vi 에디터로 /etc/inittab 를 수정!!
id:5:deafault -> id:3:deafault로 변경
Deafault runlevel. The runlevels used are:
0 - halt (Do NOT set initdefault to this)
1 - Single user mode
2 - Multiuser, without NFS
3 - Full multiuser mode
4 - unused
5 - X11
6 - reboot(Do NOT set initdefault to this)
