Reading from an os.pipe() directly to a Tkinter text box

Question

I am trying to route the output of a separate script to a Tkinter window.

Below is my attempt at the problem. The Tkinter box appears but does not update when the controller (abstracted here) writes to pipeout using os.write(pipeout, msg) .

from Tkinter import *
from controller import controller
import os


def run():
"""Top level run method which initiates program."""

    def updateInput():
        """Update the textbox with controller output."""
        readFrom = os.fdopen(pipein)
        line = readFrom.readline()
        text.insert(END, line)
        text.after(1000, updateInput)


    pipein, pipeout = os.pipe() #pipe for comms between tkinter and controller
    pid = os.fork()
    if not pid:
        #within child process, launch controller with passed pipe
        os.close(pipein)
        mainController = controller(pipeout)
    os.close(pipeout)
    root = Tk()
    text = Text(root)
    text.pack()
    text.after(1000, updateInput) #update text box each second
    root.mainloop()

if __name__ == "__main__":
    run()

The abstracted controller is writing to the pipe via

os.write(self.pipeout, msg)

where self.pipeout has been assigned from self.pipeout = pipeout in the controller class init .

Answer 1

Sounds like you forgot to flush.

self.pipeout.write(msg)
self.pipeout.flush()

Also, make sure the msg ends in a newline.

Edit: are you sure you need a pipe? There's probably neater ways to do whatever you are doing, like threading.

Answer 2

Solution came from using os.read(pipein, 100) instead of os.fdopen(pipein) in updateInput .

line = os.read(pipein, 100)
text.insert(END, line)
text.after(1000, updateInput)