shell script中read的用法

1、read基本读取

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#!/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：

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# ./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) 

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#!/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）

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

执行： 

 

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

4、超时、等待输入的秒数（read -t）

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#!/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：

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# ./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

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#!/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：

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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 

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#!/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：

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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

 

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#!/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：

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./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