[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index]
bug#17546: Problem with du
From: |
Paul Eggert |
Subject: |
bug#17546: Problem with du |
Date: |
Wed, 21 May 2014 19:42:11 -0700 |
User-agent: |
Mozilla/5.0 (X11; Linux x86_64; rv:24.0) Gecko/20100101 Thunderbird/24.5.0 |
Dale R. Worley wrote:
before release 8.6, the order of arguments didn't matter
No, order mattered even back then. For example:
$ du --version | sed 1q
du (GNU coreutils) 8.4
$ ls -li d/* e/*
11765482 -rw-r--r-- 1 eggert csfac 159910666 May 1 20:42 d/j
23558745 -rw-r--r-- 2 eggert csfac 410000000 Apr 22 21:34 d/k
23558745 -rw-r--r-- 2 eggert csfac 410000000 Apr 22 21:34 e/k
$ du d e d e
557664 d
4 e
156480 d
4 e
$ du e d e d
401188 e
156480 d
4 e
156480 d
So file argument order affected link counts even back then; it's just
that before 8.6 this was true only for files with link count greater
than 1, which led to odd behaviors such as the behavior shown above.
What changed in 8.6 is that the behavior was made consistent for all
files, not just those with link count greater than 1. so that for the
same data the current version of du generates output like this:
$ du --version | sed 1q
du (GNU coreutils) 8.22
$ du d e d e
557664 d
4 e
$ du e d e d
401188 e
156480 d
This sums to the same values independent of file order, which is a plus.
As far as I can see, POSIX doesn't allow the old behavior, but does
allow the new one.
This leads to startlingly odd behaviors
Any choice of behavior for 'du' will lead to odd behaviors sometimes,
and there's no way we can make everybody happy in all cases. There is
an important technical advantage of du's current behavior, though; you
can get the behavior you prefer by running "du X; du Y". If we chaned
du to reset itself between command-line arguments, there'd be no way to
get the behavior I prefer, which is to count files just once.