root 执行vi /etc/inittab

修改 id:5:initdefault:一行，将5修改成3，如下所示：

# Default runlevel. The runlevels used by RHS are:

#   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)

# 

id:3:initdefault:

rhel5.6图形界面修改为命令行登陆系统