ubuntu - Can't attach screen session -

i'm running ubuntu server 14.04.2 lts. trying add java app (minecraft) startup using init.d config. here's snippet:

minecraft_dir="/srv/minecraft-server" start_command="java -xincgc -xmx8g -xx:maxpermsize=128m -jar spigot.jar" screen_name="minecraft-server"  attach() {     screen -rx $screen_name }  start() {     echo "starting minecraft server..."     if cd $minecraft_dir && screen -dms $screen_name $start_command;         echo "minecraft server started. use 'sudo service minecraft attach'."     fi } 

when issue sudo service minecraft start fine, can see screen session in htop and sudo screen -list prints out screen session. can attach sudo service minecraft attach or sudo screen -x.

but after sudo update-rc.d minecraft defaults , rebooting server, though can see screen session in htop, not listed in sudo screen -list , can no longer attach it!

i tried using crontabs root or user no success.

here full init.d script.

it came out had specify shell explicitly with

bash -c "cd $minecraft_dir && screen -dms $screen_name $start_command" 

or if run user, can

username='minecraft' invocation="cd $minecraft_dir && screen -dms $screen_name $start_command" su - "$username" -s /bin/bash -c "$invocation" 

thanks this giving idea.