[src/trunk]: src/usr.bin/m4 Explain what REDIRECT is for.

[christos <christos%NetBSD.org@localhost>]

details:   https://anonhg.NetBSD.org/src/rev/61a8c68e69bc
branches:  trunk
changeset: 813278:61a8c68e69bc
user:      christos <christos%NetBSD.org@localhost>
date:      Sat Jan 23 14:24:43 2016 +0000

description:
Explain what REDIRECT is for.

diffstat:

 usr.bin/m4/main.c |  9 +++++++--
 1 files changed, 7 insertions(+), 2 deletions(-)

diffs (31 lines):

diff -r cb1e4a48acb1 -r 61a8c68e69bc usr.bin/m4/main.c
--- a/usr.bin/m4/main.c Sat Jan 23 14:03:48 2016 +0000
+++ b/usr.bin/m4/main.c Sat Jan 23 14:24:43 2016 +0000
@@ -1,5 +1,5 @@
 /*     $OpenBSD: main.c,v 1.77 2009/10/14 17:19:47 sthen Exp $ */
-/*     $NetBSD: main.c,v 1.45 2016/01/16 21:12:27 christos Exp $       */
+/*     $NetBSD: main.c,v 1.46 2016/01/23 14:24:43 christos Exp $       */
 
 /*-
  * Copyright (c) 1989, 1993
@@ -42,7 +42,7 @@
 #include "nbtool_config.h"
 #endif
 #include <sys/cdefs.h>
-__RCSID("$NetBSD: main.c,v 1.45 2016/01/16 21:12:27 christos Exp $");
+__RCSID("$NetBSD: main.c,v 1.46 2016/01/23 14:24:43 christos Exp $");
 #include <assert.h>
 #include <signal.h>
 #include <getopt.h>
@@ -325,6 +325,11 @@
                }
 
 #ifdef REDIRECT
+       /*
+        * This is meant only for debugging; it makes all output
+        * go to a known file, even if the command line options
+        * send it elsewhere. It should not be turned of in production code.
+        */
        if (freopen("/tmp/m4", "w+", stderr) == NULL)
                err(EXIT_FAILURE, "Can't redirect errors to `%s'",
                    "/tmp/m4");