Ways to Increment a counter variable in Bash Script

If you are writing a bash script and you want to increment a counter variable, below are five ways in which you can do it.

Option 1: Using += operator

#!/bin/bash

counter_variable=0

((counter_variable+=1))

echo $counter_variable 

Output:

Option 2: Using let command

#!/bin/bash

counter_variable=0

let "counter_variable=counter_variable+1"

echo $counter_variable 

Output:

Option 3: Using arithmetic expansion

#!/bin/bash

counter_variable=2

((counter_variable++))

echo $counter_variable 

Output:

Option 4: Using expr command

#!/bin/bash

counter_variable=5

counter=$(expr $counter_variable + 1)

echo $counter_variable 

Output:

Option 5: Using (( )) construct

#!/bin/bash

counter_variable=9

((counter_variable++))

echo $counter_variable 

Output:

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Documentation/Man Pages:

1. let command: Bash let command

2. Arithmetic expansion: Bash Arithmetic Expansion

3. expr command: Bash expr command

4. += operator: Bash Shell Arithmetic

5. (( )) construct: Bash Shell Arithmetic