From: "leocassarani (Leo Cassarani)" Date: 2013-04-28T21:13:24+09:00 Subject: [ruby-core:54656] [ruby-trunk - Bug #8342][Open] IO.readlines ignores Encoding.default_internal if Encoding.default_external is ASCII-8BIT Issue #8342 has been reported by leocassarani (Leo Cassarani). ---------------------------------------- Bug #8342: IO.readlines ignores Encoding.default_internal if Encoding.default_external is ASCII-8BIT https://bugs.ruby-lang.org/issues/8342 Author: leocassarani (Leo Cassarani) Status: Open Priority: Normal Assignee: Category: Target version: ruby -v: 1.9.3 Backport: 1.9.3: UNKNOWN, 2.0.0: UNKNOWN Under normal circumstances, IO.readlines will transcode from Encoding.default_external to Encoding.default_internal: File.open('hi', 'w') { |f| f.puts "hello\n" } Encoding.default_external = Encoding::US_ASCII Encoding.default_internal = Encoding::UTF_8 puts IO.readlines('hi').first.encoding #=> UTF-8 However, when Encoding.default_external is set to ASCII-8BIT, IO.readlines will always use ASCII-8BIT, regardless of what Encoding.default_internal is set to: File.open('hi', 'w') { |f| f.puts "hello\n" } Encoding.default_external = Encoding::ASCII_8BIT Encoding.default_internal = Encoding::UTF_8 puts IO.readlines('hi').first.encoding #=> ASCII-8BIT Using IO#gets instead of IO.readlines will produce the same behaviour. -- http://bugs.ruby-lang.org/