How to detect libnotify popup notification?

I would like to set while loop that checks for notifications (from liferea rss reader) and play sound when notification is shown..

Have tryed:
but no luck

Check your package system. I see 3 possibilities. FAM, pynotify and iWatch. The last one is meant to monitor for altered system files and email and administrator.

The fam server runs as a server and listens to inotify messages from the kernel, providing info on new or altered files. The fileschanged (fron libfam package) receives messages from the fam server and prints the filename or if you want other information about altered files.

Most distro's now use dbus for sending messages. There may be a way to listen to inotify messages on dbus as well. for example, a file browser will listen for messages about altered files, and then update their display with the new info.