Issue #19441 has been updated by nobu (Nobuyoshi Nakada). A `Tempfile` uses a finalizer to clean up the target file. That is the file will be removed when a dup of `Tempfile` is discarded (and also will be tried to remove again). I don't think it is a good idea to use `Tempfile#dup`. What do you want to achieve by using this method? ---------------------------------------- Bug #19441: Closing an IO#dup behaviour https://bugs.ruby-lang.org/issues/19441#change-101906 * Author: stac47 (Laurent Stacul) * Status: Open * Priority: Normal * ruby -v: ruby 3.2.1 (2023-02-08 revision 31819e82c8) [x86_64-darwin20] * Backport: 2.7: UNKNOWN, 3.0: UNKNOWN, 3.1: UNKNOWN, 3.2: UNKNOWN ---------------------------------------- Hello amazing ruby folks! I classified that ticket as a "Bug" although it is perhaps something I did not understand. Here is a ruby session: ``` ruby irb(main):001:0> file = Tempfile.new => #<File:/var/folders/m2/bljzrgq160vbf0vk466k_7gw0000gn/T/20230216-39664-davfmj> irb(main):002:0> file.fileno => 9 irb(main):003:0> dup = file.dup => #<File:/var/folders/m2/bljzrgq160vbf0vk466k_7gw0000gn/T/20230216-39664-davfmj> irb(main):004:0> dup.fileno => 10 irb(main):005:0> dup.close => nil irb(main):006:0> dup.closed? => false irb(main):007:0> file.closed? => true ``` The two last lines are unexpected to me. I would have expected the converse: ```ruby irb(main):006:0> dup.closed? => true irb(main):007:0> file.closed? => false ``` I tried this scenario in latest ruby but also in ruby 2.7. Thanks in advance for helping me to understand this behaviour. -- https://bugs.ruby-lang.org/