dbus-monitor [--system | --session | --address ADDRESS] [--profile | --monitor | --pcap | --binary] [watch expressions]
There are two well-known message buses: the systemwide message bus (installed on many systems as the "messagebus" service) and the per-user-login-session message bus (started each time a user logs in). The --system and --session options direct dbus-monitor to monitor the system or session buses respectively. If neither is specified, dbus-monitor monitors the session bus.
dbus-monitor has two different text output modes: the 'classic'-style monitoring mode, and profiling mode. The profiling format is a compact format with a single line per message and microsecond-resolution timing information. The --profile and --monitor options select the profiling and monitoring output format respectively.
dbus-monitor also has two binary output modes. The binary mode, selected by --binary, outputs the entire binary message stream (without the initial authentication handshake). The PCAP mode, selected by --pcap, adds a PCAP file header to the beginning of the output, and prepends a PCAP message header to each message; this produces a binary file that can be read by, for instance, Wireshark.
If no mode is specified, dbus-monitor uses the monitoring output format.
In order to get dbus-monitor to see the messages you are interested in, you should specify a set of watch expressions as you would expect to be passed to the dbus_bus_add_match function.
The message bus configuration may keep dbus-monitor from seeing all messages, especially if you run the monitor as a non-root user.
Monitor the system message bus.
Monitor the session message bus. (This is the default.)
Monitor an arbitrary message bus given at ADDRESS.
Use the profiling output format.
Use the monitoring output format. (This is the default.)