shift [ -p ] [ n ] [ name ... ]
       The positional parameters ${n+1} ... are renamed to $1 ..., where
       n is an arithmetic expression that defaults to 1.  If  any  names
       are given then the arrays with these names are shifted instead of
       the positional parameters.

       If  the option -p is given arguments are instead removed (popped)
       from the end rather than the start of the array.
