The x11/dbus port
dbus-1.12.20p0v0 – message bus system
D-Bus is a message bus system, a simple way for applications to talk to
one another. In addition to interprocess communication (IPC), D-Bus
helps coordinate process lifecycle; it makes it simple and reliable to
code a "single instance" application or daemon, and to launch
applications and daemons on demand when their services are needed.