I'm trying to run D-Bus on an embedded system (Yocto Linux) and connect to it from my application code.
I get the following error when I call dbus_bus_get(DBUS_BUS_SESSION, &err);
Using X11 for dbus-daemon autolaunch was disabled
at compile time, set your DBUS_SESSION_BUS_ADDRESS
instead
I realize that I need to start the dbus-daemon first so I have run dbus-launch from the command line.
This prints out a value of DBUS_SESSION_BUS_ADDRESS but how could I export it programmatically?
I've finally found the answer, running the following command exports the output of dbus-launch:
export $(dbus-launch)
dbus-daemon process. Is that desirable?
export DBUS_SESSION_BUS_ADDRESS=unix:path=/run/user/$UID/bus. It works for me. (I tried in cron, it seems to not know $XDG_RUNTIME_DIR).DBUS_SESSION_BUS_ADDRESS. See this QA answer for how to find that.pid_gnome=$(pgrep gnome-session)
DBUS_SESSION_BUS_ADDRESS=$(grep -z DBUS_SESSION_BUS_ADDRESS /proc/${pid_gnome}/environ|cut -d= -f2-)
export DBUS_SESSION_BUS_ADDRESS=${DBUS_SESSION_BUS_ADDRESS}
Please make sure that the user has the DISPLAY variable set.
Another alternative is:
export $(dbus-launch)
pgrep gnome-session may output multiple PIDs (e.g. three processes on Ubuntu 20.04), so it should be pgrep gnome-session | head -1. DBUS_SESSION_BUS_ADDRESS=$(grep ... | cut -d= -f2-) ends with 000a (\0\n), which causes warning bash: warning: command substitution: ignored null byte in input when export. So it should be DBUS_SESSION_BUS_ADDRESS=$(grep ... | cut -d= -f2- | tr -d '\0\n').grep -P, | cut is not needed. export DBUS_SESSION_BUS_ADDRESS=$(grep -P -o -a "(?<=DBUS_SESSION_BUS_ADDRESS=).+?(?=\x00)" /proc/"$(pgrep gnome-session | head -1)"/environ)Type the following command into a terminal:
eval `dbus-launch --auto-syntax`
When you launch your user session, do it like this:
dbus-daemon --session --fork --print-address 1 > /tmp/dbus-session-addr.txt
This will cause the session address to be written to /tmp/dbus-session-addr.txt. (The filename's not that important, it's just somewhere you've decided to store it.)
Then, when you need the variable set:
export DBUS_SESSION_BUS_ADDRESS=$(cat /tmp/dbus-session-addr.txt)
If your shell's sniffy about export-during-definition - some can be - do it in two stages:
DBUS_SESSION_BUS_ADDRESS=$(cat /tmp/dbus-session-addr.txt)
export DBUS_SESSION_BUS_ADDRESS
It sounds like you are trying to get the value of DBUS_SESSION_BUS_ADDRESS in order for your application to run correctly. Try running it with dbus-run-session instead of dbus-launch. According to https://dbus.freedesktop.org/doc/dbus-launch.1.html dbus-launch should not be run from the command line, but in a shell script (see also https://dbus.freedesktop.org/doc/dbus-run-session.1.html).
Type in terminal:
export $DBUS_SESSION_BUS_ADDRESS
