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Python Discussion Thread
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Aug 15th, 2008

Opening pipelines with python ?

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In the Perl language, you can fork a child process with the following syntax

perl Syntax (Toggle Plain Text)
open CHILD, " | programA | programB | program C";
print CHILD "this is an example input";
open CHILD, " | programA | programB | program C";
print CHILD "this is an example input";

(at least, you can do this under linux). This statement starts 3 processes in fact; programA, B and C. Moreover, the stdout of A is piped to the stdin of B and the stdout of B is piped to the stdin of C, forming a pipeline. Since the command starts, with a "|", CHILD is a pipe through which your program can write in the stdin of A.

I'd like to know if a similar construct exists for python, or, suppose I want to achieve the same effect with python, what would be the best way to do it ?

Last edited by Gribouillis; Aug 15th, 2008 at 7:40 pm.

Gribouillis

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Aug 18th, 2008

Re: Opening pipelines with python ?

You can use subprocess with shell on unix.

http://blog.doughellmann.com/2007/07...ubprocess.html
And
http://www.python.org/doc/current/li...ubprocess.html

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Aug 18th, 2008

Re: Opening pipelines with python ?

Thanks, it works very well this way

python Syntax (Toggle Plain Text)
import subprocess
child = subprocess.Popen( " progA | progB  |  progC",
  shell = True,
  stdin = subprocess.PIPE,
)
child.stdin.write("example input\n")
import subprocess
child = subprocess.Popen( " progA | progB  |  progC",
  shell = True,
  stdin = subprocess.PIPE,
)
child.stdin.write("example input\n")

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Aug 18th, 2008

Re: Opening pipelines with python ?

Thanks for the feedback.

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