python 在python中调用subprocess.Popen时“系统找不到指定的文件”
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"The system cannot find the file specified" when invoking subprocess.Popen in python
提问by Hobo
I'm trying to use svnmerge.py to merge some files. Under the hood it uses python, and when I use it I get an error - "The system cannot find the file specified". Colleagues at work are running the same version of svnmerge.py, and of python (2.5.2, specifically r252:60911) without an issue.
我正在尝试使用 svnmerge.py 来合并一些文件。在引擎盖下它使用 python，当我使用它时，我收到一个错误 - “系统找不到指定的文件”。工作中的同事正在运行相同版本的 svnmerge.py 和 python（2.5.2，特别是 r252:60911），没有任何问题。
I found this link, which describes my problem. Trying what was outlined there, I confirmed Python could find svn (it's in my path):
我找到了这个链接，它描述了我的问题。尝试那里概述的内容，我确认 Python 可以找到 svn（它在我的路径中）：
P:\>python
Python 2.5.2 (r252:60911, Feb 21 2008, 13:11:45) [MSC v.1310 32 bit (Intel)] on win32
Type "help", "copyright", "credits" or "license" for more information.
>>> import os
>>> i,k = os.popen4("svn --version")
>>> i.close()
>>> k.readline()
'svn, version 1.4.2 (r22196)\n'
Looking at the svnmerge.py code, though, I noticed for python versions 2.4 and higher it was following a different execution path. Rather than invoking os.popen4() it uses subprocess.Popen(). Trying that reproduces the error:
但是，查看 svnmerge.py 代码，我注意到 Python 2.4 及更高版本遵循不同的执行路径。它使用 subprocess.Popen() 而不是调用 os.popen4()。尝试重现错误：
C:\>python
Python 2.5.2 (r252:60911, Feb 21 2008, 13:11:45) [MSC v.1310 32 bit (Intel)] on win32 Type "help", "copyright", "credits" or "license" for more information.
>>> import subprocess
>>> p = subprocess.Popen("svn --version", stdout=subprocess.PIPE,
>>> close_fds=False, stderr=subprocess.PIPE)
Traceback (most recent call last):
File "", line 1, in
File "C:\Python25\lib\subprocess.py", line 594, in __init__
errread, errwrite)
File "C:\Python25\lib\subprocess.py", line 816, in _execute_child
startupinfo)
WindowsError: [Error 2] The system cannot find the file specified
>>>
For now, I've commented out the 2.4-and-higher specific code, but I'd like to find a proper solution.
现在，我已经注释掉了 2.4 及更高版本的特定代码，但我想找到一个合适的解决方案。
If it's not obvious, I'm a complete python newbie, but google hasn't helped. Any pointers?
如果不是很明显，我是一个完整的 python 新手，但谷歌没有帮助。任何指针？
回答by dF.
It's a bug, see the documentation of subprocess.Popen. There either needs to be a "shell=True" option, or the first argument needs to be a sequence ['svn', '--version']. As it is now, Popenis looking for an executable named, literally, "svn --version" which it doesn't find.
这是一个错误，看到的文档subprocess.Popen。要么需要一个"shell=True“选项，要么第一个参数需要是一个序列['svn', '--version']。就像现在一样，Popen正在寻找一个名为“svn --version”的可执行文件，但它没有找到。
I don't know why it would work for your colleagues though, if they are running the same OS and version of Python... FWIW it gives me the same error message on a mac, and either of the two ways I gave fixes it.
我不知道为什么它对你的同事有用，如果他们运行相同的操作系统和 Python 版本...... FWIW 它在 Mac 上给我相同的错误消息，我提供的两种方法中的任何一种都修复了它.
