThyra.py.in b/packages/PyTrilinos/example/exThyra.py.in
index 18614d00d130..f94e6bfaa203 100755
--- a/packages/PyTrilinos/example/exThyra.py.in
+++ b/packages/PyTrilinos/example/exThyra.py.in
@@ -1,4 +1,4 @@
-#! ${PYTHON_EXECUTABLE}
+#! ${Python3_EXECUTABLE}
 # -*- python -*-
 
 # @HEADER
diff --git a/packages/PyTrilinos/example/testutil.py.in b/packages/PyTrilinos/example/testutil.py.in
index 57f7562811bb..0f115f102758 100644
--- a/packages/PyTrilinos/example/testutil.py.in
+++ b/packages/PyTrilinos/example/testutil.py.in
@@ -1,4 +1,4 @@
-#! ${PYTHON_EXECUTABLE}
+#! ${Python3_EXECUTABLE}
 # -*- python -*-
 
 # @HEADER
diff --git a/packages/PyTrilinos/src/PyTrilinos/Isorropia/__init__.py.in b/packages/PyTrilinos/src/PyTrilinos/Isorropia/__init__.py.in
index 56d8856619a2..45bec4cbc46f 100644
--- a/packages/PyTrilinos/src/PyTrilinos/Isorropia/__init__.py.in
+++ b/packages/PyTrilinos/src/PyTrilinos/Isorropia/__init__.py.in
@@ -1,4 +1,4 @@
-#! ${PYTHON_EXECUTABLE}
+#! ${Python3_EXECUTABLE}
 # -*- python -*-
 
 # @HEADER
diff --git a/packages/PyTrilinos/src/PyTrilinos/LOCA/Epetra/__init__.py.in b/packages/PyTrilinos/src/PyTrilinos/LOCA/Epetra/__init__.py.in
index c87f4ec4e00b..23947fcef50b 100644
--- a/packages/PyTrilinos/src/PyTrilinos/LOCA/Epetra/__init__.py.in
+++ b/packages/PyTrilinos/src/PyTrilinos/LOCA/Epetra/__init__.py.in
@@ -1,4 +1,4 @@
-#! ${PYTHON_EXECUTABLE}
+#! ${Python3_EXECUTABLE}
 # -*- python -*-
 
 # @HEADER
diff --git a/packages/PyTrilinos/src/PyTrilinos/LOCA/Hopf/__init__.py.in b/packages/PyTrilinos/src/PyTrilinos/LOCA/Hopf/__init__.py.in
index c157a7d0476b..feebe7fa029b 100644
--- a/packages/PyTrilinos/src/PyTrilinos/LOCA/Hopf/__init__.py.in
+++ b/packages/PyTrilinos/src/PyTrilinos/LOCA/Hopf/__init__.py.in
@@ -1,4 +1,4 @@
-#! ${PYTHON_EXECUTABLE}
+#! ${Python3_EXECUTABLE}
 # -*- python -*-
 
 # @HEADER
diff --git a/packages/PyTrilinos/src/PyTrilinos/LOCA/Pitchfork/__init__.py.in b/packages/PyTrilinos/src/PyTrilinos/LOCA/Pitchfork/__init__.py.in
index fa29127825d3..1b274442514d 100644
--- a/packages/PyTrilinos/src/PyTrilinos/LOCA/Pitchfork/__init__.py.in
+++ b/packages/PyTrilinos/src/PyTrilinos/LOCA/Pitchfork/__init__.py.in
@@ -1,4 +1,4 @@
-#! ${PYTHON_EXECUTABLE}
+#! ${Python3_EXECUTABLE}
 # -*- python -*-
 
 # @HEADER
diff --git a/packages/PyTrilinos/src/PyTrilinos/LOCA/TurningPoint/__init__.py.in b/packages/PyTrilinos/src/PyTrilinos/LOCA/TurningPoint/__init__.py.in
index 2e07b1b2c617..80dd1dbe1325 100644
--- a/packages/PyTrilinos/src/PyTrilinos/LOCA/TurningPoint/__init__.py.in
+++ b/packages/PyTrilinos/src/PyTrilinos/LOCA/TurningPoint/__init__.py.in
@@ -1,4 +1,4 @@
-#! ${PYTHON_EXECUTABLE}
+#! ${Python3_EXECUTABLE}
 # -*- python -*-
 
 # @HEADER
diff --git a/packages/PyTrilinos/src/PyTrilinos/LOCA/__init__.py.in b/packages/PyTrilinos/src/PyTrilinos/LOCA/__init__.py.in
index a1dd9d41fe66..1089800b759b 100644
--- a/packages/PyTrilinos/src/PyTrilinos/LOCA/__init__.py.in
+++ b/packages/PyTrilinos/src/PyTrilinos/LOCA/__init__.py.in
@@ -1,4 +1,4 @@
-#! ${PYTHON_EXECUTABLE}
+#! ${Python3_EXECUTABLE}
 # -*- python -*-
 
 # @HEADER
diff --git a/packages/PyTrilinos/src/PyTrilinos/NOX/Epetra/__init__.py.in b/packages/PyTrilinos/src/PyTrilinos/NOX/Epetra/__init__.py.in
index 62fb83082991..c912295c13a0 100644
--- a/packages/PyTrilinos/src/PyTrilinos/NOX/Epetra/__init__.py.in
+++ b/packages/PyTrilinos/src/PyTrilinos/NOX/Epetra/__init__.py.in
@@ -1,4 +1,4 @@
-#! ${PYTHON_EXECUTABLE}
+#! ${Python3_EXECUTABLE}
 # -*- python -*-
 
 # @HEADER
diff --git a/packages/PyTrilinos/src/PyTrilinos/NOX/PETSc/__init__.py.in b/packages/PyTrilinos/src/PyTrilinos/NOX/PETSc/__init__.py.in
index f254110ebea3..ff799ed50ab3 100644
--- a/packages/PyTrilinos/src/PyTrilinos/NOX/PETSc/__init__.py.in
+++ b/packages/PyTrilinos/src/PyTrilinos/NOX/PETSc/__init__.py.in
@@ -1,4 +1,4 @@
-#! ${PYTHON_EXECUTABLE}
+#! ${Python3_EXECUTABLE}
 # -*- python -*-
 
 # @HEADER
diff --git a/packages/PyTrilinos/src/PyTrilinos/NOX/__init__.py.in b/packages/PyTrilinos/src/PyTrilinos/NOX/__init__.py.in
index 0d477f1a5d20..c0fc512511d7 100644
--- a/packages/PyTrilinos/src/PyTrilinos/NOX/__init__.py.in
+++ b/packages/PyTrilinos/src/PyTrilinos/NOX/__init__.py.in
@@ -1,4 +1,4 @@
-#! ${PYTHON_EXECUTABLE}
+#! ${Python3_EXECUTABLE}
 # -*- python -*-
 
 # @HEADER
diff --git a/packages/PyTrilinos/src/PyTrilinos/Teuchos/__init__.py.in b/packages/PyTrilinos/src/PyTrilinos/Teuchos/__init__.py.in
index 3cf921c10867..28c81e2b7712 100644
--- a/packages/PyTrilinos/src/PyTrilinos/Teuchos/__init__.py.in
+++ b/packages/PyTrilinos/src/PyTrilinos/Teuchos/__init__.py.in
@@ -1,4 +1,4 @@
-#! ${PYTHON_EXECUTABLE}
+#! ${Python3_EXECUTABLE}
 # -*- python -*-
 
 # @HEADER
diff --git a/packages/PyTrilinos/src/PyTrilinos/__init__.py.in b/packages/PyTrilinos/src/PyTrilinos/__init__.py.in
index 6c53789fd2c3..df2e9a056a91 100644
--- a/packages/PyTrilinos/src/PyTrilinos/__init__.py.in
+++ b/packages/PyTrilinos/src/PyTrilinos/__init__.py.in
@@ -1,4 +1,4 @@
-#! ${PYTHON_EXECUTABLE}
+#! ${Python3_EXECUTABLE}
 # -*- python -*-
 
 # @HEADER
diff --git a/packages/PyTrilinos/src/gen_teuchos_rcp.py.in b/packages/PyTrilinos/src/gen_teuchos_rcp.py.in
index ac4ac19bc823..f56c3b12dfc3 100755
--- a/packages/PyTrilinos/src/gen_teuchos_rcp.py.in
+++ b/packages/PyTrilinos/src/gen_teuchos_rcp.py.in
@@ -1,4 +1,4 @@
-#! ${PYTHON_EXECUTABLE}
+#! ${Python3_EXECUTABLE}
 # -*- python -*-
 
 import glob
diff --git a/packages/PyTrilinos/src/scripts/IsorropiaVisualizer.py.in b/packages/PyTrilinos/src/scripts/IsorropiaVisualizer.py.in
index 1a319fe5c2d3..0c0d613bd5be 100755
--- a/packages/PyTrilinos/src/scripts/IsorropiaVisualizer.py.in
+++ b/packages/PyTrilinos/src/scripts/IsorropiaVisualizer.py.in
@@ -1,4 +1,4 @@
-#! ${PYTHON_EXECUTABLE}
+#! ${Python3_EXECUTABLE}
 # -*- python -*-
 
 # TODO:
diff --git a/packages/PyTrilinos/src/scripts/testutil.py.in b/packages/PyTrilinos/src/scripts/testutil.py.in
index 846ba26319c6..ee32ee8257e4 100644
--- a/packages/PyTrilinos/src/scripts/testutil.py.in
+++ b/packages/PyTrilinos/src/scripts/testutil.py.in
@@ -1,4 +1,4 @@
-#! ${PYTHON_EXECUTABLE}
+#! ${Python3_EXECUTABLE}
 # -*- python -*-
 
 # @HEADER
diff --git a/packages/PyTrilinos/test/testAmesos.py.in b/packages/PyTrilinos/test/testAmesos.py.in
index 53837470a9b1..1378054c583a 100755
--- a/packages/PyTrilinos/test/testAmesos.py.in
+++ b/packages/PyTrilinos/test/testAmesos.py.in
@@ -1,4 +1,4 @@
-#! ${PYTHON_EXECUTABLE}
+#! ${Python3_EXECUTABLE}
 # -*- python -*-
 
 # @HEADER
diff --git a/packages/PyTrilinos/test/testAnasazi.py.in b/packages/PyTrilinos/test/testAnasazi.py.in
index 23023f3a861e..764c1c4fd17e 100755
--- a/packages/PyTrilinos/test/testAnasazi.py.in
+++ b/packages/PyTrilinos/test/testAnasazi.py.in
@@ -1,4 +1,4 @@
-#! ${PYTHON_EXECUTABLE}
+#! ${Python3_EXECUTABLE}
 # -*- python -*-
 
 # @HEADER
diff --git a/packages/PyTrilinos/test/testAztecOO.py.in b/packages/PyTrilinos/test/testAztecOO.py.in
index f991e98aa412..b807f561faf5 100755
--- a/packages/PyTrilinos/test/testAztecOO.py.in
+++ b/packages/PyTrilinos/test/testAztecOO.py.in
@@ -1,4 +1,4 @@
-#! ${PYTHON_EXECUTABLE}
+#! ${Python3_EXECUTABLE}
 # -*- python -*-
 
 # @HEADER
diff --git a/packages/PyTrilinos/test/testEpetraExt_Coloring.py.in b/packages/PyTrilinos/test/testEpetraExt_Coloring.py.in
index 5322ddd55e09..47f910d8dcf1 100755
--- a/packages/PyTrilinos/test/testEpetraExt_Coloring.py.in
+++ b/packages/PyTrilinos/test/testEpetraExt_Coloring.py.in
@@ -1,4 +1,4 @@
-#! ${PYTHON_EXECUTABLE}
+#! ${Python3_EXECUTABLE}
 # -*- python -*-
 
 # @HEADER
diff --git a/packages/PyTrilinos/test/testEpetraExt_HDF5.py.in b/packages/PyTrilinos/test/testEpetraExt_HDF5.py.in
index 8ea31e7fdb9c..051d9ee4c234 100755
--- a/packages/PyTrilinos/test/testEpetraExt_HDF5.py.in
+++ b/packages/PyTrilinos/test/testEpetraExt_HDF5.py.in
@@ -1,4 +1,4 @@
-#! ${PYTHON_EXECUTABLE}
+#! ${Python3_EXECUTABLE}
 # -*- python -*-
 
 # @HEADER
diff --git a/packages/PyTrilinos/test/testEpetraExt_Property.py.in b/packages/PyTrilinos/test/testEpetraExt_Property.py.in
index 629f89bf3e5e..82ee253e1bb6 100755
--- a/packages/PyTrilinos/test/testEpetraExt_Property.py.in
+++ b/packages/PyTrilinos/test/testEpetraExt_Property.py.in
@@ -1,4 +1,4 @@
-#! ${PYTHON_EXECUTABLE}
+#! ${Python3_EXECUTABLE}
 # -*- python -*-
 
 # @HEADER
diff --git a/packages/PyTrilinos/test/testEpetra_BlockMap.py.in b/packages/PyTrilinos/test/testEpetra_BlockMap.py.in
index d523e273cdd3..159fbae4b9db 100755
--- a/packages/PyTrilinos/test/testEpetra_BlockMap.py.in
+++ b/packages/PyTrilinos/test/testEpetra_BlockMap.py.in
@@ -1,4 +1,4 @@
-#! ${PYTHON_EXECUTABLE}
+#! ${Python3_EXECUTABLE}
 # -*- python -*-
 
 # @HEADER
diff --git a/packages/PyTrilinos/test/testEpetra_Comm.py.in b/packages/PyTrilinos/test/testEpetra_Comm.py.in
index 81ebad421004..0dc7d6c2ddb3 100755
--- a/packages/PyTrilinos/test/testEpetra_Comm.py.in
+++ b/packages/PyTrilinos/test/testEpetra_Comm.py.in
@@ -1,4 +1,4 @@
-#! ${PYTHON_EXECUTABLE}
+#! ${Python3_EXECUTABLE}
 # -*- python -*-
 
 # @HEADER
diff --git a/packages/PyTrilinos/test/testEpetra_CompObject.py.in b/packages/PyTrilinos/test/testEpetra_CompObject.py.in
index 408f30e27f48..e0d0bc923d11 100755
--- a/packages/PyTrilinos/test/testEpetra_CompObject.py.in
+++ b/packages/PyTrilinos/test/testEpetra_CompObject.py.in
@@ -1,4 +1,4 @@
-#! ${PYTHON_EXECUTABLE}
+#! ${Python3_EXECUTABLE}
 # -*- python -*-
 
 # @HEADER
diff --git a/packages/PyTrilinos/test/testEpetra_CrsGraph.py.in b/packages/PyTrilinos/test/testEpetra_CrsGraph.py.in
index 877670766ffc..4147335f209f 100755
--- a/packages/PyTrilinos/test/testEpetra_CrsGraph.py.in
+++ b/packages/PyTrilinos/test/testEpetra_CrsGraph.py.in
@@ -1,4 +1,4 @@
-#! ${PYTHON_EXECUTABLE}
+#! ${Python3_EXECUTABLE}
 # -*- python -*-
 
 # @HEADER
diff --git a/packages/PyTrilinos/test/testEpetra_CrsMatrix.py.in b/packages/PyTrilinos/test/testEpetra_CrsMatrix.py.in
index 223aa230986c..b1f8e68cd235 100755
--- a/packages/PyTrilinos/test/testEpetra_CrsMatrix.py.in
+++ b/packages/PyTrilinos/test/testEpetra_CrsMatrix.py.in
@@ -1,4 +1,4 @@
-#! ${PYTHON_EXECUTABLE}
+#! ${Python3_EXECUTABLE}
 # -*- python -*-
 
 # @HEADER
diff --git a/packages/PyTrilinos/test/testEpetra_FEVector.py.in b/packages/PyTrilinos/test/testEpetra_FEVector.py.in
index 352c2bc4783a..7eaf90871602 100755
--- a/packages/PyTrilinos/test/testEpetra_FEVector.py.in
+++ b/packages/PyTrilinos/test/testEpetra_FEVector.py.in
@@ -1,4 +1,4 @@
-#! ${PYTHON_EXECUTABLE}
+#! ${Python3_EXECUTABLE}
 # -*- python -*-
 
 # @HEADER
diff --git a/packages/PyTrilinos/test/testEpetra_ImportExport.py.in b/packages/PyTrilinos/test/testEpetra_ImportExport.py.in
index 3a578048c68a..08f25a5379eb 100755
--- a/packages/PyTrilinos/test/testEpetra_ImportExport.py.in
+++ b/packages/PyTrilinos/test/testEpetra_ImportExport.py.in
@@ -1,4 +1,4 @@
-#! ${PYTHON_EXECUTABLE}
+#! ${Python3_EXECUTABLE}
 # -*- python -*-
 
 # @HEADER
diff --git a/packages/PyTrilinos/test/testEpetra_IntSerialDense.py.in b/packages/PyTrilinos/test/testEpetra_IntSerialDense.py.in
index 11acc1d7096d..ec2077db5daa 100755
--- a/packages/PyTrilinos/test/testEpetra_IntSerialDense.py.in
+++ b/packages/PyTrilinos/test/testEpetra_IntSerialDense.py.in
@@ -1,4 +1,4 @@
-#! ${PYTHON_EXECUTABLE}
+#! ${Python3_EXECUTABLE}
 # -*- python -*-
 
 # @HEADER
diff --git a/packages/PyTrilinos/test/testEpetra_IntVector.py.in b/packages/PyTrilinos/test/testEpetra_IntVector.py.in
index fe2ece2400b9..b7aa34971ded 100755
--- a/packages/PyTrilinos/test/testEpetra_IntVector.py.in
+++ b/packages/PyTrilinos/test/testEpetra_IntVector.py.in
@@ -1,4 +1,4 @@
-#! ${PYTHON_EXECUTABLE}
+#! ${Python3_EXECUTABLE}
 # -*- python -*-
 
 # @HEADER
diff --git a/packages/PyTrilinos/test/testEpetra_LinearProblem.py.in b/packages/PyTrilinos/test/testEpetra_LinearProblem.py.in
index a69775f8eda1..d704ed688394 100755
--- a/packages/PyTrilinos/test/testEpetra_LinearProblem.py.in
+++ b/packages/PyTrilinos/test/testEpetra_LinearProblem.py.in
@@ -1,4 +1,4 @@
-#! ${PYTHON_EXECUTABLE}
+#! ${Python3_EXECUTABLE}
 # -*- python -*-
 
 # @HEADER
diff --git a/packages/PyTrilinos/test/testEpetra_LocalMap.py.in b/packages/PyTrilinos/test/testEpetra_LocalMap.py.in
index 3d7625604d8c..10c453103e59 100755
--- a/packages/PyTrilinos/test/testEpetra_LocalMap.py.in
+++ b/packages/PyTrilinos/test/testEpetra_LocalMap.py.in
@@ -1,4 +1,4 @@
-#! ${PYTHON_EXECUTABLE}
+#! ${Python3_EXECUTABLE}
 # -*- python -*-
 
 # @HEADER
diff --git a/packages/PyTrilinos/test/testEpetra_Map.py.in b/packages/PyTrilinos/test/testEpetra_Map.py.in
index 639068f2490d..bd3900a1ec7a 100755
--- a/packages/PyTrilinos/test/testEpetra_Map.py.in
+++ b/packages/PyTrilinos/test/testEpetra_Map.py.in
@@ -1,4 +1,4 @@
-#! ${PYTHON_EXECUTABLE}
+#! ${Python3_EXECUTABLE}
 # -*- python -*-
 
 # @HEADER
diff --git a/packages/PyTrilinos/test/testEpetra_MapColoring.py.in b/packages/PyTrilinos/test/testEpetra_MapColoring.py.in
index e7e960ed2dae..8dd64c962d9c 100755
--- a/packages/PyTrilinos/test/testEpetra_MapColoring.py.in
+++ b/packages/PyTrilinos/test/testEpetra_MapColoring.py.in
@@ -1,4 +1,4 @@
-#! ${PYTHON_EXECUTABLE}
+#! ${Python3_EXECUTABLE}
 # -*- python -*-
 
 # @HEADER
diff --git a/packages/PyTrilinos/test/testEpetra_MultiVector.py.in b/packages/PyTrilinos/test/testEpetra_MultiVector.py.in
index ed41555a6fd0..b33b38a9d04f 100755
--- a/packages/PyTrilinos/test/testEpetra_MultiVector.py.in
+++ b/packages/PyTrilinos/test/testEpetra_MultiVector.py.in
@@ -1,4 +1,4 @@
-#! ${PYTHON_EXECUTABLE}
+#! ${Python3_EXECUTABLE}
 # -*- python -*-
 
 # @HEADER
diff --git a/packages/PyTrilinos/test/testEpetra_Object.py.in b/packages/PyTrilinos/test/testEpetra_Object.py.in
index e3be8ccc18eb..b714ad57e0e0 100755
--- a/packages/PyTrilinos/test/testEpetra_Object.py.in
+++ b/packages/PyTrilinos/test/testEpetra_Object.py.in
@@ -1,4 +1,4 @@
-#! ${PYTHON_EXECUTABLE}
+#! ${Python3_EXECUTABLE}
 # -*- python -*-
 
 # @HEADER
diff --git a/packages/PyTrilinos/test/testEpetra_SerialDense.py.in b/packages/PyTrilinos/test/testEpetra_SerialDense.py.in
index 51c4a6551a4f..2210b3907e40 100755
--- a/packages/PyTrilinos/test/testEpetra_SerialDense.py.in
+++ b/packages/PyTrilinos/test/testEpetra_SerialDense.py.in
@@ -1,4 +1,4 @@
-#! ${PYTHON_EXECUTABLE}
+#! ${Python3_EXECUTABLE}
 # -*- python -*-
 
 # @HEADER
diff --git a/packages/PyTrilinos/test/testEpetra_Time.py.in b/packages/PyTrilinos/test/testEpetra_Time.py.in
index 7a33c8f6e15c..cc82a7a57103 100755
--- a/packages/PyTrilinos/test/testEpetra_Time.py.in
+++ b/packages/PyTrilinos/test/testEpetra_Time.py.in
@@ -1,4 +1,4 @@
-#! ${PYTHON_EXECUTABLE}
+#! ${Python3_EXECUTABLE}
 # -*- python -*-
 
 # @HEADER
diff --git a/packages/PyTrilinos/test/testEpetra_Util.py.in b/packages/PyTrilinos/test/testEpetra_Util.py.in
index 33e66c4e40e2..278823382141 100755
--- a/packages/PyTrilinos/test/testEpetra_Util.py.in
+++ b/packages/PyTrilinos/test/testEpetra_Util.py.in
@@ -1,4 +1,4 @@
-#! ${PYTHON_EXECUTABLE}
+#! ${Python3_EXECUTABLE}
 # -*- python -*-
 
 # @HEADER
diff --git a/packages/PyTrilinos/test/testEpetra_Vector.py.in b/packages/PyTrilinos/test/testEpetra_Vector.py.in
index 0b40f57e575f..eaa5942d5db6 100755
--- a/packages/PyTrilinos/test/testEpetra_Vector.py.in
+++ b/packages/PyTrilinos/test/testEpetra_Vector.py.in
@@ -1,4 +1,4 @@
-#! ${PYTHON_EXECUTABLE}
+#! ${Python3_EXECUTABLE}
 # -*- python -*-
 
 # @HEADER
diff --git a/packages/PyTrilinos/test/testGaleri_CrsMatrices.py.in b/packages/PyTrilinos/test/testGaleri_CrsMatrices.py.in
index 66f1fbc7a23b..eba9f00c69a8 100755
--- a/packages/PyTrilinos/test/testGaleri_CrsMatrices.py.in
+++ b/packages/PyTrilinos/test/testGaleri_CrsMatrices.py.in
@@ -1,4 +1,4 @@
-#! ${PYTHON_EXECUTABLE}
+#! ${Python3_EXECUTABLE}
 # -*- python -*-
 
 # @HEADER
diff --git a/packages/PyTrilinos/test/testGaleri_Maps.py.in b/packages/PyTrilinos/test/testGaleri_Maps.py.in
index c9c3b0c4cbd2..0acd72c402fc 100755
--- a/packages/PyTrilinos/test/testGaleri_Maps.py.in
+++ b/packages/PyTrilinos/test/testGaleri_Maps.py.in
@@ -1,4 +1,4 @@
-#! ${PYTHON_EXECUTABLE}
+#! ${Python3_EXECUTABLE}
 # -*- python -*-
 
 # @HEADER
diff --git a/packages/PyTrilinos/test/testIFPACK.py.in b/packages/PyTrilinos/test/testIFPACK.py.in
index 05c1567ab06f..60613f3105f9 100755
--- a/packages/PyTrilinos/test/testIFPACK.py.in
+++ b/packages/PyTrilinos/test/testIFPACK.py.in
@@ -1,4 +1,4 @@
-#! ${PYTHON_EXECUTABLE}
+#! ${Python3_EXECUTABLE}
 # -*- python -*-
 
 # @HEADER
diff --git a/packages/PyTrilinos/test/testIsorropia.py.in b/packages/PyTrilinos/test/testIsorropia.py.in
index 87e5099bbcb9..ae8002c0cf92 100755
--- a/packages/PyTrilinos/test/testIsorropia.py.in
+++ b/packages/PyTrilinos/test/testIsorropia.py.in
@@ -1,4 +1,4 @@
-#! ${PYTHON_EXECUTABLE}
+#! ${Python3_EXECUTABLE}
 # -*- python -*-
 
 # @HEADER
diff --git a/packages/PyTrilinos/test/testKomplex_LinearProblem.py.in b/packages/PyTrilinos/test/testKomplex_LinearProblem.py.in
index 6d6f8b91fcb4..8489174dc236 100755
--- a/packages/PyTrilinos/test/testKomplex_LinearProblem.py.in
+++ b/packages/PyTrilinos/test/testKomplex_LinearProblem.py.in
@@ -1,4 +1,4 @@
-#! ${PYTHON_EXECUTABLE}
+#! ${Python3_EXECUTABLE}
 # -*- python -*-
 
 # @HEADER
diff --git a/packages/PyTrilinos/test/testLOCA.py.in b/packages/PyTrilinos/test/testLOCA.py.in
index f41db067693b..97f14791dd47 100755
--- a/packages/PyTrilinos/test/testLOCA.py.in
+++ b/packages/PyTrilinos/test/testLOCA.py.in
@@ -1,4 +1,4 @@
-#! ${PYTHON_EXECUTABLE}
+#! ${Python3_EXECUTABLE}
 # -*- python -*-
 
 # @HEADER
diff --git a/packages/PyTrilinos/test/testML_CompObject.py.in b/packages/PyTrilinos/test/testML_CompObject.py.in
index ede735a8651b..ae827a4dcb9c 100755
--- a/packages/PyTrilinos/test/testML_CompObject.py.in
+++ b/packages/PyTrilinos/test/testML_CompObject.py.in
@@ -1,4 +1,4 @@
-#! ${PYTHON_EXECUTABLE}
+#! ${Python3_EXECUTABLE}
 # -*- python -*-
 
 # @HEADER
diff --git a/packages/PyTrilinos/test/testML_MultiVector.py.in b/packages/PyTrilinos/test/testML_MultiVector.py.in
index aea1919eb942..267026731d99 100755
--- a/packages/PyTrilinos/test/testML_MultiVector.py.in
+++ b/packages/PyTrilinos/test/testML_MultiVector.py.in
@@ -1,4 +1,4 @@
-#! ${PYTHON_EXECUTABLE}
+#! ${Python3_EXECUTABLE}
 # -*- python -*-
 
 # @HEADER
diff --git a/packages/PyTrilinos/test/testML_Preconditioner.py.in b/packages/PyTrilinos/test/testML_Preconditioner.py.in
index 2a5ddc99b507..04a6c87779a5 100755
--- a/packages/PyTrilinos/test/testML_Preconditioner.py.in
+++ b/packages/PyTrilinos/test/testML_Preconditioner.py.in
@@ -1,4 +1,4 @@
-#! ${PYTHON_EXECUTABLE}
+#! ${Python3_EXECUTABLE}
 # -*- python -*-
 
 # @HEADER
diff --git a/packages/PyTrilinos/test/testML_PyMatrix.py.in b/packages/PyTrilinos/test/testML_PyMatrix.py.in
index ef0344371636..5e0aab4c3e73 100755
--- a/packages/PyTrilinos/test/testML_PyMatrix.py.in
+++ b/packages/PyTrilinos/test/testML_PyMatrix.py.in
@@ -1,4 +1,4 @@
-#! ${PYTHON_EXECUTABLE}
+#! ${Python3_EXECUTABLE}
 # -*- python -*-
 
 # @HEADER
diff --git a/packages/PyTrilinos/test/testML_Space.py.in b/packages/PyTrilinos/test/testML_Space.py.in
index c332d1e4ec00..4ce1c5b4d0c4 100755
--- a/packages/PyTrilinos/test/testML_Space.py.in
+++ b/packages/PyTrilinos/test/testML_Space.py.in
@@ -1,4 +1,4 @@
-#! ${PYTHON_EXECUTABLE}
+#! ${Python3_EXECUTABLE}
 # -*- python -*-
 
 # @HEADER
diff --git a/packages/PyTrilinos/test/testML_TimeObject.py.in b/packages/PyTrilinos/test/testML_TimeObject.py.in
index 4f10253e62ca..9a580277632e 100755
--- a/packages/PyTrilinos/test/testML_TimeObject.py.in
+++ b/packages/PyTrilinos/test/testML_TimeObject.py.in
@@ -1,4 +1,4 @@
-#! ${PYTHON_EXECUTABLE}
+#! ${Python3_EXECUTABLE}
 # -*- python -*-
 
 # @HEADER
diff --git a/packages/PyTrilinos/test/testNOX_StatusTest.py.in b/packages/PyTrilinos/test/testNOX_StatusTest.py.in
index ce15bc66e34d..8e0e411fee5f 100755
--- a/packages/PyTrilinos/test/testNOX_StatusTest.py.in
+++ b/packages/PyTrilinos/test/testNOX_StatusTest.py.in
@@ -1,4 +1,4 @@
-#! ${PYTHON_EXECUTABLE}
+#! ${Python3_EXECUTABLE}
 # -*- python -*-
 
 # @HEADER
diff --git a/packages/PyTrilinos/test/testPliris.py.in b/packages/PyTrilinos/test/testPliris.py.in
index 97fb331587eb..1d7fb0008904 100755
--- a/packages/PyTrilinos/test/testPliris.py.in
+++ b/packages/PyTrilinos/test/testPliris.py.in
@@ -1,4 +1,4 @@
-#! ${PYTHON_EXECUTABLE}
+#! ${Python3_EXECUTABLE}
 # -*- python -*-
 
 # @HEADER
diff --git a/packages/PyTrilinos/test/testTeuchos.py.in b/packages/PyTrilinos/test/testTeuchos.py.in
index b24701d107d1..cdb50cd14065 100755
--- a/packages/PyTrilinos/test/testTeuchos.py.in
+++ b/packages/PyTrilinos/test/testTeuchos.py.in
@@ -1,4 +1,4 @@
-#! ${PYTHON_EXECUTABLE}
+#! ${Python3_EXECUTABLE}
 # -*- python -*-
 
 # @HEADER
diff --git a/packages/PyTrilinos/test/testTeuchos_Comm.py.in b/packages/PyTrilinos/test/testTeuchos_Comm.py.in
index bee34ae07e7b..2d61efe2f356 100755
--- a/packages/PyTrilinos/test/testTeuchos_Comm.py.in
+++ b/packages/PyTrilinos/test/testTeuchos_Comm.py.in
@@ -1,4 +1,4 @@
-#! ${PYTHON_EXECUTABLE}
+#! ${Python3_EXECUTABLE}
 # -*- python -*-
 
 # @HEADER
diff --git a/packages/PyTrilinos/test/testTeuchos_ParameterList.py.in b/packages/PyTrilinos/test/testTeuchos_ParameterList.py.in
index cd4004361e3c..ce00e6cfbddd 100755
--- a/packages/PyTrilinos/test/testTeuchos_ParameterList.py.in
+++ b/packages/PyTrilinos/test/testTeuchos_ParameterList.py.in
@@ -1,4 +1,4 @@
-#! ${PYTHON_EXECUTABLE}
+#! ${Python3_EXECUTABLE}
 # -*- python -*-
 
 # @HEADER
diff --git a/packages/PyTrilinos/test/testTeuchos_RCP.py.in b/packages/PyTrilinos/test/testTeuchos_RCP.py.in
index c36340441955..1260c3338f45 100755
--- a/packages/PyTrilinos/test/testTeuchos_RCP.py.in
+++ b/packages/PyTrilinos/test/testTeuchos_RCP.py.in
@@ -1,4 +1,4 @@
-#! ${PYTHON_EXECUTABLE}
+#! ${Python3_EXECUTABLE}
 # -*- python -*-
 
 # @HEADER
diff --git a/packages/PyTrilinos/test/testTeuchos_ScalarTraits.py.in b/packages/PyTrilinos/test/testTeuchos_ScalarTraits.py.in
index 2386d947fa23..1f454b028ece 100755
--- a/packages/PyTrilinos/test/testTeuchos_ScalarTraits.py.in
+++ b/packages/PyTrilinos/test/testTeuchos_ScalarTraits.py.in
@@ -1,4 +1,4 @@
-#! ${PYTHON_EXECUTABLE}
+#! ${Python3_EXECUTABLE}
 # -*- python -*-
 
 # @HEADER
diff --git a/packages/PyTrilinos/test/testThyra.py.in b/packages/PyTrilinos/test/testThyra.py.in
index 59d25b36de1d..2c30b5cb0022 100755
--- a/packages/PyTrilinos/test/testThyra.py.in
+++ b/packages/PyTrilinos/test/testThyra.py.in
@@ -1,4 +1,4 @@
-#! ${PYTHON_EXECUTABLE}
+#! ${Python3_EXECUTABLE}
 # -*- python -*-
 
 # @HEADER
diff --git a/packages/PyTrilinos/test/testTpetra_Map.py.in b/packages/PyTrilinos/test/testTpetra_Map.py.in
index 6819b4d6c177..2655f44d3ec5 100755
--- a/packages/PyTrilinos/test/testTpetra_Map.py.in
+++ b/packages/PyTrilinos/test/testTpetra_Map.py.in
@@ -1,4 +1,4 @@
-#! ${PYTHON_EXECUTABLE}
+#! ${Python3_EXECUTABLE}
 # -*- python -*-
 
 # @HEADER
diff --git a/packages/PyTrilinos/test/testTpetra_MultiVector.py.in b/packages/PyTrilinos/test/testTpetra_MultiVector.py.in
index 4c30729b6c9a..2f709404533e 100755
--- a/packages/PyTrilinos/test/testTpetra_MultiVector.py.in
+++ b/packages/PyTrilinos/test/testTpetra_MultiVector.py.in
@@ -1,4 +1,4 @@
-#! ${PYTHON_EXECUTABLE}
+#! ${Python3_EXECUTABLE}
 # -*- python -*-
 
 # @HEADER
diff --git a/packages/PyTrilinos/test/testTpetra_Vector.py.in b/packages/PyTrilinos/test/testTpetra_Vector.py.in
index 34ab9d87e08a..e9e228089507 100755
--- a/packages/PyTrilinos/test/testTpetra_Vector.py.in
+++ b/packages/PyTrilinos/test/testTpetra_Vector.py.in
@@ -1,4 +1,4 @@
-#! ${PYTHON_EXECUTABLE}
+#! ${Python3_EXECUTABLE}
 # -*- python -*-
 
 # @HEADER
diff --git a/packages/PyTrilinos/test/testTriUtils.py.in b/packages/PyTrilinos/test/testTriUtils.py.in
index c9bdb16ae584..46e10421c8c4 100755
--- a/packages/PyTrilinos/test/testTriUtils.py.in
+++ b/packages/PyTrilinos/test/testTriUtils.py.in
@@ -1,4 +1,4 @@
-#! ${PYTHON_EXECUTABLE}
+#! ${Python3_EXECUTABLE}
 # -*- python -*-
 
 # @HEADER
diff --git a/packages/PyTrilinos/test/testutil.py.in b/packages/PyTrilinos/test/testutil.py.in
index 86efd2f5e412..498a4ad18cbb 100644
--- a/packages/PyTrilinos/test/testutil.py.in
+++ b/packages/PyTrilinos/test/testutil.py.in
@@ -1,4 +1,4 @@
-#! ${PYTHON_EXECUTABLE}
+#! ${Python3_EXECUTABLE}
 # -*- python -*-
 
 # @HEADER
diff --git a/packages/PyTrilinos/util/CMakeCacheVariables.py.in b/packages/PyTrilinos/util/CMakeCacheVariables.py.in
index 9b22d3ec29bd..738bce362240 100755
--- a/packages/PyTrilinos/util/CMakeCacheVariables.py.in
+++ b/packages/PyTrilinos/util/CMakeCacheVariables.py.in
@@ -1,4 +1,4 @@
-#! ${PYTHON_EXECUTABLE}
+#! ${Python3_EXECUTABLE}
 
 # @HEADER
 # ***********************************************************************
diff --git a/packages/PyTrilinos/util/MakefileVariables.py.in b/packages/PyTrilinos/util/MakefileVariables.py.in
index 5df302598180..688379d7acd5 100755
--- a/packages/PyTrilinos/util/MakefileVariables.py.in
+++ b/packages/PyTrilinos/util/MakefileVariables.py.in
@@ -1,4 +1,4 @@
-#! ${PYTHON_EXECUTABLE}
+#! ${Python3_EXECUTABLE}
 
 # @HEADER
 # ***********************************************************************
diff --git a/packages/PyTrilinos/util/configFix.py.in b/packages/PyTrilinos/util/configFix.py.in
index e9b476ffca33..6783ab3cc357 100755
--- a/packages/PyTrilinos/util/configFix.py.in
+++ b/packages/PyTrilinos/util/configFix.py.in
@@ -1,4 +1,4 @@
-#! ${PYTHON_EXECUTABLE}
+#! ${Python3_EXECUTABLE}
 
 # @HEADER
 # ***********************************************************************
diff --git a/packages/PyTrilinos/util/copyWithCMakeSubstitutions.py.in b/packages/PyTrilinos/util/copyWithCMakeSubstitutions.py.in
index ee76cca284d8..6e7950e61515 100755
--- a/packages/PyTrilinos/util/copyWithCMakeSubstitutions.py.in
+++ b/packages/PyTrilinos/util/copyWithCMakeSubstitutions.py.in
@@ -1,4 +1,4 @@
-#! ${PYTHON_EXECUTABLE}
+#! ${Python3_EXECUTABLE}
 
 # @HEADER
 # ***********************************************************************