shell作为一门语言，自然也具有读数据的功能，read就是按行从文件(或标准输入或给定文件描述符)中读取数据的最佳选择。当使用管道、重定向方式组合命令时感觉达不到自己的需求时，不妨考虑下while read line。
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
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