$FreeBSD$
--- diff.c.orig	2004-04-12 15:44:35.000000000 +0800
+++ diff.c	2007-06-15 14:51:05.506679851 +0800
@@ -137,7 +137,7 @@
 }
 
 static char const shortopts[] =
-"0123456789abBcC:dD:eEfF:hHiI:lL:nNpPqrsS:tTuU:vwW:x:X:y";
+"0123456789abBcC:dD:eEfF:hHiI:lL:nNopPqrsS:tTuU:vwW:x:X:y";
 
 /* Values for long options that do not have single-letter equivalents.  */
 enum
@@ -265,14 +265,15 @@
   initialize_main (&argc, &argv);
   program_name = argv[0];
   setlocale (LC_ALL, "");
-  bindtextdomain (PACKAGE, LOCALEDIR);
   textdomain (PACKAGE);
   c_stack_action (0);
   function_regexp_list.buf = &function_regexp;
   ignore_regexp_list.buf = &ignore_regexp;
-  re_set_syntax (RE_SYNTAX_GREP | RE_NO_POSIX_BACKTRACKING);
+  re_set_syntax (RE_SYNTAX_GREP);
   excluded = new_exclude ();
 
+  prepend_default_options (getenv ("DIFF_OPTIONS"), &argc, &argv);
+
   /* Decode the options.  */
 
   while ((c = getopt_long (argc, argv, shortopts, longopts, 0)) != -1)
@@ -428,6 +429,11 @@
 	  new_file = true;
 	  break;
 
+	case 'o':
+	  /* Output in the old tradition style.  */
+	  specify_style (OUTPUT_NORMAL);
+	  break;
+
 	case 'p':
 	  show_c_function = true;
 	  add_regexp (&function_regexp_list, "^[[:alpha:]$_]");
@@ -983,8 +989,6 @@
 {
   if (output_style != style)
     {
-      if (output_style != OUTPUT_UNSPECIFIED)
-	try_help ("conflicting output style options", 0);
       output_style = style;
     }
 }