shell脚本之数学计算

#!/bin/bash a=10 b=20 val=`expr $a + $b` echo "a+b=$val" val=`expr $a - $b` echo "a-b=$val" val=`expr $a \* $b` echo "a*b=$val" val=`expr $a / $b` echo "a/b=$val" val=`expr $b % $a` echo "b%a=$val" if [ $a == $b ] then echo "a==b" fi if [ $a != $b ] then echo "a!=b" fi 输出结果: a+b=30 a-b=-10 a*b=200 a/b=0 b%a=0 a!=b 注意expr表达式里的运算符前后都有空格