每天写点shell——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 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)

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

执行：

# ./age.sh
Please enter your age:
That makes you over  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、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

  #!/bin/bash
   # testing the REPLY environment variable

   read -p "Enter a number: "
   factorial=1
   for (( count=; count<= $REPLY; count++ ))
   do
      factorial=$[ $factorial * $count ]   #等号两端不要有空格
   done
  echo "The factorial of $REPLY is $factorial"

执行：

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

5、超时, 等待输入的秒数（read -t）

   #!/bin/bash
   # timing the data entry

   if read -t  -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命令对输入的字符判断

   #!/bin/bash
   # getting just one character of input

   read -n1 -p "Do you want to continue [Y/N]? " answer
   case $answer in
   Y | y) echo
          echo "fine, continue on...";;
   N | n) echo
          echo "OK, goodbye"
         exit;;
  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

6、隐藏方式读取(read -s)

   #!/bin/bash
   # hiding input data from the monitor

   read -s -p "Enter your passwd: " pass   #-s 参数使得read读入的字符隐藏
   echo
   echo "Is your passwd readlly $pass?"
~                                          

执行：

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

7、从文本中读取

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

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

执行：

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