SHELL

bash while true

while :; do
  # loop infinitely
done

bash while loop

#!/bin/bash
i=0
While [ $i -le 10 ]
do
 echo i:$i
 ((i+=1))
done

bash while done

while CONDITION_STATEMENT; do SOME_CODE; done

bash while

#!/bin/bash
counter=$1
factorial=1
while [ $counter -gt 0 ]
do
   factorial=$(( $factorial * $counter ))
   counter=$(( $counter - 1 ))
done
echo "$factorial"