shell的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 correct input

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")'

 

匹配符[]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 accept Y,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

注意：：
如果有多个单词可以用"|"隔开，如

case $yn in

   start | begin ) return 0;;

   end | over ) return 1;;

   * ) return 3;;

 

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 not found"*

[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 "this is not a execute file";;
"-rwxrwxr-x"*) echo "this is 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 15 Jun 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 15 Jun 9 19:00 22.txt
this is a execute file

这里需要注意的是：$(ls -l $1) $()取命令输出

匹配是用两个**，因为整个var的内容是一行，要在两个之间匹配

 

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.

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.sh 22.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sys v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