--- File.new(path[, mode [, perm]])
--- File.open(path[, mode [, perm]])
--- File.open(path[, mode [, perm]]) {|file| ... }

    pathǻꤵե򥪡ץ󤷡ե륪֥Ȥ
    ֤ޤեΥץ˼Ԥ㳰 Errno::EXXX 
    ȯޤ

     mode, perm ˤĤƤ Ȥ߹ߴؿ 
    open ƱǤ

    open() ϥ֥åꤹ뤳ȤǤޤ
    ֥åꤷƸƤӽФϡե륪֥Ȥ
    Ϳƥ֥å¹Ԥޤ֥åμ¹Ԥλȡ
    եϼưŪ˥ޤ

    ֥åꤵ줿ȤΤΥ᥽åɤͤϥ֥åμ¹Է
    Ǥ

