Creating two processes in Linux and getting output

Question

I'm trying to run two processes in parallel. Both programs do not "end" without Ctrl+C (by the way, I'm on Linux), and so os.system will not return the output of a command. I want a way to create two processes independently of the main Python thread, and read text from them as it appears. I also want to be able to send characters to the process (not as a command, because the process interprets key presses by itself) I need something like this:

process1 = System("sh process1") process2 = System("sh process2") process1.Send("Hello, I'm sending text into process 1.") text = process1.Read() process2.Send(text)

Is there a way of doing this? I've looked into the Subprocess module, but I'm not sure it achieves quite what I want - or if it does, I'm not sure how to do it.

many thanks to anyone who answers,

that other guy · Accepted Answer · 2014-06-12 20:47:02Z

2

Subprocess does what you want. Here's an example of writing to and reading from an external command:

import subprocess proc = subprocess.Popen(["sed", "-u", "s/foo/bar/g"], shell=False, stdin=subprocess.PIPE, stdout=subprocess.PIPE) proc.stdin.write("foobar\n"); print proc.stdout.readline(); # Writes "barbar"

answered Jun 12, 2014 at 20:47

that other guy

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2 Comments

Barry Smith Over a year ago

I have a problem. When trying to read a line, the program freezes. It should be outputting a Line. Is there any way to avoid this?

that other guy Over a year ago

You can only read a line if the program outputs a line. Make sure it's outputting a full line, and that it's not buffering the output.

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