Display realtime output of a subprocess in a tkinter widget

Finally I found the solution. After the window construction, you must add :

frame.pack()
# force drawing of the window
win.update_idletasks()

And then after every line insertion in the widget, you must also force a refresh with the same method only on the widget.

# insert the line in the Text widget
t.insert(tk.END, out)
# force widget to display the end of the text (follow the input)
t.see(tk.END)
# force refresh of the widget to be sure that thing are displayed
t.update_idletasks()

This is an interesting solution. Would that be possible to have the whole working code?

I am asking because I was wonder how the while True does not block the usability of the whole GUI... does it not?

As suspected, I tried and this example is not really work. If you use something like "ls -Rf /" as command, you will see that the while loop will make the txt output flowing pretty well. However both windows (main and secondary) will block big time.

I suspect you need to send the print txt part in a separated thread or process. Or, if you use pygtk you can use stuff like

gobject.io_add_watch(self.ep1.stdout,       # file descriptor
                     gobject.IO_IN,         # condition
                     self.write_to_buffer ) # callback

which was actually invented for this.

Just in case someone else is looking for it...

log_box_1 = tk.Text(root, borderwidth=3, relief="sunken")

with subprocess.Popen("ls -la", shell=True, stdout=subprocess.PIPE, bufsize=1, universal_newlines=True) as p:
            for line in p.stdout:
                log_box_1.insert(tk.END, line)

From here