how does this substition work?

Shell Programming and Scripting
1

Hi all,
Would like to know how these substitution works??

FINISHED="Done"
x=126
COLS=$((${x} -${#FINISHED} - 5))

here does the #FINISHED give the ascii value of "done" ,or how does it work?

Thanks

2

That's a standard bash/ksh variable expansion:

       ${#parameter}
              The length in characters of the value of  parameter  is  substi
              tuted.   If  parameter  is  * or @, the value substituted is the
              number of positional parameters.  If parameter is an array  name
              subscripted  by  *  or @, the value substituted is the number of
              elements in the array.