Here's another example of running a single instance app.

This time using a less complicated pipe file rather than the server socket the last example used..
I've refined it a bit as i've just added this feature to my script editor.

included is a test script that first simply launches the app with 2 args that are displayed in the list view.
Then it launches the app 3 times simultaneously with a different arg for each but the app only launches once and the other 2 launches send their args to the 1st instance via the pipe file.

Hoping it may help some.

Bruce.

 This is especially useful if you have an app you can drag and drop files onto the icon.

If you drag and drop more than one file on to the app icon linux launches the app multiple times with one arg rather than once with multiple args.