shell script中read的用法

1、read基本读取

#!/bin/bash
#testing the read command  

echo -n "Enter you name:"   #echo -n 让用户直接在后面输入
read name  #输入的多个文本将保存在一个变量中
echo "Hello $name, welcome to my progra  

执行：

# ./read.sh
Enter you name: yuan
Hello yuan, welcome to my program  　

2、read -p (直接在read命令行指定提示符) 

#!/bin/bash
#testing the read -p option
read -p "Please enter your age: " age
days=$[ $age * 365 ]
echo "That makes you over $days days old!"  

3、read -p（指定多个变量）

#!/bin/bash
# entering multiple variables  

read -p "Enter your name:" first last
echo "Checking data for $last, $first"  

执行：

# ./read1.sh
Enter your name: a b
Checking data for b, a  

4、超时、等待输入的秒数（read -t）

#!/bin/bash
# timing the data entry  

if read -t 5 -p "Please enter your name: " name     #记得加-p参数， 直接在read命令行指定提示符
then
    echo "Hello $name, welcome to my script"
else
    echo
    echo "Sorry, too slow!"
fi  

执行：

# ./read3.sh
Please enter your name:
Sorry, too slow!  

# ./read3.sh
Please enter your name: wang
Hello wang, welcome to my script  

5、read命令对于输入字符的判断

• []有比较的判断的功能
• -o代表or
• &&在shell中的用法是如果&&左边的命令执行成功（即$?=0）时才能执行&&右边的命令

#!/bin/bash  

read -p "Please input(Y/N):" yn
[ "$yn" == "Y" -o "$yn" == "y" ]&&echo  "OK,continue"&&exit 0
[ "$yn" == "N" -o "$yn" == "n" ]&&echo "Oh,interrupt!"&&exit 0
echo "i don't konw what your choice is"&&exit 0

　执行：

yuanqiangfei@ubuntu:~/script$ ./sh01.sh
Please input(Y/N):y
OK,continue
yuanqiangfei@ubuntu:~/script$ ./sh01.sh
Please input(Y/N):n
Oh,interrupt!  

6、隐藏方式读取（read -s）

• 在中括号 [] 内的每个组件都需要有空白键来分隔；
• 在中括号内的变量，最好都以双引号括号起来；
• 在中括号内的常数，最好都以单或双引号括号起来。
• ==和！=两边都要有空格
• []有比较的判断的功能

#!/bin/bash
#entering muiltple variables  

while true
do
        read -s -p "Please enter your password:"  passwd  

        [ "$passwd" == "123456" ]&&echo "password is right!"&&exit 0
        [ "$passwd" != "123456" ]&&echo "password is not right,Please input again!"&&continue
done  

执行：

yuanqiangfei@ubuntu:~/script$ ./read.sh
Please enter your password:password is right!
yuanqiangfei@ubuntu:~/script$ ./read.sh
Please enter your password:password is not right,Please input again!
Please enter your password:  

7、从文本中读取

#!/bin/bash
# reading data from a file  

count=1
cat test | while read line
do
   echo "Line $count: $line"
   count=$[ $count + 1 ]
done
echo "Finished processing the file"  

执行结果：

 ./read6.sh
Line 1: The quick brown dog jumps over the lazy fox.
Line 2: This is a test, this is only a test.
Line 3: O Romeo, Romeo! Wherefore art thou Romeo?
Finished processing the file