Perl5 リファレンス

       reset EXPR

       reset   Generally used in a `continue' block at the end of
               a loop to clear variables and reset `??' searches
               so that they work again.  The expression is
               interpreted as a list of single characters
               (hyphens allowed for ranges).  All variables and
               arrays beginning with one of those letters are
               reset to their pristine state.  If the expression
               is omitted, one-match searches (`?pattern?') are
               reset to match again.  Resets only variables or
               searches in the current package.  Always returns
               1.  Examples:

                   reset 'X';          # reset all X variables
                   reset 'a-z';        # reset lower case variables
                   reset;              # just reset ?one-time? searches

               Resetting `"A-Z"' is not recommended because
               you'll wipe out your `@ARGV' and `@INC' arrays and
               your `%ENV' hash.  Resets only package
               variables--lexical variables are unaffected, but
               they clean themselves up on scope exit anyway, so
               you'll probably want to use them instead.  See the
               my entry elsewhere in this document.