Once you have installed a new package, say, MySQL you should configure Gentoo to automatically start the daemon at boot time.
This is as easy as…
rc-update add mysql default
or…
rc-update -a mysql default
This will create an init script for MySQL in the default runlevel and the dependency cache will be updated. To disable an init script simply type:
rc-update del mysql default
or…
rc-update -d mysql default
Next command will show all the available scripts and at which runlevels they will be executed.
rc-update show
Another useful command will show the init scripts for the default runlevel and its status…
rc-status