GNU bug report logs - #61884
add an option to du that allows to control which file types are counted

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Message #31 received at 61884-done <at> debbugs.gnu.org (full text, mbox):

From: Paul Eggert <eggert <at> cs.ucla.edu>
To: Christoph Anton Mitterer <calestyo <at> scientia.org>
Cc: 61884-done <at> debbugs.gnu.org
Subject: Re: bug#61884: add an option to du that allows to control which file
 types are counted
Date: Sat, 4 Mar 2023 17:00:25 -0800

[Message part 1 (text/plain, inline)]

On 2023-03-04 15:33, Christoph Anton Mitterer wrote:

> But would symlinks (i.e. their length) count for it?

Sure, because you can read symlinks by using readlink, and that gives 
you their lengths.

Come to think of it, POSIX specifies st_size only for regular files and 
symlinks among the files you'll find in a directory. So du --apparent 
should count st_size only for these file types; it should ignore st_size 
for other file types unless we know somehow that those sizes make sense 
(which for directories is problematic for the reasons you mention).


> What about hardlinked files, would they count once or n times?

That's an independent axis and is handled by -l. Hard links are not a 
file type.


>                b      block (buffered) special
>                c      character (unbuffered) special
>                d      directory
>                p      named pipe (FIFO)
>                f      regular file
>                l      symbolic link
>                s      socket
>                D      door (Solaris)

I expect Coreutils's already-existing usable_st_function should tell us 
which types have usable st_size. This will exclude directories, which 
should be the right thing for your use case.


So I installed the attached patch to fix du --apparent to count sizes 
only when st_size is well-defined. This should address your use case so 
I'm boldly closing the bug report.

[0001-du-apparent-counts-only-symlinks-and-regular.patch (text/x-patch, attachment)]

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