Improving dd's usage message

[Philipp Thomas]

We have a bug where an openSUSE user complains that only the info pages tell
of the uselesness of the directory flag for dd on Linux. In order help that
I've come up with this small change to dd's usage output which would then
also be part of the man page. Oppinions?

Philipp

diff --git a/NEWS b/NEWS
index ba0d3d7..b601061 100644
--- a/NEWS
+++ b/NEWS
@@ -15,6 +15,9 @@ GNU coreutils NEWS                                    -*- 
outline -*-
   --skip-chdir option is specified.
   [bug introduced in coreutils-8.23]
 
+** Improvements
+
+  dd now states in its help that the directory flag doesn't work on Linux.
 
 * Noteworthy changes in release 8.23 (2014-07-18) [stable]
 
diff --git a/src/dd.c b/src/dd.c
index 1e387f3..0030d1b 100644
--- a/src/dd.c
+++ b/src/dd.c
@@ -590,7 +590,10 @@ Each FLAG symbol may be:\n\
       if (O_DIRECT)
         fputs (_("  direct    use direct I/O for data\n"), stdout);
       if (O_DIRECTORY)
-        fputs (_("  directory  fail unless a directory\n"), stdout);
+        fputs (_("\
+  directory  fail unless a directory\n\
+             NOTE: This does not work on Linux\n\
+"), stdout);
       if (O_DSYNC)
         fputs (_("  dsync     use synchronized I/O for data\n"), stdout);
       if (O_SYNC)