mh6.tex

早期freebsd实现

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\title{Changes to\\ The Rand MH Message Handling System:\\
	MH \#6.5 for 4.3BSD UNIX}
\author{Marshall T.~Rose\\
	Northrop Research and Technology Center\\
	One~Research Park\\
	Palos Verdes Peninsula, CA  90274}
\date{\ifdraft \versiondate/\\ Version \versiontag/\else \today\fi}
\maketitle
\footnotetext[0]{\hskip -\parindent
This document (version \versiontag/)
was \LaTeX set \today\ with \fmtname\ v\fmtversion.}

\begin{abstract}
This document describes the user-visible change to the
UCI version of the Rand \MH/ system that were made from \mh5 to \MH/ \#6.5.
It is based on the \mh6 changes document,
but has been updated to accurately reflect the \MH/ distributed with
4.3\bsd/~\unix/.
This document does not describe bug-fixes, per se,
or internal changes,
unless these activities resulted in a visible change for the \MH/ user.

This document is meant to supplement,
not supersede, the standard \MH/ User's manual\cite{MH.USR}.

Comments concerning this documentation should be addressed to the Internet
mailbox {\sf [e-mail]}.
\end{abstract}

\newpage
\section*	{Acknowledgements}
The \MH/ system described herein is based on the original Rand \MH/ system.
It has been extensively developed (perhaps too much so) by Marshall T.~Rose
and John L.~Romine at the University of California, Irvine.
Einar A.~Stefferud, Jerry N.~Sweet,
and Terry P.~Domae provided numerous suggestions
to improve the UCI version of \MH/.
Of course,
a large number of people have helped \MH/ along.
The list of ``\MH/~immortals'' is too long to list here.
However, Van Jacobson deserves a special acknowledgement for his tireless
work in improving the performance of \MH/.
Some programs have been speeded-up by a factor of 10 or 20.
All of users of \MH/, everywhere, owe a special thanks to Van.

\section*	{Disclaimer}
The Regents of the University of California wish to make it known that:
\begin{quote}
Although each program has been tested by its contributor,
no warranty, express or implied,
is made by the contributor or the University of California,
as to the accuracy and functioning of the program
and related program material,
nor shall the fact of distribution constitute any such warranty,
and no responsibility is assumed by the contributor
or the University of California in connection herewith.
\end{quote}

\newpage
\section*	{Conventions}
In this document,
certain \LaTeX -formatting conventions are adhered to:
\begin{enumerate}
\item	The names of \unix/ commands, such as \pgm{comp},
are presented in {\it text italics}.

\item	Arguments to programs, such as \arg"msgs",
are presented in {\tt typewriter style} and delimited by single-quotes.

\item	\unix/ pathnames and envariables,
such as $$\file{/usr/uci/}\hbox{\qquad and\qquad}\file{\$SIGNATURE},$$
are presented in {\sl slanted roman}.

\item	Text presenting an example, such as
\begin{verbatim}
    comp -editor zz
\end{verbatim}
is presented in {\tt typewriter style}.
\end{enumerate}

\newpage
\section*	{General Changes}
Unlike the changes between \mh4 and \mh5,
a large number of user-visible changes have been made in \mh6.
These changes have been in the form of bug fixes and several generalizations.
The majority of these will not affect novice users.
In addition, \mh6 is a great deal faster than \mh5:
all programs have been speeded-up significantly,
thanks to work done by Van Jacobson as part of the process of including \mh6
in the 4.3\bsd/~\unix/ distribution.

This document describes all user-visible changes to \mh5 from it's initial
release to the intermediate release of \MH/ \#6.5.

\subsection*	{System-5 Support}
In addition to support for \bsd/~\unix/, V7~\unix/ and \xenix/ variants of
\unix/,
\MH/ finally has support for the AT\&T variant of \unix/, System~5.
Hopefully this will greatly expand the number of system which can run \MH/.
Ironically,
it appears that five ports of earlier versions of \MH/ (including \mh5)
were done,
but news of the work was not widespread.%
\footnote{In fact,
three groups in one large organization ported \MH/ independently,
each without knowledge of the others' work.}

\subsection*	{Documentation}
Several new documents have been included in the \mh6 distribution:
The paper {\em MH.5: How to process 200 messages a day and still get some
real work done}
was presented at the 1985 Summer Usenix Conference and Exhibition in
Portland, Orgeon.
Another paper, {\em MH: A Multifarious User Agent},
has been accepted for publication by Computer Networks.
Both describe \MH/,
the former from a more technical and somewhat humorous perspective,
the latter from a more serious and research-oriented perspective.
In addition,
a third paper has been included,
{\em Design of the TTI Prototype Trusted Mail Agent},
which describes a so-called ``trusted'' mail agent built on top of \MH/.
This paper was presented at the Second International Symposium on
Computer Message Systems in Washington, D.C.
A fourth paper,
{\em MZnet: Mail Service for Personal Micro-Computer Systems},
is also included.
This paper,
which was presented at the First International Symposium on Computer Message
Systems in Nottingham, U.K.,
describes a \cpm/-based version of \MH/.

In addition,
the \MH/ tutorial, {\em The Rand MH Message Handling System: Tutorial},
and,
{\em The Rand MH Message Handling System: The UCI BBoards Facility},
have both been updated by Jerry N.~Sweet.

For \MH/ administrators (PostMasters and the like),
there's an entirely new document,
{\em The Rand MH Message Handling System: Administrator's Guide}.
It explains most of the ``ins and outs'' of maintaining an \MH/ system.

Finally, all of the manual entries and the \MH/ manual have had a thorough
working over.
The documentation is expanded, more accurate, and more detailed.

\subsection*	{Help Listings}
When any \MH/ command is invoked with the \switch"help" switch,
in addition to listing the syntax of the command and version information,
the \MH/ configuration options will be listed.
\MH/ has so many configuration options,
that when debugging problems, this information is invaluable.

\subsection*	{The \MH/ Profile}
There are two new profile entries worth noting:
\verb"MH-Sequences" tells \MH/ the name of the file to record public
sequences in.
Users of \pgm{vm}, a proprietary, visual front-end to \MH/,
make use of this to disable the public sequences feature of \MH/.

The profile entry \verb"Unseen-Sequence" names those sequences which should be
defined as those messages recently incorporated by \pgm{inc}.
The \pgm{show} program knows to remove messages from this sequence once it
thinks they have been seen.
If this profile entry is not present, or is empty, then no sequences are
defined.
Otherwise, for each name given, the sequence is first zero'd and then each
message incorporated is added to the sequence.
As such, this profile entry is rather analogous to the
\verb"Previous-Sequence" entry in the user's \MH/ profile.

In addition, the \verb"Alternate-Mailboxes" entry in the profile has been
expanded to support simple wild-carding.
Also, the default for this profile entry is now the user's mail-id at any host.
This change was made since \MH/ can no longer reliably figure out what
the user's real outgoing address looks like.

Finally,
when the \pgm{install-mh} program is automatically invoked by \MH/,
it won't prompt the user for information.
Instead, it notes that it's setting up the default environment.
In addition,
the \MH/ administrator may set-up a file called \file{mh.profile} in the \MH/
library area which is consulted by \pgm{install-mh} when initializing the
user's \profile/.

\subsection*	{The \MH/ Context}
The \pgm{folder}, \pgm{scan}, and \pgm{show} programs have been modified to
update the user's \MH/ context prior to writing to the user's terminal.
This allows the \MH/ user interrupt output to the terminal and still have the
expected context.
This is especially useful to interrupt long \pgm{scan} listings.
This change also introduces a subtle bug between \pgm{show} and messages
denoted by the \verb"Unseen-Sequence".
See \man show(1) for the details.

\subsection*	{Addresses and 822 support}
\MH/ now fully supports the RFC-822 routing syntax for addresses
(it used to recognize the syntax, but ignore the information present).
In addition,
there are three major modes for support of non-822 addressing in \MH/:
\begin{itemize}
\item	BERK\\
This is useful on sites running \SendMail/.
It doesn't support full 822--style addressing,
in favor of recognizing such formats as ACSnet, and so on.
For sites that can't run in an 822--compliant environment,
this is the option to use
(at the price of sacrificing some of the power of 822--style addressing).
This also drastically reduces the address formatting facilities described
below.

\item	DUMB\\
Although not as liberal as BERK,
the DUMB option is useful on sites in which the message transport system
conforms to the 822 standard,
but wants to do all the defaulting itself.

\item	BANG\\
From out in left field,
the BANG option favors \UUCP/-style addressing over 822--style addressing.
Hopefully when all the \UUCP/ sites around get around to adopting domain-style
addresses, this option won't be needed.
\end{itemize}

The \pgm{ap} program (mentioned momentarily) and the \pgm{ali} program
both support a \switch"normalize" switch indicate if addresses should be
resolved to their ``official'' hostnames.

\subsection*	{New Programs}
There are five new programs available:
The \pgm{ap} program is the \MH/ stand-alone address parser.
It's useful for printing address in various formats
(and for debugging address strings).
The \pgm{dp} program is similar, but works on dates instead of addresses.

The \pgm{msgchk} program checks for new mail,
possibly using the Post Office Protocol, POP, described below.

A new receive mail hook,
the \pgm{rcvstore} program,
which was written by Julian L.~Onions is available.

Finally, a visual front-end to \pgm{msh} called \pgm{vmh} has been included.
(This program is discussed in greater detail later on.)

\subsection*	{Message Numbering}
\MH/ now no longer restricts the number of messages which may reside in a
folder
(beyond that of system memory constraints).
This means that message numbers larger than 2000 are permissible.
Hopefully this will make life easier for people reading the network news
using \MH/.

\section*	{The WhatNow Shell}
In \mh6,
there is now the concept of a unified \whatnow/ processor that
the four composition programs, \pgm{comp}, \pgm{dist}, \pgm{forw},
and \pgm{repl} all invoke.
This permits a greater flexibility in building mail applications with \MH/.
As a result, there's a new program, \pgm{whatnow}, which acts as the default
\whatnow/ program.
Consult the \man whatnow(1) manual entry for all the details.
The only important user-visible change is the \verb"headers" option went away,
which wasn't used that much anyway.


The only other thing worth noting is that unless \MH/ has been compiled with
the UCI option,
the user's \file{\$HOME/.signature} file is not consulted for the user's
personal name.

\section*	{Format Strings}
A general format string facility has been added to allow \MH/ users to tailor
the output of certain commands.

The \pgm{inc}, \pgm{scan}, \pgm{ap}, and \pgm{dp} programs all consult a
file containing format strings.
Format strings,
which look a lot like \man printf(3) strings,
give these \MH/ commands precise instructions on how to format their output.

As a result,
the \pgm{inc} and \pgm{scan} programs no longer have the
\switch"size", \switch"nosize",
\switch"time", \switch"notime",
\switch"numdate", and \switch"nonumdate"
switches.
These switches have been replaced with the
\switch"form formatfile" switch and the \switch"format string" switch.
The former directs the program to consult the named file for the format
strings.
The latter directs the program to use the named string as the format.
To get the behavior of the old \switch"time" option,
use the \switch"form scan.time" option.
Similarly,
to get the effect of \switch"size",
use \switch"form scan.size".

A fun form to use is \switch"form scan.timely" with \pgm{scan}.