Re: execute pg_dump via python

On 10/25/07, Garry Saddington <garry@schoolteachers.co.uk> wrote:
> I am using zope on windows with an external python method to backup my
> database. I am struggling to run the following command:
>
> pg_dump.exe database > file

> subprocess.Popen(['c:/dir/dir/pg_dump.exe','database','>','c:/dir/dir/output
> file'])
>
> The command string works perfectly in a terminal. Does anyone know how I
> should be doing this? I get no errors or traceback when I try the method
> through Zope.

This is probably a Python question more than anything else.  I don't
know Python, but two things come to mind:

* It probably does not open a command shell, so file redirection ('>')
does not work.  Use pg_dump's -f option instead.

* Things named "popen" usually open a pair of pipes for programmatic
input and output, meaning your app is expected to read the output of
pg_dump directly, as if you were going to display it on the screen or
write to a file yourself.

I'd suggest asking in a Python group about executing external
processes and checking for errors.