Python - Retrieving output from os.system()

[Bodsda]

Hi guys,

I am having a bit of trouble retrieving information output from os.system() calls. To be specific, I am trying to do the following:

cwd = os.system("pwd")

I was hoping to get the current working directory string that the above command prints out, stored in cwd, instead I get the exit status from the 'pwd' command.

Is there any way to retrieve the data I need, through os.system() or any other type of system call.

Kind regards,
Bodsda

[credobyte]

I'm far away from "I know Python", but .. answer could be found @ http://mail.python.org/pipermail/pyt...er/343901.html

[Bodsda]

I'm far away from "I know Python", but .. answer could be found @ http://mail.python.org/pipermail/pyt...er/343901.html

Yeah, I tried using the subprocess module, specifically:

cwd = subprocess.call(["pwd"])

But I just got the exit status again.

Thanks,
Kind regards,
Bodsda

[unutbu]

Hi Bodsda, how about this:

#!/usr/bin/env python
from subprocess import Popen,PIPE,STDOUT,call

proc=Popen('pwd', shell=True, stdout=PIPE, )
output=proc.communicate()[0]
print output 

or, in this case,

import os
print(os.getcwd()) 

PS. The subprocess code I learned from Doug Hellmann's wonderful Python Module of the Week blog: http://blog.doughellmann.com/2007/07...ubprocess.html

[Bodsda]

Hmm,

ouput = os.popen("pwd").readlines()

seems to get me a list of the output. Thanks for everyones help.

Kind regards,
Bodsda

[Bodsda]

Hi Bodsda, how about this:

#!/usr/bin/env python
from subprocess import Popen,PIPE,STDOUT,call

proc=Popen('pwd', shell=True, stdout=PIPE, )
output=proc.communicate()[0]
print output 

or, in this case,

import os
print(os.getcwd()) 

PS. The subprocess code I learned from Doug Hellmann's wonderful Python Module of the Week blog: http://blog.doughellmann.com/2007/07...ubprocess.html

Hi unutbu,

Could you explain your first code block please. I'm new to the popen attribute

Thanks,
Kind regards,
Bodsda

[unutbu]

Explanation? Uh-oh...
Here is where I expose my lack of understanding:

proc=Popen('pwd', shell=True, stdout=PIPE)

This makes proc an instance of the Popen class.
This line, as I understand it, sets up a subshell which runs the 'pwd' command.
The stdout file handle is directed to PIPE. If you don't do this, then the subshell prints its output to the terminal. By directing it to the PIPE, you can then read what has been sent to the PIPE via the command

proc.communicate()

proc.communicate() returns a 2-tuple: (stdout, stderr)

So

output=proc.communicate()[0]

picks of the stdout, and ignores stderr.

Hope this helps. I'm sure Doug Hellmann explains it better.

PS. The official documentation on the subprocess module can be found here: http://docs.python.org/library/subpr...ule-subprocess

[Bodsda]

Explanation? Uh-oh...
Here is where I expose my lack of understanding:

proc=Popen('pwd', shell=True, stdout=PIPE)

This makes proc an instance of the Popen class.
This line, as I understand it, sets up a subshell which runs the 'pwd' command.
The stdout file handle is directed to PIPE. If you don't do this, then the subshell prints its output to the terminal. By directing it to the PIPE, you can then read what has been sent to the PIPE via the command

proc.communicate()

proc.communicate() returns a 2-tuple: (stdout, stderr)

So

output=proc.communicate()[0]

picks of the stdout, and ignores stderr.

Hope this helps. I'm sure Doug Hellmann explains it better.

PS. The official documentation on the subprocess module can be found here: http://docs.python.org/library/subpr...ule-subprocess

Brilliant, thanks again unutbu,

Kind regards,
Bodsda

[MadMan2k]

import commands
print commands.getoutput("pwd") 

[days_of_ruin]

import os
print os.getcwd()