Without argument, setmetamode prints the current Meta key mode. With argument, it sets the Meta key mode as indicated. The setting before and after the change are reported.
The Meta key mode is specific for each VT (and the VT corresponding to stdin is used). One might use setmetamode in /etc/rc to define the initial state of the Meta key mode, e.g. by
for t in 1 2 3 4 5 6 7 8; do
setmetamode escprefix < /dev/tty$t
done