dbus-launch

dbus-launch [OPTION...] [-- [PROGRAM [ARGS...]]]

--autolaunch=<machine-id>
    Print autolaunch address for given machine ID and exit.

--binary=<filename>
    Use specified binary instead of dbus-daemon.

--close-stderr
    Close stderr when forking the daemon.

--config-file=<filename>
    Pass config file to daemon's --config-file.

--desktop=<desktop>
    Pass desktop identifier to daemon's --desktop.

--exit-with-session
    Exit when session bus exits.

--exit-with-x11
    Exit if DISPLAY vanishes (e.g., X server exits).

--exit-with-xsession
    Exit if USER_XSESSION_RUNNING unsets.

--sh-syntax
    Print DBUS_SESSION_BUS_ADDRESS in Bourne shell syntax.

--version
    Print version and exit.

D-Bus is a message bus system for interprocess communication (IPC) in Linux, enabling applications to interact seamlessly.
dbus-launch starts a new dbus-daemon session bus if none exists, configures it with standard settings, and exports environment variables like DBUS_SESSION_BUS_ADDRESS and DBUS_SESSION_BUS_PID.

Primarily used in user sessions via shell scripts (e.g., .xinitrc, login managers), it ensures desktop apps like notifications, file managers, and power daemons can communicate. Invoke as eval $(dbus-launch --sh-syntax) to set variables, or dbus-launch some-program to run a program with the bus.

If a bus already runs (checked via DBUS_SESSION_BUS_ADDRESS), it reuses it without starting a new one, preventing duplicates.

In modern systems (GNOME, KDE), PAM or session managers auto-start the bus, reducing dbus-launch necessity. Still vital for custom X sessions, containers, or headless setups needing per-session D-Bus.

Deprecated in D-Bus 1.12+: Session buses auto-start; prefer dbus-run-session for new scripts.
Does not daemonize by default; use with --exit-with-session for cleanup.

eval $(dbus-launch --sh-syntax) to set vars.
dbus-launch --exit-with-session xterm to run program with bus.

Exports DBUS_SESSION_BUS_ADDRESS (address), DBUS_SESSION_BUS_PID (PID), DBUS_SESSION_BUS_WINDOWID (optional XID).

Introduced ~2002 in D-Bus 0.30 (freedesktop.org project by Havoc Pennington et al.) for GNOME/KDE IPC standardization. Evolved through D-Bus 1.x; largely obsoleted by auto-activation in systemd-logind/PAM integrations post-2017.

dbus-daemon(1), dbus-run-session(1), dbus-send(1), dbus-monitor(1)