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#!/usr/bin/env python
"""
- read subprocess output without threads using Tkinter
- show the output in the GUI
- stop subprocess on a button press
"""
import logging
import os
import sys
from subprocess import Popen, PIPE, STDOUT
try:
import Tkinter as tk
except ImportError: # Python 3
import tkinter as tk
info = logging.getLogger(__name__).info
# define dummy subprocess to generate some output
cmd = [sys.executable or "python", "-u", "-c", """
import itertools, time
for i in itertools.count():
print(i)
time.sleep(0.5)
"""]
class ShowProcessOutputDemo:
def __init__(self, root):
"""Start subprocess, make GUI widgets."""
self.root = root
# start subprocess
self.proc = Popen(cmd, stdout=PIPE, stderr=STDOUT)
# show subprocess' stdout in GUI
self.root.createfilehandler(
self.proc.stdout, tk.READABLE, self.read_output)
self._var = tk.StringVar() # put subprocess output here
tk.Label(root, textvariable=self._var).pack()
# stop subprocess using a button
tk.Button(root, text="Stop subprocess", command=self.stop).pack()
def read_output(self, pipe, mask):
"""Read subprocess' output, pass it to the GUI."""
data = os.read(pipe.fileno(), 1 << 20)
if not data: # clean up
info("eof")
self.root.deletefilehandler(self.proc.stdout)
self.root.after(5000, self.stop) # stop in 5 seconds
return
info("got: %r", data)
self._var.set(data.strip(b'\n').decode())
def stop(self, stopping=[]):
"""Stop subprocess and quit GUI."""
if stopping:
return # avoid killing subprocess more than once
stopping.append(True)
info('stopping')
self.proc.terminate() # tell the subprocess to exit
# kill subprocess if it hasn't exited after a countdown
def kill_after(countdown):
if self.proc.poll() is None: # subprocess hasn't exited yet
countdown -= 1
if countdown < 0: # do kill
info('killing')
self.proc.kill() # more likely to kill on *nix
else:
self.root.after(1000, kill_after, countdown)
return # continue countdown in a second
self.proc.stdout.close() # close fd
self.proc.wait() # wait for the subprocess' exit
self.root.destroy() # exit GUI
kill_after(countdown=5)
logging.basicConfig(level=logging.INFO, format='%(asctime)s %(message)s')
root = tk.Tk()
app = ShowProcessOutputDemo(root)
root.protocol("WM_DELETE_WINDOW", app.stop) # exit subprocess if GUI is closed
root.mainloop()
info('exited')
@zenatureza

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@zenatureza zenatureza commented Jul 4, 2018

Thanks!

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