dbus-monitor

Monitor session bus

$ dbus-monitor

$ dbus-monitor --system

$ dbus-monitor "interface='[org.freedesktop.Notifications]'"

$ dbus-monitor "sender='[org.gnome.Shell]'"

$ dbus-monitor "type='method_call'"

$ dbus-monitor --profile

dbus-monitor [options] [filter...]

dbus-monitor displays D-Bus messages passing through the message bus. It's useful for debugging D-Bus services, understanding inter-process communication, and reverse-engineering application behavior.
The tool connects to the bus and becomes an eavesdropper, showing all messages matching the specified filters. Without filters, it shows all messages.

--system

Monitor system bus.

Monitor session bus (default).

Connect to specific bus address.

Output in profile format.

Output in monitor format (default).

Output in pcap format.

type='signal': Signal messages
type='method_call': Method calls
type='method_return': Method returns
type='error': Error messages
sender='name': From specific sender
destination='name': To specific destination
interface='name': Specific interface
member='name': Specific method/signal
path='path': Specific object path

May require permissions to eavesdrop. Some buses restrict monitoring. High traffic buses produce verbose output. Security policies may limit visibility.

dbus-monitor is part of the D-Bus project, started by Red Hat in 2002. D-Bus became the standard IPC mechanism for Linux desktops, and dbus-monitor has been essential for debugging and development since the early days of the project.

dbus-send(1), busctl(1), gdbus(1), qdbus(1)