From: "jmthomas (Jason Thomas)" Date: 2012-05-05T00:34:22+09:00 Subject: [ruby-core:44874] [ruby-trunk - Bug #6401][Open] Windows bug with File.pos Issue #6401 has been reported by jmthomas (Jason Thomas). ---------------------------------------- Bug #6401: Windows bug with File.pos https://bugs.ruby-lang.org/issues/6401 Author: jmthomas (Jason Thomas) Status: Open Priority: Normal Assignee: Category: Target version: 1.9.3 ruby -v: ruby 1.9.3p194 (2012-04-20) [i386-mingw32] On Windows since Ruby 1.9.3p125 there have been issues with File.pos and File.readline. Ruby 1.9.3p0 does not have this issue. I have created the following test: def test_pos_with_readline t = make_tempfile random = Random.new(1234) open(t.path, "w") do |f| 500.times do f.puts "X"*random.rand(80) end end i = 0 lines = open(t.path,'r').read.split("\n") open(t.path, "r") do |f| lines.length.times do f.pos assert_equal lines[i], f.readline.chomp i += 1 end end end If you comment out the f.pos line this test case will pass. I originally submitted issue #6179 but the fixes applied there made things better but did not complete solve the problem. I apologize for the test case but it requires many lines with newlines to reproduce. -- http://bugs.ruby-lang.org/