Setting up an external screen

x220:~$ cat /etc/udev/rules.d/20-hdmi.rules
KERNEL=="card0", ACTION=="change", RUN+="/usr/sbin/hdmi"
x220:~$ cat /usr/sbin/hdmi
#!/bin/sh

export XAUTHORITY=/home/hendry/.Xauthority
export DISPLAY=:0.0

/usr/bin/xrandr --output LVDS1 --auto --output HDMI1 --left-of LVDS1 --auto
x220:~$