Thanks for the bug report. I installed the attached patch. It uses a
hand-maintained date, which is more likely to give the user the (accurate)
impression that the grep man page is not the focus of our documentation efforts.
>From 8d1953300ef03d05fb3864d944d1de81613a9bb6 Mon Sep 17 00:00:00 2001
From: Paul Eggert <egg...@cs.ucla.edu>
Date: Tue, 11 Jul 2017 08:20:26 -0700
Subject: [PATCH] doc: define Dt string in man page
Problem reported by Bjarni I. Gislason via Santiago R.R. (Bug#27651).
* doc/grep.in.1 (dT): New macro.
(Dt): Define this string.
---
doc/grep.in.1 | 15 +++++++++++++++
1 file changed, 15 insertions(+)
diff --git a/doc/grep.in.1 b/doc/grep.in.1
index 40c9586..ecc8105 100644
--- a/doc/grep.in.1
+++ b/doc/grep.in.1
@@ -1,4 +1,14 @@
.\" GNU grep man page
+.de dT
+.ds Dt \\$2
+..
+.dT Time-stamp: "2017-06-21"
+.\" Update the above date whenever a change to either this file or
+.\" grep.c's 'usage' function results in a nontrivial change to the man page.
+.\" In Emacs, you can update the date by running 'M-x time-stamp'
+.\" after you make a change that you decide is nontrivial.
+.\" It is no big deal to forget to update the date.
+.
.if !\n(.g \{\
. if !\w|\*(lq| \{\
. ds lq ``
@@ -1213,3 +1223,8 @@ This man page is maintained only fitfully;
the full documentation is often more up-to-date.
.\" Work around problems with some troff -man implementations.
.br
+.
+.\" Format for Emacs-maintained Dt string defined at this file's start.
+.\" Local variables:
+.\" time-stamp-format: "%:y-%02m-%02d"
+.\" End:
--
2.7.4
