Re: How to disable spawnv's child process output messages
 

Hi Donn. Thanks for your response. Yes, in this case my parent process
is hello_moon.py that is spwaning the child process, hello_earth.py. I
am simply printing a hello world from each process and do not wish to
see any output messages from the child process, and i *have to* see
the output from the parent process, hello_moon.py

Could you please elaborate more on how i can use dup2( ) to disable
the output of the child process spawned by spawnv( ) API?

Regards,
BB (Nushin)

"Donn Cave" <donn@drizzle.com> wrote in message news:<1058938603.850678@yasure>...
> Quoth nushin2@yahoo.com (nushin):
> | I have a program called hello_earth.py that is spawned by
> | hello_moon.py, using spawnv( ) API as:
> |
> | os.spawnv(os.P_NOWAIT,'/usr/bin/python',('python','hello_earth.py'),('>/dev/null
> | &'))
> |
> | I do not wish to see any output messages from the hello_earth.py when
> | it is launched by its parent process and i do wish to see *only* the
> | output messages from the parent process in the shell. Is Python
> | capable to so such a thing?
>
> What is the parent process in the shell? You mean the one that calls
> spawnv()? If so - yes, Python can do that. But not so easily. You
> can look at how spawnv is implemented (it's in Python), and read up
> on the dup2 function (man 2 dup2) to see what's needed. spawnv can't
> do any kind of redirection. I think I posted an example here a couple
> weeks ago.
>
> Or you can use the shell, more or less the way you were going but you
> never invoked it -
> os.spawnv(os.P_NOWAIT, '/bin/sh', ['sh', '-c', 'python hello_earth.py > /dev/null'])
>
> which is really about the same as
> os.system('python hello_earth.py > /dev/null &')
>
> Donn Cave, donn@drizzle.com

Re: How to disable spawnv's child process output messages
 

In article <db3b6d24.0307231030.7dfa1b70@posting.google.com >,
nushin2@yahoo.com (nushin) wrote:

> Hi Donn. Thanks for your response. Yes, in this case my parent process
> is hello_moon.py that is spwaning the child process, hello_earth.py. I
> am simply printing a hello world from each process and do not wish to
> see any output messages from the child process, and i *have to* see
> the output from the parent process, hello_moon.py
>
> Could you please elaborate more on how i can use dup2( ) to disable
> the output of the child process spawned by spawnv( ) API?

It can't be done - as I said, spawnv can't do any kind of redirection,
and that is what it would take.

Donn Cave, donn@u.washington.edu
-----------------------------------
> "Donn Cave" <donn@drizzle.com> wrote in message
> news:<1058938603.850678@yasure>...
> > Quoth nushin2@yahoo.com (nushin):
> > | I have a program called hello_earth.py that is spawned by
> > | hello_moon.py, using spawnv( ) API as:
> > |
> > | os.spawnv(os.P_NOWAIT,'/usr/bin/python',('python','hello_earth.py'),('>/de
> > | v/null
> > | &'))
> > |
> > | I do not wish to see any output messages from the hello_earth.py when
> > | it is launched by its parent process and i do wish to see *only* the
> > | output messages from the parent process in the shell. Is Python
> > | capable to so such a thing?
> >
> > What is the parent process in the shell? You mean the one that calls
> > spawnv()? If so - yes, Python can do that. But not so easily. You
> > can look at how spawnv is implemented (it's in Python), and read up
> > on the dup2 function (man 2 dup2) to see what's needed. spawnv can't
> > do any kind of redirection. I think I posted an example here a couple
> > weeks ago.
> >
> > Or you can use the shell, more or less the way you were going but you
> > never invoked it -
> > os.spawnv(os.P_NOWAIT, '/bin/sh', ['sh', '-c', 'python hello_earth.py >
> > /dev/null'])
> >
> > which is really about the same as
> > os.system('python hello_earth.py > /dev/null &')
> >
> > Donn Cave, donn@drizzle.com