In this article, we will see the different options available in performing arithmetic operations in UNIX . These will come handy while working at the command prompt or for writing scripts. For the sake of simplicity,we will take the example of adding two numbers.

**1**. The first example makes use of the

**expr**command. All the other arithmetic operators(-,/,%) can be used in the same way except for *(multiplication).

$ x=3 $ y=4 $ expr $x + $y 7

To multiply the numbers, precede the * with a \. This is done in order to prevent the shell from interpreting the * as a wild card.

$expr $x \* $y 12

**2**.

**bc**command can also be used for arithmetic operations.

$ echo $x + $y | bc 7

**3**. The ((..)) notation does provide options for arithmetic operations.

$ echo $(($x+$y)) 7

**4**. The

**let**command can also be used for arithmetic operations. Notice here the $ symbol is not used against the variable.

$ let z=x+y $ echo $z 7

**let**can work with unary operators as shown below:

$ let z=++z $ echo $z 8

**5**. The

**awk**command used as shown below to do the arithmetic operations of shell variables.

$ echo "" | awk '{print '$x' + '$y'}' 7Enjoy Arithmetic!!!

Note: The above mentioned methods are applicable for shells ksh, sh and bash, and not in csh or tcsh.

echo $[ $x + $y ] This can also work well

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