As you saw in the previous sections, an MH sequence is a list of message numbers. You choose names for the sequences. When you want to use the messages in the sequence, you can type the sequence name instead of typing all the numbers. Each folder can have up to 26 sequences (in earlier MH versions and on systems that aren't 32-bit, the limit is 10). Each sequence can have hundreds of messages. A sequence name can be made of letters only; it can't be one of the reserved message names like first, last, and so on (see the Section Find and Specify with scan, pick, Ranges, Sequences). This section has examples. Newer versions of the mh-sequence(5) manual page have a complete description; if you have an old version, see the Section Online Manual Pages.
Sequences are great for keeping track of certain messages -- temporarily or for weeks or months. In my user-consulting job, for instance, we kept a sequence named common in each folder -- a list of messages which answer common questions that we might want to reuse:
% scan common +file_xfr 3 03/23 To:ann@suxpr.mar. Re: FTP in the background<<> Is 19 06/02 To:xvhang Re: UUEncode<<> Can Quark handle 61 11/13 To:carolo Re: .arc unpacking<<> A while ba 63 11/17 To:danr Re: shar type file packager<<Tha 85 01/15 To:Rudy Valleyfor Re: 7 & 8 bit switches<<> It isYou've seen that the pick command can create or add to sequences. The other MH command for working with sequences is mark. With mark, you can create, add messages to, delete messages from, or remove sequences.
If the sequence already exists and you want to change it completely, the -zero switch deletes any old message numbers from the list before adding the new ones. Or, to merge messages to an existing sequence without deleting existing message numbers, use -nozero. By default, mark uses -nozero. (The pick default is -zero.)
Here's an example. First pick creates or replaces a sequence named picked; it stores the message numbers from alison. Second, pick adds the message from steven to the same sequence. Third, the mark command adds the current message to the sequence. (If you don't tell mark which one to add, it adds the current message.) Fourth, I use scan to see what's in the sequence. Finally, I start forw to forward copies of the messages (4, 21, 23, 44) to allan@mukluk.bitnet, as shown in the following example:
% pick -from alison -sequence picked 2 hits % pick -from steven -sequence picked -nozero 1 hit % mark -add -sequence picked % scan picked 4 03/21 Alison Cosgreave What's happening here at UMass<< 21 04/01 Steven Dommer Re: meeting minutes<<> A while ba 23 04/02 Alison Cosgreave Re: What's happening at Tek<<Not 44+ 04/29 To:jbq@animals.sc What we talked about at lunch<<Jo % forw picked To: allan@mukluk.bitnet cc: Subject: Messages from Alison, Steven, and me ...If you give mark the -sequence option, the default action is -add. (Otherwise, the default is -list.) So, to add messages 12-25 to the foo sequence, you can type:
% mark -seq foo 12-25Sometimes I need to save a message number in a folder that I can come back to later. The Section Make Message Bookmarks with mark shows an easy way to do that with a one-message sequence named here.
To take messages out of a sequence yourself, use mark -delete. To remove one or a few messages, just give the message numbers -- the first command below removes message numbers 1 and 3 from the sequence called info. To remove a sequence completely, use the sequence name as the message range -- as in the second command below, which removes the temp sequence from your current folder. Remember that you can abbreviate MH switches (in fact, you can abbreviate most mark switches to single letters, though I haven't here):
% mark -del -seq info 1 3 % mark -del -seq temp tempThere's a weird twist that you should know about. If you use -zero with -delete, it will add all messages from the folder to the sequence except the messages you name. An example will help here. Let's say that your current folder has messages numbered 1 through 10. The command:
% mark -delete -zero -sequence most 1would put messages 2 through 10 in the sequence called most. Even more surprising, that command will create the sequence if it doesn't exist!
You can delete from (or add to) more than one sequence at a time. For example, to remove all messages from the sequences march and april (and thereby remove the sequences too), type the following:
% mark -del all -seq march -seq april
% mark -list cur: 2 info: 4 6 myinfo: 12-18 20 25-36 % mark -list -sequence info info: 4 6In fact, if you don't give a -sequence switch, the default is -list. So, to get a list of all sequences, just type mark.
The mark -list command lists message numbers two ways: in ranges like 12-18, and in single message numbers like 6. For example, the info sequence above has messages 4 and 6 in it. The myinfo sequence has messages 12, 13, 14, 15, 16, 17, and 18; message 20; and messages 25 through 36, inclusive.
The message ranges in mark -list output always contain exactly those messages, with no gaps. For instance, if your folder has messages 12, 14, and 16 in it, mark -list will always list those as:
seqname: 12 14 16and never as:
seqname: 12-16The special sequence named cur holds the current message number for the folder.
If you edit your MH profile and add an entry like this:
Previous-Sequence: pseqthen MH will save the message numbers from the previous MH command in a sequence named pseq (you can use any legal sequence name; I just like pseq). For example, if you scan four messages, you can show all of them on the next command line without typing their numbers -- just use pseq:
% scan 1 2 113 227
1 01/09 Joe Doe Test message<<Hi!>>
2 01/09 Joe Doe Another test<<Well, this is anot
113+ 01/11 Joe Doe The latest on my project<<It's g
227 01/13 Joe Doe <<I can't get MH to work so I'm
% show pseq
...Messages 1, 2, 113, 227 appear...
% mark -list -seq pseq
pseq: 1-2 113 227
NOTE: A Previous-Sequence: entry can cause trouble if your folders have hundreds or thousands of messages with gaps in the numbering. If you run a command like scan or refile all in those folders, MH tries to put a complete listing of all the folder's message numbers on a single line in the .mh_sequences file. If the line gets too long, you'll see the error message xxx/.mh_sequences is poorly formatted.
To prevent this, keep big folders packed with folder -pack.
If it happens anyway, use the following five commands to delete the long line from the .mh_sequences file and pack the folder (these commands assume that your previous sequence is named pseq):
% cd `mhpath` % mv .mh_sequences temp_sequences % sed /pseq:/d temp_sequences > .mh_sequences % folder -pack % rm temp_sequences(If you aren't confident about this, check with an expert first.) I used the command sed /pseq:/d instead of grep -v pseq: because some versions of grep truncate long lines.
Here's the other useful entry. If you put something like this in your MH profile:
Sequence-Negation: notand put not before the name of a sequence, MH will use all messages from the current folder that are not in the sequence. For example, if your folder has messages numbered 1 through 10 and the sequence named important has messages 1, 3, 5, 7, and 9 in it, then typing the following line:
% refile notimportant +junkwould move messages 2, 4, 6, 8, and 10 into the junk folder.
The sequence-negation shouldn't be part of a sequence name you already use. For example, a sequence named notes starts with the characters not, so not would be a bad sequence-negation. You can use nonalphabetic sequence-negation characters, like the exclamation point (!) and the tilde (~), but your shell may treat those as special characters and force you to type a backslash (\) before them. For example, if you set this entry in your MH profile:
Sequence-Negation: !the C shell makes you type \! before a sequence name, like this:
% scan \!importantOne compromise is a colon (:) character:
Sequence-Negation: :In the previous example, you could have typed the following cryptic-looking command:
% refile :important +junkIf you never start your folder names with an uppercase X, you might use that letter for a sequence-negation, so a negated sequence could look like Ximportant.
A folder doesn't always have a cur sequence. For instance, when you first make a new folder, it won't have a current message.
If you remove or refile the current message, the cur sequence will not be deleted, though. That's so commands like next and prev will still be able to find the next or previous message.
(Public sequences are stored in a file named .mh_sequences in the folder directory. The .mh_sequences is mode 644, but users won't be able to read it unless they have access to the top-level mail directory and the folder. Private sequences are stored in the file named context in the user's MH directory. The context file is mode 600, and each user has his/her own context file; other users' context files are never used. See the Figure Important parts of a UNIX filesystem.)
When you define a sequence, or add to one, you can use the switch -nopublic to make it private. If the sequence was public before, now it'll be private.
Here's an example that shows the user of mark -nopublic changing a sequence from public to private. Compare the listings for the myinfo sequence in the two mark -list outputs:
% mark -list cur: 2 info: 4 6 myinfo: 4-6 % mark -add -seq myinfo -nopublic 8 % mark -list cur: 2 info: 4 6 myinfo (private): 4-6 8There is a bug in MH 6.6 through MH 6.8.3 (and maybe others). If you give mark -list the name of a private sequence, it won't show you that it's (private). Compare the listings of the previous myinfo sequence to the following:
% mark -list -seq myinfo myinfo: 4-6 8To make all sequences private, add the empty entry:
mh-sequences:to your MH profile. See the Section Changing MH Directory Name for an example of where this is useful.
[Table of Contents] [Index] [Previous: Finding Messages with pick] [Next: Storing Messages]
This file is from the third edition of the book MH & xmh: Email for Users & Programmers, ISBN 1-56592-093-7, by Jerry Peek. Copyright © 1991, 1992, 1995 by O'Reilly & Associates, Inc. This file is freely-available; you can redistribute it and/or modify it under the terms of the GNU General Public License as published by the Free Software Foundation. For more information, see the file copying.htm.
Suggestions are welcome: Jerry Peek <jpeek@jpeek.com>