Question

我目前使用Python 3.4作为我的默认Python版本，但我想暂时将Python 2.7设置为默认值。

我在Windows 7上，我的Python脚本使用Python Windows启动器运行。 The documentation says我可以通过创建py.ini文件来自定义它，但这不起作用。我创建了一个包含以下内容的文件：

[defaults]
python=2.7

我已尝试将其放在与我正在运行的文件相同的文件夹中，我尝试将其放在C:\Users\Administrator\，C:\Users\Administrator\AppData\和C:\Users\Administrator\AppData\Local\中，但这些都没有工作。启动程序仍然使用Python 3.4。（当我双击Windows UI中的文件时，以及我直接启动启动器时都是这两种情况，例如py my_file.py。）

为什么Python Windows启动程序会忽略我的py.ini文件？

以下是运行py age.py并设置了环境变量PYLAUNCH_DEBUG的输出：

launcher build: 32bit                                                                 
launcher executable: Console                                                          
Using local configuration file 'C:\Users\Administrator\AppData\Local\py.ini'          
File 'C:\Windows\py.ini' non-existent                                                 
Called with command line: age.py                                                      
maybe_handle_shebang: read 256 bytes                                                  
maybe_handle_shebang: BOM not found, using UTF-8                                      
parse_shebang: found command: python                                                  
searching PATH for python executable                                                  
Python on path: C:\python34\python.EXE                                                
located python on PATH: C:\python34\python.EXE                                        
run_child: about to run 'C:\python34\python.EXE age.py'                               
Traceback (most recent call last):                                                    
  File "age.py", line 17, in <module>                                                 
    name = raw_input("Enter a person's name to check their age: ")                    
NameError: name 'raw_input' is not defined                                            
child process exit code: 1

Answer 1

documentation for Python 3.5描述了这种行为：

shebang line的/usr/bin/env形式还有一个特殊属性。在查找已安装的Python解释器之前，此表单将在可执行文件PATH中搜索Python可执行文件。这与Unix env程序的行为相对应，后者执行PATH搜索。

奇怪的是，尽管corresponding documentation page for Python 3.4没有提及，但同样的功能似乎也适用于Python 3.4（或至少版本3.4.3）。我已经在这个答案的底部包含了这种行为的复制品。

您的脚本似乎在顶部包含了shebang行#!/usr/bin/env python，C:\Python34在PATH出现之前就在您的系统C:\Python27上。你在评论中说

对于这个特定的剧本而言，没有一个shebang
非常重要

但行

parse_shebang: found command: python

在你的启动器输出中，它表明脚本必须确实有一个shebang行。

我的系统上安装了Python 2.7.10和Python 3.4.3，PATH上的3.4之前有3.4。我在py.ini中还有一个C:\Users\Luke\AppData\Local文件，其中包含以下内容：

[defaults]
python=2

和包含

的test.py脚本

#!/usr/bin/env python
import sys; print(sys.version_info)

我已将环境变量PYLAUNCH_DEBUG的值设置为1。使用py test.py运行此脚本，我得到以下输出：

launcher build: 32bit
launcher executable: Console
Using local configuration file 'C:\Users\Luke\AppData\Local\py.ini'
File 'C:\WINDOWS\py.ini' non-existent
Called with command line: test.py
maybe_handle_shebang: read 60 bytes
maybe_handle_shebang: BOM not found, using UTF-8
parse_shebang: found command: python
searching PATH for python executable
Python on path: C:\Python34\python.EXE
located python on PATH: C:\Python34\python.EXE
run_child: about to run 'C:\Python34\python.EXE test.py'
sys.version_info(major=3, minor=4, micro=3, releaselevel='final', serial=0)
child process exit code: 0

如果我将test.py脚本更改为

#! python
import sys; print(sys.version_info)

（即从shebang线移除/usr/bin/env）并重新运行py test.py，我得到以下内容：

launcher build: 32bit
launcher executable: Console
Using local configuration file 'C:\Users\Luke\AppData\Local\py.ini'
File 'C:\WINDOWS\py.ini' non-existent
Called with command line: test.py
maybe_handle_shebang: read 48 bytes
maybe_handle_shebang: BOM not found, using UTF-8
parse_shebang: found command: python
locating Pythons in 64bit registry
locate_pythons_for_key: unable to open PythonCore key in HKCU
locate_pythons_for_key: unable to open PythonCore key in HKLM
locating Pythons in native registry
locate_pythons_for_key: unable to open PythonCore key in HKCU
locate_pythons_for_key: C:\Python27\python.exe is a 32bit executable
locate_pythons_for_key: C:\Python27\PCBuild\python.exe: The system cannot find the path specified.
locate_pythons_for_key: C:\Python27\PCBuild\amd64\python.exe: The system cannot find the path specified.
locate_pythons_for_key: C:\Python34\python.exe is a 32bit executable
locate_pythons_for_key: C:\Python34\PCBuild\python.exe: The system cannot find the path specified.
locate_pythons_for_key: C:\Python34\PCBuild\amd64\python.exe: The system cannot find the path specified.
found configured value 'python=2' in C:\Users\Luke\AppData\Local\py.ini
search for default Python found version 2.7 at 'C:\Python27\python.exe'
run_child: about to run 'C:\Python27\python.exe test.py'
sys.version_info(major=2, minor=7, micro=10, releaselevel='final', serial=0)
child process exit code: 0

Python Windows启动程序不读取`py.ini`

1 个答案: