Running long script in the background

[tleeuwenburg at gmail.com]

On Feb 8, 10:42 am, "Karthik Gurusamy" <kar1... at gmail.com> wrote:
> On Feb 6, 5:26 am, "watter... at gmail.com" <watter... at gmail.com> wrote:
>
> > Hello,
>
> > I am trying to write a python cgi that calls a script over ssh, the
> > problem is the script takes a very long time to execute so Apache
> > makes the CGI time out and I never see any output.  The script is set
> > to print a progress report to stdout every 3 seconds but I never see
> > any output until the child process is killed.
>
> > Here's what I have in my python script:
>
> > command = "ssh -l root %s /scripts/xen/xen-create-win-vps1.sh %s" %
> > (host, domuname)
> > output = os.popen(command)
>
> Apart from other buffering issues, it could be very well that ssh
> returns all the output in one  single big chunk. Try running the ssh
> command (with the trailing 'command') from your shell and see if it
> generates output immediately.
>
> There may be some option to make ssh not buffer the data it reads from
> the remove command execution. If there is no such option, most likely
> you are out of luck. In this case, even if you making your remote
> script unbufferred, ssh may be buffering it.
>
> If both the machines have any shared filesystem, you can do a trick.
> Make your script write it's output unbuffered to a file. Since the
> file is mounted and available on both the machines.. start reading the
> file from this main python script (note that you may need a thread to
> do it, as your script will anyway be stuck waiting for the ssh to
> complete).
>
> Karthik
>
> > for line in output:
> >    print line.strip()
>
> > Here's a copy of the bash script.
>
> >http://watters.ws/script.txt
>
> > I also tried using os.spawnv to run ssh in the background and nothing
> > happens.
>
> > Does anybody know a way to make output show in real time?


You could also try flushing the buffer after each status message