Note that sorting uniq's input is often useful.

Suggested by Eric Blake.

3 files changed, 16 insertions, 0 deletions

diff --git a/ChangeLog b/ChangeLog
index 83b141087..8d5c1ab84 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,3 +1,8 @@
+2007-12-18  Jim Meyering  <meyering@redhat.com>
+
+	* src/uniq.c (usage): Note that sorting uniq's input is often useful.
+	Suggested by Eric Blake.
+
 2007-12-15  Jim Meyering  <meyering@redhat.com>
 
 	Version 6.9.91.
diff --git a/NEWS b/NEWS
index 60be2de8f..5285d51e6 100644
--- a/NEWS
+++ b/NEWS
@@ -1,5 +1,9 @@
 GNU coreutils NEWS                                    -*- outline -*-
 
+* Noteworthy changes in release 6.? (????-??-??) [?]
+
+
+
 * Noteworthy changes in release 6.9.91 (2007-12-15) [beta]
 
 ** Bug fixes
diff --git a/src/uniq.c b/src/uniq.c
index 286452249..5fcbed9a4 100644
--- a/src/uniq.c
+++ b/src/uniq.c
@@ -168,6 +168,13 @@ Mandatory arguments to long options are mandatory for short options too.\n\
 A field is a run of whitespace, then non-whitespace characters.\n\
 Fields are skipped before chars.\n\
 "), stdout);
+     fputs (_("\
+\n\
+Note: while uniq can be useful even with unsorted input, in most applications\n\
+the input is sorted in a manner consistent with field-selection options.\n\
+E.g., use `sort' if `uniq' uses no such option (or simply use `sort -u');\n\
+use `sort -k 3b' with uniq -f2.\n\
+"), stdout);
       emit_bug_reporting_address ();
     }
   exit (status);