dbus-monitor

D-Bus message bus monitoring and debugging tool

TLDR

Monitor session bus

$ dbus-monitor

Monitor system bus

$ dbus-monitor --system

Filter by interface

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

Monitor specific sender

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

Monitor method calls only

$ dbus-monitor "type='method_call'"

Profile mode (machine-readable)

$ dbus-monitor --profile

SYNOPSIS

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.

PARAMETERS

--system

Monitor system bus.

--session

Monitor session bus (default).

--address addr

Connect to specific bus address.

--profile

Output in profile format.

--monitor

Output in monitor format (default).

--pcap

Output in pcap format.

FILTER EXPRESSIONS

type='signal': Signal messagestype='method_call': Method callstype='method_return': Method returnstype='error': Error messagessender='name': From specific senderdestination='name': To specific destinationinterface='name': Specific interfacemember='name': Specific method/signalpath='path': Specific object path

CAVEATS

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

HISTORY

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.