存储子流程的输出。Popen调用字符串。

I'm trying to make a system call in Python and store the output to a string that I can manipulate in the Python program.

我尝试在Python中创建一个系统调用，并将输出存储到我可以在Python程序中操作的字符串中。

#!/usr/bin/python
import subprocess
p2 = subprocess.Popen("ntpq -p")

I've tried a few things including some of the suggestions here:

我尝试了一些东西，包括一些建议:

Retrieving the output of subprocess.call()

检索子进程的输出。

but without any luck.

但是没有任何运气。

9 个解决方案

#1

In Python 2.7 or Python 3

在Python 2.7或Python 3中。

Instead of making a Popen object directly, you can use the subprocess.check_output() function to store output of a command in a string:

您可以使用subprocess.check_output()函数将一个命令的输出存储在字符串中，而不是直接创建一个Popen对象。

from subprocess import check_output
out = check_output(["ntpq", "-p"])

In Python 2.4-2.6

在Python 2.4 - -2.6

Use the communicate method.

使用交流方法。

import subprocess
p = subprocess.Popen(["ntpq", "-p"], stdout=subprocess.PIPE)
out, err = p.communicate()

out is what you want.

你想要的就是出去。

Important note about the other answers

关于其他答案的重要提示。

Note how I passed in the command. The "ntpq -p" example brings up another matter. Since Popen does not invoke the shell, you would use a list of the command and options—["ntpq", "-p"].

注意我是如何通过命令的。“ntpq -p”的例子引出了另一个问题。由于Popen不调用shell，所以您将使用命令和选项列表—[“ntpq”，“-p”]。

#2

This worked for me for redirecting stdout (stderr can be handled similarly):

这对我来说是为了重定向stdout (stderr可以类似地处理):

from subprocess import Popen, PIPE
pipe = Popen(path, stdout=PIPE)
text = pipe.communicate()[0]

If it doesn't work for you, please specify exactly the problem you're having.

如果它对你不起作用，请详细说明你的问题。

#3

Assuming that pwd is just an example, this is how you can do it:

假设pwd只是一个例子，那么您可以这样做:

import subprocess

p = subprocess.Popen("pwd", stdout=subprocess.PIPE)
result = p.communicate()[0]
print result

See the subprocess documentation for another example and more information.

有关另一个示例和更多信息，请参阅子流程文档。

#4

subprocess.Popen: http://docs.python.org/2/library/subprocess.html#subprocess.Popen

子流程。Popen:http://docs.python.org/2/library/subprocess.html # subprocess.Popen

import subprocess

command = "ntpq -p"  # the shell command
process = subprocess.Popen(command, stdout=subprocess.PIPE, stderr=None, shell=True)

#Launch the shell command:
output = process.communicate()

print output[0]

In the Popen constructor, if shell is True, you should pass the command as a string rather than as a sequence. Otherwise, just split the command into a list:

在Popen构造函数中，如果shell是True，那么您应该将命令作为字符串传递，而不是按顺序传递。否则，只需将命令分解为一个列表:

command = ["ntpq", "-p"]  # the shell command
process = subprocess.Popen(command, stdout=subprocess.PIPE, stderr=None)

If you need to read also the standard error, into the Popen initialization, you can set stderr to subprocess.PIPE or to subprocess.STDOUT:

如果您需要读取标准错误，进入Popen初始化，您可以将stderr设置为子进程。管道或subprocess.STDOUT:

import subprocess

command = "ntpq -p"  # the shell command
process = subprocess.Popen(command, stdout=subprocess.PIPE, stderr=subprocess.PIPE, shell=True)

#Launch the shell command:
output, error = process.communicate()

#5

This works perfectly for me:

这对我来说是完美的:

import subprocess
try:
    #prints results and merges stdout and std
    result = subprocess.check_output("echo %USERNAME%", stderr=subprocess.STDOUT, shell=True)
    print result
    #causes error and merges stdout and stderr
    result = subprocess.check_output("copy testfds", stderr=subprocess.STDOUT, shell=True)
except subprocess.CalledProcessError, ex: # error code <> 0 
    print "--------error------"
    print ex.cmd
    print ex.message
    print ex.returncode
    print ex.output # contains stdout and stderr together 

#6

for Python 2.7+ the idiomatic answer is to use subprocess.check_output()

对于Python 2.7+的惯用答案是使用subprocess.check_output()

You should also note the handling of arguments when invoking a subprocess, as it can be a little confusing....

你也应该注意当调用子流程的处理参数,因为它可能会让人有些迷惑....

If args is just single command with no args of its own (or you have shell=True set), it can be a string. Otherwise it must be a list.

如果args只是单个命令，而没有自己的args(或者您有shell=True set)，那么它可以是一个字符串。否则它必须是一个列表。

for example... to invoke the ls command, this is fine:

例如……要调用ls命令，这很好:

from subprocess import check_call
check_call('ls')

so is this:

所以是这样的:

from subprocess import check_call
check_call(['ls',])

however, if you want to pass some args to the shell command, you can't do this:

但是，如果您想要传递一些args到shell命令，您不能这样做:

from subprocess import check_call
check_call('ls -al')

instead, you must pass it as a list:

相反，你必须把它作为一个列表来传递:

from subprocess import check_call
check_call(['ls', '-al'])

the shlex.split() function can sometimes be useful to split a string into shell-like syntax before creating a subprocesses... like this:

split()函数在创建子进程之前，有时可以将字符串拆分为类似shell的语法。是这样的:

from subprocess import check_call
import shlex
check_call(shlex.split('ls -al'))

#7

 import os   
 list = os.popen('pwd').read()

In this case you will only have one element in the list.

在这种情况下，列表中只有一个元素。

#8

I wrote a little function based on the other answers here:

我写了一个基于其他答案的函数

def pexec(*args):
    return subprocess.Popen(args, stdout=subprocess.PIPE).communicate()[0].rstrip()

Usage:

用法:

changeset = pexec('hg','id','--id')
branch = pexec('hg','id','--branch')
revnum = pexec('hg','id','--num')
print('%s : %s (%s)' % (revnum, changeset, branch))

#9

This was perfect for me. You will get the return code, stdout and stderr in a tuple.

这对我来说太完美了。您将获得一个tuple中的返回代码、stdout和stderr。

from subprocess import Popen, PIPE

def console(cmd):
    p = Popen(cmd, shell=True, stdout=PIPE)
    out, err = p.communicate()
    return (p.returncode, out, err)

For Example:

例如:

result = console('ls -l')
print 'returncode: %s' % result[0]
print 'output: %s' % result[1]
print 'error: %s' % result[2]