Ruby 4.0 リファレンスマニュアル

instance method Pathname#write

write(string, offset=nil, **opts) -> IntegerRuby 2.1.0 から[permalink][rdoc][edit]
(String content, ?Integer offset, ?mode: Integer | String, ?flags: Integer, ?external_encoding: encoding, ?internal_encoding: encoding, ?encoding: encoding, ?textmode: boolish, ?binmode: boolish, ?autoclose: boolish) → Integer

IO.write(self.to_s, string, offset, **opts)と同じです。

[SEE_ALSO] IO.write