sets magic cookie for current value of $DISPLAY

sort-magic-cookie.sh

#!/bin/bash
#script based on answer to this question https://unix.stackexchange.com/questions/209746/how-to-resolve-no-protocol-specified-for-su-user
if [ -z "$DISPLAY" ]; then
        echo "DISPLAY not defined"
        exit 1
fi
rm ~/.Xauthority
touch ~/.Xauthority
ROOT_XAUTHORITY_FILE="$(pgrep -a Xorg | awk '{print $7}')"
if ! sudo test -e "$ROOT_XAUTHORITY_FILE"; then
        echo "The candidate Xauthority file " "$ROOT_XAUTHORITY_FILE" " does not exist"
        exit 2
fi
MAGIC_COOKIE_1=$(sudo xauth -f "$ROOT_XAUTHORITY_FILE" list | head -n 1 | sed -rn "s/.*MIT-MAGIC-COOKIE-1\s+([0-9a-f]{32}).*/\1/p")
xauth add "$DISPLAY" MIT-MAGIC-COOKIE-1 "$MAGIC_COOKIE_1"