I currently keep my app code on S3 and have a startup.sh script which is fired via /etc/rc.local and installs the apps and any edits etc. Thus when I make a change, I need to reboot all my instances for the change to take effect. Is there a way to trigger the script without rebooting the instance? EDIT: I do not want to individually log into all my instances. I would prefer a method that I can script up to apply to all my instances at once - which are in an autoscaling group.