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To: python-list@python.org
From: Peter Otten <__peter__@web.de>
Subject: Re: Linux shell to python
Date: Mon, 30 Jul 2012 13:58:56 +0200
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Xref: csiph.com comp.lang.python:26247

Vikas Kumar Choudhary wrote:


> let me know if someone has tried to implement (grep and PIPE)  shell
> commands in python `lspci | grep Q | grep  "$isp_str1" | grep "$isp_str2"
> | cut -c1-7'
> 
> I tried to use python subprocess and OS.Popen modules.

subprocess is the way to go.

> I was trying porting from bash shell to python.

Here's an example showing how to translate a shell pipe:

http://docs.python.org/library/subprocess.html#replacing-shell-pipeline

But even if you can port the shell script literally I recommend a more 
structured approach:

import subprocess
import itertools

def parse_data(lines):
    for not_empty, group in itertools.groupby(lines, key=bool):
        if not_empty:
            triples = (line.partition(":") for line in group)
            pairs = ((left, right.strip()) for left, sep, right in triples)
            yield dict(pairs)

if __name__ == "__main__":
    def get(field):
        return entry.get(field, "").lower()
    output = subprocess.Popen(["lspci", "-vmm"], 
stdout=subprocess.PIPE).communicate()[0]
    for entry in parse_data(output.splitlines()):
        if "nvidia" in get("Vendor") and "usb" in get("Device"):
            print entry["Slot"]
            print entry["Device"]
            print