Dbus

Dbus is a messaging system used in Linux display managers such as GNOME.

Accessing Dbus

Dbus is accessed using a socket whose location is defined as an environment variable named DBUS_SESSION_BUS_ADDRESS. Typically, it will look something like:

DBUS_SESSION_BUS_ADDRESS=unix:abstract=/tmp/dbus-2L2ZxqLwNR,guid=9bf5b79ea33d45373491174856252e15

This environment variable must be defined in order for Dbus utilities to work properly.

Watching For Messages / Events

You can watch the dbus for messages using the dbus-monitor utility. A filter can be passed as an argument. For example, to limit only messages sent by the GNOME SessionManager:

dbus-monitor "type=signal,sender='org.gnome.SessionManager'"

Sending Messages

Messages can be sent using dbus call or dbus-send.

Eg:

gdbus call --session --dest org.gnome.SessionManager \
  --object-path /org/gnome/SessionManager/Presence \
  --method org.gnome.SessionManager.Presence.SetStatus 0

See Also

• http://dbus.freedesktop.org/doc/dbus-send.1.html

Gnome Presence Key

• https://people.gnome.org/~mccann/gnome-session/docs/gnome-session.html#org.gnome.SessionManager.Presence:status

Gnome Screensaver (doesn't seem to work)

• http://unix.stackexchange.com/questions/107787/how-can-i-trigger-the-screensavers-locking-feature-using-d-bus-from-the-command