shell流程控制之多分支case語句

1. case與if…elif…else

它們都是多分支條件句，不同的是，case語句只能判斷一種條件關係，而if語句可以判斷多種關係

case $變數名 in

"值1") 如果變數的值等於值1，則執行程式1;;
"值2") 如果變數的值等於值2，則執行程式2;;
......
*) 如果變數的值都不是以上的值，則執行此程式;;
esac

#!/bin/bash

#判斷使用者輸入
read -p "please choose yes/no:" -t 30 cho
case $cho in
"yes") echo "your choose is yes";;
"no") echo "your chosse is no";;
*) echo "please input yes|no";;
esac

[root@catyuan ~]# chmod 755 case1.sh 

[root@catyuan ~]# ./case1.sh 
please choose yes/no:yes
your choose is yes
[root@catyuan ~]# ./case1.sh 
please choose yes/no:no
your chosse is no
[root@catyuan ~]# ./case1.sh 
please choose yes/no:dv
please input yes|no

[root@catyuan ~]# vim case2.sh

#!/bin/bash
#選擇你想去的城市
echo "shanghai:please input 1"
echo "xi'an:please input 2"
echo "beijing:please input 3"
read -t 30 -p "please input your choose:" cho
case $cho in
"1") echo "shanghai";;
"2") echo "xi'an";;
"3") echo "beijing";;
*) echo "please input 1|2|3"
esac

[root@catyuan ~]# chmod 755 case2.sh 

[root@catyuan ~]# ./case2.sh 
shanghai:please input 1
xi'an:please input 2
beijing:please input 3
please input your choose:1
shanghai
[root@catyuan ~]# ./case2.sh 
shanghai:please input 1
xi'an:please input 2
beijing:please input 3
please input your choose:2
xi'an
[root@catyuan ~]# ./case2.sh 
shanghai:please input 1
xi'an:please input 2
beijing:please input 3
please input your choose:3
beijing
[root@catyuan ~]# ./case2.sh 
shanghai:please input 1
xi'an:please input 2
beijing:please input 3
please input your choose:5
please input 1|2|3

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