Shell编程，read的用法_shell read用法

1、read基本读取

  1 #!/bin/bash
  2 #testing the read command
  3 
  4 echo -n "Enter you name:"   #echo -n 让用户直接在后面输入 
  5 read name  #输入的多个文本将保存在一个变量中
  6 echo "Hello $name, welcome to my program."                                      
执行：

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

2、read -p （直接在read命令行指定提示符）

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

# ./age.sh
Please enter your age: 23
That makes you over 8395 days old!

3、read -p （指定多个变量）

  1 #!/bin/bash
  2 # entering multiple variables
  3 
  4 read -p "Enter your name:" first last
  5 echo "Checking data for $last, $first"
执行：

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

4、read 命令中不指定变量，那么read命名将它收到的任何数据都放在特殊环境变量REPLY中

  1 #!/bin/bash
  2 # testing the REPLY environment variable
  3 
  4 read -p "Enter a number: "
  5 factorial=1                         
  6 for (( count=1; count< = $REPLY; count++ ))
  7 do
  8    factorial=$[ $factorial * $count ]   #等号两端不要有空格
  9 done
 10 echo "The factorial of $REPLY is $factorial"
执行：

./read2.sh
Enter a number: 6
The factorial of 6 is 720

5、超时, 等待输入的秒数（read -t）

  1 #!/bin/bash
  2 # timing the data entry
  3 
  4 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
  5 then
  6     echo "Hello $name, welcome to my script"
  7 else
  8     echo 
  9     echo "Sorry, too slow!"
 10 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

6、read命令对输入的字符判断

  1 #!/bin/bash
  2 # getting just one character of input
  3 
  4 read -n1 -p "Do you want to continue [Y/N]? " answer
  5 case $answer in
  6 Y | y) echo
  7        echo "fine, continue on...";;
  8 N | n) echo 
  9        echo "OK, goodbye"
 10        exit;;
 11 esac   
执行：

# ./read4.sh
Do you want to continue [Y/N]? y
fine, continue on...

./read4.sh
Do you want to continue [Y/N]? n
OK, goodbye

7、隐藏方式读取（read -s）

  1 #!/bin/bash
  2 # hiding input data from the monitor
  3 
  4 read -s -p "Enter your passwd: " pass   #-s 参数使得read读入的字符隐藏
  5 echo 
  6 echo "Is your passwd readlly $pass?"
~                                          
执行：

# ./read5.sh
Enter your passwd: 
Is your passwd readlly osfile@206?

8、从文本中读取

  1 #!/bin/bash
  2 # reading data from a file
  3 
  4 count=1
  5 cat test | while read line
  6 do
  7    echo "Line $count: $line"
  8    count=$[ $count + 1 ]
  9 done
 10 echo "Finished processing the file"
执行：

 ./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