This is how you create an infinite loop in bash to run a piece of code infinitely at defined intervals.

#!/bin/bash
while [ 1 ]
do
       # Your code goes here

       # Modify sleep time (in seconds) as needed below
       sleep 2
done

I needed such code to monitor the size of a file every 2 seconds.

Source: http://blog.taragana.com/index.php/archive/how-to-write-infinite-loop-in-bash/