linux-shell编程-case语句

#!/bin/sh
echo -e "a:\c"
read a
echo -e "b:\c"
read b
echo -e "select(+ - * /):\c"
read var 
case $var in
    '+') echo "a+b="`expr $a "+" $b`;;
	"-") echo "a-b="`expr $a "-" $b`;;
	"*") echo "a*b="`expr $a "*" $b`;;
	"/") echo "a/b="`expr $a "/" $b`;;
	*) echo "error"
esac
exit 0

echo -e命令详细解释
echo-e 含义
Linux expr命令

#/bin/sh
read var
case $var in 
yes ly |Y echo "true";;
no|n| N) echo "flase" ;;
*) echo "input error";;
esac
exit 0