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     Posts tagged "processes"

How to capture stdout in real-time with Python

Date: 2009-10-12  |   Tags: notestoself, processes, python

This solution is thanks to this article.

import subprocess

def myrun(cmd):
    """from http://blog.kagesenshi.org/2008/02/teeing-python-subprocesspopen-output.html
    """
    p = subprocess.Popen(cmd, shell=True, stdout=subprocess.PIPE, stderr=subprocess.STDOUT)
    stdout = []
    while True:
        line = p.stdout.readline()
        stdout.append(line)
        print line,
        if line == '' and p.poll() != None:
            break
    return ''.join(stdout)
... read more »

How to get stdout and stderr using Python's subprocess module

Date: 2008-09-23  |   Tags: processes, python   |   2 Comments

I wrote previously about how to get stdout and stderr using os.popen4. However, per the Python documentation, using the subprocess module is preferred:

The subprocess module allows you to spawn new processes, connect to their input/output/error pipes, and obtain their return codes. This module intends to replace several other, older modules and functions, such as:

os.system
os.spawn*
os.popen*
popen2.*
commands.*

See the subprocess module documentation for more information.

Here is how to get stdout and stderr from a program using the subprocess module:

from subprocess import Popen, PIPE, STDOUT

cmd = 'ls /etc/fstab /etc ...
... read more »

How to use python and popen4 to capture stdout and stderr from a command

Date: 2007-03-12  |   Tags: processes, python
You can use popen to capture stdout from a command:
import os
stdout = os.popen("dir asdkfhqweiory")
print stdout.read()
And your output will be something like:
>>> ================================ RESTART ================================
 >>> 
  Volume in drive C has no label.
  Volume Serial Number is XXXXXXXX
 
  Directory of C:\Python25
 
 
 >>>
If you wanted the error message, popen won't give it to you. To capture both stdout and stderr, use popen4:
import os

(dummy, stdout_and_stderr) = os.popen4("dir asdkfhqweiory")
print stdout_and_stderr.read()
This will give you the following output (which includes the error message):
>>> ================================ RESTART ================================
 >>> 
  Volume in drive C has no label.
  Volume Serial Number is ...
... read more »
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