standardize some error messages

* maint.mk: (sc_error_message_warn_fatal, sc_error_message_uppercase):
(sc_error_message_period): Add automatic checks for non-standard error
messages.
* .x-sc_error_message_uppercase: explicit exclusion for this check
* src/cp.c: Standardize some error messages.
* src/date.c: Likewise.
* src/dircolors.c: Likewise.
* src/du.c: Likewise.
* src/expr.c: Likewise.
* src/install.c: Likewise.
* src/join.c: Likewise.
* src/ln.c: Likewise.
* src/mv.c: Likewise.
* src/od.c: Likewise.
* src/pr.c: Likewise.
* src/split.c: Likewise.
* src/truncate.c: Likewise.
* src/wc.c: Likewise.
* tests/du/files0-from: Expect new error message.
* tests/misc/join: Likewise.
* tests/misc/split-a: Likewise.
* tests/misc/wc-files0-from: Likewise.
* tests/misc/xstrtol: Likewise.
* lib/xmemxfrm.c: Likewise.

src/cp.c

@@ -592,7 +592,7 @@ do_copy (int n_files, char **file, const char *target_directory,
     {
       if (target_directory)
 	error (EXIT_FAILURE, 0,
-	       _("Cannot combine --target-directory (-t) "
+	       _("cannot combine --target-directory (-t) "
 		 "and --no-target-directory (-T)"));
       if (2 < n_files)
 	{

src/date.c

@@ -441,8 +441,8 @@ main (int argc, char **argv)
 	{
 	  error (0, 0,
 		 _("the argument %s lacks a leading `+';\n"
-		   "When using an option to specify date(s), any non-option\n"
-		   "argument must be a format string beginning with `+'."),
+		   "when using an option to specify date(s), any non-option\n"
+		   "argument must be a format string beginning with `+'"),
 		 quote (argv[optind]));
 	  usage (EXIT_FAILURE);
 	}

src/dircolors.c

@@ -448,8 +448,8 @@ to select a shell syntax are mutually exclusive"));
       error (0, 0, _("extra operand %s"), quote (argv[!print_database]));
       if (print_database)
 	fprintf (stderr, "%s\n",
-		 _("File operands cannot be combined with "
-		   "--print-database (-p)."));
+		 _("file operands cannot be combined with "
+		   "--print-database (-p)"));
       usage (EXIT_FAILURE);
     }
 

src/du.c

@@ -937,7 +937,7 @@ main (int argc, char **argv)
 	{
 	  error (0, 0, _("extra operand %s"), quote (argv[optind]));
 	  fprintf (stderr, "%s\n",
-		   _("File operands cannot be combined with --files0-from."));
+		   _("file operands cannot be combined with --files0-from"));
 	  usage (EXIT_FAILURE);
 	}
 

src/expr.c

@@ -777,9 +777,9 @@ eval2 (bool evaluate)
 	      if (errno)
 		{
 		  error (0, errno, _("string comparison failed"));
-		  error (0, 0, _("Set LC_ALL='C' to work around the problem."));
+		  error (0, 0, _("set LC_ALL='C' to work around the problem"));
 		  error (EXPR_INVALID, 0,
-			 _("The strings compared were %s and %s."),
+			 _("the strings compared were %s and %s"),
 			 quotearg_n_style (0, locale_quoting_style, l->u.s),
 			 quotearg_n_style (1, locale_quoting_style, r->u.s));
 		}

src/install.c

@@ -420,8 +420,8 @@ main (int argc, char **argv)
 	case PRESERVE_CONTEXT_OPTION:
 	  if ( ! selinux_enabled)
 	    {
-	      error (0, 0, _("Warning: ignoring --preserve-context; "
-			     "this kernel is not SELinux-enabled."));
+	      error (0, 0, _("WARNING: ignoring --preserve-context; "
+			     "this kernel is not SELinux-enabled"));
 	      break;
 	    }
 	  x.preserve_security_context = true;
@@ -430,8 +430,8 @@ main (int argc, char **argv)
 	case 'Z':
 	  if ( ! selinux_enabled)
 	    {
-	      error (0, 0, _("Warning: ignoring --context (-Z); "
-			     "this kernel is not SELinux-enabled."));
+	      error (0, 0, _("WARNING: ignoring --context (-Z); "
+			     "this kernel is not SELinux-enabled"));
 	      break;
 	    }
 	  scontext = optarg;
@@ -487,7 +487,7 @@ main (int argc, char **argv)
     {
       if (target_directory)
 	error (EXIT_FAILURE, 0,
-	       _("Cannot combine --target-directory (-t) "
+	       _("cannot combine --target-directory (-t) "
 		 "and --no-target-directory (-T)"));
       if (2 < n_files)
 	{

src/join.c

@@ -380,7 +380,7 @@ check_order (const struct line *prev,
 	    {
 	      error ((check_input_order == CHECK_ORDER_ENABLED
 		      ? EXIT_FAILURE : 0),
-		     0, _("File %d is not in sorted order"), whatfile);
+		     0, _("file %d is not in sorted order"), whatfile);
 
 	      /* If we get to here, the message was just a warning, but we
 		 want only to issue it once. */

src/ln.c

@@ -507,7 +507,7 @@ main (int argc, char **argv)
     {
       if (target_directory)
 	error (EXIT_FAILURE, 0,
-	       _("Cannot combine --target-directory "
+	       _("cannot combine --target-directory "
 		 "and --no-target-directory"));
       if (n_files != 2)
 	{

src/mv.c

@@ -450,7 +450,7 @@ main (int argc, char **argv)
     {
       if (target_directory)
 	error (EXIT_FAILURE, 0,
-	       _("Cannot combine --target-directory (-t) "
+	       _("cannot combine --target-directory (-t) "
 		 "and --no-target-directory (-T)"));
       if (2 < n_files)
 	{

src/od.c

@@ -1838,7 +1838,7 @@ it must be one character from [doxn]"),
 	{
 	  error (0, 0, _("extra operand %s"), quote (argv[optind + 1]));
 	  error (0, 0, "%s\n",
-		 _("Compatibility mode supports at most one file."));
+		 _("compatibility mode supports at most one file"));
 	  usage (EXIT_FAILURE);
 	}
     }

src/pr.c

@@ -913,7 +913,7 @@ main (int argc, char **argv)
 	      error (EXIT_FAILURE, 0,
 		     _("`--pages=FIRST_PAGE[:LAST_PAGE]' missing argument"));
 	    else if (! first_last_page (oi, 0, optarg))
-	      error (EXIT_FAILURE, 0, _("Invalid page range %s"),
+	      error (EXIT_FAILURE, 0, _("invalid page range %s"),
 		     quote (optarg));
 	    break;
 	  }
@@ -1099,11 +1099,11 @@ main (int argc, char **argv)
 
   if (parallel_files & explicit_columns)
     error (EXIT_FAILURE, 0,
-	 _("Cannot specify number of columns when printing in parallel."));
+	 _("cannot specify number of columns when printing in parallel"));
 
   if (parallel_files & print_across_flag)
     error (EXIT_FAILURE, 0,
-       _("Cannot specify both printing across and printing in parallel."));
+       _("cannot specify both printing across and printing in parallel"));
 
 /* Translate some old short options to new/long options.
    To meet downward compatibility with other UNIX pr utilities
@@ -2394,7 +2394,7 @@ print_header (void)
   print_white_space ();
 
   if (page_number == 0)
-    error (EXIT_FAILURE, 0, _("Page number overflow"));
+    error (EXIT_FAILURE, 0, _("page number overflow"));
 
   /* The translator must ensure that formatting the translation of
      "Page %"PRIuMAX does not generate more than (sizeof page_text - 1)

src/split.c

@@ -189,7 +189,7 @@ next_file_name (void)
 	  sufindex[i] = 0;
 	  outfile_mid[i] = suffix_alphabet[sufindex[i]];
 	}
-      error (EXIT_FAILURE, 0, _("Output file suffixes exhausted"));
+      error (EXIT_FAILURE, 0, _("output file suffixes exhausted"));
     }
 }
 

src/truncate.c

@@ -326,7 +326,7 @@ main (int argc, char **argv)
   /* must specify either size or reference file */
   if ((ref_file && got_size) || (!ref_file && !got_size))
     {
-      error (0, 0, _("You must specify one of %s or %s"),
+      error (0, 0, _("you must specify one of %s or %s"),
              quote_n (0, "--size"), quote_n (1, "--reference"));
       usage (EXIT_FAILURE);
     }

src/wc.c

@@ -646,7 +646,7 @@ main (int argc, char **argv)
 	{
 	  error (0, 0, _("extra operand %s"), quote (argv[optind]));
 	  fprintf (stderr, "%s\n",
-		   _("File operands cannot be combined with --files0-from."));
+		   _("file operands cannot be combined with --files0-from"));
 	  usage (EXIT_FAILURE);
 	}