Ensure that command wrapping only runs on Windows

cmake/macros/Public.cmake

@@ -141,7 +141,7 @@ function(pxr_python_bin BIN_NAME)
             COMMENT "Creating Python cmd wrapper"
             COMMAND
                 ${PYTHON_EXECUTABLE}
-                ${PROJECT_SOURCE_DIR}/cmake/macros/shebang.py
+                ${PROJECT_SOURCE_DIR}/cmake/macros/winpycmd.py
                 ${BIN_NAME}
                 ${outfile}.cmd
         )

cmake/macros/shebang.py

@@ -24,27 +24,18 @@
 #
 # Usage:
 #   shebang shebang-str source.py dest.py
-#   shebang file output.cmd
 #
-# The former substitutes '/pxrpythonsubst' in <source.py> with <shebang-str>
-# and writes the result to <dest.py>.  The latter generates a file named
-# <output.cmd> with the contents '@python "%~dp0<file>"';  this is a
-# Windows command script to execute "python <file>" where <file> is in
-# the same directory as the command script.
+# This substitutes '/pxrpythonsubst' in <source.py> with <shebang-str>
+# and writes the result to <dest.py>.
 
-from __future__ import print_function
 import sys
 
-if len(sys.argv) < 3 or len(sys.argv) > 4:
-    print("Usage: %s {shebang-str source.py dest|file output.cmd}" % sys.argv[0])
+if len(sys.argv) != 4:
+    print(f"Usage: {sys.argv[0]} {{shebang-str source.py dest}}",
+          file=sys.stderr)
     sys.exit(1)
 
-if len(sys.argv) == 3:
-    with open(sys.argv[2], 'w') as f:
-        print('@python "%%~dp0%s" %%*' % (sys.argv[1], ), file=f)
-
-else:
-    with open(sys.argv[2], 'r') as s:
-        with open(sys.argv[3], 'w') as d:
-            for line in s:
-                d.write(line.replace('/pxrpythonsubst', sys.argv[1]))
+with open(sys.argv[2], 'r') as s:
+    with open(sys.argv[3], 'w') as d:
+        for line in s:
+            d.write(line.replace('/pxrpythonsubst', sys.argv[1]))

cmake/macros/winpycmd.py

@@ -0,0 +1,44 @@
+#
+# Copyright 2017 Pixar
+#
+# Licensed under the Apache License, Version 2.0 (the "Apache License")
+# with the following modification; you may not use this file except in
+# compliance with the Apache License and the following modification to it:
+# Section 6. Trademarks. is deleted and replaced with:
+#
+# 6. Trademarks. This License does not grant permission to use the trade
+#    names, trademarks, service marks, or product names of the Licensor
+#    and its affiliates, except as required to comply with Section 4(c) of
+#    the License and to reproduce the content of the NOTICE file.
+#
+# You may obtain a copy of the Apache License at
+#
+#     http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the Apache License with the above modification is
+# distributed on an "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
+# KIND, either express or implied. See the Apache License for the specific
+# language governing permissions and limitations under the Apache License.
+#
+#
+# Usage:
+#   wrappy file output.cmd
+#
+# This generates a file named <output.cmd> with the contents
+# '@python "%~dp0<file>"';  this is a Windows command script to execute
+# "python <file>" where <file> is in the same directory as the command script.
+
+import sys
+import platform
+import warnings
+
+if not platform.system() == 'Windows':
+    warnings.warn(f"{sys.argv[0]} should only be run on Windows")
+
+if len(sys.argv) != 3:
+    print(f"Usage: {sys.argv[0]} {{file output.cmd}}", file=sys.stderr)
+    sys.exit(1)
+
+with open(sys.argv[2], 'w') as f:
+    print(f'@python "%~dp0{sys.argv[1]}" %*', file=f)