Restore an application that is running while using QtSingleApplication

[wysota]

n MSWin, the standard trick is a named mutex (not available on other platforms).

On u*ix you can use system semaphores or message queues for that. Based on the fact that MacOS is also a u*ix, it should be available there as well. On modern Linuxes, it would be wise to just use dbus

[ber_44]

One thing that bothers me now is that when the user exits with Alt+F4 or through the Task Manager, then the mutex/textfile/etc. will never get deleted, so it will be impossible to restart the program.

[elcuco]

so... there is no gpl code available for doing this?

[wysota]

One thing that bothers me now is that when the user exits with Alt+F4 or through the Task Manager, then the mutex/textfile/etc. will never get deleted, so it will be impossible to restart the program.

You should be able to catch the signal using C function signal() and clean up the mutex before exiting the program.