mh.rf

<B>Digital的Unix操作系统VAX 4.2源码</B>

.br
pick\0\-from\0freida\0\-seq\0sgroup\0\-nozero
.in -.5i

finds all those messages in the current folder which were from
\*(lqfrated\*(rq, \*(lqfear\*(rq, or \*(lqfreida\*(rq,
and defines the sequence called \*(lqsgroup\*(rq as exactly those messages.
These operations amounted to an \*(lqinclusive\-or\*(rq of three selection
criteria,
using \fIpick\fR,
one can also generate the \*(lqand\*(rq of some selection criteria as well:

.in +.5i
pick\0\-from\0frated\0\-seq\0fred
.br
pick\0\-before\0friday\0\-seq\0fred\0fred
.in -.5i

This example defines the sequence called \*(lqfred\*(rq as exactly those
messages from \*(lqfrated\*(rq that were dated prior to \*(lqfriday\*(rq.\**
.(f
\** Of course,
it is much easier to simply use the built\-in boolean operation of
\fIpick\fR to get the desired results:

.ti +.5i
pick\0\-from\0frated\0\-or\0\-from\0fear\0\-or\0\-from\0freida\0\-seq\0sgroup

and

.ti +.5i
pick\0\-from\0frated\0\-and\0\-before\0friday\0\-seq\0fred

do exactly the same thing as the five commands listed above.
Hence, the `\-nozero' option to \fIpick\fR is only useful to manipulate
existing sequences.
.)f
.pp
\fIPick\fR is normally used as a back\-quoted command,
for example,

.ti +.5i
scan\0`pick\0\-from\0postmaster`

Now suppose that the user decides that another command should be issued,
using exactly those messages.
Since,
\fIpick\fR wasn't given a `\-sequence\ name' argument in this example,
the user would end\-up typing the entire back\-quoted command again.
A simpler way is to add a default sequence name to the \&.mh\(ruprofile.
For example,

.ti +.5i
pick:\0\-seq\0select\0\-list

will tell \fIpick\fR to always define the sequence \*(lqselect\*(rq whenever
it's run.
The `-list' is necessary since the `\-sequence\ name' switch sets `\-nolist'
whenever the former is encountered.
Hence, this profile entry makes \fIpick\fR define the \*(lqselect\*(rq
sequence and otherwise behave exactly as if there was no profile entry at all.
.UH "Mark and User\-Defined Sequences"
.pp
The \fImark\fR command lets the user perform low\-level manipulation of
sequences,
and also provides a well\-needed debug facility to the
implementors/developers/maintainers of \fIMH\fR (the \fIMH\fR\-hacks).
In the future, a user\-friendly \*(lqfront\-end\*(rq for \fImark\fR will
probably be developed to give the \fIMH\fR user a way to take better
advantage of the underlying facilities.
.UH "Public and Private User\-Defined Sequences"
.pp
There are two kinds of sequences: \fIpublic\fR sequences,
and \fIprivate\fR sequences.
\fIPublic\fR sequences of a folder are accessible to any \fIMH\fR user that
can read that folder and are kept in the \&.mh\(rusequences file in the folder.
\fIPrivate\fR sequences are accessible only to the \fIMH\fR user that defined
those sequences and are kept in the user's \fIMH\fR context file.
By default,
\fIpick\fR (and \fImark\fR\0) create \fIpublic\fR sequences
if the folder for which the sequences are being defined is writable by the
\fIMH\fR user.
Otherwise, \fIprivate\fR sequences are created.
This can be overridden with the `\-public' and `\-private' switches.
.UH "Sequence Negation"
.pp
In addition to telling an \fIMH\fR command to use the messages in the sequence
\*(lqseen\*(rq, as in

.ti +.5i
refile\0seen\0+old

it would be useful to be easily able to tell an \fIMH\fR command to use all
messages \fIexcept\fR those in the sequence.
One way of doing this would be to use \fImark\fR and define the sequence
explicitly,
as in

.ti +.5i
mark\0\-delete\0\-zero\0seen\0\-seq\0notseen

which,
owing to \fImark\fR\0's cryptic interpretation of `\-delete' and `\-zero',
defines the sequence \*(lqnotseen\*(rq to be all messages not in the sequence
\*(lqseen\*(rq.
Naturally,
anytime the sequence \*(lqseen\*(rq is changed,
\*(lqnotseen\*(rq will have to be updated.
Another way to achieve this is to define the entry
\*(lqSequence\-Negation:\*(rq in the \&.mh\(ruprofile.
If the entry was

.ti +.5i
Sequence\-Negation:\0not

then anytime an \fIMH\fR command was given \*(lqnotseen\*(rq as a `msg' or
`msgs' argument,
it would substitute all messages that are not a member of the sequence
\*(lqseen\*(rq.
That is,

.ti +.5i
refile\0notseen\0+new

does just that.
The value of the \*(lqSequence\-Negation:\*(rq entry in the profile can be
any string.
Hence,
experienced users of \fIMH\fR do not use a word,
but rather a special character which their shell does not interpret
(users of the \fICShell\fR use a single caret or circumflex (usually shift\-6),
while users of the Bourne shell use an exclamation\-mark).
This is because there is nothing to prevent a user of \fIMH\fR from defining a
sequence with this string as its prefix,
if the string is nothing by letters and digits.
Obviously,
this could lead to confusing behavior
if the \*(lqSequence\-Negation:\*(rq entry leads \fIMH\fR to believe that two
sequences are opposites by virtue of their names differing by the prefix
string.
.UH "The Previous Sequence"
.pp
Many times users find themselves issuing a series of commands on the same
sequences of messages.
If the user first defined these messages as a sequence,
then considerable typing may be saved.
If the user doesn't have this foresight,
\fIMH\fR provides a handy way of having \fIMH\fR remember the `msgs' or
`msg' argument last given to an \fIMH\fR command.
If the entry \*(lqPrevious\-Sequence:\*(rq is defined in the
\&.mh\(ruprofile,
then when the command finishes,
it will define the sequence(s) named in the value of this entry as being
exactly those messages that were specified.
Hence, a profile entry of

.ti +.5i
Previous\-Sequence:\0pseq

directs any \fIMH\fR command that accepts a `msg' or `msgs' argument to
define the sequence \*(lqpseq\*(rq as those messages when it finishes.
More than one sequence name may be placed in this entry,
separated with spaces.
The one disadvantage of this approach
is that the \fIMH\fR progams have to update the sequence information for
the folder each time they run
(although most programs read this information,
usually only \fIpick\fR and \fImark\fR have to write this information out).
.UH "The Unseen Sequence"
.pp
Finally, some users like to distinguish between messages which have been
previously seen by them.
Both \fIinc\fR and \fIshow\fR honorthe profile entry
\*(lqUnseen\-Sequence\*(rq to support this activity.
Whenever \fIinc\fR places new messages in a folder,
if the entry \*(lqUnseen\-Sequence\*(rq is defined in the \&.mh\(ruprofile,
then when the command finishes,
\fIinc\fR will add the new messages to the sequence(s) named in the value of
this entry.
Hence, a profile entry of

.ti +.5i
Unseen\-Sequence:\0 unseen

directs \fIinc\fR to add new messages to the sequence \*(lqunseen\*(rq.
Unlike the behavior of the \*(lqPrevious\-Sequence\*(rq entry in the profile
however,
the sequence(s) will \fBnot\fR be zero'd.
.pp
Similarly,
whenever \fIshow\fR (or \fInext\fR or \fIprev\fR\0) displays a message,
they remove those messages from any sequences named by the
\*(lqUnseen\-Sequence\*(rq entry in the profile.
.uh "COMPOSITION OF MAIL"
.pp
There are a number of interesting advanced facilities for the composition of
outgoing mail.

.UH "The Draft Folder"
.pp
The \fIcomp\fR, \fIdist\fR, \fIforw\fR, and \fIrepl\fR commands have two
switches, `\-draftfolder\0+folder' and `\-draftmessage\0msg'.
If `\-draftfolder\0+folder' is used,
these commands are directed to construct a draft message in the indicated
folder.
(The \*(lqDraft\-Folder:\*(rq profile entry may be used to declare a
default draft folder for use with
\fIcomp\fR, \fIdist\fR, \fIforw\fR, and \fIrepl\fR)
If `\-draftmessage\0msg' is not used, it defaults to `new'
(unless the user invokes \fIcomp\fR with `\-use',
in which case the default is `cur').
Hence, the user may have several message compositions in progress
simultaneously.
Now, all of the \fIMH\fR tools are available on each of the user's message
drafts
(e.g., \fIshow\fR, \fIscan\fR, \fIpick\fR, and so on).
If the folder does not exist,
the user is asked if it should be created (just like with \fIrefile\fR\0).
Also,
the last draft message the user was composing is known as `cur' in the
draft folder.
.pp
Furthermore,
the \fIsend\fR command has these switches as well.
Hence, from the shell,
the user can send off whatever drafts desired using the
standard \fIMH\fR `msgs' convention with `\-draftmessage msgs'.
If no `msgs' are given, it defaults to `cur'.
.pp
In addition,
all five programs have a `\-nodraftfolder' switch,
which undoes the last occurrence of `\-draftfolder\0folder'
(useful if the latter occurs in the user's \fIMH\fR profile).
.pp
If the user does not give the `\-draftfolder\0+folder' switch,
then all these commands act ``normally''.
Note that the `\-draft' switch to \fIsend\fR and \fIshow\fR
still refers to the file called `draft' in the user's \fIMH\fR
directory.
In the interests of economy of expression,
when using \fIcomp\fR or \fIsend\fR,
the user needn't prefix the draft `msg' or `msgs' with
`\-draftmessage'.
Both of these commands accept a `file' or `files' argument,
and they will, if given `\-draftfolder\0+folder' treat these arguments
as `msg' or `msgs'.\**
.(f
\** This may appear to be inconsistent, at first,
but it saves a lot of typing.
.)f
Hence,

.ti +.5i
send -draftf +drafts first

is the same as

.ti +.5i
send -draftf +drafts -draftm first

.pp
To make all this a bit more clear, here are some examples.
Let's assume that the following entries are in the \fIMH\fR profile:

.in +.5i
.nf
Draft\-Folder: +drafts
sendf: -draftfolder +drafts
.fi
.in -.5i

Furthermore,
let's assume that the program \fIsendf\fR is a (symbolic) link in the user's 
\fB$HOME/bin/\fR directory to \fIsend\fR.
Then, any of the commands

.in +.5i
.nf
comp
dist
forw
repl
.fi
.in -.5i

constructs the message draft in the `draft' folder using the `new'
message number.
Furthermore,
they each define `cur' in this folder to be that message draft.
If the user were to use the \fIquit\fR option at `What now?' level,
then later on,
if no other draft composition was done,
the draft could be sent with simply

.ti +.5i
sendf

Or,
if more editing was required,
the draft could be edited with

.ti +.5i
comp -use

Instead,
if other drafts had been composed in the meantime,
so that this message draft was no longer known as `cur' in the `draft'
folder,
then the user could \fIscan\fR the folder to see which message draft in the
folder should be used for editing or sending.
Clever users could even employ a back-quoted \fIpick\fR to do the work:

.ti +.5i
comp -use `pick +drafts -to bug-mh`

or

.ti +.5i
sendf `pick +drafts -to bug-mh`

Note that in the \fIcomp\fR example,
the output from \fIpick\fR must resolve to a single message draft
(it makes no sense to talk about composing two or more drafts with one
invocation of \fIcomp\fR\0).
In contrast,
in the \fIsend\fR example,
as many message drafts as desired can appear,
since \fIsend\fR doesn't mind sending more than one draft at a time.
.pp
Note that the argument `\-draftfolder\0+folder' is not
included in the profile entry for \fIsend\fR,
since when \fIcomp\fR, et. al., invoke \fIsend\fR directly,
they supply \fIsend\fR with the UNIX pathname of the message draft,
and \fBnot\fR a `draftmessage\0msg' argument.
As far as \fIsend\fR is concerned,
a \fIdraft folder\fR is not being used.
.pp
It is important to realize that \fIMH\fR treats the draft folder like a standard
\fIMH\fR folder in nearly all respects.
There are two exceptions:
.u first ,
under no circumstancs will the `\-draftfolder\0folder' switch cause the
named folder to become the current folder.\**
.(f
\** Obviously,
if the folder appeared in the context of a standard `+folder'
argument to an \fIMH\fR program, as in

.ti +.5i
scan +drafts

it might become the current folder, depending on the context changes of the
\fIMH\fR program in question.
.)f
.u Second ,
although conceptually \fIsend\fR deletes the `msgs' named in the draft
folder,
it does not call `delete-prog' to perform the deletion.

.UH "What Happens if the Draft Exists"
.pp
When the \fIcomp\fR, \fIdist\fR, \fIforw\fR, and \fIrepl\fR commands are
invoked and the draft you indicated already exists,
these programs will prompt the user for a reponse directing the program's
action.
The prompt is

.ti +.5i
Draft ``/usr/src/uci/mh/mhbox/draft'' exists (xx bytes).
.ti +.5i
Disposition?

The appropriate responses and their meanings are:
.u replace :
deletes the draft and starts afresh;
.u list :
lists the draft;
.u refile :
files the draft into a folder and starts afresh;
and,
.u quit :
leaves the draft intact and exits.
In addition, if you specified `\-draftfolder\0folder' to the command,
then one other response will be accepted:
.u new :
finds a new draft,
just as if `\-draftmessage\0new' had been given.
Finally, the \fIcomp\fR command will accept one more response:
.u use :
re-uses the draft,
just as if `\-use' had been given.

.UH "The Push Option at What now? Level"
.pp
The \fIpush\fR option to the \*(lqWhat now?\*(rq query
in the \fIcomp\fR, \fIdist\fR, \fIforw\fR, and \fIrepl\fR commands,
directs the command to \fIsend\fR the draft
in a special detached fashion,
with all normal output discarded.
If \fIpush\fR is used and the draft can not be sent,
then \fIMH\fR will send the user a message,
indicating the name of the draft file,
and an explanation of the failure.
.\" Although using \fIpush\fR calls \fIsend\fR\0(1),
.\" the \fIsend\fR command will consult the profile entry for \fIpush\fR.
.pp
The user can also invoke \fIsend\fR from the shell with the `\-push'
switch,
which makes \fIsend\fR act like it had been \fIpush\fR\0'd by one of the
composition commands.
.\" composition commands.\**