133-Unit2 System Initialization and Services

Boot Sequence Overview :BIOS-MBR(512byte)-Kernel(driver)-init(RunLevel)

BIOS Initializatin :POST-Boot Device Selected-First sector(MBR)

Boot Loader (MBR) : or in a partition's boot sector

    first.MBR 446byte  second.GRUB /boot

GRUB and grub.conf: /boot/grub/grub.conf

Starting the Boot Process :GRUB

Kernel Initialization:device detection -device driver initialization -mount root fs as ro -init

init Initialization: /etc/inittab {init run level(5);/etc/rc.sysinit;/etc/rc.d/rc 5;trap key;UPS;tty;x11}

Run levels : 0 -Halt; 1/S/emergency -Single-user mode;2 -multi-user without NFS;3 -multi-user text mode ; 4 -user define (3);5 -x11;6 -Reboot    

init n ; runlevel command

/etc/rc.d/rc.sysinit:activate udev and seliunx;set system clock ;keymaps;swap;hostname;root fs check and remount;activate RAID and LVM;disk quotas;check and mount other fs;clean locks and PID files

/etc/rc.d/rc: runlevel files

daemon process:standalone;transient(xinetd--super daemon)

system V script:/etc/rc.d/init.d;/etc/init.d/script start/stop

/etc/rc.d/rc.local

virtual consoles:/etc/inittab /sbin/mingetty

controlling services:default startup{ntsysv;chkconfig};manually{service(/etc/init.d/xxx start);chkconfig}

system shutdown:shutdown -h now;halt;poweroff;init 0 (都会作sync)

system reboot: shutdown -r now ;reboot ;init 6 ;Ctrl+Alt+Del(Virtual Console)