mh.rf

<B>Digital的Unix操作系统VAX 4.2源码</B>

.\"	@(MHWARNING)
.\" @(#)$Id: MH.rf,v 1.2 90/11/25 18:55:54 sharpe Exp $
.po +.75i
.de $c                          \" Major Heading printer
.ce
.b "\\s12\\n+(ch.\\ \\$1\\s0"   \" 12 Point Bold Header
.(x

\ \ \ \\n(ch.\\ \\ \\$1
.)x
.sp 45p         \" 45 point space or about 1/2 inch
..
\".nr xs .15v     \" Put index entries closer together
.(x

Section
.)x _
.de $0          \" Sub-Heading macro called AFTER printing the heading
.(x
.sp .3v
.ti .5i
\\$1
.)x
..
.de $s          \" Macro to print footnote separator
\"\l'2i'        \" No line drawn
.if n \
.       sp 1.3  \" But extra space to make up for it.
..
.fc ^ ~         \" The characters ^ and ~ CANNOT BE USED
\"                 throughout this document except as field
\"                 delimiter & pad indicator!
.he ''-%-''
.ll 32P         \" 32 Picas or about 5+1/3 inch Line Length
.if n .ll 72m   \" Use 72 ems for nroff
.nr ss 30p      \" 30 point space before section titles
.nr fm 5v       \" RAND likes bigger than normal [3v] bottom margins
.nr bm 7v       \"   ditto
.ds . \\fB.\\fP\\h'-(1m/3)' \" Bold period to stand out.
.ds << <\\h!-(\\w'<'/2)!<
.ds >> >\\h!-(\\w'>'/2)!>
.ds ** \v'-3p'\s+1*\s0\v'+3p'
.so version.rf
.tp
.(l C
\fIdiscard this page\fR
.sp 4
The RAND \fIMH\fR
Message Handling System:
User's Manual
.sp
UCI Version
.sp 2
\*(td
\*(MH
.)l
.++ C
.+c INTRODUCTION
.pp
Although people can travel cross-country in hours and can
reach others by telephone in seconds, communications still depend
heavily upon paper, most of which is distributed through the mails.
.pp
There are several major reasons for this continued dependence on
written documents.
First, a written document may be proofread
and corrected prior to its distribution, giving the author
complete control over his words.
Thus, a written document is
better than a telephone conversation in this respect.
Second,
a carefully written document is far less likely to be
misinterpreted or poorly translated than a phone conversation.
Third, a signature offers reasonable verification of authorship,
which cannot be provided with media such as telegrams.
.pp
However, the need for
.u fast ,
accurate, and reproducible document distribution is
obvious.
One solution in widespread use is the telefax.
Another
that is rapidly gaining popularity is electronic mail.
Electronic mail is similar to telefax in that the data to be sent
are digitized, transmitted via phone lines, and
turned back into a document at the receiver.
The advantage of
electronic mail is in its compression factor.
Whereas a telefax
must scan a page in very fine lines and send all of the black and
white information, electronic mail assigns characters fixed
codes which can be transmitted as a few bits of information.
Telefax presently has the advantage of being able to transmit an
arbitrary page, including pictures, but electronic mail is
beginning to deal with this problem.
Electronic mail also integrates well
with current directions in office automation, allowing documents
prepared with sophisticated equipment at one site to be quickly
transferred and printed at another site.
.pp
Currently, most electronic mail is intraorganizational,
with mail transfer remaining within one computer.
As computer
networking becomes more common, however, it is becoming more feasible to
communicate with anyone whose computer can be linked to your
own via a network.
.pp
The pioneering efforts on general-purpose electronic mail
were by organizations using the DoD ARPAnet[1].
The capability to send messages between computers existed before
the ARPAnet was developed, but it was used only in limited ways.
With the advent of the
ARPAnet, tools began to be developed which made it convenient for
individuals or organizations to distribute messages
over broad geographic areas, using
diverse computer facilities.
The interest and activity in
message systems has now reached such proportions that steps
have been taken within the DoD to coordinate and
unify the development of military message systems.
The use of electronic mail is expected to increase
dramatically in the next few years.
The utility of such systems
in the command and control and intelligence environments is
clear, and applications in these areas will probably lead the
way.
As the costs for sending and handling electronic messages
continue their rapid decrease, such uses can be
expected to spread rapidly into other areas and, of course, will
not be limited to the DoD.
.pp
A message system provides tools that help users (individuals
or organizations) deal with messages in various ways.
Messages
must be composed, sent, received, stored, retrieved,
forwarded, and replied to.
Today's best interactive computer
systems provide a variety of word-processing and information
handling capabilities.
The message handling facilities should be
well integrated with the rest of the system, so as to be a
graceful extension of overall system capability.
.pp
The message system described in this report, \fIMH\fR, provides most of the
features that can be found in other message systems and also
incorporates some new ones.
It has been built on the UNIX time-sharing
system[2], a popular operating system for the DEC PDP-11\**
and VAX-11 classes of computers.
.(f
\** PDP and VAX are trademarks of Digital Equipment Corporation.
.)f
A \*(lqsecure\*(rq operating
system similar to UNIX is currently being developed[3],
and that system will also run \fIMH\fR.
.pp
This report provides a complete description of \fIMH\fR and
thus may serve as a user's manual, although parts of the report
will be of interest to non-users as well.
Sections 2 and 3, the
Overview and Tutorial, present the key
ideas of \fIMH\fR and will give those not familiar with message systems
an idea of what such systems are like.
.pp
\fIMH\fR consists of a set of commands which use some special
files and conventions.
The final section is divided into three parts.
The first part covers the information
a user needs to know in addition to the
commands.
Then, each of the \fIMH\fR commands is described in detail.
Finally, other obscure details are revealed.
A summary of the commands is given in Appendix A,
and the syntax of message sequences is given in Appendix B.
.pp
A novel approach has been taken in the design of \fIMH\fR.
Instead of creating a large subsystem that appears as a single
command to the user (such as MS[4]),
\fIMH\fR is a collection of separate commands
which are run as separate programs.
The file and directory
system of UNIX are used directly.
Messages are stored as
individual files (datasets), and collections of them are grouped
into directories.
In contrast, most other message systems store
messages in a complicated data structure within a monolithic
file.
With the \fIMH\fR approach, UNIX commands can be
interleaved with commands invoking the functions of the message
handler.
Conversely, existing UNIX commands
can be used in connection with messages.
For
example, all the usual UNIX editing, text-formatting, and printing
facilities can be applied directly to individual messages.
MH,
therefore, consists of a relatively small amount of new code; it
makes extensive use of other UNIX software to provide the
capabilities found in other message systems.
.+c OVERVIEW
.pp
There are three main aspects of \fIMH\fR\0:  the  way  messages  are
stored (the message database), the user's profile (which directs
how certain actions of the message handler take place), and the
commands for dealing with messages.
.pp
Under \fIMH\fR, each message is stored as a separate file.
A user
can take any action with a message that he could with an ordinary
file in UNIX.
A UNIX directory in which messages are stored is
called a folder.
Each folder contains some standard entries to support
the message-handling functions.
The messages in a folder have numerical
names.
These folders (directories)
are entries in a particular directory path, described in
the user profile, through which \fIMH\fR can find message folders.
Using the UNIX \*(lqlink\*(rq facility, it is possible for one copy of a
message to be \*(lqfiled\*(rq in more than one folder, providing a
message index facility.
Also, using the UNIX tree-structured
file system, it is possible to have a folder within a folder,
nested arbitrarily deep,
and have the full power of the \fIMH\fR commands available.
.pp
Each user of \fIMH\fR has a user profile, a file in
his \fB$HOME\fR (initial login) directory called \fI\&.mh\(ruprofile\fR.
This profile contains several
pieces of information used by the \fIMH\fR commands:
a path name to the directory that contains the message folders
and parameters that tailor \fIMH\fR commands
to the individual user's requirements.
There is also another file,
called the user context,
which contains information concerning which folder the user last referenced
(the \*(lqcurrent\*(rq folder).
It also contains
most of the necessary state information concerning how
the user is dealing with his messages, enabling \fIMH\fR to be
implemented as a set of individual UNIX commands, in contrast to the
usual approach of a monolithic subsystem.
.pp
In \fIMH\fR, incoming mail is appended
to the end of a file in a system spooling area for the user.
This area is called the mail drop directory,
and the file is called the user's mail drop.
Normally when the user logins in,
s/he is informed of new mail
(or the \fIMH\fR program \fImsgchk\fR may be run).
The user adds the new messages to his/her collection of \fIMH\fR messages
by invoking the command
\fIinc\fR.
The \fIinc\fR (incorporate) command adds the new
messages to a folder called \*(lqinbox\*(rq, assigning them names which
are consecutive integers starting with the next highest integer
available in inbox.
\fIinc\fR also produces a
\fIscan\fR summary of
the messages thus incorporated.
A folder can be compacted into a single file,
for easy storage,
by using the \fIpackf\fR command.
Also,
messages within a folder can be sorted by date and time with the \fIsortm\fR
command.

.pp
There are four commands for examining the messages in a
folder:
\fIshow\fR,
\fIprev\fR,
\fInext\fR,
and
\fIscan\fR.
The \fIshow\fR command displays a message in a folder,
\fIprev\fR displays the message preceding the current message, and
\fInext\fR displays the message following the current message.
\fIMH\fR lets the user choose the program that displays individual messages.
A special program, \fImhl\fR, can be used to display messages according
to the user's preferences.
The \fIscan\fR command summarizes the messages in a folder,
normally producing one line per message, showing who the message is from,
the date, the subject, etc.
.pp
The user may move a message from one folder to another with
the command
\fIrefile\fR.
Messages may be removed from a folder
by means of the command
\fIrmm\fR.
In addition, a user may query
what the current folder is and may specify that a new folder
become the current folder, through the command
\fIfolder\fR.
All folders may be summarized with the \fIfolders\fR command.
A message folder (or subfolder) may be removed by means of
the command
\fIrmf\fR.
.pp
A set of messages based on content may be selected by
use of the command \fIpick\fR.
This command searches through
messages in a folder and selects those that match a given
set of criteria.
These messages are then bound to a \*(lqsequence\*(rq name for use with other
\fIMH\fR commands.
The \fImark\fR command manipulates these sequences.
.pp
There are five commands enabling the user to create new
messages and send them:
\fIcomp\fR,
\fIdist\fR,
\fIforw\fR,
\fIrepl\fR,
and
\fIsend\fR.
The \fIcomp\fR command
provides the facility for the user to compose a
new message;
\fIdist\fR redistributes mail to additional addressees;
\fIforw\fR enables the user to forward messages; and
\fIrepl\fR facilitates the generation of a reply to an incoming message.
The last three commands may optionally annotate the original message.
Messages may be arbitrarily annotated with the \fIanno\fR command.
Once a draft has been constructed by one of the four above composition
programs,
a user\-specifiable program is run to query the user as to the disposition of
the draft prior to sending.
\fIMH\fR provides the simple \fIwhatnow\fR program to start users off.
If
a message is not sent directly by one of these commands, it may
be sent at a later time using the command
\fIsend\fR.
\fIMH\fR allows the use of any UNIX editor when composing a message.
For rapid entry, a special editor, \fIprompter\fR, is provided.
For programs, a special mail-sending program, \fImhmail\fR, is provided.
.pp
\fIMH\fR supports a personal aliasing facility which gives users the
capability to considerably shorten address typein
and use meaningful names for addresses.
The \fIali\fR program can be used to query \fIMH\fR as to the expansion of a
list of aliases.
After composing a message, but prior to sending, the \fIwhom\fR command
can be used to determine exactly who a message would go to.
.pp
\fIMH\fR provides a natural interface for telling the user's shell the names
of \fIMH\fR messages and folders.
The \fImhpath\fR program achieves this capability.
.pp
@BEGIN: BBOARDS
Finally, \fIMH\fR supports the UCI BBoards facility.
\fIbbc\fR can be used to query the status of a group of BBoards,
while \fImsh\fR can be used to read them.
@BEGIN: BBSERVER
BBoard leaders are also well supported, with the \fIbbl\fR program.
@END: BBSERVER
@END: BBOARDS
The \fIburst\fR command can be used to \*(lqshred\*(rq digests of messages
into individual messages.
.pp
All of the elements summarized above
are described in more detail in the following sections.
Many of the
normal facilities of UNIX provide additional capabilities for
dealing with messages in various ways.
For example, it is
possible to print messages
on the line-printer without requiring any additional code within
\fIMH\fR\0.
Using standard UNIX facilities, any terminal output can be
redirected to a file for repeated or future viewing.
In general,
the flexibility and capabilities of the UNIX interface with the
user are preserved as a result of the integration of \fIMH\fR into the UNIX
structure.
.+c TUTORIAL
.pp
This tutorial provides a brief introduction to the \fIMH\fR commands.
It should be sufficient
to allow the user to read his mail, do some simple manipulations of
it, and create and send messages.
.pp
A message has two major pieces:  the
header and the body.
The body consists of the text of the message
(whatever you care to type in).
It follows the header and is separated from
it by an empty line.
(When you compose a message, the form that appears
on your terminal shows a line of dashes after the header.
This is for
convenience and is replaced by an empty line when the message is
sent.)  The header is composed of several components, including the
subject of the message and the person to whom it is addressed.
Each component starts with a name
and a colon; components must not start with a blank.
The text of the
component may take more than one line, but each continuation line must
start with a blank.
Messages typically have \*(lqTo:\*(rq, \*(lqcc:\*(rq, and
\*(lqSubject:\*(rq components.
When composing a message, you should include
the \*(lqTo:\*(rq and \*(lqSubject:\*(rq components;
the \*(lqcc:\*(rq (for people you want to send copies to) is not necessary.
.pp
The basic \fIMH\fR commands are
\fIinc\fR,
\fIscan\fR,