$REPLY : 当没有参数变量提供给read命令的时候，这个变量会作为默认变量提供给read命令


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#!/bin/bash
#reply.sh
#REPLY是提供给'read'命令的默认变量.

echo
echo -n "What is you favorite vegetable?"
read

#当没有变量提供给'read'命令时，REPLY才保存最后一个'read'命令读入的值
echo "Your favorite vegetable is $REPLY"

echo "----------------"

echo

echo -n "What is you favorite fruit?"
read fruit
echo "Your favorite fruit is $fruit"
echo "but..."
#$REPLY还是保存着上一个命令的值，因为变量$fruit被传入到了这个新的"read"命令中
echo "Value of \$REPLY is still $REPLY"
echo
exit 0



--------------运行结果-------------
[root@cy-cloud02 exercise]# sh reply.sh

What is you favorite vegetable?123
Your favorite vegetable is 123
----------------

What is you favorite fruit?apple
Your favorite fruit is apple
but...
Value of $REPLY is still 123