Windows subprocess.Popen 不带 shell=True 的批处理文件

我有一个运行的函数lessc（安装有npm install -g less):

>>> import subprocess
>>> subprocess.Popen(['lessc'])
Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
  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

不幸的是，除非我添加，否则它不起作用shell=True:

>>> subprocess.Popen(['lessc'], shell=True)
<subprocess.Popen object at 0x01F619D0>

我能做些什么来使lessc运行而不使用shell=True?

来自两者https://docs.python.org/3/library/subprocess.html#subprocess.Popen https://docs.python.org/3/library/subprocess.html#subprocess.Popen and https://docs.python.org/2/library/subprocess.html#subprocess.Popen https://docs.python.org/2/library/subprocess.html#subprocess.Popen:

你不需要shell=True运行批处理文件或基于控制台的可执行文件。

已经一样由 @JBernardo 引用 https://stackoverflow.com/questions/16137556/windows-subprocess-popen-a-batch-file-without-shell-true#comment23054228_16137556.

那么，让我们尝试一下：

where lessc实际上告诉

C:\Users\myname\AppData\Roaming\npm\lessc
C:\Users\myname\AppData\Roaming\npm\lessc.cmd

这意味着要执行的文件是lessc.cmd，不是一些.bat文件。确实：

>>> import subprocess
>>> subprocess.Popen([r'C:\Users\myname\AppData\Roaming\npm\lessc.cmd'])
<subprocess.Popen object at 0x035BA070>
>>> lessc: no input files

usage: lessc [option option=parameter ...] <source> [destination]

所以这does如果指定完整路径，则有效。我认为当你有一个错字时这次经历 https://stackoverflow.com/questions/16137556/windows-subprocess-popen-a-batch-file-without-shell-true#comment23054022_16137556。可能是你写的.bat代替.cmd?

如果您不想修补完整路径lessc到你的脚本中，你可以自己烘焙一个where:

import plaform
import os

def where(file_name):
    # inspired by http://nedbatchelder.com/code/utilities/wh.py
    # see also: http://stackoverflow.com/questions/11210104/
    path_sep = ":" if platform.system() == "Linux" else ";"
    path_ext = [''] if platform.system() == "Linux" or '.' in file_name else os.environ["PATHEXT"].split(path_sep)
    for d in os.environ["PATH"].split(path_sep):
        for e in path_ext:
            file_path = os.path.join(d, file_name + e)
            if os.path.exists(file_path):
                return file_path
    raise Exception(file_name + " not found")

然后你可以写：

import subprocess
subprocess.Popen([where('lessc')])