From fe8eebd4161a3a852aab7d87d11178f5d6a1d229 Mon Sep 17 00:00:00 2001 From: simon Date: Sun, 6 Dec 2009 14:08:52 +0000 Subject: [PATCH] Come clean about a false-positive scenario in agedu. I don't have the faintest idea how it could generally be solved, but I got bitten by it last month so the least I can do is warn about it in the man page. git-svn-id: svn://svn.tartarus.org/sgt/agedu@8766 cda61777-01e9-0310-a592-d414129be87e --- agedu.but | 12 ++++++++++++ 1 file changed, 12 insertions(+) diff --git a/agedu.but b/agedu.but index 3fc1a23..1494140 100644 --- a/agedu.but +++ b/agedu.but @@ -596,6 +596,18 @@ willingness to do additional coding \dash to run a system-wide \cw{agedu} scan on a \cw{cron} job and serve the right subset of reports to each user. +In certain circumstances, \cw{agedu} can report false positives +(reporting files as disused which are in fact in use) as well as the +more benign false negatives (reporting files as in use which are +not). This arises when a file is, semantically speaking, \q{read} +without actually being physically \e{read}. Typically this occurs +when a program checks whether the file's mtime has changed and only +bothers re-reading it if it has; programs which do this include +\cw{rsync}(\e{1}) and \cw{make}(\e{1}). Such programs will fail to +update the atime of unmodified files despite depending on their +continued existence; a directory full of such files will be reported +as disused by \cw{agedu} but deleting them will cause trouble. + \U LICENCE \cw{agedu} is free software, distributed under the MIT licence. Type -- 2.11.0