From: "apatniv (Vivek Ak)" Date: 2022-04-04T01:00:27+00:00 Subject: [ruby-core:108166] [Ruby master Bug#18676] Misleading Documentation/Bug: Incorrect File.position on a file opened with "a" mode Issue #18676 has been updated by apatniv (Vivek Ak). Hi Jeremy. Thanks you for your response. Should we update the documentation to indicate the same so that it help anyone who encounters the same issue? ---------------------------------------- Bug #18676: Misleading Documentation/Bug: Incorrect File.position on a file opened with "a" mode https://bugs.ruby-lang.org/issues/18676#change-97140 * Author: apatniv (Vivek Ak) * Status: Rejected * Priority: Normal * ruby -v: ruby 2.7.0p0 (2019-12-25 revision 647ee6f091) [x86_64-linux-gnu] * Backport: 2.6: UNKNOWN, 2.7: UNKNOWN, 3.0: UNKNOWN, 3.1: UNKNOWN ---------------------------------------- Documentation says that whenever a file is opened in "a" mode, the stream is positioned at the end of stream. However, #tell method returns 0 instead of the size of the file. (https://ruby-doc.org/core-3.1.1/IO.html#class-IO-label-Position) Issue happens with latest version of ruby 3.1.1 as well. How to reproduce: ``` ruby cat code_to_reproduce.txt fp = File.open("sample_data.txt", "a") puts "File size=#{fp.size} position=#{fp.tell}" ``` Output: See the **position value** ``` shell ->ruby -v ruby 2.7.0p0 (2019-12-25 revision 647ee6f091) [x86_64-linux-gnu] ->wc sample_data.txt 1 2 12 sample_data.txt ->cat sample_data.txt hello world ->ruby code_to_reproduce.txt File size=12 position=0 ->cat code_to_reproduce.txt fp = File.open("sample_data.txt", "a") puts "File size=#{fp.size} position=#{fp.tell}" ``` Further debugging with **`irb`** ``` ruby rb(main):009:0> fp = File.open("sample_data.txt", "a") irb(main):010:0> fp.tell => 0 irb(main):011:0> fp.size => 12 irb(main):012:0> fp.fileno => 7 irb(main):013:0> Process.pid => 22675 ``` Examining the offset in /proc filesytem ``` shell ->cat /proc/22675/fdinfo/7 pos: 0 flags: 02102001 mnt_id: 30 ``` -- https://bugs.ruby-lang.org/ Unsubscribe: