redhat linux的运行级

# 0 - halt (Do NOT set initdefault to this)
# 1 - Single user mode
# 2 - Multiuser, without NFS (The same as 3, if you do not have networking)
# 3 - Full multiuser mode
# 4 - unused
# 5 - X11
# 6 - reboot (Do NOT set initdefault to this)

需要参考/etc/inittab才能判断系统缺省的运行级别：id:3:initdefault:
切换运行级telinit X