Bash provides different operators that we can use in our Bash Script.
- Arithmetic
- Assignment
- Bitwise
- Logical
- Relational
Arithmetic Operator
Bash provides multiple operations through which we can perform Mathematical/Arithmetic operations on variables.
| Operator | Description |
+ | Addition |
* | Multiplication |
- | Subtraction |
/ | Divison |
% | Modulo |
** | Exponentiation |
+= | Plus-Equal(Increments a Variable value) |
*= | Times-Equal(Multiply a Variable value) |
-= | Minus-Equal(Decrement a Variable value) |
/= | Slash-Equal(Divide a Variable Value) |
%= | Mod-Equal( Remainder of Dividing a Variable) |
Let’s see some of the examples below.
# Addition
~$ echo $[5+5]
10
# Subtraction
~$ echo $[ 10 -3 ]
7
# Multiplication
~$ echo $[ 10 * 3 ]
30
# Division
~$ echo $[10/5]
2
# Modulus Operation
~$ echo $[10%5]
0
~$ echo $[10%3]
1
## Another way of using the internal Calulator.
~$ echo $((10 + 5 ))
15
Assignment Operator
Bash provides mainly equals to = as an assignment operator.
| Operator | Description |
= | Initialize/Change the value of the variable assigned |
Bitwise Operator
Bitwise operators process bits or bit patterns, unlike other operators.
| Operator | Description |
<< | Bitwise Left Shift |
<<== | Left-Shift-Equal |
| >> | Bitwise Right Shift |
| >>== | Right-Shift-Equal |
| | Bitwise OR |
|= | Bitwise OR-Equal |
& | Bitwise AND |
&= | Bitwise OR-Equal |
| ~ | Bitwise NOT |
| ^ | Bitwise XOR |
^= | Bitwise XOR-Equal |
Logical Operator
| Operators | Description |
| ! | NOT |
| && | AND |
| || | OR |
Relational Operator
These Operators work on two operands or Variables and return True or False accordingly. Some of this operator like lt can be used in if statements.
| Operator | Description |
== or -eq | Not Equal. The result is True if two operands/variables is not equal, else gives a False |
!= or -ne | Less Than. The result is true if the First Operand/Variable is less than the Second Operand, else gives False |
< or -lt | Equals to. The result is True if two operands/variables are equal, else gives a False |
<= or -le | Greater than or equal. The result is true if the First Operand is greater than or Equal to the Operand Second |
> or -gt | Less than or equal. The result is true if the First Operand/Variable is less than or equals to The second Operand, else Return False |
>= or -ge | Greater than or equal. The result is true if the First Operand is greater than or Equal to the Operand Second |
-Z | Checks if the value of an operand is null or not |
When we compare Strings, it is recommended to put the variables into double quotes " so that it minimizes the error if the variable is null or contains paces.
Example:
name1="nitendratech"
name2="nitendratech"
if [ "$name1" == "$name2" ]