How should I use grep from python?

[Diez B. Roggisch]

Matthew Wilson wrote:

> I'm writing a command-line application and I want to search through lots
> of text files for a string.  Instead of writing the python code to do
> this, I want to use grep.
> 
> This is the command I want to run:
> 
> $ grep -l foo dir
> 
> In other words, I want to list all files in the directory dir that
> contain the string "foo".
> 
> I'm looking for the "one obvious way to do it" and instead I found no
> consensus.  I could os.popen, commands.getstatusoutput, the subprocess
> module, backticks, etc.
> 
> As of May 2009, what is the recommended way to run an external process
> like grep and capture STDOUT and the error code?

subprocess. Which becomes pretty clear when reading it's docs:

"""
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.*
"""

Diez