Why cannot I define an empty function in shell?

Question

I am learning bash. I accidentally encounter a syntax error with empty function.

#!/bin/bash
# script name : empty_function.sh
function empty_func() {
}

bas         


        

Answer 1

Try this instead:

empty_func() {
  :
}

Answer 2

The bash shell's grammar simply doesn't allow empty functions. A function's grammar is:

  name () compound-command [redirection]
  function name [()] compound-command [redirection]

And in a compound command of the form:

{ list; }

list can't be empty. The closest you can get is to use a null statement or return:

function empty_func() {
    : 
}

or

function empty_func() {
    return
}