Playing with threads

Devin Jeanpierre jeanpierreda at
Thu Jan 8 03:09:24 CET 2015

I can't tell what you mean, but you can start a process via
subprocess.Popen, do some work, and wait for it to finish.

Note that you don't need the stdout (or likely the stdin) of the
process, you just need the return code -- whether or not grep
succeeded -- so you can redirect stdout and stderr to os.devnull and
avoid using .communicate().  Also, if you can't use .communicate(),
but need to access stdout, this is the most common reason to need
threads with subprocess.

-- Devin

On Wed, Jan 7, 2015 at 8:00 PM, Ganesh Pal <ganesh1pal at> wrote:
> Hi friends,
> I'm trying to use threads  to achieve the below work flow
> 1. Start a process , while its running grep for a string 1
> 2. Apply the string 1 to the command in step 1 and exit step 2
> 3. Monitor the stdout of step1 and print success if the is pattern  found
> Questions:
> 1. Can the above be achieved without threads ? I prefer keep ing code simple
> .threads can become confusion when this workflow grows larger
> Regards,
> Ganesh
> --

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