In Linux: how to exit a program but not kill it?

Question

I use Ubuntu 10.10, and I have a Python program (Mnemosyne) that I synchronize the data files using Dropbox. Here is my problem scenario. I leave the program running at home and go to work, but if I open the program at work and work on it the data file is changed, and I loose my progress at home when I exit (it automatically saves) when exiting.

I thought I could create a cron job to automatically close Mnemosyne every morning regardless of me remembering to do it or not, but if I use kill the program it exits without saving the datafile, and I end up with a tmp file and an error message when I restart it. Is there a better way of sending the exit signal to this program emulating me clicking file>exit menu option.

Answer 1

Are there man pages on mnemosyne? Perhaps there is a close command in the docs that you could use in your cron job.

Answer 2

Try using a lower kill signal to the program such as 3 (SIGQUIT).

Answer 3

How about starting the program in a screen session at home so you can reconnect to it at work and have full control of what's happening?

http://www.howtoforge.com/linux_screen

Answer 4

The correct answer to this depends on what your program supports. A well-behaved program should save all work and terminate gracefully when receiving the TERM signal, which is the default in kill, so I assume that that's the one you were trying. If the program doesn't tolerate that and doesn't offer any other way, for example over a control socket, you may be out of luck. In that case, try using a screen session or fix the program or use a different one.

Answer 5

By your description, I assume this is a GUI program running on an X server. Try wmctrl:

wmctrl -c "RegEx for Window Name"

From the man page: -c <WIN> Close the window <WIN> gracefully.

Answer 6

This is highly application-dependent. If mnemosyne's authors have not foreseen this kind of situation and specifically created a "save and quit on receiving signal X" behavior, then you're pretty much stuck with having to manipulate its user interface to accomplish this.

However, as already suggested, the better solution would probably be to run mnemosyne under some form of display-sharing utility so that you can access the same session from both locations rather than shutting it down and restarting whenever you relocate. VNC is the GUI desktop sharing option I'm most familiar with, but there's probably a way to get X to let you do this at the application level (as opposed to than the whole desktop) and there are many other options out there these days which may work better for you.

If it were a command-line app, screen works wonderfully (I use it daily for just this purpose, giving me access to a single instance of mutt from multiple locations), but I don't think it handles GUI apps (the man page doesn't appear to reference "GUI" or "X").

Answer 7

As a general rule, the only way to close a program is a signal. As others have said, if it's not responding well to default kill (which sends SIGTERM) it's not likely to have the proper handler for other signals either. There is no 'kinder gentler' signal. All signals other than SIGKILL treat the process the same, running the handler if it has one, or killing the app.

That said, as a gui app, there is a very small chance it links to a library that you can control the app. You can try to see if you can send it messages with dcop, or d-bus. See http://dbus.freedesktop.org/doc/dbus-tutorial.html