????????????????RHEL??????????????????????:
????POST??????-->BIOS(Boot Sequence)-->?????????????MBR(bootloader) -->?????????ü?????BootLoader-->Kernel?????-->initrd—>/etc/init???????/etc/inittab
?????????BootLoader(RHEL???Grub)?????????????????.
????1. ????Grub?????????Kernel??????(/boot/vmlinuz)???????????棬???????????????е??????????(????η?????POST????????)
????2. ????Initial RAM Disk(/boot/initrd)??????????н???????????kernel????????????????????????????????????????????????????????.
????3. ??????????????????????????????????????????????????????/sbin/init?? init?????????/etc/inittab????/etc/inittab?У????1漲?????????:
??????? runlevel ????????е?????????.
??????? /etc/rc.d/rc.sysinit ???????????
????????runlevel???????????????????????????????
?????????Щ?????????????????.
????/sbin/init ???????????????????е??????????????????????????????á???????????????????????????????????????е????????????/etc/inittab?е?????.
????/etc/rc.d?? ????????rc.local?? rc.sysinit?? init.d?? rcX.d (X????0-6??????runlevel)
????/etc/rc.d/init.d?? ?????????????????????????????/etc/init.d???????????????.
????/etc/rc.d/rcX.d?? ?????????Щ??????????????K?????????STOP????????????S????????Start???????????е?????????д????????С?????????.
????/etc/rcX.d????????????????????rcX.d??????????????/etc/rc.d/init.d?????????????.
????/etc/rc.d/rc.local?? ??????????????·????/etc/rc.local??
??????????runlevel?????rcX.d?е???????????rc.local??????????????????????????3??5????????????????????????rc3.d??rc5.d???????????????????.