Linux command-line call not returning what it should from os.system?

Question

I need to make some command line calls to linux and get the return from this, however doing it as below is just returning 0 when it should return a time value, like 00:08:19, I am testing the exact same call in regular command line and it returns the time value 00:08:19 so I am confused as to what I am doing wrong as I thought this was how to do it in python.

import os retvalue = os.system("ps -p 2993 -o time --no-headers") print retvalue 

Answer 1

What gets returned is the return value of executing this command. What you see in while executing it directly is the output of the command in stdout. That 0 is returned means, there was no error in execution.

Use popen etc for capturing the output .

Some thing along this line:

import subprocess as sub p = sub.Popen(['your command', 'arg1', 'arg2', ...],stdout=sub.PIPE,stderr=sub.PIPE) output, errors = p.communicate() print output 

or

import os p = os.popen('command',"r") while 1:     line = p.readline()     if not line: break     print line 

ON SO : Popen and python