blocks|key|1690378|text|如果您需要的只是stdout输出，那么可以看看subprocess.check_output()|type|unstyled|depth|inlineStyleRanges|offset|length|style|CODE|entityRanges|data|1690379|import+subprocess

batcmd="dir"
result+=+subprocess.check_output(batcmd,+shell=True)|code-block|syntax|javascript|1690380|因为您使用的是os.system()，所以必须设置shell=True才能获得相同的行为。您确实希望注意security+concerns关于将不可信的参数传递给shell的问题。|1690381|如果您还需要捕获stderr，只需将stderr=subprocess.STDOUT添加到调用：|1690382|result+=+subprocess.check_output([batcmd],+stderr=subprocess.STDOUT)|1690383|将错误输出重定向到默认输出流。|1690384|如果您知道输出是文本，则添加text=True以使用平台默认编码解码返回的字节值；如果该编解码器对您接收的数据不正确，请使用encoding="..."。|1690385|entityMap|0|LINK|mutability|MUTABLE|url|http://docs.python.org/3/library/subprocess.html#subprocess.check_output|1|https://docs.python.org/3/library/subprocess.html#security-considerations^0|8|6|N|P|N|P|0|0|0|7|B|P|A|1G|H|1|0|8|6|I|O|0|0|0|E|9|1Q|E|0^^$0|@$1|2|3|4|5|6|7|14|8|@$9|15|A|16|B|C]|$9|17|A|18|B|C]]|D|@$9|19|A|1A|1|1B]]|E|$]]|$1|F|3|G|5|H|7|1C|8|@]|D|@]|E|$I|J]]|$1|K|3|L|5|6|7|1D|8|@$9|1E|A|1F|B|C]|$9|1G|A|1H|B|C]]|D|@$9|1I|A|1J|1|1K]]|E|$]]|$1|M|3|N|5|6|7|1L|8|@$9|1M|A|1N|B|C]|$9|1O|A|1P|B|C]]|D|@]|E|$]]|$1|O|3|P|5|H|7|1Q|8|@]|D|@]|E|$I|J]]|$1|Q|3|R|5|6|7|1R|8|@]|D|@]|E|$]]|$1|S|3|T|5|6|7|1S|8|@$9|1T|A|1U|B|C]|$9|1V|A|1W|B|C]]|D|@]|E|$]]|$1|U|3|-4|5|6|7|1X|8|@]|D|@]|E|$]]]|V|$W|$5|X|Y|Z|E|$10|11]]|12|$5|X|Y|Z|E|$10|13]]]]

If all you need is the <code>stdout</code> output, then take a look at <a href="http://docs.python.org/3/library/subprocess.html#subprocess.check_output" rel="noreferrer"><code>subprocess.check_output()</code></a>:

<pre><code>import subprocess

batcmd="dir"
result = subprocess.check_output(batcmd, shell=True)
</code></pre>

Because you were using <code>os.system()</code>, you'd have to set <code>shell=True</code> to get the same behaviour. You do want to heed the <a href="https://docs.python.org/3/library/subprocess.html#security-considerations" rel="noreferrer">security concerns</a> about passing untrusted arguments to your shell.

If you need to capture <code>stderr</code> as well, simply add <code>stderr=subprocess.STDOUT</code> to the call:

<pre><code>result = subprocess.check_output([batcmd], stderr=subprocess.STDOUT)
</code></pre>

to redirect the error output to the default output stream.

If you know that the output is text, add <code>text=True</code> to decode the returned bytes value with the platform default encoding; use <code>encoding="..."</code> instead if that codec is not correct for the data you receive.

blocks|key|1690488|text|这些答案对我不起作用。我不得不使用以下代码：|type|unstyled|depth|inlineStyleRanges|entityRanges|data|1690489|import+subprocess
p+=+subprocess.Popen(["pwd"],+stdout=subprocess.PIPE)
out+=+p.stdout.read()
print+out|code-block|syntax|javascript|1690490|或者作为一个函数(我在Python2.6.7上需要使用shell=True，并且直到2.7时才添加check_output，这使得它在这里不可用)：|1690491|def+system_call(command):
++++p+=+subprocess.Popen([command],+stdout=subprocess.PIPE,+shell=True)
++++return+p.stdout.read()|1690492|entityMap^0|0|0|0|0^^$0|@$1|2|3|4|5|6|7|M|8|@]|9|@]|A|$]]|$1|B|3|C|5|D|7|N|8|@]|9|@]|A|$E|F]]|$1|G|3|H|5|6|7|O|8|@]|9|@]|A|$]]|$1|I|3|J|5|D|7|P|8|@]|9|@]|A|$E|F]]|$1|K|3|-4|5|6|7|Q|8|@]|9|@]|A|$]]]|L|$]]

These answers didn't work for me. I had to use the following:

<pre><code>import subprocess
p = subprocess.Popen(["pwd"], stdout=subprocess.PIPE)
out = p.stdout.read()
print out
</code></pre>

Or as a function (using shell=True was required for me on Python 2.6.7 and check_output was not added until 2.7, making it unusable here):

<pre><code>def system_call(command):
 p = subprocess.Popen([command], stdout=subprocess.PIPE, shell=True)
 return p.stdout.read()
</code></pre>

blocks|key|1690522|text|import+subprocess
string="echo+Hello+world"
result=subprocess.getoutput(string)
print("result:::+",result)|type|code-block|depth|inlineStyleRanges|entityRanges|data|syntax|javascript|1690523|unstyled|entityMap^0|0^^$0|@$1|2|3|4|5|6|7|G|8|@]|9|@]|A|$B|C]]|$1|D|3|-4|5|E|7|H|8|@]|9|@]|A|$]]]|F|$]]

<pre><code>import subprocess
string="echo Hello world"
result=subprocess.getoutput(string)
print("result::: ",result)
</code></pre>

blocks|key|1903858|text|我想详细介绍一下Windows解决方案。在Python2.7.5中使用IDLE时，当我从文件Expts.py运行以下代码时：|type|unstyled|depth|inlineStyleRanges|entityRanges|data|1903859|import+subprocess
r+=+subprocess.check_output('cmd.exe+dir',shell=False)+
print+r|code-block|syntax|javascript|1903860|在Python+Shell中，我只得到了对应于“cmd.exe”的输出；忽略了“...in”部分。但是，当我添加诸如/K或/C之类的开关时...|1903861|import+subprocess
r+=+subprocess.check_output('cmd.exe+/K+dir',shell=False)+
print+r|1903862|...then在Python+Shell中，我得到了我想要的所有东西，包括目录清单。哇哦！|1903863|现在，如果我在DOS+Python命令窗口中尝试任何相同的事情，不使用开关，或使用/K开关，它似乎使窗口挂起，因为它正在运行子进程cmd.exe，并等待进一步的输入-键入'exit‘然后按enter释放。但是使用/K开关，它可以完美地工作，并返回到python提示符。那好吧。|1903864|更进一步...我以为这是cool...When，而不是用Expts.py：|1903865|import+subprocess
r+=+subprocess.call("cmd.exe+dir",shell=False)+
print+r|1903866|...a新的DOS窗口打开并保留在那里，只显示"cmd.exe“的结果，而不显示"dir”的结果。当我添加/C开关时，在我看到任何东西之前，DOS窗口很快就会打开和关闭(正如预期的那样，因为完成后/C会终止)。当我添加/K开关时，DOS窗口弹出并保持不变，我得到了我期望的所有输出，包括目录清单。|1903867|如果我从DOS+Python命令窗口尝试相同的操作(subprocess.call而不是subprocess.check_output)；所有输出都在同一个窗口中，则没有弹出窗口。如果不使用此开关，"dir“部分将再次被忽略，并且提示符将从python提示符变为DOS提示符(因为退出子进程正在python中运行；再次键入‘cmd.exe’，您将恢复到python提示符)。添加python开关将打印出目录清单，并将提示符从/K更改为DOS，因为/K不会终止子进程。将开关更改为/C将为我们提供所有预期的输出，并返回到python提示符，因为子流程将根据/C终止。|1903868|很抱歉长篇大论的回复，但我对许多简洁的“答案”感到沮丧，这些答案充其量是不起作用的(似乎是因为它们没有经过测试-就像我上面的Eduard+F的回复没有切换)，或者更糟糕的是，它们太简洁了，根本没有帮助(例如，“试试子流程而不是os.system”……是的，好的，现在怎么办??)。相反，我提供了一些我测试过的解决方案，并展示了它们之间的细微差别。花了很多时间但是..。希望这能有所帮助。|1903869|entityMap^0|0|0|0|0|0|0|0|0|0|0|0^^$0|@$1|2|3|4|5|6|7|10|8|@]|9|@]|A|$]]|$1|B|3|C|5|D|7|11|8|@]|9|@]|A|$E|F]]|$1|G|3|H|5|6|7|12|8|@]|9|@]|A|$]]|$1|I|3|J|5|D|7|13|8|@]|9|@]|A|$E|F]]|$1|K|3|L|5|6|7|14|8|@]|9|@]|A|$]]|$1|M|3|N|5|6|7|15|8|@]|9|@]|A|$]]|$1|O|3|P|5|6|7|16|8|@]|9|@]|A|$]]|$1|Q|3|R|5|D|7|17|8|@]|9|@]|A|$E|F]]|$1|S|3|T|5|6|7|18|8|@]|9|@]|A|$]]|$1|U|3|V|5|6|7|19|8|@]|9|@]|A|$]]|$1|W|3|X|5|6|7|1A|8|@]|9|@]|A|$]]|$1|Y|3|-4|5|6|7|1B|8|@]|9|@]|A|$]]]|Z|$]]

I would like to expand on the Windows solution. Using IDLE with Python 2.7.5, When I run this code from file Expts.py:

<pre><code>import subprocess
r = subprocess.check_output('cmd.exe dir',shell=False) 
print r
</code></pre>

...in the Python Shell, I ONLY get the output corresponding to "cmd.exe"; the "dir" part is ignored. HOWEVER, when I add a switch such as /K or /C ...

<pre><code>import subprocess
r = subprocess.check_output('cmd.exe /K dir',shell=False) 
print r
</code></pre>

...then in the Python Shell, I get all that I expect including the directory listing. Woohoo !

Now, if I try any of those same things in DOS Python command window, without the switch, or with the /K switch, it appears to make the window hang because it is running a subprocess cmd.exe and it awaiting further input - type 'exit' then hit [enter] to release. But with the /K switch it works perfectly and returns you to the python prompt. Allrightee then.

Went a step further...I thought this was cool...When I instead do this in Expts.py:

<pre><code>import subprocess
r = subprocess.call("cmd.exe dir",shell=False) 
print r
</code></pre>

...a new DOS window pops open and remains there displaying only the results of "cmd.exe" not of "dir". When I add the /C switch, the DOS window opens and closes very fast before I can see anything (as expected, because /C terminates when done). When I instead add the /K switch, the DOS window pops open and remain, AND I get all the output I expect including the directory listing.

If I try the same thing (subprocess.call instead of subprocess.check_output) from a DOS Python command window; all output is within the same window, there are no popup windows. Without the switch, again the "dir" part is ignored, AND the prompt changes from the python prompt to the DOS prompt (since a cmd.exe subprocess is running in python; again type 'exit' and you will revert to the python prompt). Adding the /K switch prints out the directory listing and changes the prompt from python to DOS since /K does not terminate the subprocess. Changing the switch to /C gives us all the output expected AND returns to the python prompt since the subprocess terminates in accordance with /C.

Sorry for the long-winded response, but I am frustrated on this board with the many terse 'answers' which at best don't work (seems because they are not tested - like Eduard F's response above mine which is missing the switch) or worse, are so terse that they don't help much at all (e.g., 'try subprocess instead of os.system' ... yeah, OK, now what ??). In contrast, I have provided solutions which I tested, and showed how there are subtle differences between them. Took a lot of time but...
Hope this helps.

blocks|key|1903911|text|我不得不使用os.system，因为对于较大的任务，子进程会给我一个内存错误。此问题的参考资料here。因此，为了获得os.system命令的输出，我使用了以下解决方法：|type|unstyled|depth|inlineStyleRanges|entityRanges|offset|length|data|1903912|import+os

batcmd+=+'dir'
result_code+=+os.system(batcmd+%2B+'+>+output.txt')
if+os.path.exists('output.txt'):
++++fp+=+open('output.txt',+"r")
++++output+=+fp.read()
++++fp.close()
++++os.remove('output.txt')
++++print(output)|code-block|syntax|javascript|1903913|entityMap|0|LINK|mutability|MUTABLE|url|https://stackoverflow.com/questions/1367373/python-subprocess-popen-oserror-errno-12-cannot-allocate-memory/13329386#13329386^0|1B|4|0|0|0^^$0|@$1|2|3|4|5|6|7|Q|8|@]|9|@$A|R|B|S|1|T]]|C|$]]|$1|D|3|E|5|F|7|U|8|@]|9|@]|C|$G|H]]|$1|I|3|-4|5|6|7|V|8|@]|9|@]|C|$]]]|J|$K|$5|L|M|N|C|$O|P]]]]

I had to use os.system, since subprocess was giving me a memory error for larger tasks. Reference for this problem <a href="https://stackoverflow.com/questions/1367373/python-subprocess-popen-oserror-errno-12-cannot-allocate-memory/13329386#13329386">here</a>. So, in order to get the output of the os.system command I used this workaround:

<pre><code>import os

batcmd = 'dir'
result_code = os.system(batcmd + ' &gt; output.txt')
if os.path.exists('output.txt'):
 fp = open('output.txt', "r")
 output = fp.read()
 fp.close()
 os.remove('output.txt')
 print(output)
</code></pre>

blocks|key|1903894|text|commands也可以工作。|type|unstyled|depth|inlineStyleRanges|offset|length|style|CODE|entityRanges|data|1903895|import+commands
batcmd+=+"dir"
result+=+commands.getoutput(batcmd)
print+result|code-block|syntax|javascript|1903896|它可以在linux上运行，python+2.7。|1903897|entityMap^0|0|8|0|0|0^^$0|@$1|2|3|4|5|6|7|O|8|@$9|P|A|Q|B|C]]|D|@]|E|$]]|$1|F|3|G|5|H|7|R|8|@]|D|@]|E|$I|J]]|$1|K|3|L|5|6|7|S|8|@]|D|@]|E|$]]|$1|M|3|-4|5|6|7|T|8|@]|D|@]|E|$]]]|N|$]]

<code>commands</code> also works.

<pre><code>import commands
batcmd = "dir"
result = commands.getoutput(batcmd)
print result
</code></pre>

It works on linux, python 2.7.

I want to get the <code>stdout</code> in a variable after running the <code>os.system</code> call.

Lets take this line as an example: 

<pre><code>batcmd="dir"
result = os.system(batcmd)
</code></pre>

<code>result</code> will contain the error code (<code>stderr</code> <code>0</code> under Windows or <code>1</code> under some linux for the above example).

How can I get the <code>stdout</code> for the above command without using redirection in the executed command?

Python: How to get stdout after running os.system?

Windows

Python

在运行os.system调用之后，我希望在一个变量中获得stdout。让我们以这一行为例：batcmd="dir"result = os.system(batcmd)result将包含错误代码(对于上面的示例，在Windows下是stderr 0，在某些linux下是1 )。如何在执行的命令中不使用重定向的情况下获取上述命令的stdout？

问Python:在运行os.system后如何获取标准输出？
EN

回答 6

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问Python:在运行os.system后如何获取标准输出？EN

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问Python:在运行os.system后如何获取标准输出？
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