shell 学习之case语句

通常建议变量用引号括起来

-v 显示信息 

case 
shift
把刚才的变量踢掉

 

1、case语句：语法结构
case stitch in
value1)
    statement
    ...
    ;;
value2)
    statement
    ...
    ;;
*)
;;

esac

 

示例（给出选项让用户选择，而后根据用户所选显示出相应的信息）：

[root@lovelace case]# cat showmenu.sh
#!/bin/bash
#Version:0.1
#Auther:lovelace
#pragram:show menu and wait user choice
#
#difine an function to display the menu
showmenu(){
echo -n '+----------'
echo  -n -e "\033[1;32mshowmenu\033[0m"
echo '-----------+'
echo -e "| \033[31md|D) show disk information\033[0m  |"
echo -e "| \033[31mm|M) show memory usage\033[0m      |"
echo -e "| \033[31ms|S) show swap usage\033[0m        |"
echo -e "| \033[31mq|Q) quitting\033[0m               |"
echo -n '+-------------'
echo  -n -e "\033[5,33mEND\033[0m"
echo '--------------+'
}
#call showmenu function
echo
showmenu
echo
#read the argument for user input
read -p "Your choice is:" choice
#use while statement to loop
while [ "$choice" != "q" -o "$choice" != "Q" ];do
#jugement the choice values and dispaly the result
case $choice in
d|D)
echo "Disk information:"
df -h
;;
m|M)
echo "Memory information:"
free -m | grep "Mem"
;;
s|S)
echo "Swap information:"
free -m | grep "Swap"
;;
q|Q)
echo "quitting...."
exit 8
;;
*)
echo "Unknow argument."
;;
esac
#call showmenu function again
echo
showmenu
#read user input again
echo
read -p "Please select again:" choice
done

 

 

后记：这个好像就只是提了下case的语法结构，case在进行条件判断的时候相对于if来说，我的更直观一些，无论怎么讲，脚本注重的是实现的目的，而不是过程，因此无论黑猫白猫，只要能抓住老鼠，就是好猫。