From 0ef1b0fc23cc39cb4775920c773f4b37d06e8ff2 Mon Sep 17 00:00:00 2001
From: Michael Kerrisk <mtk.manpages@gmail.com>
Date: Sun, 29 Jun 2008 06:16:33 +0000
Subject: [PATCH] Add discussion of POSIX.1 utmpx specification. Move some text
 from CONFORMING To to NOTES.

---
 man5/utmp.5 | 17 ++++++++++++++++-
 1 file changed, 16 insertions(+), 1 deletion(-)

diff --git a/man5/utmp.5 b/man5/utmp.5
index b66fc312d..557e4154e 100644
--- a/man5/utmp.5
+++ b/man5/utmp.5
@@ -219,6 +219,20 @@ removed, record-keeping is turned off.
 .br
 /var/log/wtmp
 .SH "CONFORMING TO"
+.PP
+POSIX.1 does not specify a
+.I utmp
+structure, but rather one named
+.IR utmpx ,
+with specifications for the fields
+.IR ut_type ,
+.IR ut_pid ,
+.IR ut_line ,
+.IR ut_id ,
+.IR ut_user ,
+and
+.IR ut_tv .
+.SS Comparison with Historical Systems
 Linux utmp entries conform neither to v7/BSD nor to System V; they are a
 mix of the two.
 v7/BSD has fewer fields; most importantly it lacks
@@ -244,6 +258,7 @@ such as \fB"new time"\fP in the line field.
 \fBUT_UNKNOWN\fP seems
 to be a Linux invention.
 System V has no \fIut_host\fP or \fIut_addr_v6\fP fields.
+.SH NOTES
 .PP
 Unlike various other
 systems, where utmp logging can be disabled by removing the file, utmp
@@ -256,7 +271,7 @@ Note that the \fIutmp\fP struct from libc5 has changed in libc6.
 Because of this,
 binaries using the old libc5 struct will corrupt
 .IR /var/run/utmp " and/or " /var/log/wtmp .
-.SH NOTES
+.PP
 The file format is machine-dependent, so it is recommended that it be
 processed only on the machine architecture where it was created.
 .PP