在Python中使用subprocess.call('dir'，shell = True)时找不到指定的文件 [英] Cannot find the file specified when using subprocess.call('dir', shell=True) in Python

问题描述

在安装了32位python 2.7的64位系统中，我尝试执行以下操作:

In a 64-bit system with 32 bit python 2.7 installed I am trying to do the following:

import subprocess
p = subprocess.call('dir', shell=True)
print p

但这给了我

Traceback (most recent call last):
  File "test.py", line 2, in <module>
    p = subprocess.call('dir', shell=True)
  File "C:\Python27\lib\subprocess.py", line 522, in call
    return Popen(*popenargs, **kwargs).wait()
  File "C:\Python27\lib\subprocess.py", line 709, in __init__
    errread, errwrite)
  File "C:\Python27\lib\subprocess.py", line 957, in _execute_child
    startupinfo)
  WindowsError: [Error 2] The system cannot find the file specified

如果我在航站楼里...

If I in the terminal do...

dir

...它当然会打印当前的文件夹内容.

...it of course prints the present folder content.

我试图将shell参数更改为shell = False.

I have tried to change the shell parameter to shell=False.

实际上，我不能使用subprocess.call()在路径上调用任何可执行文件.语句p = subprocess.call('dir', shell=True)在另一台机器上可以正常工作，我认为这是相关的.

Actually I cannot call any executable on the path with subprocess.call(). The statement p = subprocess.call('dir', shell=True) works fine on another machine and I think that it is related.

如果我愿意

 subprocess.call('PATH', shell=True)

然后我得到

Traceback (most recent call last):
  File "test.py", line 4, in <module>
    subprocess.call('PATH', shell=True)
  File "C:\Python27\lib\subprocess.py", line 522, in call
     return Popen(*popenargs, **kwargs).wait()
  File "C:\Python27\lib\subprocess.py", line 709, in __init__
    errread, errwrite)
  File "C:\Python27\lib\subprocess.py", line 957, in _execute_child
    startupinfo)
WindowsError: [Error 2] The system cannot find the file specified

如果我这样做:

import os
print os.curdir

然后我得到

.

以上所有操作均在以管理员模式启动的终端中执行.

All of the above is executed in the terminal started in Administrator mode.

推荐答案

我认为您的COMSPEC环境变量可能有问题:

I think you may have a problem with your COMSPEC environment variable:

>>> import os
>>> os.environ['COMSPEC']
'C:\\Windows\\system32\\cmd.exe'
>>> import subprocess
>>> subprocess.call('dir', shell=True)

    (normal output here)

>>> os.environ['COMSPEC'] = 'C:\\nonexistent.exe'
>>> subprocess.call('dir', shell=True)
Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
  File "c:\Python27\lib\subprocess.py", line 493, in call
    return Popen(*popenargs, **kwargs).wait()
  File "c:\Python27\lib\subprocess.py", line 679, in __init__
    errread, errwrite)
  File "c:\Python27\lib\subprocess.py", line 896, in _execute_child
    startupinfo)
WindowsError: [Error 2] The system cannot find the file specified

我发现了潜在的问题，方法是深入研究subprocess.py并查看_execute_child函数，如回溯所指出的那样.在那里，您会找到一个以if shell:开头的块，它将在环境中搜索所述变量，并使用它来创建用于启动该过程的参数.

I discovered this potential issue by digging into subprocess.py and looking in the _execute_child function, as pointed-to by the traceback. There, you'll find a block starting with if shell: that will search the environment for said variable and use it to create the arguments used to launch the process.

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