[Tutor] Processing Linux command line output

[Prasad, Ramit]

Gareth Allen wrote:
> Hi all,
> 
> I'm trying to get the output of a command and split it into a list that I can process.  What is the
> best way to go about doing this? In bash I would use tools like grep, sed awk etc.
> 
> Here's an example:
> 
> ifconfig
> 
> lo        Link encap:Local Loopback
>           inet addr:127.0.0.1  Mask:255.0.0.0
>           inet6 addr: ::1/128 Scope:Host
>           UP LOOPBACK RUNNING  MTU:16436  Metric:1
>           RX packets:84253 errors:0 dropped:0 overruns:0 frame:0
>           TX packets:84253 errors:0 dropped:0 overruns:0 carrier:0
>           collisions:0 txqueuelen:0
>           RX bytes:11763964 (11.2 MiB)  TX bytes:11763964 (11.2 MiB)
> 
> I would like to end up with something like this in a file:
> 
> <unix timestamp>,lo,rx_errors=0,rx_dropped=0,rx_overruns=0,rx_frame=0
> 

Look at the subprocess module it is better than os.system().
http://docs.python.org/2/library/subprocess.html#subprocess.Popen.communicate


>>> process = subprocess.Popen(['/sbin/ifconfig'], stdout=subprocess.PIPE)
>>> output = process.communicate() # block until job finishes then return 
                                   # (stdout, stderr)
>>> print output[0] # do something with output

It is sometimes tempting using shell=True (it is False by default),
but it can be insecure and should be avoided when possible.


~Ramit


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