subprocess.Popen()/call() and appending file

[hiral]

On Jun 14, 7:11 pm, Kushal Kumaran <kushal.kumaran+pyt... at gmail.com>
wrote:
> On Mon, Jun 14, 2010 at 7:01 PM,hiral<hiralsmaill... at gmail.com> wrote:
> > Hi,
>
> > Do we have any facility to append file from Popen()/call(); see below
> > example...
>
> > 1 import subprocess
> > 2 f=open('log', 'w')
> > 3 ...# writing some log-into into log file
> > 4 p = subprocess.Popen(cmd, stdout=f, stderr=f) # (Q)
> > 5 ...# do remaining stuff
>
> > Q: At line# 4, the output of the 'cmd' will wipe-out everything in
> > 'log' file. So to avoid this do we have any mechanism to append into
> > the existing file from subprocess.
>
> > Currently I am doing following...
> > p = subprocess.Popen(cmd, stdout=subprocess.PIPE,
> > stderr=subprocess.PIPE)
> > o, e = p.communicate()
> > print >> log, o
> > print >> log, e
>
> > Pleaese let me know if there is any better mechanism.
>
> It is not actually wiping out the old contents.  You might be running
> into buffering issues.  Explicitly flushing should help when switching
> between the high level IO functions provided by file objects and the
> low level IO that subprocess uses.  Do a f.flush() before your
> subprocess.Popen call.
>
> --
> regards,
> kushal- Hide quoted text -
>
> - Show quoted text -

Thanx it works fine.