Date: 15 Jul 2003 07:02:32 -0000 From: Colin Percival <cperciva@daemonology.net> To: FreeBSD-gnats-submit@FreeBSD.org Subject: bin/54492: tail -F duplicates lines Message-ID: <20030715070232.26214.qmail@builder.daemonology.net> Resent-Message-ID: <200307150710.h6F7AHYD067014@freefall.freebsd.org>
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>Number: 54492 >Category: bin >Synopsis: tail -F duplicates lines >Confidential: no >Severity: serious >Priority: medium >Responsible: freebsd-bugs >State: open >Quarter: >Keywords: >Date-Required: >Class: sw-bug >Submitter-Id: current-users >Arrival-Date: Tue Jul 15 00:10:17 PDT 2003 >Closed-Date: >Last-Modified: >Originator: Colin Percival >Release: FreeBSD 4.7-SECURITY >Organization: >Environment: >Description: tail -F sometimes duplicates lines after the first rotation. >How-To-Repeat: cperciva@beastie$ rm foo && touch foo && ( for x in 1 2 3 4 5; do echo hello $x > foo && sleep 2 && echo world $x >> foo;done & tail -F foo ) hello 1 world 1 hello 2 hello 2 # this line shouldn't be here world 2 hello 3 hello 3 # this line shouldn't be here world 3 hello 4 hello 4 # this line shouldn't be here world 4 hello 5 hello 5 # this line shouldn't be here world 5 I've also observed this when using `tail -F` on Apache logfiles (again, after the file has been rotated once; when that happens, it prints out all the lines in the file again, as if the file had been rotated). >Fix: Based on the symptoms, I'd say it looks like a bug in either the rotation-detection or the truncation-detection code; but I'm not familiar enough with kqueue to say any more than that. >Release-Note: >Audit-Trail: >Unformatted:
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