raspberry pi turn on hdmi connected display. Use fbset -s to find the current values for xres and yres. You need to make some change to the fb values before the refresh call or nothing happens.

display_on.sh

#!/bin/bash
set -o pipefail
tvservice -s | grep -q '\[TV is off\]'
if [[ $? -eq 0 ]]; then
  # Turn display on.
  /usr/bin/tvservice -p &> /dev/null
  # Change color depth to 8 and back to 16.
  /bin/fbset -xres 1920 -yres 1200 -depth 8
  /bin/fbset -xres 1920 -yres 1200 -depth 16
  # Now that something has changed refresh.
  /usr/bin/xrefresh -d :0
fi