du vs. hard links and argument order: improve documentation

* doc/coreutils.texi (du invocation): Document default behavior on
hard links, and why argument order matters.

diff --git a/doc/coreutils.texi b/doc/coreutils.texi
index 040a1de9c7d4c2bb19bf87c0aebe32b293f3d097..df6792d7ecfad6d1cfcc5b21d95dece82905167b 100644 (file)
--- a/doc/coreutils.texi
+++ b/doc/coreutils.texi
@@ -9686,6 +9686,11 @@ directory.  Normally the disk space is printed in units of
 1024 bytes, but this can be overridden (@pxref{Block size}).
 Non-integer quantities are rounded up to the next higher unit.
 
+If two or more hard links point to the same file, only one of the hard
+links is counted.  The @var{file} argument order affects which links
+are counted, and changing the argument order may change the numbers
+that @command{du} outputs.
+
 The program accepts the following options.  Also see @ref{Common options}.
 
 @table @samp