shell-trap-屏蔽信号&锁定终端屏幕

trap可以屏蔽信号
详细情况：
http://man.linuxde.net/trap

#!/bin/bash
trap "" 2

n=1
while (( $n<=100 ))
do
        echo "number is $n"
        sleep 1s
        let n++
done
~          

运行上面脚本，ctrl+c无法终止。（可以后台运行，然后kill进程）
下面是一个扩展，可以锁定终端屏幕

#!/bin/bash
#lock the terminal
#屏蔽终止信号，按ctrl+c会执行lock_nice函数
trap "lock_nice" 2 3 15
#tab键上面的反引号
TTY=`tty`

lock_nice()
{
        echo -e "\r Nice.lock nice. the terminal stays locked ! \r"
}

SAVEDSTTY=`stty -g`
#不显示输入字符
stty -echo
echo -n -e "Enter you passwd to lock $TTY :"
read PASSWD
echo -e "\r"

while :
do
        #read form tty only !!
        echo -e -n  "input passwd for unlock:"
        read RESPONSE < $TTY
        echo -e "\r"
if [ "$RESPONSE" = "$PASSWD" ];
then
        echo   " unlocking..."
        break
fi

        # wrong passwd. return
       lock_nice
       echo -e " wrong passwd and terminal is locked ! \r"
done
#以终端可读的格式显示
stty $SAVEDSTTY

也可以固定密码

#!/bin/bash
#lock the terminal
trap "lock_nice" 2 3 15

TTY=`tty`

lock_nice()
{
        echo -e "\r Nice.lock nice. the terminal stays locked ! \r"
}

SAVEDSTTY=`stty -g`
PASSWD=qwe

while :
do
        #read form tty only !!
        echo -e -n  "input passwd for unlock:"
        read RESPONSE < $TTY
        echo -e "\r"
if [ "$RESPONSE" = "$PASSWD" ];
then
        echo   " unlocking..."
        break
fi

        # wrong passwd. return
	lock_nice
	echo -e " wrong passwd and terminal is locked ! \r"
	done
#以终端可读的格式显示
stty $SAVEDSTTY