1、Redhat 5.X/CentOS5.X
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使用Root账户登陆系统，修改/etc/inittab
# Trap CTRL-ALT-DELETE
ca::ctrlaltdel:/sbin/shutdown -t3 -r now

这句前面加“#”注销掉 就可以了！
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2、Fedora 10/11

按照上面的方法，当我们修改/etc/inittab文件时我们发现该文件的内容变了如下：
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# inittab is only used by upstart for the default runlevel.
#
# ADDING OTHER CONFIGURATION HERE WILL HAVE NO EFFECT ON YOUR SYSTEM.
#
# System initialization is started by /etc/event.d/rcS
#
# Individual runlevels are started by /etc/event.d/rc[0-6]
#
# Ctrl-Alt-Delete is handled by /etc/event.d/control-alt-delete
#
# Terminal gettys (tty[1-6]) are handled by /etc/event.d/tty[1-6] and
# /etc/event.d/serial
-----------------------------------------

注意看提示，内容已经告诉我们该如何去做了。

编辑/etc/event.d/control-alt-delete

[root@mypc ~]# vim /etc/event.d/control-alt-delete
-----------------------------------------------------
# control-alt-delete - emergency keypress handling
#
# This task is run whenever the Control-Alt-Delete key combination is
# pressed. Usually used to shut down the machine.

start on control-alt-delete

exec /sbin/shutdown -r now "Control-Alt-Delete pressed"

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上面的内容最后两句注释掉 就好了！

注意：图形界面下Ctrl+Alt+Delete仍然有效，但是在字符界面被禁用了。