Shell Programming and Scripting

fun1()
{
  : fun2  # what is the use of this statement?

  command1
  command2
  ....

}

fun2 ()
{
  VAR1=1
  VAR2="some string"

  : f $VAR1 s $VAR2     #what is the use of this statement?
}

If an option character not contained in the optstring operand is  found
       where  an option character is expected, the shell variable specified by
       name is set to the question-mark ( ? ) character. In this case, if  the
       first  character  in optstring is a colon (:, the shell variable OPTARG
       is set to the option character found, but no output is written to stan-
       dard  error;  otherwise, the shell variable OPTARG is unset and a diag-
       nostic message is written to standard error. This condition is  consid-
       ered to be an error detected in the way arguments were presented to the
       invoking application, but is not an error in getopts processing.

       If an option-argument is missing:

	   o	  If the first character of optstring is a  colon,  the  shell
		  variable specified by name is set to the colon character and
		  the shell variable OPTARG is set  to	the  option  character
		  found.

	   o	  Otherwise,  the  shell  variable specified by name is set to
		  the question-mark character (?), the shell  variable	OPTARG
		  is  unset,  and  a diagnostic message is written to standard
		  error. This condition is considered to be an error  detected
		  in the way arguments were presented to the invoking applica-
		  tion, but is not an error in getopts processing; a  diagnos-
		  tic  message	is  written  as stated, but the exit status is
		  zero.

fun1 ()
{
    : whatever
}

fun1 ()
{
    # whatever
}

place_holder_for_a_new_function()
{
        :
}

place_holder_for_a_new_function()
{
        # Comment!
}