D-Bus: Difference between revisions

Revision as of 07:05, 7 May 2025

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

Some services rely on a D-Bus session instance or expect it by default (including Pipewire). Other processes will only be able to communicate with these services if d-bus is running.

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 use the service immediately without restarting, start it manually:

# rc-service dbus start

The above commands related to dbus service only starts the system D-bus. The D-Bus session needs to be started separately for each user.

D-Bus session

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).

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 5: / Line 5: @@
 == Installation ==
-Install the dbus package:
+Install the dbus package: {{cmd|# apk add {{pkg|dbus}}}}
-{{cmd|# apk add {{pkg|dbus}}}}
+If you are using x11 you might also want to install the X11 add-ons which provide the <code>dbus-launch</code> command:{{cmd|# apk add {{pkg|dbus-x11}}}}
-If you are using x11 you might also want to install the X11 add-ons which provide the <code>dbus-launch</code> command:
+If you want dbus to be started at system startup enable the [[OpenRC]] service: {{cmd|# rc-update add dbus}}
-{{cmd|# apk add {{pkg|dbus-x11}}}}
+To use the service immediately without restarting, start it manually: {{cmd|# rc-service dbus start}}
-If you want dbus to be started at system startup enable the service:
-{{cmd|# rc-update add dbus}}
+The above commands related to {{ic|dbus service}} only starts the system D-bus. The [[#D-Bus session|D-Bus session]] needs to be started separately for each user.
-To use the service without restarting you need to start it manually:
-{{cmd|# rc-service dbus start}}
-{{note|This only starts the system dbus. The dbus session is started separatly for each user.}}
 == D-Bus session ==
-You can start a dbus session like this: <code>dbus-run-session -- sh</code>(replacing sh with your shell or a window manager), or, <code>export $(dbus-launch)</code>.
+You can start a {{ic|dbus session}} using the command like this: {{ic|dbus-run-session -- sh}}, by replacing '''sh''' with your shell or a window manager.
-D-Bus passes the environment variable <code>$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.
+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 $(dbus-launch)</code>.
-If <code>$DBUS_SESSION_BUS_ADDRESS</code> is undefined, many applications will attempt to use the standard path:
+If <code>$DBUS_SESSION_BUS_ADDRESS</code> is undefined, many applications will attempt to use the standard path:{{ic|$XDG_RUNTIME_DIR/bus}}
- $XDG_RUNTIME_DIR/bus
-Running D-Bus like so should work for many applications:
-{{Cmd|dbus-daemon --nofork --address unix:path{{=}}$XDG_RUNTIME_DIR/bus --session}}
+Running D-Bus like so should work for many applications: {{Cmd|dbus-daemon --nofork --address unix:path{{=}}$XDG_RUNTIME_DIR/bus --session}}
 For applications that dont work without <code>$DBUS_SESSION_BUS_ADDRESS</code> you can prepend your program with the follow workaround script which avoid launching multiple user dbus sessions:
@@ Line 48: / Line 40: @@
 == See also ==
 * [[PipeWire#D-Bus|Pipewire and D-Bus]]
 * [https://wiki.archlinux.org/title/D-Bus Archwiki]