case只能判断一种条件关系,而if能判断多种条件关系
#!/bin/bash read -p "please input your choice (high/middle/low):" -t 30 choice case $choice in "high") echo "your choice is $choice" ;; ##千万别漏下 "middle") echo "your choice is $choice" ;; "low") echo "your choice is $choice" ;; *) echo "error high/middle/low" ;; esac ##千万别漏下