$ sudo update-rc.d apache2 disable
update-rc.d: warning: apache2 start runlevel arguments (none) do not match LSB Default-Start values (2 3 4 5)
update-rc.d: warning: apache2 stop runlevel arguments (none) do not match LSB Default-Stop values (0 1 6)
Disabling system startup links for /etc/init.d/apache2 ...
Removing any system startup links for /etc/init.d/apache2 ...
/etc/rc0.d/K09apache2
/etc/rc1.d/K09apache2
/etc/rc2.d/S91apache2
/etc/rc3.d/S91apache2
/etc/rc4.d/S91apache2
/etc/rc5.d/S91apache2
/etc/rc6.d/K09apache2
Adding system startup for /etc/init.d/apache2 ...
/etc/rc0.d/K09apache2 -> ../init.d/apache2
/etc/rc1.d/K09apache2 -> ../init.d/apache2
/etc/rc6.d/K09apache2 -> ../init.d/apache2
/etc/rc2.d/K09apache2 -> ../init.d/apache2
/etc/rc3.d/K09apache2 -> ../init.d/apache2
/etc/rc4.d/K09apache2 -> ../init.d/apache2
/etc/rc5.d/K09apache2 -> ../init.d/apache2