shell编程 case语句

case语句格式

# vi test.sh : echo "input : " read num echo "the input data is $num" case $num in 1) echo"January";;    双分号结束 2) echo "Feburary";; 5) echo"may"         每个case可以有多条命令          echo "sdfd"    echo"sdf";;       但最后一条命令一定是双分号结束 *) echo "not correct input";;   *）是其他值、default的意思      esac

# sh ./test.sh input : 2 the input data is 2 Feburary # sh ./test.sh input : ter the input data is ter not correctinput

 
    case 语句如果某个选项没有任何语句，也要加;;否则会出下边错误
test: line 166: syntax error near unexpected token `)'
test: line 166: `"system hostname config")'


    为什么输入no,仍不匹配到[no]
原来[]是专门针对 单字符的值,如果用[no],就是n和o之一

case $yn in    [no]) return 1;;   * )  echo "only acceptY,y,N,n,YES,yes,NO,no">&2;;

[macg@mac-home ~]$ sh test.sh enter y/n : no                           only accept Y,y,N,n,YES,yes,NO,no

改正

case $yn in     no) return 1;;   NO) return 1;;   * ) echo "only accept Y,y,N,n,YES,yes,NO,no">&2;;  esac

[macg@mac-home ~]$ sh test.sh enter y/n : no

    一个getyn()函数的例子

getyn( ) { while echo "enter y/n:" do  read yn  case $yn in   [Yy]) return 0 ;;   yes) return 0 ;;   YES) return 0 ;;   [Nn]) return 1 ;;   no) return 1;;   NO) return 1;;   * ) echo "only accept Y,y,N,n,YES,yes,NO,no";;  esac done }

if getyn 调用函数     以函数作为if条件,必须用if command法 then    注意0为真 echo " your answer is yes" else echo "your anser is no" fi

    if, case，匹配字符串最常见，但如何匹配一段很长的输出，一堆文字？最好方法，用“*”，如：*"command notfound"*

[macg@machome ~]$ vi test.sh var=$(ls -l$1)     $()取命令输出，$1是命令行参数 echo "output is $var" case $var in "-rw-rw-r--"*) echo "thisis not a execute file";; "-rwxrwxr-x"*) echo "thisis a execute file"; 注意*在双引号外边 esac

[macg@machome ~]$ sh test.sh 22.txt output is -rw-rw-r--  1 macg macg 15Jun  9 19:00 22.txt this is not a execute file [macg@machome ~]$ chmod +x 22.txt [macg@machome ~]$ sh test.sh 22.txt output is -rwxrwxr-x  1 macg macg 15Jun  9 19:00 22.txt this is a execute file

   例2．匹配file命令输出的一堆文字,以获知文件类型
用’ ’ 取输出,然后用CASE+*对输出做修饰处理.

[macg@machome ~]$ vi test.sh var=`file$1`       `  `和$()作用相同，是取命令输出 echo "output is $var" case $var in "$1: ASCII text"*) echo "this is a text file";; "$1: directory"*) echo "this is a directory";; 注意*在双引号外边 esac

[macg@machome ~]$ sh test.sh22.txt output is 22.txt: ASCII text this is a text file [macg@machome ~]$ sh test.sh test-dir output is test-dir: directory this is a directory

     最典型的shell case命令匹配命令行，用于sysv启动脚本的start|stop|restart|status处理
  case  "$@"  in    
($@ 字符串数组：以"参数1" "参数2" ...的字符串数组形式保存所有参数 
对于单个参数的情况，$@就是一个字符串)

 start)    
         echo  -n  "Starting  firewall..."    
         。。。  
         echo  "OK!"    
         exit  0    
         ;;    
 stop)    
         echo  -n  "Stopping   firewall..."
         。。。   
         exit  0    
         ;;   
restart)    
          $0  stop    $0即执行原始程序       
          $0  start    
         ;;    
status)    
         clear    
         echo  ">------------------------------------------"    
         iptables  -L    
         echo  ">------------------------------------------"    
         iptables  -t  nat  -L  POSTROUTING    
         exit  0   
    *)    
         echo  "Usage:  $0  {start|stop|restart|status}"    
         exit  1    
 esac