From 8013a92f9a11ef63a3fa44107fc58f974b0132ef Mon Sep 17 00:00:00 2001
From: bapt <bapt@FreeBSD.org>
Date: Sat, 11 Mar 2017 06:24:49 +0000
Subject: [PATCH] Extend functionality MANPATH in man(1) to followup with
 apropos(1) from mandoc.

If MANPATH begins with a colon, it is appended to the default list; if it ends
with a colon, it is prepended to the default list; or if it contains two
adjacent colons, the standard search path is inserted between the colons.  If
none of these conditions are met, it overrides the standard search path.

Import the MANPATH description from mandoc into the man(1) man page

Reported by:	kargl
MFC after:	1 week
---
 usr.bin/man/man.1  | 25 +++++++++++++++++--------
 usr.bin/man/man.sh | 25 ++++++++++++++++++++++++-
 2 files changed, 41 insertions(+), 9 deletions(-)

diff --git a/usr.bin/man/man.1 b/usr.bin/man/man.1
index 79626562d7d2..93cbc723cfd7 100644
--- a/usr.bin/man/man.1
+++ b/usr.bin/man/man.1
@@ -25,7 +25,7 @@
 .\"
 .\" $FreeBSD$
 .\"
-.Dd January 28, 2017
+.Dd March 11, 2017
 .Dt MAN 1
 .Os
 .Sh NAME
@@ -295,13 +295,22 @@ Corresponds to the
 .Fl m
 option.
 .It Ev MANPATH
-Used to find the location of the manual files.
-See
-.Xr manpath 1
-for additional information.
-Corresponds to the
-.Fl M
-option.
+The standard search path used by
+.Xr man 1
+may be changed by specifying a path in the
+.Ev MANPATH
+environment variable.
+Invalid paths, or paths without manual databases, are ignored.
+Overridden by
+.Fl M .
+If
+.Ev MANPATH
+begins with a colon, it is appended to the default list;
+if it ends with a colon, it is prepended to the default list;
+or if it contains two adjacent colons,
+the standard search path is inserted between the colons.
+If none of these conditions are met, it overrides the
+standard search path.
 .It Ev MANROFFSEQ
 Used to determine the preprocessors for the manual source before running
 .Xr nroff 1
diff --git a/usr.bin/man/man.sh b/usr.bin/man/man.sh
index 5f0462fb7755..2cb2a301ea0e 100755
--- a/usr.bin/man/man.sh
+++ b/usr.bin/man/man.sh
@@ -68,7 +68,23 @@ build_manpath() {
 
 	# If the user has set a manpath, who are we to argue.
 	if [ -n "$MANPATH" ]; then
-		return
+		case "$MANPATH" in
+		*:) PREPEND_MANPATH=${MANPATH} ;;
+		:*) APPEND_MANPATH=${MANPATH} ;;
+		*::*)
+			PREPEND_MANPATH=${MANPATH%%::*}
+			APPEND_MANPATH=${MANPATH#*::}
+			;;
+		*) return ;;
+		esac
+	fi
+
+	if [ -n "$PREPEND_MANPATH" ]; then
+		IFS=:
+		for path in $PREPEND_MANPATH; do
+			add_to_manpath "$path"
+		done
+		unset IFS
 	fi
 
 	search_path
@@ -82,6 +98,13 @@ build_manpath() {
 
 	parse_configs
 
+	if [ -n "$APPEND_MANPATH" ]; then
+		IFS=:
+		for path in $APPEND_MANPATH; do
+			add_to_manpath "$path"
+		done
+		unset IFS
+	fi
 	# Trim leading colon
 	MANPATH=${manpath#:}