Passing string from python programs to external programs

Jeff McNeil jeff at
Tue May 26 15:16:27 EDT 2009

On May 26, 2:12 pm, lone_eagle <icym... at> wrote:
> Hi all,
> On Linux, I do something like this
> $ program_to_execute < input_file
> ... get some output ...
> I have the content of the input_file as a string inside a python
> program and would like to pass this string to the external program
> from inside the python program and get back the programs output in a
> string/file. Can someone tell me how to achieve this. I have been
> through the documentation for Popen, but this one beats me.
> Cheers,
> Chaitanya

Sounds like subprocess is what you want.  Here's a quick ad-hoc
example. You can find more information on the module at

[GCC 4.3.3] on linux2
Type "help", "copyright", "credits" or "license" for more information.
>>> import subprocess
>>> sub = subprocess.Popen('/bin/gzip', stdin=subprocess.PIPE, stdout=subprocess.PIPE)
>>> g = sub.communicate('Please, sir, gzip me?')
>>> import gzip
>>> import StringIO
>>> gzip.GzipFile(fileobj=StringIO.StringIO(g[0])).read()
'Please, sir, gzip me?'



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