dbus-setenv is a compiled Lisp function in `dbus.el'.

(dbus-setenv BUS VARIABLE VALUE)

Set the value of the BUS environment variable named VARIABLE to VALUE.

BUS is either a Lisp symbol, `:system' or `:session', or a string
denoting the bus address. Both VARIABLE and VALUE should be strings.

Normally, services inherit the environment of the BUS daemon. This
function adds to or modifies that environment when activating services.

Some bus instances, such as `:system', may disable setting the environment.