Provide some options to enable/disable "stuff" that takes up the boot up time?

[jiande-my]

provide option for user to change run level program.

Depending on your default init level setting, the system will execute the programs from one of the following directories. Run level 0 – /etc/rc.d/rc0.d/ Run level 1 – /etc/rc.d/rc1.d/ Run level 2 – /etc/rc.d/rc2.d/ Run level 3 – /etc/rc.d/rc3.d/ Run level 4 – /etc/rc.d/rc4.d/ Run level 5 – /etc/rc.d/rc5.d/ Run level 6 – /etc/rc.d/rc6.d/ ref : https://www.thegeekstuff.com/2011/02/linux-boot-process/

we can inspire from sysv-rc-conf UI