Create A Infinite Loop in Shell Script

Written by Rahul, Updated on August 20, 2020

Question – How do I create an infinite loop in shell script on Unix/Linux operating system?

An infinite loop is used for running a set of instruction with never ending repeat. In this we create a loop which runs endlessly and keep executing the instructions until force stopped externally.

Bash Infinite While Loop

In this scenario, which loop is the best option. The following syntax is used for create infinite while loop in a shell script.

Loop Example:

#!/usr/bin/env bash

while :
do
    echo "Press [CTRL+C] to exit this loop..."
    # Add more instructions here
    sleep 2
done

#!/usr/bin/env bash

while :

echo "Press [CTRL+C] to exit this loop..."

# Add more instructions here

sleep 2

done

You can also Unix true command with while loop to run it endlessly. The while loop syntax with true command will look like below example.

Loop Example:

#!/usr/bin/env bash

while true
do
    echo "Press [CTRL+C] to exit this loop..."
    # Add more instructions here
    sleep 2
done

#!/usr/bin/env bash

while true

echo "Press [CTRL+C] to exit this loop..."

# Add more instructions here

sleep 2

done

Add Exist Instruction in Infinite Loop

Sometimes you may need to exit from a never ending loop based on a condition. If a specific condition meet and your want that infinite loop should break on that condition.

#!/usr/bin/env bash

while true
do
    echo "Press [CTRL+C] to exit this loop..."
    # Add more instructions here
    sleep 2

   if [ condition ]
   then
       break
   fi
done

#!/usr/bin/env bash

while true

echo "Press [CTRL+C] to exit this loop..."

# Add more instructions here

sleep 2

if [ condition ]

then

break

done

Add a if statement in above loop to break on matching condition.

Bash Infinite While Loop

Add Exist Instruction in Infinite Loop

Rahul

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