i have tried this but will not run my script on boot or when running the rc.local from prompt.
It shows the ip as in it but not my screen command it looks like this
execute it set
root@raspberrypi:~# ls -lasi /etc/rc.local
523710 4 -rwxr-xr-x 1 root root 538 Jun 21 08:04 /etc/rc.local

rc.local looks like this

!/bin/sh -e

rc.local

This script is executed at the end of each multiuser runlevel.

Make sure that the script will "exit 0" on success or any other

value on error.

In order to enable or disable this script just change the execution

bits.

By default this script does nothing.

Print the IP address

IP=$(hostname -I) || true
if [ "$IP" ]; then
printf "My IP address is %s\n" "$_IP"
fi

screen -d -m -S cgminer /home/pi/chminer/cgminer -c /home/pi/cgminer.conf

exit 0

what do i have wrong the screen works by hand but need it to start on boot

regards