From: Francois-Denis Gonthier <neumann@lostwebsite.net>
Date: Thu, 20 Sep 2018 15:01:18 +0300
Subject: [PATCH] Load man-pages from system-wide directory

Patch allows one to use standard man path with erl -man command.
(Erlang manual pages are placed to /usr/share/man/ hierarchy
as required by Debian policy.)

diff --git a/erts/etc/common/erlexec.c b/erts/etc/common/erlexec.c
index 23bbb86333..741b492668 100644
--- a/erts/etc/common/erlexec.c
+++ b/erts/etc/common/erlexec.c
@@ -722,8 +722,10 @@ int main(int argc, char **argv)
 			error("-man not supported on Windows");
 #else
 			argv[i] = "man";
-			erts_snprintf(tmpStr, sizeof(tmpStr), "%s/man", rootdir);
-			set_env("MANPATH", tmpStr);
+			/*
+			* Conform to erlang-manpages content.
+			*/
+			putenv(strsave("MANSECT=3erl:1:5:7"));
 			execvp("man", argv+i);
 			error("Could not execute the 'man' command.");
 #endif