相关疑难解决方法(0)

我用subprocess模块调用不同的进程.但是,我有一个问题.

在以下代码中:

callProcess = subprocess.Popen(['ls', '-l'], shell=True)

和

callProcess = subprocess.Popen(['ls', '-l']) # without shell

两者都有效.阅读文档后,我开始知道这shell=True意味着通过shell执行代码.这意味着在缺席的情况下,该过程将直接启动.

那么我应该更喜欢我的情况 - 我需要运行一个进程并获得其输出.从shell内部或外部调用它有什么好处.

我使用Python 2.6的原因是我无法避免的.我在Idle命令行上运行了以下一小段代码,并且遇到了一个我不明白的错误.我怎么能绕过这个？

>>> import subprocess
>>> x = subprocess.call(["dir"])

Traceback (most recent call last):
  File "<pyshell#1>", line 1, in <module>
    x = subprocess.call(["dir"])
  File "C:\Python26\lib\subprocess.py", line 444, in call
    return Popen(*popenargs, **kwargs).wait()
  File "C:\Python26\lib\subprocess.py", line 595, in __init__
    errread, errwrite)
  File "C:\Python26\lib\subprocess.py", line 821, in _execute_child
    startupinfo)
WindowsError: [Error 2] The system cannot find the file specified
>>> 

我想要获取视频片段的持续时间.但它无法获取文件.这是我的代码:

import subprocess
import os
def getLength(input_video):
    result = subprocess.Popen('ffprobe -i input_video -show_entries format=duration -v quiet -of csv="p=0"', stdout=subprocess.PIPE,stderr=subprocess.STDOUT)
    output = result.communicate()
    return output[0]
BASE_DIR = os.path.dirname(os.path.dirname(os.path.abspath(__file__)))
x = (os.path.join(BASE_DIR,'uploads/video.mkv'))
getLength(x)

这是我得到的错误:

Traceback (most recent call last):
  File "/home/aman/Desktop/stream/src/stream/uploads/sadf.py", line 9, in <module>
    getLength(x)
  File "/home/aman/Desktop/stream/src/stream/uploads/sadf.py", line 4, in getLength
    result = subprocess.Popen('ffprobe -i input_video -show_entries format=duration -v quiet -of csv="p=0"', stdout=subprocess.PIPE,stderr=subprocess.STDOUT)
  File "/usr/lib/python2.7/subprocess.py", line 711, in __init__
    errread, errwrite)
  File "/usr/lib/python2.7/subprocess.py", line 1343, in _execute_child
    raise child_exception
OSError: [Errno …