Unix - Shell Arithmetic Operators Example
Here is an example which uses all the arithmetic operators −
#!/bin/sh 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 $b / $a` echo "b / a : $val" val=`expr $b % $a` echo "b % a : $val" if [ $a == $b ] then echo "a is equal to b" fi if [ $a != $b ] then echo "a is not equal to b" fi
This would produce following result −
a + b : 30 a - b : -10 a * b : 200 b / a : 2 b % a : 0 a is not equal to b
There are following points to note down −
There must be spaces between operators and expressions for example 2+2 is not correct, where as it should be written as 2 + 2.
Complete expression should be enclosed between ``, called inverted commas.
You should use \ on the * symbol for multiplication.
if...then...fi statement is a decision making statement which has been explained in next chapter.