RHEL - Basic knowledge

Boot loader
LILO, GRUB

Kernel load
inittab
/etc/inittab - 부팅 시 실행 될 프로그램 목록

id : runlevel : action : process
id - 1~4 개의 글자로  구성된 고유 이름
runlevel : 특정 레벨에서 실행하도록 명시
action : 필요한 동작
process : 실행 시킬 process

runlevel
0 - System halt (power off)
1 - Single user mode by root account (=s, S)
2 - multi user mode without network
3 - multi user mode with full function
4 - Not define for user
5 -  X Windows
6 - System Reboot

/etc/rc.d
init.d/ rc0.d/ rc1.d/ rc2.d/ rc3.d/ rc4.d/ rc5.d/ rc6.d/
8개의 실행 Script

K? - ? 순으로 프로세스 종료 (먼저실행)
S? - ? 순으로 프로세스 시작 (나중실행)

LILO - Linux loader
/etc/lilo.conf : configuration file
/sbin/lilo : excute file

GRUB - GRand Unified Boot-loader
[a] grub.conf 로드중 kernel parameter edit
[e] grub.conf edit
[c] QnA boot
[TAB] key로 명령어 자동완성가능

Edit > grub.conf에 영구 적용이 아님<ESC>로 취소
e : edit
d : delete
o : add
b : boot

Shutdown

1) Shutdown
-r : reboot
-h : halt
-c : cancel
-f : Quick boot without check filesystem
-k : warn
-t secs : secs delay after
-t tm : m min after
now : excute now
23:59(specific time) : excute specific time

2) Ctrl + Alt + Del : by root > reboot
3) init 6 : by root > reboot(not recommand)
4) init 0 : shutdown
5) poweroff : shutdown
6) reboot : reboot