get-poetry.py fallback to standard executables

README.md

@@ -23,6 +23,13 @@ curl -sSL https://raw.githubusercontent.com/python-poetry/poetry/master/get-poet
 
 Alternatively, you can download the `get-poetry.py` file and execute it separately.
 
+The setup script must be able to find one of following executables in your shell's path environment:
+
+- `python` (which can be a py3 or py2 interpreter)
+- `python3`
+- `py.exe -3` (Windows)
+- `py.exe -2` (Windows)
+
 If you want to install prerelease versions, you can do so by passing `--preview` to `get-poetry.py`:
 
 ```bash

get-poetry.py

@@ -197,8 +197,7 @@ def expanduser(path):
 POETRY_LIB_BACKUP = os.path.join(POETRY_HOME, "lib-backup")
 
 
-BIN = """#!/usr/bin/env python
-# -*- coding: utf-8 -*-
+BIN = """# -*- coding: utf-8 -*-
 import glob
 import sys
 import os
@@ -213,7 +212,7 @@ def expanduser(path):
     main()
 """
 
-BAT = u('@echo off\r\npython "{poetry_bin}" %*\r\n')
+BAT = u('@echo off\r\n{python_executable} "{poetry_bin}" %*\r\n')
 
 
 PRE_MESSAGE = """# Welcome to {poetry}!
@@ -585,23 +584,46 @@ def _make_lib(self, version):
             finally:
                 gz.close()
 
+    def _which_python(self):
+        allowed_executables = ["python", "python3"]
+        if WINDOWS:
+            allowed_executables += ["py.exe -3", "py.exe -2"]
+
+        for executable in allowed_executables:
+            try:
+                subprocess.check_call(executable + " --version", shell=True)
+            except subprocess.CalledProcessError:
+                continue
+
+            return executable
+
+        raise RuntimeError(
+            "No python executable found in shell environment. Tried: "
+            + str(allowed_executables)
+        )
+
     def make_bin(self):
         if not os.path.exists(POETRY_BIN):
             os.mkdir(POETRY_BIN, 0o755)
 
+        python_executable = self._which_python()
+
         if WINDOWS:
             with open(os.path.join(POETRY_BIN, "poetry.bat"), "w") as f:
                 f.write(
                     u(
                         BAT.format(
+                            python_executable=python_executable,
                             poetry_bin=os.path.join(POETRY_BIN, "poetry").replace(
                                 os.environ["USERPROFILE"], "%USERPROFILE%"
-                            )
+                            ),
                         )
                     )
                 )
 
         with open(os.path.join(POETRY_BIN, "poetry"), "w", encoding="utf-8") as f:
+            if not WINDOWS:
+                f.write(u("#!/usr/bin/env {}\n".format(python_executable)))
             f.write(u(BIN))
 
         if not WINDOWS: