[PATCH] doc: clarify that du operands are interdependent

[Pádraig Brady]

Following on from http://bugs.gnu.org/17546
make it more obvious that du may elide specified operands
to avoid double counting in the set.

* src/du.c (usage): Specify that du operates on the set of
operands, rather than each independently.
* doc/coreutils.texi (du invocation): Likewise.  Also state
that the number of entries printed may change due to the
order specified.  Currently, deeper items specified earlier
will result in them being displayed, but don't mention that
implementation detail in the documentation.
* THANKS.in: Add reporter.
Reported by Stephen Shirley
---
 THANKS.in          | 1 +
 doc/coreutils.texi | 4 ++--
 src/du.c           | 2 +-
 3 files changed, 4 insertions(+), 3 deletions(-)

diff --git a/THANKS.in b/THANKS.in
index 3f71fef..3451c63 100644
--- a/THANKS.in
+++ b/THANKS.in
@@ -573,6 +573,7 @@ Stéphane Chazelas                   address@hidden
 Stephen Depooter                    address@hidden
 Stephen Eglen                       address@hidden
 Stephen Gildea                      address@hidden
+Stehpen Shirley                     address@hidden
 Stephen Smoogen                     address@hidden
 Steve McConnel                      address@hidden
 Steve McIntyre                      address@hidden
diff --git a/doc/coreutils.texi b/doc/coreutils.texi
index f6aef2d..1cc6532 100644
--- a/doc/coreutils.texi
+++ b/doc/coreutils.texi
@@ -11496,7 +11496,7 @@ or @option{-x} is used together with a file name 
argument.
 @cindex file space usage
 @cindex disk usage for files
 
-@command{du} reports the amount of disk space used by the specified files
+@command{du} reports the amount of disk space used by the set of specified 
files
 and for each subdirectory (of directory arguments).  Synopsis:
 
 @example
@@ -11511,7 +11511,7 @@ 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.
+and entries that @command{du} outputs.
 
 The program accepts the following options.  Also see @ref{Common options}.
 
diff --git a/src/du.c b/src/du.c
index e803e69..65fc074 100644
--- a/src/du.c
+++ b/src/du.c
@@ -283,7 +283,7 @@ Usage: %s [OPTION]... [FILE]...\n\
   or:  %s [OPTION]... --files0-from=F\n\
 "), program_name, program_name);
       fputs (_("\
-Summarize disk usage of each FILE, recursively for directories.\n\
+Summarize disk usage of the set of FILEs, recursively for directories.\n\
 "), stdout);
 
       emit_mandatory_arg_note ();
-- 
2.1.0