D-Bus

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

Installation

Install the dbus package:

# apk add dbus

If Xorg is used, install the dbus-x11 package which provides the dbus-launch command needed for D-Bus session bus as follows:

# apk add dbus-x11

Configuration

System D-Bus

To start system D-Bus service dbus at startup, enable it as follows:

# rc-update add dbus

To start the system D-Bus service immediately, use OpenRC 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 bus

Note: System D-Bus service needs to be running before launching an instance of D-Bus session bus.

To start a window manager along with D-bus session bus, use the command: $ dbus-run-session -- <your_wm> by replacing <your_wm> with your shell or a window manager.

If X11 based window manager is started using .xinitrc, to ensure that D-Bus session bus passes the environment variable $DBUS_SESSION_BUS_ADDRESS, add an entry as follows

Contents of .xinitrc

exec dbus-launch --exit-with-session <your_wm>

Running dbus-launch in a terminal requires export $(dbus-launch). If not, other running process won't find the socket of D-Bus session Bus.

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

See also

• Archwiki
• Gentoo Wiki