running shell command using python

Question

I'm trying to run a shell script in python and save the output to a variable.

This is my python script:

import os
os.system("sh ./temp.sh > outfile.txt") 
file = open("outfile.txt", "r") 
var = file.readLine() 
#I do more stuff using var

Right now this works. However is there a more efficient way to do this? It seems a little inefficient to output to a file and then read from the file again. My goal is to set var directly from the output of the os command. For example var = os.system(unix command). (I know this doesn't work).

• Ranjith Ramachandra: You might want to look at the answer to this question stackoverflow.com/questions/4760215/…
• R Sahu: This answer to another SO post might be helpful. stackoverflow.com/a/2339494/434551.
• Some programmer dude: Read about the subprocess module, especially the Popen class.

Answer 1

You can use the subprocess module to store the output in a variable, thus making your script something like this :

import subprocess
var = subprocess.check_output(['sh', 'temp.sh']) //

The subprocess module basically allows you to execute shell commands which passed to it as an array of arguments so like to execute ls -l you need to pass it as ['ls', '-l'], similarly you can pass call to your script as above. You can read about subprocess here.

Answer 2

You can use the subprocess module

import subprocess
output = subprocess.check_output(//unix command here)