Shell脚本之：while

while循环用于不断执行一系列命令，也用于从输入文件中读取数据；命令通常为测试条件。其格式为：

while command
do
   Statement(s) to be executed if command is true
done

下面是一个基本的while循环的例子

#!/bin/bash
COUNTER=0
while [ $COUNTER -lt 5 ]
do
    COUNTER=`expr $COUNTER + 1`
    echo $COUNTER
done

while循环也可用于读取键盘信息

#!/bin/bash
echo ‘type <CTRL-D> to terminate‘
echo -n ‘enter something: ‘
while read FILM
do
    echo "you enter $FILM"
    echo -n ‘enter something: ‘
done