3個常用的 runlevel

[root@cacti ~]# vim /etc/inittab

# 0 - halt (Do NOT set initdefault to this)

# 1 - Single user mode(常用)

# 2 - Multiuser, without NFS (The same as 3, if you do not have networking)

# 3 - Full multiuser mode(常用)

# 4 - unused

# 5 - X11(常用)

# 6 - reboot