xset --help
usage: xset [-display host:dpy] option ...
To control Energy Star (DPMS) features:
-dpms Energy Star features off
+dpms Energy Star features on
dpms [standby [suspend [off]]]
force standby
force suspend
force off
force on
(also implicitly enables DPMS features)
a timeout value of zero disables the mode
Portanto, se você obtiver o ${DISPLAY}
do monitor, poderá:
xset -display ${DISPLAY} dpms force on