Detect user logout / shutdown in Python / GTK under Linux - SIGTERM/HUP not received

Question

OK this is presumably a hard one, I\'ve got an pyGTK application that has random crashes due to X Window errors that I can\'t catch/control.

So I created a wrapper t

Answer 1

You forgot to close gtk's event loop.

This code exits with code 0 when you close the window:

import gtk

class Test(gtk.Window):
    def destroy_event(self, widget, data=None):
        gtk.main_quit()

    def __init__(self):
        gtk.Window.__init__(self, gtk.WINDOW_TOPLEVEL)
        self.connect("destroy", self.destroy_event)
        self.show()

f = Test()
gtk.main()

---

EDIT: Here's the code to catch the SIGTERM signal:

import signal

def handler(signum, frame):
    print 'Signal handler called with signal', signum
    print 'Finalizing main loop'
    gtk.main_quit()

signal.signal(signal.SIGTERM, handler)

The rest of the code is exactly as above, no changes. It works here when I send SIGTERM to the python process: gtk main loop ends and program exits with exit code 0.

Answer 2

OK, I finally found the solution :)

You simply can't rely on signals in this case. You have to connect to the Desktop Session in order to get notified that a logout is going to happen.

import gnome.ui

gnome.program_init('Program', self.version) # This is going to trigger a warning that program name has been set twice, you can ignore this, it seems to be a problem with a recent version of glib, the warning is all over the place out there
client = gnome.ui.master_client() # connect us to gnome session manager, we need to init the program before this
client.connect('save-yourself', self.on_logout) # This gets called when the user confirms the logout/shutdown
client.connect('shutdown-cancelled', self.on_logout_cancel) # This gets called when the logout/shutdown is canceled
client.connect('die', self.on_logout) # Don't know when this gets called it never got in my tests

def on_logout(self, *args):
    # save settings an create a file that tells the wrapper that we have exited correctly!
    # we'll still return with status code 1, but that's just gtk crashing somehow

def on_logout_cancel(self, *args):
    # simply delete the logout file if it exists

One important note here: Don't try to exit your program in on_logout, if you do so, GNOME won't recognize that your program has been exited and will give you the dialog that some programs are still running.