CODEWITHSUNDEEP
pythonlinuxbashuser-interface
user1971707
user1971707

Reputation: 13

GUI not opening

I have written a python script which scans my gmail INBOX for a particular mail, and if that mail is present it opens up a GUI. I have tested this script and works correctly. I want to run this script whenever the network connection is established. So, I have added a script in the dispatch.d directory of the NetworkManager. My bash script is shown below.

#!/bin/bash
#/etc/NetworkManager/dispatcher.d/90filename.sh

IF=$1
STATUS=$2

if [ "$IF" == "wlan0" ];  # for wireless internet
then
    case "$2" in
        up)
        logger -s "NM Script up triggered"
        python /home/rahul/python/expensesheet/emailReader.py
    logger -s "emailReader completed"
    exitValue=$?
    python3.2 /home/rahul/python/expensesheet/GUI.py &
    logger -s "GUI completed with exit status $exitValue"
        ;;
        down)
        logger -s "NM Script down triggered"
        #place custom here
        ;;
        pre-up)
        logger -s "NM Script pre-up triggered"
        #place custom here
        ;;
        post-down)
        logger -s "NM Script post-down triggered"
        #place custom here
        ;;
        *)
        ;;
    esac
fi

I have used tkinter to design my GUI. My problem is that, emailReader(which has no GUI) gets executed correctly, but GUI.py doesn't get executed. It exits with the exit status 1. Can somebody throw some light on this matter and explain what I'm doing wrong?

Upvotes: 0

Views: 1394

Answers (1)

umläute
umläute

Reputation: 31284

NetworkManager is a process that is running on a virtual terminal, outside of your X-server. (e.g. NetworkManager get's started on bootup before your window manager gets started; they are totally unrelated).

therefore, any script started by NetworkManager will not (directly) be able to access the GUI. (it is very similar to what you get when you change from your desktop to a virtual terminal (e.g. Ctrl-Alt-1), and then try to run your GUI from there: you will most likely get an error like "Can't open display".

if you want to start a GUI-program, you have 2 possibilities

  • tell a notification daemon (a sub-process of your window-manager) to start your GUI
  • tell your GUI to start on the correct display (the one, where your desktop is running)

i'd go for the first solution (notification daemons are designed for that very purpose), but how to do it, heavily depends on the window-manager you use.

the 2nd solution is a bit more dirty and involves potential security breaches but basically try something like starting DISPLAY=:0.0 myguiapp.py instead of starting myguiapp.py (this assumes you are running an X-server on localhost:0.0). you can check whether this works by simply launching the command with the DISPLAY-line from a virtualterminal. to get the display you are actually using, simply run echo $DISPLAY in a terminal within your X-server. usually, remote connections are disabled to your running Xserver (as it allows non-proviliged users to take over your desktop - everything from starting new GUI-programs (which is what you want) to installing keyloggers); if that's the case check man xhost (or go for solution #1)

UPDATE

for the 1st solution, you probably want to check out libraries like libnotify (there's python bindings in python-notify and python-notify2).

if you want more than simple "notification popups", you probably have to dig into D-BUS. a simple example (haven't tested it personally, though), can be found here.

Upvotes: 1

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