D-Bus: Difference between revisions

Revision as of 16:10, 31 May 2025

D-Bus is a message bus system that provides a mechanism for inter-process communication.

Installation

Install the dbus package:

# apk add dbus

If you are using x11 you might also want to install the X11 add-ons which provide the dbus-launch command:

# apk add dbus-x11

If you want dbus to be started at system startup enable the OpenRC service:

# rc-update add dbus

To start the service immediately, use service start|stop|restart commands as follows:

# rc-service dbus start

Tip: If system D-Bus is running, the command:$ rc-service dbus status will output * status: started.

D-Bus session

System D-Bus service needs to be installed and running before launching a D-Bus session instance. You can start a dbus session using the command like this: dbus-run-session -- sh, by replacing sh with your shell or a window manager.

If you are running a X11 based window manager using .xinitrc, use : exec dbus-launch --exit-with-session your_favourite_wm so that D-Bus passes the environment variable $DBUS_SESSION_BUS_ADDRESS to its children. Running dbus-launch in a terminal means that other running process won't find this D-Bus's socket without a export $(dbus-launch).

Tip: If D-Bus session bus is properly configured, the command:$ echo $DBUS_SESSION_BUS_ADDRESS must provide a output.

If $DBUS_SESSION_BUS_ADDRESS is undefined, many applications will attempt to use the standard path:$XDG_RUNTIME_DIR/bus

Running D-Bus like so should work for many applications:

dbus-daemon --nofork --address unix:path=$XDG_RUNTIME_DIR/bus --session

For applications that dont work without $DBUS_SESSION_BUS_ADDRESS you can prepend your program with the follow workaround script which avoid launching multiple user dbus sessions:

#!/bin/sh
if [ ! -e "/tmp/dbus-$USER-env" ]; then
       echo "Creating new dbus session on /tmp/dbus-$USER-env"
       export $(dbus-launch)
       echo "${DBUS_SESSION_BUS_ADDRESS}" > /tmp/dbus-$USER-env
       echo "Dbus session address is: ${DBUS_SESSION_BUS_ADDRESS}"
else
       echo "Using dbus session address from /tmp/dbus-$USER-env"
       export DBUS_SESSION_BUS_ADDRESS="$(cat /tmp/dbus-$USER-env)"
       echo "Dbus session address is: ${DBUS_SESSION_BUS_ADDRESS}"
fi
if [ -n "$1" ]; then
       $@
fi

@@ Line 1: / Line 1: @@
-[https://en.wikipedia.org/wiki/D-Bus D-Bus] is a message bus system that provides a mechanism for inter-process communication. System D-Bus service needs to be [[#Installation|installed]] before launching a [[#D-Bus session|D-Bus session]] instance.
+[https://en.wikipedia.org/wiki/D-Bus D-Bus] is a message bus system that provides a mechanism for inter-process communication.
-Some services like [[PipeWire#D-Bus|Pipewire]] rely on a [[#D-Bus session|D-Bus session]] instance or expect it by default. Other processes will only be able to communicate with these services if D-Bus is running.
 == Installation ==
-{{Tip|Check if system D-Bus service is already installed and running:{{ic|$ rc-service dbus status}}, before proceeding futher.}}
 Install the dbus package: {{cmd|# apk add {{pkg|dbus}}}}
@@ Line 11: / Line 7: @@
 If you want dbus to be started at system startup enable the [[OpenRC]] service: {{cmd|# rc-update add dbus}}
 To start the service immediately, use service '''start|stop|restart''' commands as follows: {{cmd|# rc-service dbus start}}
+{{Tip|If system D-Bus is running, the command:{{ic|$ rc-service dbus status}} will output {{ic|* status: started}}.}}
 == D-Bus session ==
-{{Tip| If D-Bus session bus is properly configured, the command:{{ic|$ echo $DBUS_SESSION_BUS_ADDRESS}} must provide a output.}}
+System D-Bus service needs to be installed and running before launching a D-Bus session instance. You can start a {{ic|dbus session}} using the command like this: {{ic|dbus-run-session -- sh}}, by replacing '''sh''' with your shell or a window manager.
-You can start a {{ic|dbus session}} using the command like this: {{ic|dbus-run-session -- sh}}, by replacing '''sh''' with your shell or a window manager.
+If you are running a X11 based window manager using {{Path|.xinitrc}}, use : {{ic|exec dbus-launch --exit-with-session your_favourite_wm}} so that D-Bus passes the environment variable <code>$DBUS_SESSION_BUS_ADDRESS</code> to its children. Running <code>dbus-launch</code> in a terminal means that other running process won't find this  D-Bus's socket without a <code>export $(dbus-launch)</code>.
-If you are running a X11 based window manager using {{Path|.xinitrc}}, use : {{ic|exec dbus-launch --exit-with-session your_favourite_wm}} so that D-Bus passes the environment variable <code>$DBUS_SESSION_BUS_ADDRESS</code> to its children. Running <code>dbus-launch</code> in a terminal means that other running process won't find this  D-Bus's socket without a <code>export $(dbus-launch)</code>.
+{{Tip| If D-Bus session bus is properly configured, the command:{{ic|$ echo $DBUS_SESSION_BUS_ADDRESS}} must provide a output.}}
 If <code>$DBUS_SESSION_BUS_ADDRESS</code> is undefined, many applications will attempt to use the standard path:{{ic|$XDG_RUNTIME_DIR/bus}}
@@ Line 43: / Line 41: @@
 == See also ==
-* [[PipeWire#D-Bus|Pipewire and D-Bus]]
 * [https://wiki.archlinux.org/title/D-Bus Archwiki]
 * [https://wiki.gentoo.org/wiki/D-Bus Gentoo Wiki]
 [[Category:System Administration]]