notify-send –hint=int:transient:1 -i /usr/share/icons/gnome/scalable/actions/media-playback-start-symbolic.svg “MPD: Now Playing -> ” “`mpc status | head -1`”

will get you the notification, without keeping it in the notification tray.

However, the notification stays in the notification area. Which is not really bothering me. But it is
Apparently there is no easy way to remove a bunch of notifications in one go.

When I click on a url in gnome-terminal, I get the notification that the link is being opened (in Firefox) but this is not stored in the notification area. So, there must be a way to accomplish this.

notify-send –help is rather to the point:

Usage:
notify-send [OPTION...] [BODY] – create a notification

Help Options:
-?, –help Show help options

Application Options:
-u, –urgency=LEVEL Specifies the urgency level (low, normal, critical).
-t, –expire-time=TIME Specifies the timeout in milliseconds at which to expire the notification.
-i, –icon=ICON[,ICON...] Specifies an icon filename or stock icon to display.
-c, –category=TYPE[,TYPE...] Specifies the notification category.
-h, –hint=TYPE:NAME:VALUE Specifies basic extra data to pass. Valid types are int, double, string and byte.
-v, –version Version of the package.

Urgency doesn’t seem to be doing anything. Maybe category?
Any suggestions?