Why is an empty loop invalid in shell script?

Question

I wanted to make my shell script wait infinitely and thought the below code would do it.

#!/bin/bash
while true
do
done

However, the above script reports syntax error.

./Infinite_Loop.sh: line 4: syntax error near unexpected token `done'

./Infinite_Loop.sh: line 4: `done'

Unlike programming languages, why does shell script expect at least one statement in loops?

Answer 1

Another option is just to set a NOP(no op) which is basically, do nothing.

In bash, the equivalent for a NOP is :.

while true; do
  :
done