docs/master: ch03.roff annotate

docs/master

annotate ch03.roff @ 104:2818ca27d24c

Various text rework.

author	markus schnalke <meillo@marmaro.de>
date	Thu, 21 Jun 2012 00:01:13 +0200
parents	a782488c85f5
children	9ff356d84c57

rev	line source
meillo@58	1 .H0 "Discussion
meillo@0	2 .P
meillo@58	3 This main chapter discusses the practical work done in the mmh project.
meillo@104	4 It is structured along the goals to achieve.
meillo@104	5 The concrete work done
meillo@58	6 is described in the examples of how the general goals were achieved.
meillo@87	7 The discussion compares the current version of mmh with the state of
meillo@87	8 nmh just before the mmh project started, i.e. Fall 2011.
meillo@87	9 Current changes of nmh will be mentioned only as side notes.
meillo@87	10 .\" XXX where do I discuss the parallel development of nmh?
meillo@58	11
meillo@58	12
meillo@58	13
meillo@100	14 .H1 "Stream-Lining
meillo@58	15
meillo@0	16 .P
meillo@58	17 MH had been considered an all-in-one system for mail handling.
meillo@58	18 The community around nmh has a similar understanding.
meillo@87	19 In fundamental difference, mmh shall be a MUA only.
meillo@87	20 I believe that the development of all-in-one mail systems is obsolete.
meillo@87	21 Today, email is too complex to be fully covered by single projects.
meillo@87	22 Such a project won't be able to excel in all aspects.
meillo@87	23 Instead, the aspects of email should be covered my multiple projects,
meillo@87	24 which then can be combined to form a complete system.
meillo@87	25 Excellent implementations for the various aspects of email exist already.
meillo@87	26 Just to name three examples: Postfix is a specialized MTA,
meillo@87	27 Procmail is a specialized MDA, and Fetchmail is a specialized MRA.
meillo@89	28 I believe that it is best to use such specialized tools instead of
meillo@87	29 providing the same function again as a side-component in the project.
meillo@58	30 .P
meillo@87	31 Doing something well, requires to focus on a small set of specific aspects.
meillo@87	32 Under the assumption that focused development produces better results
meillo@100	33 in the particular area, specialized projects will be superior
meillo@87	34 in their field of focus.
meillo@87	35 Hence, all-in-one mail system projects \(en no matter if monolithic
meillo@87	36 or modular \(en will never be the best choice in any of the fields.
meillo@87	37 Even in providing the best consistent all-in-one system they are likely
meillo@87	38 to be beaten by projects that focus only on integrating existing mail
meillo@89	39 components to a homogeneous system.
meillo@87	40 .P
meillo@87	41 The limiting resource in Free Software community development
meillo@87	42 is usually man power.
meillo@87	43 If the development power is spread over a large development area,
meillo@87	44 it becomes even more difficult to compete with the specialists in the
meillo@87	45 various fields.
meillo@87	46 The concrete situation for MH-based mail systems is even tougher,
meillo@87	47 given the small and aged community, including both developers and users,
meillo@87	48 it has.
meillo@87	49 .P
meillo@87	50 In consequence, I believe that the available development resources
meillo@100	51 should focus on the point where MH is most unique.
meillo@87	52 This is clearly the user interface \(en the MUA.
meillo@87	53 Peripheral parts should be removed to stream-line mmh for the MUA task.
meillo@60	54
meillo@60	55
meillo@100	56 .H2 "Mail Transfer Facilities
meillo@60	57 .P
meillo@60	58 In contrast to nmh, which also provides mail submission and mail retrieval
meillo@87	59 agents, mmh is a MUA only.
meillo@100	60 This general difference initiated the development of mmh.
meillo@66	61 Removing the mail transfer facilities had been the first work task
meillo@76	62 in the mmh project.
meillo@60	63 .P
meillo@100	64 The Mail Submission Agent (MSA) is called
meillo@100	65 \fIMessage Transfer Service\fP (MTS) in nmh.
meillo@76	66 The facility established network connections and spoke SMTP to submit
meillo@60	67 messages for relay to the outside world.
meillo@76	68 This part was implemented by the
meillo@60	69 .Pn post
meillo@60	70 command.
meillo@96	71 The changes in email in the last years
meillo@87	72 demanded changes in this part of nmh too.
meillo@89	73 Encryption and authentication for network connections
meillo@87	74 needed to be supported, hence TLS and SASL were introduced into nmh.
meillo@87	75 This added complexity to nmh without improving it in its core functions.
meillo@87	76 Also, keeping up with recent developments in the field of
meillo@87	77 mail transfer requires development power and specialists.
meillo@87	78 In mmh this whole facility was simply cut off.
meillo@76	79 .Ci f6aa95b724fd8c791164abe7ee5468bf5c34f226
meillo@76	80 .Ci fecd5d34f65597a4dfa16aeabea7d74b191532c3
meillo@76	81 .Ci 156d35f6425bea4c1ed3c4c79783dc613379c65b
meillo@87	82 Instead, mmh depends on an external MSA.
meillo@60	83 The only outgoing interface available to mmh is the
meillo@60	84 .Pn sendmail
meillo@87	85 command, which almost any MSA provides.
meillo@87	86 If not, a wrapper program can be written.
meillo@87	87 It must read the message from the standard input, extract the
meillo@87	88 recipient addresses from the message header, and hand the message
meillo@87	89 over to the MSA.
meillo@87	90 For example, a wrapper script for qmail would be:
meillo@87	91 .VS
meillo@87	92 #!/bin/sh
meillo@87	93 # ignore command line arguments
meillo@87	94 exec qmail-inject
meillo@87	95 VE
meillo@87	96 The requirement to parse the recipient addresses out of the message header
meillo@87	97 is likely to be removed in the future.
meillo@87	98 Then mmh would give the recipient addresses as command line arguments.
meillo@100	99 This appears to be the better interface.
meillo@87	100 .\" XXX implement it
meillo@60	101 .P
meillo@60	102 To retrieve mail, the
meillo@60	103 .Pn inc
meillo@100	104 command acted as Mail Retrieval Agent (MRA).
meillo@100	105 It established network connections
meillo@76	106 and spoke POP3 to retrieve mail from remote servers.
meillo@76	107 As with mail submission, the network connections required encryption and
meillo@87	108 authentication, thus TLS and SASL were added.
meillo@87	109 Support for message retrieval through IMAP will become necessary
meillo@100	110 to be added soon, too, and likewise for any other changes in mail transfer.
meillo@100	111 Not so for mmh because it has dropped the support for retrieving mail
meillo@100	112 from remote locations.
meillo@76	113 .Ci ab7b48411962d26439f92f35ed084d3d6275459c
meillo@76	114 Instead, it depends on an external tool to cover this task.
meillo@100	115 In mmh exist two paths for messages to enter mmh's mail storage:
meillo@100	116 (1) Mail can be incorporated with
meillo@60	117 .Pn inc
meillo@87	118 from the system maildrop, or (2) with
meillo@60	119 .Pn rcvstore
meillo@87	120 by reading them, one at a time, from the standard input.
meillo@60	121 .P
meillo@60	122 With the removal of the MSA and MRA, mmh converted from an all-in-one
meillo@87	123 mail system to being a MUA only.
meillo@60	124 Now, of course, mmh depends on third-party software.
meillo@87	125 An external MSA is required to transfer mail to the outside world;
meillo@60	126 an external MRA is required to retrieve mail from remote machines.
meillo@60	127 There exist excellent implementations of such software,
meillo@76	128 which do this specific task likely better than the internal
meillo@87	129 versions had done it.
meillo@87	130 Also, the best suiting programs can be freely chosen.
meillo@60	131 .P
meillo@60	132 As it had already been possible to use an external MSA or MRA,
meillo@60	133 why not keep the internal version for convenience?
meillo@76	134 The question whether there is sense in having a fall-back pager in all
meillo@76	135 the command line tools, for the cases when
meillo@60	136 .Pn more
meillo@60	137 or
meillo@60	138 .Pn less
meillo@76	139 aren't available, appears to be ridiculous.
meillo@100	140 Of course, MSAs and MRAs are more complex than text pagers
meillo@87	141 and not necessarily available but still the concept of orthogonal
meillo@87	142 design holds: ``Write programs that do one thing and do it well.''
meillo@87	143 .[
meillo@87	144 mcilroy unix phil
meillo@87	145 p. 53
meillo@87	146 .]
meillo@87	147 .[
meillo@87	148 mcilroy bstj foreword
meillo@87	149 .]
meillo@87	150 Here, this part of the Unix philosophy was applied not only
meillo@87	151 to the programs but to the project itself.
meillo@87	152 In other words:
meillo@87	153 ``Develop projects that focus on one thing and do it well.''
meillo@87	154 Projects grown complex should be split for the same reasons programs grown
meillo@87	155 complex should be split.
meillo@100	156 If it is conceptionally more elegant to have the MSA and MRA as
meillo@87	157 separate projects then they should be separated.
meillo@87	158 This is the case here, in my opinion.
meillo@87	159 The RFCs propose this separation by clearly distinguishing the different
meillo@87	160 mail handling tasks.
meillo@87	161 .[
meillo@87	162 rfc 821
meillo@87	163 .]
meillo@87	164 The small interfaces between the mail agents support the separation.
meillo@76	165 .P
meillo@87	166 In the beginning, email had been small and simple.
meillo@100	167 At that time,
meillo@60	168 .Pn /bin/mail
meillo@100	169 had covered anything there was to email and still had been small
meillo@100	170 and simple.
meillo@100	171 Later, the essential complexity of email increased.
meillo@87	172 (Essential complexity is the complexity defined by the problem itself.\0
meillo@87	173 .[[
meillo@87	174 brooks no silver bullet
meillo@87	175 .]])
meillo@87	176 Email systems reacted to this change: They grew.
meillo@100	177 RFCs started to introduce the concept of mail agents to separate the
meillo@100	178 various tasks because they became more extensive and new tasks appeared.
meillo@100	179 As the mail systems grew even more, parts were split off.
meillo@100	180 In nmh, for instance, the POP server, which was included in the original
meillo@100	181 MH, was removed.
meillo@100	182 Now is the time to go one step further and split the MSA and MRA off, too.
meillo@87	183 Not only does this decrease the code size of the project,
meillo@87	184 but, more important, it unburdens mmh of the whole field of
meillo@87	185 message transfer with all its implications for the project.
meillo@100	186 There is no more need to concern with changes in network transfer.
meillo@76	187 This independence is received by depending on an external program
meillo@76	188 that covers the field.
meillo@76	189 Today, this is a reasonable exchange.
meillo@60	190 .P
meillo@100	191 Functionality can be added in three different ways:
meillo@87	192 .BU
meillo@87	193 Implementing the function originally in the project.
meillo@87	194 .BU
meillo@87	195 Depending on a library that provides the function.
meillo@87	196 .BU
meillo@87	197 Depending on a program that provides the function.
meillo@87	198 .P
meillo@87	199 Whereas adding the function originally to the project increases the
meillo@76	200 code size most and requires most maintenance and development work,
meillo@87	201 it makes the project most independent of other software.
meillo@87	202 Using libraries or external programs require less maintenance work
meillo@87	203 but introduces dependencies on external software.
meillo@87	204 Programs have the smallest interfaces and provide the best separation
meillo@87	205 but possibly limit the information exchange.
meillo@87	206 External libraries are stronger connected than external programs,
meillo@87	207 thus information can be exchanged more flexible.
meillo@87	208 Adding code to a project increases maintenance work.
meillo@87	209 .\" XXX ref
meillo@100	210 Implementing complex functions originally in the project adds
meillo@87	211 a lot of code.
meillo@87	212 This should be avoided if possible.
meillo@66	213 Hence, the dependencies only change in kind, not in their existence.
meillo@66	214 In mmh, library dependencies on
meillo@66	215 .Pn libsasl2
meillo@66	216 and
meillo@66	217 .Pn libcrypto /\c
meillo@66	218 .Pn libssl
meillo@66	219 were treated against program dependencies on an MSA and an MRA.
meillo@87	220 This also meant treating build-time dependencies against run-time
meillo@87	221 dependencies.
meillo@66	222 Besides program dependencies providing the stronger separation
meillo@66	223 and being more flexible, they also allowed
meillo@66	224 over 6\\|000 lines of code to be removed from mmh.
meillo@66	225 This made mmh's code base about 12\\|% smaller.
meillo@87	226 Reducing the project's code size by such an amount without actually
meillo@87	227 losing functionality is a convincing argument.
meillo@87	228 Actually, as external MSAs and MRAs are likely superior to the
meillo@87	229 project's internal versions, the common user even gains functionality.
meillo@66	230 .P
meillo@76	231 Users of MH should not have problems to set up an external MSA and MRA.
meillo@60	232 Also, the popular MSAs and MRAs have large communities and a lot
meillo@60	233 of documentation available.
meillo@87	234 Choices for MSAs range from full-featured MTAs like
meillo@60	235 .I Postfix
meillo@87	236 over mid-size MTAs like
meillo@60	237 .I masqmail
meillo@60	238 and
meillo@60	239 .I dma
meillo@60	240 to small forwarders like
meillo@60	241 .I ssmtp
meillo@60	242 and
meillo@60	243 .I nullmailer .
meillo@60	244 Choices for MRAs include
meillo@60	245 .I fetchmail ,
meillo@60	246 .I getmail ,
meillo@60	247 .I mpop
meillo@60	248 and
meillo@60	249 .I fdm .
meillo@60	250
meillo@60	251
meillo@100	252 .H2 "Non-MUA Tools
meillo@60	253 .P
meillo@87	254 One goal of mmh is to remove the tools that are not part of the MUA's task.
meillo@89	255 Further more, any tools that don't improve the MUA's job significantly
meillo@87	256 should be removed.
meillo@87	257 Loosely related and rarely used tools distract from the lean appearance.
meillo@87	258 They require maintenance work without adding much to the core task.
meillo@100	259 By removing these tools, the project shall become more stream-lined
meillo@87	260 and focused.
meillo@76	261 In mmh the following tools are not available anymore:
meillo@62	262 .BU
meillo@58	263 .Pn conflict
meillo@87	264 was removed
meillo@76	265 .Ci 8b235097cbd11d728c07b966cf131aa7133ce5a9
meillo@87	266 because it is a mail system maintenance tool that is not MUA-related.
meillo@87	267 It even checked
meillo@58	268 .Fn /etc/passwd
meillo@58	269 and
meillo@58	270 .Fn /etc/group
meillo@87	271 for consistency, which is completely unrelated to email.
meillo@87	272 A tool like
meillo@87	273 .Pn conflict
meillo@87	274 is surely useful, but it should not be shipped with mmh.
meillo@76	275 .\" XXX historic reasons?
meillo@62	276 .BU
meillo@58	277 .Pn rcvtty
meillo@87	278 was removed
meillo@87	279 .Ci 14767c94b3827be7c867196467ed7aea5f6f49b0
meillo@89	280 because its use case of writing to the user's terminal
meillo@76	281 on receiving of mail is obsolete.
meillo@87	282 If users like to be informed of new mail, the shell's
meillo@58	283 .Ev MAILPATH
meillo@87	284 variable or graphical notifications are technically more appealing.
meillo@100	285 Writing directly to terminals is hardly ever wanted today.
meillo@62	286 If though one wants to have it this way, the standard tool
meillo@58	287 .Pn write
meillo@58	288 can be used in a way similar to:
meillo@82	289 .VS
meillo@58	290 scan -file - \| write `id -un`
meillo@82	291 VE
meillo@62	292 .BU
meillo@58	293 .Pn viamail
meillo@87	294 was removed
meillo@87	295 .Ci eda72d6a7a7c20ff123043fb7f19c509ea01f932
meillo@87	296 when the new attachment system was activated, because
meillo@58	297 .Pn forw
meillo@76	298 could then cover the task itself.
meillo@62	299 The program
meillo@58	300 .Pn sendfiles
meillo@62	301 was rewritten as a shell script wrapper around
meillo@58	302 .Pn forw .
meillo@76	303 .Ci 0e82199cf3c991a173e0ac8aa776efdb3ded61e6
meillo@62	304 .BU
meillo@58	305 .Pn msgchk
meillo@87	306 was removed
meillo@87	307 .Ci bb9360ead7eb7a3fedcce2eeedfc660014e41dbe ,
meillo@87	308 because it lost its use case when POP support was removed.
meillo@76	309 A call to
meillo@58	310 .Pn msgchk
meillo@87	311 provided hardly more information than:
meillo@82	312 .VS
meillo@58	313 ls -l /var/mail/meillo
meillo@82	314 VE
meillo@100	315 It did distinguish between old and new mail, but
meillo@100	316 this detail information can be retrieved with
meillo@76	317 .Pn stat (1),
meillo@62	318 too.
meillo@100	319 A small shell script could be written to print the information
meillo@76	320 in a similar way, if truly necessary.
meillo@76	321 As mmh's
meillo@76	322 .Pn inc
meillo@87	323 only incorporates mail from the user's local maildrop,
meillo@62	324 and thus no data transfers over slow networks are involved,
meillo@76	325 there's hardly any need to check for new mail before incorporating it.
meillo@62	326 .BU
meillo@58	327 .Pn msh
meillo@87	328 was removed
meillo@76	329 .Ci 916690191222433a6923a4be54b0d8f6ac01bd02
meillo@87	330 because the tool was in conflict with the philosophy of MH.
meillo@76	331 It provided an interactive shell to access the features of MH,
meillo@76	332 but it wasn't just a shell, tailored to the needs of mail handling.
meillo@76	333 Instead it was one large program that had several MH tools built in.
meillo@76	334 This conflicts with the major feature of MH of being a tool chest.
meillo@76	335 .Pn msh 's
meillo@76	336 main use case had been accessing Bulletin Boards, which have seized to
meillo@62	337 be popular.
meillo@62	338 .P
meillo@62	339 Removing
meillo@58	340 .Pn msh ,
meillo@76	341 together with the truly archaic code relicts
meillo@58	342 .Pn vmh
meillo@58	343 and
meillo@58	344 .Pn wmh ,
meillo@62	345 saved more than 7\\|000 lines of C code \(en
meillo@66	346 about 15\\|% of the project's original source code amount.
meillo@100	347 Having less code \(en with equal readability, of course \(en
meillo@76	348 for the same functionality is an advantage.
meillo@63	349 Less code means less bugs and less maintenance work.
meillo@76	350 As
meillo@63	351 .Pn rcvtty
meillo@63	352 and
meillo@63	353 .Pn msgchk
meillo@87	354 are assumed to be rarely used and can be implemented in different ways,
meillo@87	355 why should one keep them?
meillo@76	356 Removing them stream-lines mmh.
meillo@63	357 .Pn viamail 's
meillo@63	358 use case is now partly obsolete and partly covered by
meillo@63	359 .Pn forw ,
meillo@76	360 hence there's no reason to still maintain it.
meillo@63	361 .Pn conflict
meillo@76	362 is not related to the mail client, and
meillo@63	363 .Pn msh
meillo@63	364 conflicts with the basic concept of MH.
meillo@76	365 Theses two tools might still be useful, but they should not be part of mmh.
meillo@63	366 .P
meillo@76	367 Finally, there's
meillo@76	368 .Pn slocal .
meillo@76	369 .Pn slocal
meillo@76	370 is an MDA and thus not directly MUA-related.
meillo@100	371 It should be removed from mmh, because including it conflicts with
meillo@100	372 the idea that mmh is a MUA only.
meillo@100	373 .Pn slocal
meillo@100	374 should rather become a separate project.
meillo@87	375 However,
meillo@76	376 .Pn slocal
meillo@76	377 provides rule-based processing of messages, like filing them into
meillo@76	378 different folders, which is otherwise not available in mmh.
meillo@87	379 Although
meillo@76	380 .Pn slocal
meillo@87	381 does neither pull in dependencies nor does it include a separate
meillo@100	382 technical area (cf. Sec. XXX), still,
meillo@100	383 it accounts for about 1\\|000 lines of code that need to be maintained.
meillo@76	384 As
meillo@76	385 .Pn slocal
meillo@76	386 is almost self-standing, it should be split off into a separate project.
meillo@76	387 This would cut the strong connection between the MUA mmh and the MDA
meillo@76	388 .Pn slocal .
meillo@87	389 For anyone not using MH,
meillo@87	390 .Pn slocal
meillo@87	391 would become yet another independent MDA, like
meillo@87	392 .I procmail .
meillo@100	393 Then
meillo@87	394 .Pn slocal
meillo@100	395 could be installed without the complete MH system.
meillo@76	396 Likewise, mmh users could decide to use
meillo@76	397 .I procmail
meillo@87	398 without having a second, unused MDA,
meillo@87	399 .Pn slocal ,
meillo@76	400 installed.
meillo@100	401 That appears to be conceptionally the best solution.
meillo@76	402 Yet,
meillo@76	403 .Pn slocal
meillo@87	404 is not split off.
meillo@100	405 I defer the decision over
meillo@78	406 .Pn slocal
meillo@100	407 in need for deeper investigation.
meillo@100	408 In the meanwhile, it remains part of mmh.
meillo@100	409 That does not hurt because
meillo@100	410 .Pn slocal
meillo@100	411 is unrelated to the rest of the project.
meillo@0	412
meillo@58	413
meillo@76	414 .H2 "\fLshow\fP and \fPmhshow\fP
meillo@58	415 .P
meillo@69	416 Since the very beginning \(en already in the first concept paper \(en
meillo@58	417 .Pn show
meillo@62	418 had been MH's message display program.
meillo@58	419 .Pn show
meillo@76	420 mapped message numbers and sequences to files and invoked
meillo@58	421 .Pn mhl
meillo@89	422 to have the files formatted.
meillo@88	423 With MIME, this approach wasn't sufficient anymore.
meillo@100	424 MIME messages can consist of multiple parts. Some parts are not
meillo@100	425 directly displayable and text content might be encoded in
meillo@58	426 foreign charsets.
meillo@58	427 .Pn show 's
meillo@76	428 understanding of messages and
meillo@58	429 .Pn mhl 's
meillo@88	430 display capabilities couldn't cope with the task any longer.
meillo@62	431 .P
meillo@88	432 Instead of extending these tools, additional tools were written from
meillo@88	433 scratch and added to the MH tool chest.
meillo@88	434 Doing so is encouraged by the tool chest approach.
meillo@88	435 Modular design is a great advantage for extending a system,
meillo@88	436 as new tools can be added without interfering with existing ones.
meillo@62	437 First, the new MIME features were added in form of the single program
meillo@58	438 .Pn mhn .
meillo@58	439 The command
meillo@82	440 .Cl "mhn -show 42
meillo@58	441 would show the MIME message numbered 42.
meillo@58	442 With the 1.0 release of nmh in February 1999, Richard Coleman finished
meillo@58	443 the split of
meillo@58	444 .Pn mhn
meillo@88	445 into a set of specialized tools, which together covered the
meillo@88	446 multiple aspects of MIME.
meillo@88	447 One of them was
meillo@69	448 .Pn mhshow ,
meillo@88	449 which replaced
meillo@88	450 .Cl "mhn -show" .
meillo@88	451 It was capable of displaying MIME messages appropriately.
meillo@62	452 .P
meillo@88	453 From then on, two message display tools were part of nmh,
meillo@76	454 .Pn show
meillo@76	455 and
meillo@76	456 .Pn mhshow .
meillo@88	457 To ease the life of users,
meillo@69	458 .Pn show
meillo@69	459 was extended to automatically hand the job over to
meillo@69	460 .Pn mhshow
meillo@69	461 if displaying the message would be beyond
meillo@69	462 .Pn show 's
meillo@69	463 abilities.
meillo@88	464 In consequence, the user would simply invoke
meillo@69	465 .Pn show
meillo@69	466 (possibly through
meillo@69	467 .Pn next
meillo@69	468 or
meillo@69	469 .Pn prev )
meillo@69	470 and get the message printed with either
meillo@69	471 .Pn show
meillo@69	472 or
meillo@69	473 .Pn mhshow ,
meillo@69	474 whatever was more appropriate.
meillo@69	475 .P
meillo@69	476 Having two similar tools for essentially the same task is redundant.
meillo@88	477 Usually,
meillo@88	478 users wouldn't distinguish between
meillo@88	479 .Pn show
meillo@88	480 and
meillo@88	481 .Pn mhshow
meillo@88	482 in their daily mail reading.
meillo@88	483 Having two separate display programs was therefore mainly unnecessary
meillo@88	484 from a user's point of view.
meillo@88	485 Besides, the development of both programs needed to be in sync,
meillo@76	486 to ensure that the programs behaved in a similar way,
meillo@76	487 because they were used like a single tool.
meillo@76	488 Different behavior would have surprised the user.
meillo@69	489 .P
meillo@69	490 Today, non-MIME messages are rather seen to be a special case of
meillo@100	491 MIME messages, although it is the other way round.
meillo@69	492 As
meillo@69	493 .Pn mhshow
meillo@88	494 had already be able to display non-MIME messages, it appeared natural
meillo@69	495 to drop
meillo@69	496 .Pn show
meillo@69	497 in favor of using
meillo@69	498 .Pn mhshow
meillo@69	499 exclusively.
meillo@88	500 .Ci 4c1efddfd499300c7e74263e57d8aa137e84c853
meillo@88	501 Removing
meillo@88	502 .Pn show
meillo@88	503 is no loss in function, because functionally
meillo@88	504 .Pn mhshow
meillo@88	505 covers it completely.
meillo@88	506 The old behavior of
meillo@88	507 .Pn show
meillo@88	508 can still be emulated with the simple command line:
meillo@88	509 .VS
meillo@88	510 mhl `mhpath c`
meillo@88	511 VE
meillo@88	512 .P
meillo@76	513 For convenience,
meillo@76	514 .Pn mhshow
meillo@88	515 was renamed to
meillo@88	516 .Pn show
meillo@88	517 after
meillo@88	518 .Pn show
meillo@88	519 was gone.
meillo@88	520 It is clear that such a rename may confuse future developers when
meillo@88	521 trying to understand the history.
meillo@88	522 Nevertheless, I consider the convenience on the user's side,
meillo@88	523 to call
meillo@88	524 .Pn show
meillo@88	525 when they want a message to be displayed, to outweigh the inconvenience
meillo@88	526 on the developer's side when understanding the project history.
meillo@69	527 .P
meillo@88	528 To prepare for the transition,
meillo@69	529 .Pn mhshow
meillo@69	530 was reworked to behave more like
meillo@69	531 .Pn show
meillo@69	532 first.
meillo@88	533 (cf. Sec. XXX)
meillo@88	534 Once the tools behaved more alike, the replacing appeared to be
meillo@88	535 even more natural.
meillo@88	536 Today, mmh's new
meillo@69	537 .Pn show
meillo@88	538 became the one single message display program again, with the difference
meillo@88	539 that today it handles MIME messages as well as non-MIME messages.
meillo@88	540 The outcome of the transition is one program less to maintain,
meillo@88	541 no second display program for users to deal with,
meillo@88	542 and less system complexity.
meillo@69	543 .P
meillo@88	544 Still, removing the old
meillo@69	545 .Pn show
meillo@88	546 hurts in one regard: It had been such a simple program.
meillo@88	547 Its lean elegance is missing to the new
meillo@69	548 .Pn show .
meillo@88	549 But there is no chance;
meillo@88	550 supporting MIME demands for higher essential complexity.
meillo@58	551
meillo@58	552
meillo@100	553 .H2 "Configure Options
meillo@58	554 .P
meillo@76	555 Customization is a double-edged sword.
meillo@76	556 It allows better suiting setups, but not for free.
meillo@76	557 There is the cost of code complexity to be able to customize.
meillo@76	558 There is the cost of less tested setups, because there are
meillo@72	559 more possible setups and especially corner-cases.
meillo@76	560 And, there is the cost of choice itself.
meillo@76	561 The code complexity directly affects the developers.
meillo@72	562 Less tested code affects both, users and developers.
meillo@76	563 The problem of choice affects the users, for once by having to
meillo@100	564 choose, but also by more complex interfaces that require more documentation.
meillo@72	565 Whenever options add little advantages, they should be considered for
meillo@72	566 removal.
meillo@72	567 I have reduced the number of project-specific configure options from
meillo@72	568 fifteen to three.
meillo@74	569
meillo@76	570 .U3 "Mail Transfer Facilities
meillo@74	571 .P
meillo@85	572 With the removal of the mail transfer facilities five configure
meillo@85	573 options vanished:
meillo@85	574 .P
meillo@85	575 The switches
meillo@85	576 .Sw --with-tls
meillo@85	577 and
meillo@85	578 .Sw --with-cyrus-sasl
meillo@89	579 had activated the support for transfer encryption and authentication.
meillo@85	580 This is not needed anymore.
meillo@85	581 .Ci fecd5d34f65597a4dfa16aeabea7d74b191532c3
meillo@85	582 .Ci 156d35f6425bea4c1ed3c4c79783dc613379c65b
meillo@85	583 .P
meillo@85	584 The configure switch
meillo@85	585 .Sw --enable-pop
meillo@85	586 activated the message retrieval facility.
meillo@85	587 The code area that would be conditionally compiled in for TLS and SASL
meillo@85	588 support had been small.
meillo@85	589 The conditionally compiled code area for POP support had been much larger.
meillo@85	590 Whereas the code base changes would only slightly change on toggling
meillo@85	591 TLS or SASL support, it changed much on toggling POP support.
meillo@85	592 The changes in the code base could hardly be overviewed.
meillo@85	593 By having POP support togglable a second code base had been created,
meillo@85	594 one that needed to be tested.
meillo@85	595 This situation is basically similar for the conditional TLS and SASL
meillo@85	596 code, but there the changes are minor and can yet be overviewed.
meillo@85	597 Still, conditional compilation of a code base creates variations
meillo@85	598 of the original program.
meillo@85	599 More variations require more testing and maintenance work.
meillo@85	600 .P
meillo@85	601 Two other options only specified default configuration values:
meillo@100	602 .Sw --with-mts
meillo@100	603 defined the default transport service, either
meillo@100	604 .Ar smtp
meillo@100	605 or
meillo@100	606 .Ar sendmail .
meillo@85	607 In mmh this fixed to
meillo@85	608 .Ar sendmail .
meillo@85	609 .Ci f6aa95b724fd8c791164abe7ee5468bf5c34f226
meillo@85	610 With
meillo@100	611 .Sw --with-smtpservers
meillo@85	612 default SMTP servers for the
meillo@85	613 .Ar smtp
meillo@85	614 transport service could be specified.
meillo@72	615 .Ci 128545e06224233b7e91fc4c83f8830252fe16c9
meillo@85	616 Both of them became irrelevant.
meillo@72	617
meillo@74	618 .U3 "Backup Prefix
meillo@74	619 .P
meillo@76	620 The backup prefix is the string that was prepended to message
meillo@76	621 filenames to tag them as deleted.
meillo@76	622 By default it had been the comma character `\f(CW,\fP'.
meillo@78	623 In July 2000, Kimmo Suominen introduced
meillo@78	624 the configure option
meillo@78	625 .Sw --with-hash-backup
meillo@78	626 to change the default to the hash symbol `\f(CW#\fP'.
meillo@78	627 The choice was probably personal preference, because first, the
meillo@78	628 option was named
meillo@78	629 .Sw --with-backup-prefix.
meillo@78	630 and had the prefix symbol as argument.
meillo@100	631 But giving the hash symbol as argument caused too many problems
meillo@100	632 for Autoconf,
meillo@100	633 thus the option was limited to use the hash symbol as the default prefix.
meillo@100	634 This supports the assumption, that the choice for the hash was
meillo@100	635 personal preference only.
meillo@100	636 Being related or not, words that start with the hash symbol
meillo@78	637 introduce a comment in the Unix shell.
meillo@72	638 Thus, the command line
meillo@72	639 .Cl "rm #13 #15
meillo@72	640 calls
meillo@72	641 .Pn rm
meillo@72	642 without arguments because the first hash symbol starts the comment
meillo@72	643 that reaches until the end of the line.
meillo@72	644 To delete the backup files,
meillo@72	645 .Cl "rm ./#13 ./#15"
meillo@72	646 needs to be used.
meillo@100	647 Using the hash as backup prefix can be seen as a precaution against
meillo@78	648 data loss.
meillo@78	649 .P
meillo@72	650 I removed the configure option but added the profile entry
meillo@72	651 .Pe backup-prefix ,
meillo@72	652 which allows to specify an arbitrary string as backup prefix.
meillo@72	653 .Ci 6c40d481d661d532dd527eaf34cebb6d3f8ed086
meillo@76	654 Profile entries are the common method to change mmh's behavior.
meillo@76	655 This change did not remove the choice but moved it to a location where
meillo@72	656 it suited better.
meillo@76	657 .P
meillo@78	658 Eventually, however, the new trash folder concept
meillo@78	659 .Cf "Sec. XXX
meillo@78	660 obsoleted the concept of the backup prefix completely.
meillo@78	661 .Ci 8edc5aaf86f9f77124664f6801bc6c6cdf258173
meillo@100	662 .\" (Well, there still are corner-cases to remove until the backup
meillo@100	663 .\" prefix can be laid to rest, eventually.)
meillo@72	664 .\" FIXME: Do this work in the code!
meillo@76	665
meillo@76	666 .U3 "Editor and Pager
meillo@74	667 .P
meillo@74	668 The two configure options
meillo@74	669 .CW --with-editor=EDITOR
meillo@74	670 .CW --with-pager=PAGER
meillo@74	671 were used to specify the default editor and pager at configure time.
meillo@74	672 Doing so at configure time made sense in the Eighties,
meillo@76	673 when the set of available editors and pagers varied much across
meillo@76	674 different systems.
meillo@89	675 Today, the situation is more homogeneous.
meillo@74	676 The programs
meillo@74	677 .Pn vi
meillo@74	678 and
meillo@74	679 .Pn more
meillo@76	680 can be expected to be available on every Unix system,
meillo@74	681 as they are specified by POSIX since two decades.
meillo@74	682 (The specifications for
meillo@74	683 .Pn vi
meillo@74	684 and
meillo@74	685 .Pn more
meillo@74	686 appeared in
meillo@74	687 .[
meillo@74	688 posix 1987
meillo@74	689 .]
meillo@74	690 and,
meillo@74	691 .[
meillo@74	692 posix 1992
meillo@74	693 .]
meillo@74	694 respectively.)
meillo@74	695 As a first step, these two tools were hard-coded as defaults.
meillo@74	696 .Ci 5d43a99db70c12a673028c7758c20cbe3e13ef5f
meillo@74	697 Not changed were the
meillo@74	698 .Pe editor
meillo@74	699 and
meillo@74	700 .Pe moreproc
meillo@76	701 profile entries, which allowed the user to override the system defaults.
meillo@74	702 Later, the concept was reworked to respect the standard environment
meillo@74	703 variables
meillo@74	704 .Ev VISUAL
meillo@74	705 and
meillo@74	706 .Ev PAGER
meillo@76	707 if they are set.
meillo@74	708 Today, mmh determines the editor to use in the following order,
meillo@74	709 taking the first available and non-empty item:
meillo@74	710 .IP (1)
meillo@74	711 Environment variable
meillo@74	712 .Ev MMHEDITOR
meillo@74	713 .IP (2)
meillo@74	714 Profile entry
meillo@74	715 .Pe Editor
meillo@74	716 .IP (3)
meillo@74	717 Environment variable
meillo@74	718 .Ev VISUAL
meillo@74	719 .IP (4)
meillo@74	720 Environment variable
meillo@74	721 .Ev EDITOR
meillo@74	722 .IP (5)
meillo@74	723 Command
meillo@74	724 .Pn vi .
meillo@74	725 .P
meillo@76	726 .Ci f85f4b7ae62e3d05a945dcd46ead51f0a2a89a9b
meillo@76	727 .P
meillo@89	728 The pager to use is determined in a similar order,
meillo@74	729 also taking the first available and non-empty item:
meillo@74	730 .IP (1)
meillo@74	731 Environment variable
meillo@74	732 .Ev MMHPAGER
meillo@74	733 .IP (2)
meillo@74	734 Profile entry
meillo@74	735 .Pe Pager
meillo@74	736 (replaces
meillo@74	737 .Pe moreproc )
meillo@74	738 .IP (3)
meillo@74	739 Environment variable
meillo@74	740 .Ev PAGER
meillo@74	741 .IP (4)
meillo@74	742 Command
meillo@74	743 .Pn more .
meillo@74	744 .P
meillo@74	745 .Ci 0c4214ea2aec6497d0d67b436bbee9bc1d225f1e
meillo@74	746 .P
meillo@76	747 By respecting the
meillo@74	748 .Ev VISUAL /\c
meillo@74	749 .Ev EDITOR
meillo@74	750 and
meillo@74	751 .Ev PAGER
meillo@76	752 environment variables,
meillo@76	753 the new behavior confirms better to the common style on Unix systems.
meillo@76	754 Additionally, the new approach is more uniform and clearer to users.
meillo@72	755
meillo@72	756
meillo@76	757 .U3 "ndbm
meillo@72	758 .P
meillo@74	759 .Pn slocal
meillo@78	760 used to depend on
meillo@74	761 .I ndbm ,
meillo@74	762 a database library.
meillo@76	763 The database is used to store the `\fLMessage-ID\fP's of all
meillo@76	764 messages delivered.
meillo@74	765 This enables
meillo@74	766 .Pn slocal
meillo@74	767 to suppress delivering the same message to the same user twice.
meillo@74	768 (This features was enabled by the
meillo@74	769 .Sw -suppressdup
meillo@74	770 switch.)
meillo@74	771 .P
meillo@100	772 A variety of versions of the database library exist.
meillo@78	773 .[
meillo@78	774 wolter unix incompat notes dbm
meillo@78	775 .]
meillo@74	776 Complicated autoconf code was needed to detect them correctly.
meillo@74	777 Further more, the configure switches
meillo@74	778 .Sw --with-ndbm=ARG
meillo@74	779 and
meillo@74	780 .Sw --with-ndbmheader=ARG
meillo@74	781 were added to help with difficult setups that would
meillo@78	782 not be detected automatically or correctly.
meillo@74	783 .P
meillo@74	784 By removing the suppress duplicates feature of
meillo@74	785 .Pn slocal ,
meillo@74	786 the dependency on
meillo@74	787 .I ndbm
meillo@78	788 vanished and 120 lines of complex autoconf code could be saved.
meillo@74	789 .Ci ecd6d6a20cb7a1507e3a20d6c4cb3a1cf14c6bbf
meillo@89	790 The change removed functionality too, but that is minor to the
meillo@78	791 improvement by dropping the dependency and the complex autoconf code.
meillo@72	792
meillo@74	793 .U3 "mh-e Support
meillo@72	794 .P
meillo@74	795 The configure option
meillo@74	796 .Sw --disable-mhe
meillo@74	797 was removed when the mh-e support was reworked.
meillo@74	798 Mh-e is the Emacs front-end to MH.
meillo@76	799 It requires MH to provide minor additional functions.
meillo@76	800 The
meillo@76	801 .Sw --disable-mhe
meillo@76	802 configure option could switch these extensions off.
meillo@76	803 After removing the support for old versions of mh-e,
meillo@74	804 only the
meillo@74	805 .Sw -build
meillo@76	806 switches of
meillo@74	807 .Pn forw
meillo@74	808 and
meillo@74	809 .Pn repl
meillo@76	810 are left to be mh-e extensions.
meillo@76	811 They are now always built in because they add little code and complexity.
meillo@76	812 In consequence, the
meillo@74	813 .Sw --disable-mhe
meillo@76	814 configure option was removed
meillo@72	815 .Ci a7ce7b4a580d77b6c2c4d980812beb589aa4c643
meillo@74	816 Removing the option removed a second code setup that would have
meillo@74	817 needed to be tested.
meillo@76	818 This change was first done in nmh and thereafter merged into mmh.
meillo@76	819 .P
meillo@76	820 The interface changes in mmh require mh-e to be adjusted in order
meillo@76	821 to be able to use mmh as back-end.
meillo@76	822 This will require minor changes to mh-e, but removing the
meillo@76	823 .Sw -build
meillo@76	824 switches would require more rework.
meillo@72	825
meillo@74	826 .U3 "Masquerading
meillo@72	827 .P
meillo@74	828 The configure option
meillo@74	829 .Sw --enable-masquerade
meillo@76	830 could take up to three arguments:
meillo@76	831 `draft_from', `mmailid', and `username_extension'.
meillo@74	832 They activated different types of address masquerading.
meillo@74	833 All of them were implemented in the SMTP-speaking
meillo@74	834 .Pn post
meillo@76	835 command, which provided an MSA.
meillo@76	836 Address masquerading is an MTA's task and mmh does not cover
meillo@76	837 this field anymore.
meillo@76	838 Hence, true masquerading needs to be implemented in the external MTA.
meillo@74	839 .P
meillo@74	840 The
meillo@74	841 .I mmailid
meillo@74	842 masquerading type is the oldest one of the three and the only one
meillo@74	843 available in the original MH.
meillo@74	844 It provided a
meillo@74	845 .I username
meillo@74	846 to
meillo@74	847 .I fakeusername
meillo@76	848 mapping, based on the password file's GECOS field.
meillo@74	849 The man page
meillo@74	850 .Mp mh-tailor(5)
meillo@74	851 described the use case as being the following:
meillo@98	852 .QS
meillo@74	853 This is useful if you want the messages you send to always
meillo@74	854 appear to come from the name of an MTA alias rather than your
meillo@74	855 actual account name. For instance, many organizations set up
meillo@74	856 `First.Last' sendmail aliases for all users. If this is
meillo@74	857 the case, the GECOS field for each user should look like:
meillo@74	858 ``First [Middle] Last <First.Last>''
meillo@98	859 .QE
meillo@74	860 .P
meillo@74	861 As mmh sends outgoing mail via the local MTA only,
meillo@76	862 the best location to do such global rewrites is there.
meillo@74	863 Besides, the MTA is conceptionally the right location because it
meillo@74	864 does the reverse mapping for incoming mail (aliasing), too.
meillo@76	865 Further more, masquerading set up there is readily available for all
meillo@74	866 mail software on the system.
meillo@76	867 Hence, mmailid masquerading was removed.
meillo@74	868 .Ci 0836c8000ccb34b59410ef1c15b1b7feac70ce5f
meillo@74	869 .P
meillo@74	870 The
meillo@74	871 .I username_extension
meillo@76	872 masquerading type did not replace the username but would append a suffix,
meillo@76	873 specified by the
meillo@74	874 .Ev USERNAME_EXTENSION
meillo@76	875 environment variable, to it.
meillo@76	876 This provided support for the
meillo@74	877 .I user-extension
meillo@74	878 feature of qmail and the similar
meillo@74	879 .I "plussed user
meillo@74	880 processing of sendmail.
meillo@74	881 The decision to remove this username_extension masquerading was
meillo@74	882 motivated by the fact that
meillo@74	883 .Pn spost
meillo@76	884 hadn't supported it already.
meillo@76	885 .Ci 2abae0bfd0ad5bf898461e50aa4b466d641f23d9
meillo@76	886 Username extensions are possible in mmh, but less convenient to use.
meillo@76	887 .\" XXX format file %(getenv USERNAME_EXTENSION)
meillo@74	888 .P
meillo@74	889 The
meillo@74	890 .I draft_from
meillo@74	891 masquerading type instructed
meillo@74	892 .Pn post
meillo@84	893 to use the value of the
meillo@84	894 .Hd From
meillo@84	895 header field as SMTP envelope sender.
meillo@76	896 Sender addresses could be replaced completely.
meillo@74	897 .Ci b14ea6073f77b4359aaf3fddd0e105989db9
meillo@76	898 Mmh offers a kind of masquerading similar in effect, but
meillo@74	899 with technical differences.
meillo@76	900 As mmh does not transfer messages itself, the local MTA has final control
meillo@76	901 over the sender's address. Any masquerading mmh introduces may be reverted
meillo@76	902 by the MTA.
meillo@76	903 In times of pedantic spam checking, an MTA will take care to use
meillo@76	904 sensible envelope sender addresses to keep its own reputation up.
meillo@84	905 Nonetheless, the MUA can set the
meillo@84	906 .Hd From
meillo@84	907 header field and thereby propose
meillo@76	908 a sender address to the MTA.
meillo@74	909 The MTA may then decide to take that one or generate the canonical sender
meillo@74	910 address for use as envelope sender address.
meillo@74	911 .P
meillo@74	912 In mmh, the MTA will always extract the recipient and sender from the
meillo@84	913 message header (\c
meillo@74	914 .Pn sendmail 's
meillo@74	915 .Sw -t
meillo@74	916 switch).
meillo@84	917 The
meillo@84	918 .Hd From
meillo@84	919 header field of the draft may be set arbitrary by the user.
meillo@74	920 If it is missing, the canonical sender address will be generated by the MTA.
meillo@74	921
meillo@74	922 .U3 "Remaining Options
meillo@74	923 .P
meillo@74	924 Two configure options remain in mmh.
meillo@74	925 One is the locking method to use:
meillo@74	926 .Sw --with-locking=[dot\|fcntl\|flock\|lockf] .
meillo@76	927 The idea of removing all methods except the portable dot locking
meillo@76	928 and having that one as the default is appealing, but this change
meillo@76	929 requires deeper technical investigation into the topic.
meillo@76	930 The other option,
meillo@74	931 .Sw --enable-debug ,
meillo@74	932 compiles the programs with debugging symbols and does not strip them.
meillo@74	933 This option is likely to stay.
meillo@72	934
meillo@72	935
meillo@58	936
meillo@63	937
meillo@100	938 .H2 "Command Line Switches
meillo@58	939 .P
meillo@93	940 The command line switches of MH tools follow the X Window style.
meillo@93	941 They are words, introduced by a single dash.
meillo@93	942 For example:
meillo@93	943 .Cl "-truncate" .
meillo@93	944 Every program in mmh has two generic switches:
meillo@93	945 .Sw -help ,
meillo@93	946 to print a short message on how to use the program, and
meillo@93	947 .Sw -Version ,
meillo@93	948 to tell what version of mmh the program belongs to.
meillo@93	949 .P
meillo@93	950 Switches change the behavior of programs.
meillo@93	951 Programs that do one thing in one way require no switches.
meillo@93	952 In most cases, doing something in exactly one way is too limiting.
meillo@97	953 If there is basically one task to accomplish, but it should be done
meillo@93	954 in various ways, switches are a good approach to alter the behavior
meillo@93	955 of a program.
meillo@93	956 Changing the behavior of programs provides flexibility and customization
meillo@97	957 to users, but at the same time it complicates the code, documentation and
meillo@93	958 usage of the program.
meillo@97	959 .\" XXX: Ref
meillo@93	960 Therefore, the number of switches should be kept small.
meillo@93	961 A small set of well-chosen switches does no harm.
meillo@93	962 But usually, the number of switches increases over time.
meillo@93	963 Already in 1985, Rose and Romine have identified this as a major
meillo@93	964 problem of MH:
meillo@93	965 .[ [
meillo@93	966 rose romine real work
meillo@93	967 .], p. 12]
meillo@98	968 .QS
meillo@93	969 A complaint often heard about systems which undergo substantial development
meillo@93	970 by many people over a number of years, is that more and more options are
meillo@93	971 introduced which add little to the functionality but greatly increase the
meillo@93	972 amount of information a user needs to know in order to get useful work done.
meillo@93	973 This is usually referred to as creeping featurism.
meillo@93	974 .QP
meillo@93	975 Unfortunately MH, having undergone six years of off-and-on development by
meillo@93	976 ten or so well-meaning programmers (the present authors included),
meillo@93	977 suffers mightily from this.
meillo@98	978 .QE
meillo@93	979 .P
meillo@97	980 Being reluctant to adding new switches \(en or `options',
meillo@97	981 as Rose and Romine call them \(en is one part of a counter-action,
meillo@97	982 the other part is removing hardly used switches.
meillo@97	983 Nmh's tools had lots of switches already implemented,
meillo@97	984 hence, cleaning up by removing some of them was the more important part
meillo@97	985 of the counter-action.
meillo@93	986 Removing existing functionality is always difficult because it
meillo@93	987 breaks programs that use these functions.
meillo@93	988 Also, for every obsolete feature, there'll always be someone who still
meillo@93	989 uses it and thus opposes its removal.
meillo@93	990 This puts the developer into the position,
meillo@93	991 where sensible improvements to style are regarded as destructive acts.
meillo@97	992 Yet, living with the featurism is far worse, in my eyes, because
meillo@97	993 future needs will demand adding further features,
meillo@93	994 worsening the situation more and more.
meillo@93	995 Rose and Romine added in a footnote,
meillo@93	996 ``[...]
meillo@93	997 .Pn send
meillo@93	998 will no doubt acquire an endless number of switches in the years to come.''
meillo@97	999 Although clearly humorous, the comment points to the nature of the problem.
meillo@97	1000 Refusing to add any new switches would encounter the problem at its root,
meillo@97	1001 but this is not practical.
meillo@97	1002 New needs will require new switches and it would be unwise to block
meillo@97	1003 them strictly.
meillo@97	1004 Nevertheless, removing obsolete switches still is an effective approach
meillo@97	1005 to deal with the problem.
meillo@97	1006 Working on an experimental branch without an established user base,
meillo@97	1007 eased my work because I did not offend users when I removed existing
meillo@97	1008 funtions.
meillo@93	1009 .P
meillo@93	1010 Rose and Romine counted 24 visible and 9 more hidden switches for
meillo@93	1011 .Pn send .
meillo@97	1012 In nmh, they increased up to 32 visible and 12 hidden ones.
meillo@97	1013 At the time of writing, no more than 7 visible switches and 1 hidden switch
meillo@97	1014 have remained in mmh's
meillo@97	1015 .Pn send .
meillo@97	1016 (These numbers include two generic switches, help and version.)
meillo@93	1017 .P
meillo@97	1018 Fig. XXX
meillo@93	1019 .\" XXX Ref
meillo@97	1020 displays the number of switches for each of the tools that is available
meillo@97	1021 in both, nmh and mmh.
meillo@100	1022 The tools are sorted by the number of switches they had in nmh.
meillo@100	1023 Visible and hidden switches were counted,
meillo@97	1024 but not the generic help and version switches.
meillo@93	1025 Whereas in the beginning of the project, the average tool had 11 switches,
meillo@93	1026 now it has no more than 5 \(en only half as many.
meillo@93	1027 If the `no' switches and similar inverse variant are folded onto
meillo@100	1028 their counter-parts, the average tool had 8 switches in pre-mmh times and
meillo@100	1029 has 4 now.
meillo@93	1030 The total number of functional switches in mmh dropped from 465
meillo@93	1031 to 234.
meillo@58	1032
meillo@93	1033 .KS
meillo@93	1034 .in 1c
meillo@93	1035 .so input/switches.grap
meillo@93	1036 .KE
meillo@58	1037
meillo@93	1038 .P
meillo@93	1039 A part of the switches vanished after functions were removed.
meillo@93	1040 This was the case for network mail transfer, for instance.
meillo@97	1041 Sometimes, however, the work flow was the other way:
meillo@97	1042 I looked through the
meillo@97	1043 .Mp mh-chart (7)
meillo@97	1044 man page to identify the tools with apparently too many switches.
meillo@97	1045 Then considering the value of each of the switches by examining
meillo@97	1046 the tool's man page and source code, aided by recherche and testing.
meillo@97	1047 This way, the removal of functions was suggested by the aim to reduce
meillo@97	1048 the number of switches per command.
meillo@97	1049
meillo@58	1050
meillo@93	1051 .U3 "Draft Folder Facility
meillo@93	1052 .P
meillo@100	1053 A change early in the project was the complete transition from
meillo@93	1054 the single draft message to the draft folder facility.
meillo@97	1055 .Ci 337338b404931f06f0db2119c9e145e8ca5a9860
meillo@100	1056 The draft folder facility was introduced in the mid-Eighties, when
meillo@100	1057 Rose and Romine called it a ``relatively new feature''.
meillo@93	1058 .[
meillo@93	1059 rose romine real work
meillo@93	1060 .]
meillo@97	1061 Since then, the facility had existed but was deactivated by default.
meillo@93	1062 The default activation and the related rework of the tools made it
meillo@93	1063 possible to remove the
meillo@93	1064 .Sw -[no]draftfolder ,
meillo@93	1065 and
meillo@93	1066 .Sw -draftmessage
meillo@93	1067 switches from
meillo@93	1068 .Pn comp ,
meillo@93	1069 .Pn repl ,
meillo@93	1070 .Pn forw ,
meillo@93	1071 .Pn dist ,
meillo@93	1072 .Pn whatnow ,
meillo@93	1073 and
meillo@93	1074 .Pn send .
meillo@97	1075 .Ci 337338b404931f06f0db2119c9e145e8ca5a9860
meillo@97	1076 The only flexibility removed with this change is having multiple
meillo@97	1077 draft folders within one profile.
meillo@97	1078 I consider this a theoretical problem only.
meillo@93	1079 In the same go, the
meillo@93	1080 .Sw -draft
meillo@93	1081 switch of
meillo@93	1082 .Pn anno ,
meillo@93	1083 .Pn refile ,
meillo@93	1084 and
meillo@93	1085 .Pn send
meillo@93	1086 was removed.
meillo@93	1087 The special-casing of `the' draft message became irrelevant after
meillo@93	1088 the rework of the draft system.
meillo@93	1089 (See Sec. XXX.)
meillo@95	1090 Equally,
meillo@95	1091 .Pn comp
meillo@95	1092 lost its
meillo@95	1093 .Sw -file
meillo@95	1094 switch.
meillo@95	1095 The draft folder facility, together with the
meillo@95	1096 .Sw -form
meillo@95	1097 switch, are sufficient.
meillo@93	1098
meillo@95	1099
meillo@102	1100 .U3 "In Place Editing
meillo@93	1101 .P
meillo@93	1102 .Pn anno
meillo@93	1103 had the switches
meillo@93	1104 .Sw -[no]inplace
meillo@100	1105 to either annotate the message in place and thus preserve hard links,
meillo@93	1106 or annotate a copy to replace the original message, breaking hard links.
meillo@97	1107 Following the assumption that linked messages should truly be the
meillo@97	1108 same message, and annotating it should not break the link, the
meillo@93	1109 .Sw -[no]inplace
meillo@93	1110 switches were removed and the previous default
meillo@93	1111 .Sw -inplace
meillo@93	1112 was made the only behavior.
meillo@97	1113 .Ci c8195849d2e366c569271abb0f5f60f4ebf0b4d0
meillo@93	1114 The
meillo@93	1115 .Sw -[no]inplace
meillo@93	1116 switches of
meillo@93	1117 .Pn repl ,
meillo@93	1118 .Pn forw ,
meillo@93	1119 and
meillo@93	1120 .Pn dist
meillo@93	1121 could be removed, too, as they were simply passed through to
meillo@93	1122 .Pn anno .
meillo@93	1123 .P
meillo@93	1124 .Pn burst
meillo@93	1125 also had
meillo@93	1126 .Sw -[no]inplace
meillo@95	1127 switches, but with different meaning.
meillo@95	1128 With
meillo@95	1129 .Sw -inplace ,
meillo@95	1130 the digest had been replaced by the table of contents (i.e. the
meillo@95	1131 introduction text) and the bursted messages were placed right
meillo@95	1132 after this message, renumbering all following messages.
meillo@95	1133 Also, any trailing text of the digest was lost, though,
meillo@95	1134 in practice, it usually consists of an end-of-digest marker only.
meillo@95	1135 Nontheless, this behavior appeared less elegant than the
meillo@95	1136 .Sw -noinplace
meillo@95	1137 behavior, which already had been the default.
meillo@95	1138 Nmh's
meillo@95	1139 .Mp burst (1)
meillo@95	1140 man page reads:
meillo@95	1141 .sp \n(PDu
meillo@98	1142 .QS
meillo@93	1143 If -noinplace is given, each digest is preserved, no table
meillo@93	1144 of contents is produced, and the messages contained within
meillo@93	1145 the digest are placed at the end of the folder. Other messages
meillo@93	1146 are not tampered with in any way.
meillo@98	1147 .QE
meillo@95	1148 .LP
meillo@93	1149 The decision to drop the
meillo@93	1150 .Sw -inplace
meillo@95	1151 behavior was supported by the code complexity and the possible data loss
meillo@95	1152 it caused.
meillo@93	1153 .Sw -noinplace
meillo@95	1154 was chosen to be the definitive behavior.
meillo@97	1155 .Ci 68a686adeb39223a5e1ad35e4a24890ec053679d
meillo@93	1156
meillo@95	1157
meillo@95	1158 .U3 "Forms and Format Strings
meillo@93	1159 .P
meillo@95	1160 Historically, the tools that had
meillo@95	1161 .Sw -form
meillo@95	1162 switches to supply a form file had
meillo@95	1163 .Sw -format
meillo@95	1164 switches as well to supply the contents of a form file as a string
meillo@95	1165 on the command line directly.
meillo@95	1166 In consequence, the following two lines equaled:
meillo@95	1167 .VS
meillo@95	1168 scan -form scan.mailx
meillo@95	1169 scan -format "`cat .../scan.mailx`"
meillo@95	1170 VE
meillo@95	1171 The
meillo@95	1172 .Sw -format
meillo@95	1173 switches were dropped in favor for extending the
meillo@95	1174 .Sw -form
meillo@95	1175 switches.
meillo@97	1176 .Ci f51956be123db66b00138f80464d06f030dbb88d
meillo@95	1177 If their argument starts with an equal sign (`='),
meillo@95	1178 then the rest of the argument is taken as a format string,
meillo@95	1179 otherwise the arguments is treated as the name of a format file.
meillo@95	1180 Thus, now the following two lines equal:
meillo@95	1181 .VS
meillo@95	1182 scan -form scan.mailx
meillo@95	1183 scan -form "=`cat .../scan.mailx`"
meillo@95	1184 VE
meillo@95	1185 This rework removed the prefix collision between
meillo@95	1186 .Sw -form
meillo@95	1187 and
meillo@95	1188 .Sw -format .
meillo@95	1189 Now, typing
meillo@95	1190 .Sw -fo
meillo@95	1191 suffices to specify form or format string.
meillo@95	1192 .P
meillo@95	1193 The different meaning of
meillo@95	1194 .Sw -format
meillo@95	1195 for
meillo@95	1196 .Pn repl
meillo@95	1197 and
meillo@95	1198 .Pn forw
meillo@95	1199 was removed in mmh.
meillo@95	1200 .Pn forw
meillo@95	1201 was completely switched to MIME-type forwarding, thus removing the
meillo@95	1202 .Sw -[no]format .
meillo@97	1203 .Ci 6e271608b7b9c23771523f88d23a4d3593010cf1
meillo@95	1204 For
meillo@95	1205 .Pn repl ,
meillo@95	1206 the
meillo@95	1207 .Sw -[no]format
meillo@95	1208 switches were reworked to
meillo@95	1209 .Sw -[no]filter
meillo@95	1210 switches.
meillo@97	1211 .Ci 67411b1f95d6ec987b4c732459e1ba8a8ac192c6
meillo@95	1212 The
meillo@95	1213 .Sw -format
meillo@95	1214 switches of
meillo@95	1215 .Pn send
meillo@95	1216 and
meillo@95	1217 .Pn post ,
meillo@95	1218 which had a third meaning,
meillo@95	1219 were removed likewise.
meillo@97	1220 .Ci f3cb7cde0e6f10451b6848678d95860d512224b9
meillo@95	1221 Eventually, the ambiguity of the
meillo@95	1222 .Sw -format
meillo@95	1223 switches was resolved by not anymore having any such switch in mmh.
meillo@95	1224
meillo@95	1225
meillo@95	1226 .U3 "MIME Tools
meillo@95	1227 .P
meillo@95	1228 The MIME tools, which were once part of
meillo@100	1229 .Pn mhn
meillo@100	1230 [sic!],
meillo@95	1231 had several switches that added little practical value to the programs.
meillo@95	1232 The
meillo@95	1233 .Sw -[no]realsize
meillo@95	1234 switches of
meillo@95	1235 .Pn mhbuild
meillo@95	1236 and
meillo@95	1237 .Pn mhlist
meillo@97	1238 were removed, doing real size calculations always now
meillo@97	1239 .Ci 8d8f1c3abc586c005c904e52c4adbfe694d2201c ,
meillo@97	1240 as
meillo@95	1241 ``This provides an accurate count at the expense of a small delay.''
meillo@95	1242 This small delay is not noticable on modern systems.
meillo@95	1243 .P
meillo@95	1244 The
meillo@95	1245 .Sw -[no]check
meillo@95	1246 switches were removed together with the support for
meillo@95	1247 .Hd Content-MD5
meillo@95	1248 header fields.
meillo@95	1249 .[
meillo@95	1250 rfc 1864
meillo@95	1251 .]
meillo@97	1252 .Ci 31dc797eb5178970d68962ca8939da3fd9a8efda
meillo@95	1253 (See Sec. XXX)
meillo@95	1254 .P
meillo@95	1255 The
meillo@95	1256 .Sw -[no]ebcdicsafe
meillo@95	1257 and
meillo@95	1258 .Sw -[no]rfc934mode
meillo@95	1259 switches of
meillo@95	1260 .Pn mhbuild
meillo@95	1261 were removed because they are considered obsolete.
meillo@97	1262 .Ci 01a3480928da485b4d6109d36d751dfa71799d58
meillo@97	1263 .Ci 3363e2624dce0eb8164cf8b3f1ab385c8ff72e88
meillo@95	1264 .P
meillo@95	1265 Content caching of external MIME parts, activated with the
meillo@95	1266 .Sw -rcache
meillo@95	1267 and
meillo@95	1268 .Sw -wcache
meillo@95	1269 switches was completely removed.
meillo@97	1270 .Ci d1fefd9f614e4dc3cda16da6c69133c1b2005269
meillo@97	1271 External MIME parts are rare today, having a caching facility
meillo@96	1272 for them is appears to be unnecessary.
meillo@95	1273 .P
meillo@95	1274 In pre-MIME times,
meillo@95	1275 .Pn mhl
meillo@95	1276 had covered many tasks that are part of MIME handling today.
meillo@95	1277 Therefore,
meillo@95	1278 .Pn mhl
meillo@95	1279 could be simplified to a large extend, reducing the number of its
meillo@95	1280 switches from 21 to 6.
meillo@97	1281 .Ci 350ad6d3542a07639213cf2a4fe524e829c1e7b6
meillo@97	1282 .Ci 0e46503be3c855bddaeae3843e1b659279c35d70
meillo@95	1283
meillo@95	1284
meillo@95	1285 .U3 "Mail Transfer Switches
meillo@95	1286 .P
meillo@95	1287 With the removal of the mail transfer facilities, a lot of switches
meillo@95	1288 vanished automatically.
meillo@95	1289 .Pn inc
meillo@95	1290 lost 9 switches, namely
meillo@95	1291 .Sw -host ,
meillo@95	1292 .Sw -port ,
meillo@95	1293 .Sw -user ,
meillo@95	1294 .Sw -proxy ,
meillo@95	1295 .Sw -snoop ,
meillo@95	1296 .Sw -[no]pack ,
meillo@95	1297 as well as
meillo@95	1298 .Sw -sasl
meillo@95	1299 and
meillo@95	1300 .Sw -saslmech .
meillo@95	1301 .Pn send
meillo@95	1302 and
meillo@95	1303 .Pn post
meillo@95	1304 lost 11 switches each, namely
meillo@95	1305 .Sw -server ,
meillo@95	1306 .Sw -port ,
meillo@95	1307 .Sw -client ,
meillo@95	1308 .Sw -user ,
meillo@95	1309 .Sw -mail ,
meillo@95	1310 .Sw -saml ,
meillo@95	1311 .Sw -send ,
meillo@95	1312 .Sw -soml ,
meillo@95	1313 .Sw -snoop ,
meillo@95	1314 as well as
meillo@95	1315 .Sw -sasl ,
meillo@95	1316 .Sw -saslmech ,
meillo@95	1317 and
meillo@95	1318 .Sw -tls .
meillo@95	1319 .Pn send
meillo@95	1320 had the switches only to pass them further to
meillo@95	1321 .Pn post ,
meillo@95	1322 because the user would invoke
meillo@95	1323 .Pn post
meillo@95	1324 not directly, but through
meillo@95	1325 .Pn send .
meillo@95	1326 All these switches, except
meillo@95	1327 .Sw -snoop
meillo@95	1328 were usually defined as default switches in the user's profile,
meillo@95	1329 but hardly given in interactive usage.
meillo@95	1330 .P
meillo@95	1331 Of course, those switches did not really ``vanish'', but the configuration
meillo@95	1332 they did was handed over to external MSAs and MRAs.
meillo@95	1333 Instead of setting up the mail transfer in mmh, it is set up in
meillo@95	1334 external tools.
meillo@95	1335 Yet, this simplifies mmh.
meillo@95	1336 Specialized external tools will likely have simple configuration files.
meillo@95	1337 Hence, instead of having one complicated central configuration file,
meillo@95	1338 the configuration of each domain is separate.
meillo@95	1339 Although the user needs to learn to configure each of the tools,
meillo@95	1340 each configuration is likely much simpler.
meillo@95	1341
meillo@95	1342
meillo@95	1343 .U3 "Maildrop Formats
meillo@95	1344 .P
meillo@95	1345 With the removal of MMDF maildrop format support,
meillo@95	1346 .Pn packf
meillo@95	1347 and
meillo@95	1348 .Pn rcvpack
meillo@95	1349 no longer needed their
meillo@95	1350 .Sw -mbox
meillo@95	1351 and
meillo@95	1352 .Sw -mmdf
meillo@95	1353 switches.
meillo@95	1354 .Sw -mbox
meillo@95	1355 is the sole behavior now.
meillo@97	1356 .Ci 3916ab66ad5d183705ac12357621ea8661afd3c0
meillo@95	1357 In the same go,
meillo@95	1358 .Pn packf
meillo@97	1359 and
meillo@97	1360 .Pn rcvpack
meillo@97	1361 were reworked (see Sec. XXX) and their
meillo@95	1362 .Sw -file
meillo@95	1363 switch became unnecessary.
meillo@97	1364 .Ci ca1023716d4c2ab890696f3e41fa0d94267a940e
meillo@95	1365
meillo@95	1366
meillo@95	1367 .U3 "Terminal Magic
meillo@95	1368 .P
meillo@95	1369 Mmh's tools will no longer clear the screen (\c
meillo@95	1370 .Pn scan 's
meillo@95	1371 and
meillo@95	1372 .Pn mhl 's
meillo@95	1373 .Sw -[no]clear
meillo@97	1374 switches
meillo@97	1375 .Ci e57b17343dcb3ff373ef4dd089fbe778f0c7c270
meillo@97	1376 .Ci 943765e7ac5693ae177fd8d2b5a2440e53ce816e ).
meillo@95	1377 Neither will
meillo@95	1378 .Pn mhl
meillo@95	1379 ring the bell (\c
meillo@97	1380 .Sw -[no]bell
meillo@97	1381 .Ci e11983f44e59d8de236affa5b0d0d3067c192e24 )
meillo@95	1382 nor page the output itself (\c
meillo@97	1383 .Sw -length
meillo@97	1384 .Ci 5b9d883db0318ed2b84bb82dee880d7381f99188 ).
meillo@95	1385 .P
meillo@95	1386 Generally, the pager to use is no longer specified with the
meillo@95	1387 .Sw -[no]moreproc
meillo@95	1388 command line switches for
meillo@95	1389 .Pn mhl
meillo@95	1390 and
meillo@95	1391 .Pn show /\c
meillo@95	1392 .Pn mhshow .
meillo@97	1393 .Ci 39e87a75b5c2d3572ec72e717720b44af291e88a
meillo@95	1394 .P
meillo@95	1395 .Pn prompter
meillo@95	1396 lost its
meillo@95	1397 .Sw -erase
meillo@95	1398 and
meillo@95	1399 .Sw -kill
meillo@95	1400 switches because today the terminal cares for the line editing keys.
meillo@95	1401
meillo@95	1402
meillo@95	1403 .U3 "Header Printing
meillo@95	1404 .P
meillo@95	1405 .Pn folder 's
meillo@95	1406 data output is self-explaining enough that
meillo@95	1407 displaying the header line makes few sense.
meillo@95	1408 Hence, the
meillo@95	1409 .Sw -[no]header
meillo@95	1410 switch was removed and headers are never printed.
meillo@97	1411 .Ci 601cc73d1fa05ce96faa728f036d6c51b91701c7
meillo@95	1412 .P
meillo@95	1413 In
meillo@95	1414 .Pn mhlist ,
meillo@95	1415 the
meillo@95	1416 .Sw -[no]header
meillo@95	1417 switches were removed, too.
meillo@97	1418 .Ci b24f96523aaf60e44e04a3ffb1d22e69a13a602f
meillo@95	1419 But in this case headers are always printed,
meillo@95	1420 because the output is not self-explaining.
meillo@95	1421 .P
meillo@95	1422 .Pn scan
meillo@95	1423 also had
meillo@95	1424 .Sw -[no]header
meillo@95	1425 switches.
meillo@95	1426 Printing the header had been sensible until the introduction of
meillo@95	1427 format strings made it impossible to display the column headings.
meillo@95	1428 Only the folder name and the current date remained to be printed.
meillo@95	1429 As this information can be perfectly retrieved by
meillo@95	1430 .Pn folder
meillo@95	1431 and
meillo@95	1432 .Pn date ,
meillo@95	1433 consequently, the switches were removed.
meillo@97	1434 .Ci c477dc5d1d03fa6d9a8ab3dd3508c63cbddc044e
meillo@95	1435 .P
meillo@95	1436 By removing all
meillo@95	1437 .Sw -header
meillo@95	1438 switches, the collision with
meillo@95	1439 .Sw -help
meillo@95	1440 on the first two letters was resolved.
meillo@95	1441 Currently,
meillo@95	1442 .Sw -h
meillo@95	1443 evaluates to
meillo@95	1444 .Sw -help
meillo@95	1445 for all tools of mmh.
meillo@95	1446
meillo@95	1447
meillo@95	1448 .U3 "Suppressing Edits or the WhatNow Shell
meillo@95	1449 .P
meillo@95	1450 The
meillo@95	1451 .Sw -noedit
meillo@100	1452 switch of
meillo@95	1453 .Pn comp ,
meillo@95	1454 .Pn repl ,
meillo@95	1455 .Pn forw ,
meillo@95	1456 .Pn dist ,
meillo@95	1457 and
meillo@95	1458 .Pn whatnow
meillo@95	1459 was removed, but it can now be replaced by specifying
meillo@95	1460 .Sw -editor
meillo@95	1461 with an empty argument.
meillo@97	1462 .Ci 75fca31a5b9d5c1a99c74ab14c94438d8852fba9
meillo@95	1463 (Specifying
meillo@95	1464 .Cl "-editor true
meillo@95	1465 is nearly the same, only differing by the previous editor being set.)
meillo@95	1466 .P
meillo@95	1467 The more important change is the removal of the
meillo@95	1468 .Sw -nowhatnowproc
meillo@95	1469 switch.
meillo@97	1470 .Ci ee4f43cf2ef0084ec698e4e87159a94c01940622
meillo@95	1471 This switch had introduced an awkward behavior, as explained in nmh's
meillo@95	1472 man page for
meillo@95	1473 .Mp comp (1):
meillo@98	1474 .QS
meillo@98	1475 The \-editor editor switch indicates the editor to use for
meillo@98	1476 the initial edit. Upon exiting from the editor, comp will
meillo@98	1477 invoke the whatnow program. See whatnow(1) for a discussion
meillo@98	1478 of available options. The invocation of this program can be
meillo@98	1479 inhibited by using the \-nowhatnowproc switch. (In truth of
meillo@98	1480 fact, it is the whatnow program which starts the initial
meillo@98	1481 edit. Hence, \-nowhatnowproc will prevent any edit from
meillo@95	1482 occurring.)
meillo@98	1483 .QE
meillo@95	1484 .P
meillo@95	1485 Effectively, the
meillo@95	1486 .Sw -nowhatnowproc
meillo@100	1487 switch creates only a draft message.
meillo@95	1488 As
meillo@95	1489 .Cl "-whatnowproc true
meillo@95	1490 causes the same behavior, the
meillo@95	1491 .Sw -nowhatnowproc
meillo@95	1492 switch was removed for being redundant.
meillo@100	1493 Likely, the
meillo@95	1494 .Sw -nowhatnowproc
meillo@100	1495 switch was intended to be used by front-ends.
meillo@95	1496
meillo@95	1497
meillo@95	1498 .U3 "Compatibility Switches
meillo@95	1499 .BU
meillo@95	1500 The hidden
meillo@95	1501 .Sw -[no]total
meillo@95	1502 switches of
meillo@95	1503 .Pn flist .
meillo@95	1504 They were simply the inverse of the visible
meillo@95	1505 .Sw -[no]fast
meillo@95	1506 switches:
meillo@95	1507 .Sw -total
meillo@95	1508 was
meillo@95	1509 .Sw -nofast
meillo@95	1510 and
meillo@95	1511 .Sw -nototal
meillo@95	1512 was
meillo@95	1513 .Sw -fast .
meillo@95	1514 I removed the
meillo@95	1515 .Sw -[no]total
meillo@95	1516 legacy.
meillo@97	1517 .Ci ea21fe2c4bd23c639bef251398fae809875732ec
meillo@95	1518 .BU
meillo@95	1519 The
meillo@95	1520 .Sw -subject
meillo@95	1521 switch of
meillo@95	1522 .Pn sortm
meillo@95	1523 existed for compatibility only.
meillo@95	1524 It can be fully replaced by
meillo@95	1525 .Cl "-textfield subject
meillo@95	1526 thus it was removed.
meillo@97	1527 .Ci 00140a3c86e9def69d98ba2ffd4d6e50ef6326ea
meillo@95	1528
meillo@95	1529
meillo@95	1530 .U3 "Various
meillo@95	1531 .BU
meillo@96	1532 In order to avoid prefix collisions among switch names, the
meillo@95	1533 .Sw -version
meillo@95	1534 switch was renamed to
meillo@95	1535 .Sw -Version
meillo@95	1536 (with capital `V').
meillo@97	1537 .Ci 32b2354dbaf4bf934936eb5b102a4a3d2fdd209a
meillo@95	1538 Every program has the
meillo@95	1539 .Sw -version
meillo@95	1540 switch but its first three letters collided with the
meillo@95	1541 .Sw -verbose
meillo@95	1542 switch, present in many programs.
meillo@95	1543 The rename solved this problem once for all.
meillo@95	1544 Although this rename breaks a basic interface, having the
meillo@95	1545 .Sw -V
meillo@95	1546 abbreviation to display the version information, isn't all too bad.
meillo@95	1547 .BU
meillo@95	1548 .Sw -[no]preserve
meillo@95	1549 of
meillo@95	1550 .Pn refile
meillo@95	1551 was removed because what use was it anyway?
meillo@98	1552 .QS
meillo@95	1553 Normally when a message is refiled, for each destination
meillo@95	1554 folder it is assigned the number which is one above the current
meillo@95	1555 highest message number in that folder. Use of the
meillo@95	1556 \-preserv [sic!] switch will override this message renaming, and try
meillo@95	1557 to preserve the number of the message. If a conflict for a
meillo@95	1558 particular folder occurs when using the \-preserve switch,
meillo@95	1559 then refile will use the next available message number which
meillo@95	1560 is above the message number you wish to preserve.
meillo@98	1561 .QE
meillo@95	1562 .BU
meillo@95	1563 The removal of the
meillo@95	1564 .Sw -[no]reverse
meillo@95	1565 switches of
meillo@95	1566 .Pn scan
meillo@97	1567 .Ci 8edc5aaf86f9f77124664f6801bc6c6cdf258173
meillo@95	1568 is a bug fix, supported by the comments
meillo@95	1569 ``\-[no]reverse under #ifdef BERK (I really HATE this)''
meillo@95	1570 by Rose and
meillo@95	1571 ``Lists messages in reverse order with the `\-reverse' switch.
meillo@95	1572 This should be considered a bug.'' by Romine in the documentation.
meillo@97	1573 The question remains why neither Rose and Romine had fixed this
meillo@95	1574 bug in the Eighties when they wrote these comments nor has anyone
meillo@95	1575 thereafter.
meillo@93	1576
meillo@93	1577
meillo@93	1578 .ig
meillo@93	1579
meillo@95	1580 forw: [no]dashstuffing(mhl)
meillo@93	1581
meillo@95	1582 mhshow: [no]pause [no]serialonly
meillo@93	1583
meillo@93	1584 mhmail: resent queued
meillo@93	1585 inc: snoop, (pop)
meillo@93	1586
meillo@95	1587 mhl: [no]faceproc folder sleep
meillo@95	1588 [no]dashstuffing(forw) digest list volume number issue number
meillo@93	1589
meillo@95	1590 prompter: [no]doteof
meillo@93	1591
meillo@93	1592 refile: [no]preserve [no]unlink [no]rmmproc
meillo@93	1593
meillo@95	1594 send: [no]forward [no]mime [no]msgid
meillo@93	1595 [no]push split [no]unique (sasl) width snoop [no]dashstuffing
meillo@93	1596 attach attachformat
meillo@93	1597 whatnow: (noedit) attach
meillo@93	1598
meillo@93	1599 slocal: [no]suppressdups
meillo@93	1600
meillo@95	1601 spost: [no]filter [no]backup width [no]push idanno
meillo@93	1602 [no]check(whom) whom(whom)
meillo@93	1603
meillo@93	1604 whom: ???
meillo@93	1605
meillo@95	1606 ..
meillo@93	1607
meillo@93	1608
meillo@93	1609 .ig
meillo@93	1610
meillo@93	1611 .P
meillo@93	1612 In the best case, all switches are unambiguous on the first character,
meillo@93	1613 or on the three-letter prefix for the `no' variants.
meillo@96	1614 Reducing switch prefix collisions, shortens the necessary prefix length
meillo@93	1615 the user must type.
meillo@93	1616 Having less switches helps best.
meillo@93	1617
meillo@93	1618 ..
meillo@58	1619
meillo@95	1620
meillo@102	1621 .\" XXX: whatnow prompt commands
meillo@102	1622
meillo@102	1623
meillo@95	1624
meillo@95	1625
meillo@74	1626 .H1 "Modernizing
meillo@102	1627 .P
meillo@102	1628 The code base of mmh originates from the late Seventies.
meillo@102	1629 Through the Eighties, extensive work had been done on it.
meillo@102	1630 In the Nineties, it had been partly reorganized and extended.
meillo@102	1631 Relicts from each decade have gathered in the code base.
meillo@102	1632 My goal was to modernize the code base.
meillo@102	1633
meillo@102	1634 .P
meillo@102	1635 FIXME functional aspect only here
meillo@102	1636 .P
meillo@102	1637 FIXME ref to `code style' for non-functional aspects.
meillo@58	1638
meillo@58	1639
meillo@100	1640 .H2 "Code Relicts
meillo@0	1641 .P
meillo@102	1642 My position to drop obsolete functionality of mmh to remove old code
meillo@104	1643 is much more revolutional than the nmh community likes to have it.
meillo@104	1644 Working on an experimental version, I was able to quickly drop
meillo@104	1645 functionality I considered ancient.
meillo@104	1646 The need for consensus with peers would have slowed this process down.
meillo@104	1647 Without the need to justify my decisions, I was able to rush forward.
meillo@104	1648 In Dezember 2011, Paul Vixie motivated the nmh developers to just
meillo@104	1649 do the work:
meillo@104	1650 .[
meillo@104	1651 paul vixie edginess nmh-workers
meillo@104	1652 .]
meillo@104	1653 .QS
meillo@104	1654 let's stop walking on egg shells with this code base. there's no need to
meillo@104	1655 discuss whether to keep using vfork, just note in [sic!] passing, [...]
meillo@104	1656 we don't need a separate branch for removing vmh
meillo@104	1657 or ridding ourselves of #ifdef's or removing posix replacement functions
meillo@104	1658 or depending on pure ansi/posix "libc".
meillo@104	1659 .QP
meillo@104	1660 these things should each be a day or two of work and the "main branch"
meillo@104	1661 should just be modern. [...]
meillo@104	1662 let's push forward, aggressively.
meillo@104	1663 .QE
meillo@104	1664 .LP
meillo@104	1665 I did so already in the months before.
meillo@104	1666 I pushed forward.
meillo@104	1667 I simply dropped the cruft.
meillo@104	1668 .P
meillo@104	1669 The decision to drop a feature was based on literature research and
meillo@104	1670 careful thinking, but whether having had contact to this particular
meillo@104	1671 feature within my own computer life served as a rule of thumb.
meillo@104	1672 My reasons are always made clean in the commit message for the
meillo@102	1673 version control system.
meillo@104	1674 Hence, others can comprehend my view and argue for undoing the change
meillo@104	1675 if I have missed an important aspect.
meillo@12	1676
meillo@102	1677
meillo@104	1678 .U3 "Forking
meillo@12	1679 .P
meillo@104	1680 In being a tool chest, MH creates many processes.
meillo@104	1681 In earlier times
meillo@104	1682 .Fu fork()
meillo@104	1683 had been an expensive system call, because the process's image needed
meillo@104	1684 to be duplicated completely at once.
meillo@104	1685 This was especially painfull in the common case when the image gets
meillo@104	1686 replaced by a call to
meillo@104	1687 .Fu exec()
meillo@104	1688 right after having forked the child process.
meillo@104	1689 The
meillo@104	1690 .Fu vfork()
meillo@104	1691 system call was invented to speed up this particular case.
meillo@104	1692 It completely omits the duplication of the image.
meillo@104	1693 On old systems this resulted in significant speed ups.
meillo@104	1694 Therefore MH used
meillo@104	1695 .Fu vfork()
meillo@104	1696 whenever possible.
meillo@12	1697 .P
meillo@104	1698 Modern memory management units support copy-on-write semantics, which make
meillo@104	1699 .Fu fork()
meillo@104	1700 almost as fast as
meillo@104	1701 .Fu vfork() .
meillo@104	1702 The man page of
meillo@104	1703 .Mp vfork (2)
meillo@104	1704 in FreeBSD 8.0 states:
meillo@104	1705 .QS
meillo@104	1706 This system call will be eliminated when proper system sharing mechanisms
meillo@104	1707 are implemented. Users should not depend on the memory sharing semantics
meillo@104	1708 of vfork() as it will, in that case, be made synonymous to fork(2).
meillo@104	1709 .QE
meillo@104	1710 .LP
meillo@104	1711 Vixie supports the removal with the note that ``the last
meillo@104	1712 system on which fork was so slow that an mh user would notice it, was
meillo@104	1713 Eunice. that was 1987''.
meillo@104	1714 .[
meillo@104	1715 nmh-workers vixie edginess
meillo@104	1716 .]
meillo@104	1717 I replaced all calls to
meillo@104	1718 .Fu vfork()
meillo@104	1719 with calls to
meillo@104	1720 .Fu fork() .
meillo@104	1721 .P
meillo@104	1722 Related to the costs of
meillo@104	1723 .Fu fork()
meillo@104	1724 is the probability of its success.
meillo@104	1725 In the Eighties on heavy loaded systems, calls to
meillo@104	1726 .Fu fork()
meillo@104	1727 were prone to failure.
meillo@104	1728 Hence, many of the
meillo@104	1729 .Fu fork()
meillo@104	1730 calls in the code were wrapped into loops to retry the
meillo@104	1731 .Fu fork()
meillo@104	1732 several times, for higher changes to succeed, eventually.
meillo@104	1733 On modern systems, failing calls to
meillo@104	1734 .Fu fork()
meillo@104	1735 are unusual.
meillo@104	1736 Hence, in the rare case when
meillo@104	1737 .Fu fork()
meillo@104	1738 fails, mmh programs simply abort.
meillo@12	1739
meillo@12	1740
meillo@104	1741 .U3 "Obsolete Header Fields
meillo@104	1742 .BU
meillo@84	1743 The
meillo@84	1744 .Hd Encrypted
meillo@104	1745 header field was introduced by RFC\\|822,
meillo@104	1746 but already marked legacy in RFC\\|2822.
meillo@104	1747 OpenPGP provides the basis for standardized exchange of encrypted
meillo@104	1748 messages [RFC\\|4880, RFC\\|3156].
meillo@104	1749 The support for
meillo@104	1750 .Hd Encrypted
meillo@104	1751 header fields is removed in mmh.
meillo@104	1752 .BU
meillo@84	1753 Native support for
meillo@84	1754 .Hd Face
meillo@104	1755 header fields has been removed, as well.
meillo@104	1756 This feature is similar to the
meillo@84	1757 .Hd X-Face
meillo@84	1758 header field in its intent,
meillo@21	1759 but takes a different approach to store the image.
meillo@84	1760 Instead of encoding the image data directly into the header field,
meillo@84	1761 the it contains the hostname and UDP port where the image
meillo@21	1762 date could be retrieved.
meillo@104	1763 There is even a third system, invented in 2005.
meillo@104	1764 Although it re-uses the
meillo@104	1765 .Hd Face
meillo@104	1766 header field, it is the successor of
meillo@84	1767 .Hd X-Face
meillo@104	1768 with support for colored PNG images.
meillo@104	1769 None of the Face systems described here is popular today.
meillo@104	1770 Hence, mmh has no direct support for them.
meillo@104	1771 .BU
meillo@104	1772 The
meillo@104	1773 .Hd Content-MD5
meillo@104	1774 header field was introduced by RFC\\|1864.
meillo@104	1775 It provides detection of data corruption during the transfer.
meillo@104	1776 But it can not ensure verbatim end-to-end delivery of the contents
meillo@104	1777 [RFC\\|1864].
meillo@104	1778 The proper approach to verify content integrity in an
meillo@104	1779 end-to-end relationship is the use of digital cryptography.
meillo@104	1780 .\" XXX (RFCs FIXME).
meillo@104	1781 On the other hand, transfer protocols should detect corruption during
meillo@104	1782 each transmission. The TCP includes a checksum field therefore.
meillo@104	1783 These two approaches in combinations render the
meillo@104	1784 .Hd Content-MD5
meillo@104	1785 header field superfluous.
meillo@104	1786 The nmh-workers mailing list archive contains about 4\\|200 messages,
meillo@104	1787 ranging from 1992 until today.
meillo@104	1788 Not a single one had a
meillo@104	1789 .Hd Content-MD5
meillo@104	1790 header field.
meillo@104	1791 Neither did any of the 60\\|000 messages in my personal mail storage.
meillo@104	1792 Removing the support for this header field,
meillo@104	1793 removed the last place where MD5 computation was needed.
meillo@104	1794 Hence, the MD5 code could be removed as well.
meillo@104	1795 Over 500 lines of code vanished by this one change.
meillo@104	1796
meillo@104	1797
meillo@104	1798 .U3 "MMDF maildrop support
meillo@21	1799 .P
meillo@104	1800 This type of format is conceptionally similar to the mbox format,
meillo@104	1801 but uses a different message delimiter (`\fL^A^A^A^A\fP' instead of
meillo@104	1802 `\fLFrom\0\fP').
meillo@104	1803 Mbox is the de-facto standard maildrop format on Unix,
meillo@104	1804 whereas the MMDF maildrop format is hardly still known today.
meillo@104	1805 I did drop MMDF maildrop format support.
meillo@104	1806 .P
meillo@104	1807 The simplifications within the code were only moderate.
meillo@104	1808 Switches could be removed from
meillo@104	1809 .L packf
meillo@104	1810 and
meillo@104	1811 .L rcvpack ,
meillo@104	1812 which generate packed mailboxes.
meillo@104	1813 Only one packed mailbox format remained: mbox.
meillo@104	1814 The more important changes affected the equally named mail parsing
meillo@104	1815 routine in
meillo@104	1816 .Fn sbr/m_getfld.c .
meillo@104	1817 The MMDF code had been removed there, but as now only one packed mailbox
meillo@104	1818 format is left, further code structure simplifications may be possible.
meillo@104	1819 I have not worked on them yet because
meillo@104	1820 .Fu m_getfld()
meillo@104	1821 is heavily optimized and thus dangerous to touch.
meillo@104	1822 The risk of damaging the intricate workings of the optimized code is
meillo@104	1823 too high.
meillo@104	1824 .\" XXX: move somewhere else
meillo@104	1825 This problem is know to the developers of nmh, too.
meillo@104	1826 They also avoid touching this minefield if possible.
meillo@104	1827
meillo@12	1828
meillo@101	1829 .U3 "Prompter's Control Keys
meillo@20	1830 .P
meillo@20	1831 The program
meillo@20	1832 .Pn prompter
meillo@104	1833 queries the user to fill in a message form.
meillo@104	1834 When used by
meillo@20	1835 .Pn comp
meillo@104	1836 as
meillo@104	1837 .Cl "comp -editor prompter" ,
meillo@20	1838 the resulting behavior is similar to
meillo@20	1839 .Pn mailx .
meillo@51	1840 Apparently,
meillo@20	1841 .Pn prompter
meillo@104	1842 hadn't been touched lately.
meillo@104	1843 Otherwise it's hardly explainable why it
meillo@20	1844 still offered the switches
meillo@84	1845 .Sw -erase
meillo@84	1846 .Ar chr
meillo@20	1847 and
meillo@84	1848 .Sw -kill
meillo@84	1849 .Ar chr
meillo@20	1850 to name the characters for command line editing.
meillo@21	1851 The times when this had been necessary are long time gone.
meillo@20	1852 Today these things work out-of-the-box, and if not, are configured
meillo@20	1853 with the standard tool
meillo@20	1854 .Pn stty .
meillo@104	1855 The switches are removed now
meillo@104	1856 .Ci 0bd9750710cdbab80cfb4036dd87af20afe1552f .
meillo@20	1857
meillo@104	1858
meillo@104	1859 .U3 "Hardcopy terminal support
meillo@21	1860 .P
meillo@104	1861 More of a funny anecdote is a check for printing to a
meillo@104	1862 hardcopy terminal that remained in the code until Spring 2012,
meillo@104	1863 when I finally removed it
meillo@104	1864 .Ci b7764c4a6b71d37918a97594d866258f154017ca .
meillo@104	1865 I surely would be very happy to see such a terminal in action,
meillo@104	1866 maybe actually being able to work on it, but I fear my chances are null.
meillo@21	1867 .P
meillo@104	1868 The check only prevented a pager to be placed between the outputting
meillo@104	1869 program (\c
meillo@104	1870 .Pn mhl )
meillo@104	1871 and the terminal.
meillo@104	1872 In nmh, this could have been ensured with the
meillo@104	1873 .Sw -nomoreproc
meillo@104	1874 at the command line statically, too.
meillo@104	1875 In mmh, set the profile entry
meillo@104	1876 .Pe Pager
meillo@104	1877 or the environment variable
meillo@104	1878 .Ev PAGER
meillo@104	1879 to
meillo@104	1880 .Pn cat .
meillo@104	1881
meillo@104	1882
meillo@21	1883
meillo@12	1884
meillo@58	1885 .H2 "Attachments
meillo@22	1886 .P
meillo@101	1887 The mind model of email attachments is unrelated to MIME.
meillo@101	1888 Although the MIME RFCs (2045 through 2049) define the technical
meillo@101	1889 requirements for having attachments, they do not mention the the word
meillo@101	1890 ``attachment''.
meillo@101	1891 Instead of attachments, MIME talks about ``multi-part message bodies''
meillo@101	1892 [RFC\\|2045], a more general concept.
meillo@101	1893 Multi-part messages are messages
meillo@101	1894 ``in which one or more different
meillo@101	1895 sets of data are combined in a single body''
meillo@101	1896 [RFC\\|2046].
meillo@101	1897 MIME keeps its descriptions generic;
meillo@101	1898 it does not imply specific usage models.
meillo@101	1899 In email one usage model became prevalent: attachments.
meillo@101	1900 The idea is having a main text document with files of arbitrary kind
meillo@101	1901 attached to it.
meillo@101	1902 In MIME terms, this is a multi-part message having a text part first
meillo@101	1903 and parts of arbitray type following.
meillo@101	1904 .P
meillo@101	1905 MH's MIME support is a direct implementation of the RFCs.
meillo@101	1906 The perception of the topic described in the RFCs is clearly visible
meillo@101	1907 in MH's implementation.
meillo@101	1908 Thus, MH had all the MIME features but no idea of attachments.
meillo@101	1909 Today, however, users don't need all the MIME features but they want
meillo@101	1910 convenient attachment handling.
meillo@102	1911
meillo@102	1912 .U3 "Composing MIME Messages
meillo@102	1913 .P
meillo@102	1914 In order to improve the situation on the message composing side,
meillo@102	1915 Jon Steinhart had added an attachment system to nmh in 2002.
meillo@101	1916 .Ci 7480dbc14bc90f2d872d434205c0784704213252
meillo@102	1917 In the file
meillo@102	1918 .Fn docs/README-ATTACHMENTS ,
meillo@102	1919 he described his motivation to do so as such:
meillo@101	1920 .QS
meillo@101	1921 Although nmh contains the necessary functionality for MIME message handing,
meillo@101	1922 the interface to this functionality is pretty obtuse.
meillo@101	1923 There's no way that I'm ever going to convince my partner to write
meillo@101	1924 .Pn mhbuild
meillo@101	1925 composition files!
meillo@101	1926 .QE
meillo@102	1927 .LP
meillo@102	1928 With this change, the mind model of attachments entered nmh.
meillo@102	1929 In the same document:
meillo@101	1930 .QS
meillo@101	1931 These changes simplify the task of managing attachments on draft files.
meillo@101	1932 They allow attachments to be added, listed, and deleted.
meillo@101	1933 MIME messages are automatically created when drafts with attachments
meillo@101	1934 are sent.
meillo@101	1935 .QE
meillo@102	1936 .LP
meillo@102	1937 Unfortunately, the attachment system,
meillo@102	1938 like any new facilities in nmh,
meillo@102	1939 was deactive by default.
meillo@101	1940 .P
meillo@101	1941 During my work in Argentina, I tried to improve the attachment system.
meillo@102	1942 But, because of great opposition in the nmh community,
meillo@102	1943 my patch died as a proposal on the mailing list, after long discussions.
meillo@101	1944 .[
meillo@101	1945 nmh-workers attachment proposal
meillo@101	1946 .]
meillo@102	1947 In Januar 2012, I extended the patch and applied it to mmh.
meillo@101	1948 .Ci 8ff284ff9167eff8f5349481529332d59ed913b1
meillo@102	1949 In mmh, the attachment system is active by default.
meillo@102	1950 Instead of command line switches, the
meillo@102	1951 .Pe Attachment-Header
meillo@102	1952 profile entry is used to specify
meillo@102	1953 the name of the attachment header field.
meillo@102	1954 It is pre-defined to
meillo@102	1955 .Hd Attach .
meillo@101	1956 .P
meillo@101	1957 To add an attachment to a draft, simply add an attachment header:
meillo@101	1958 .VS
meillo@101	1959 To: bob
meillo@101	1960 Subject: The file you wanted
meillo@101	1961 Attach: /path/to/the/file-bob-wanted
meillo@101	1962 --------
meillo@101	1963 Here it is.
meillo@101	1964 VE
meillo@101	1965 The header field can be added to the draft manually in the editor,
meillo@102	1966 or by using the `attach' command at the WhatNow prompt, or
meillo@102	1967 non-interactively with
meillo@101	1968 .Pn anno :
meillo@101	1969 .VS
meillo@102	1970 anno -append -nodate -component Attach -text /path/to/attachment
meillo@101	1971 VE
meillo@102	1972 Drafts with attachment headers are converted to MIME automatically by
meillo@102	1973 .Pn send .
meillo@102	1974 The conversion to MIME is invisible to the user.
meillo@102	1975 The draft stored in the draft folder is always in source form, with
meillo@101	1976 attachment headers.
meillo@101	1977 If the MIMEification fails, for instance because the file to attach
meillo@101	1978 is not accessible, the original draft is not changed.
meillo@101	1979 .P
meillo@102	1980 The attachment system handles the forwarding of messages, too.
meillo@101	1981 If the attachment header value starts with a plus character (`+'),
meillo@101	1982 like in
meillo@101	1983 .Cl "Attach: +bob 30 42" ,
meillo@101	1984 The given messages in the specified folder will be attached.
meillo@101	1985 This allowed to simplify
meillo@101	1986 .Pn forw .
meillo@101	1987 .Ci f41f04cf4ceca7355232cf7413e59afafccc9550
meillo@101	1988 .P
meillo@101	1989 Closely related to attachments is non-ASCII text content,
meillo@101	1990 because it requires MIME too.
meillo@102	1991 In nmh, the user needed to call `mime' at the WhatNow prompt
meillo@101	1992 to have the draft converted to MIME.
meillo@102	1993 This was necessary whenever the draft contained non-ASCII characters.
meillo@101	1994 If the user did not call `mime', a broken message would be sent.
meillo@101	1995 Therefore, the
meillo@101	1996 .Pe automimeproc
meillo@101	1997 profile entry could be specified to have the `mime' command invoked
meillo@102	1998 automatically each time.
meillo@101	1999 Unfortunately, this approach conflicted with with attachment system
meillo@101	2000 because the draft would already be in MIME format at the time
meillo@101	2001 when the attachment system wanted to MIMEify it.
meillo@102	2002 To use nmh's attachment system, `mime' must not be called at the
meillo@102	2003 WhatNow prompt and
meillo@101	2004 .Pe automimeproc
meillo@102	2005 must not be set in the profile.
meillo@101	2006 But then the case of non-ASCII text without attachment headers was
meillo@101	2007 not caught.
meillo@102	2008 All in all, the solution was complex and irritating.
meillo@102	2009 My patch from December 2010 would have simplified the situation.
meillo@102	2010 .P
meillo@101	2011 Mmh's current solution is even more elaborate.
meillo@101	2012 Any necessary MIMEification is done automatically.
meillo@101	2013 There is no `mime' command at the WhatNow prompt anymore.
meillo@102	2014 The draft will be converted automatically to MIME when either an
meillo@102	2015 attachment header or non-ASCII text is present.
meillo@101	2016 Further more, the special meaning of the hash character (`#')
meillo@102	2017 at line beginnings in the draft message is removed.
meillo@102	2018 Users need not at all deal with the whole topic.
meillo@101	2019 .P
meillo@102	2020 Although the new approach does not anymore support arbitrary MIME
meillo@102	2021 compositions directly, the full power of
meillo@101	2022 .Pn mhbuild
meillo@101	2023 can still be accessed.
meillo@102	2024 Given no attachment headers are included, the user can create
meillo@101	2025 .Pn mhbuild
meillo@102	2026 composition drafts like in nmh.
meillo@101	2027 Then, at the WhatNow prompt, he needs to invoke
meillo@101	2028 .Cl "edit mhbuild
meillo@101	2029 to convert it to MIME.
meillo@102	2030 Because the resulting draft does neither contain non-aASCII characters
meillo@102	2031 nor has it attachment headers, the attachment system will not touch it.
meillo@101	2032 .P
meillo@101	2033 The approach taken in mmh is taylored towards todays most common case:
meillo@101	2034 a text part with possibly attachments.
meillo@102	2035 This case is simplified a lot for users.
meillo@102	2036
meillo@102	2037 .U3 "MIME Type Guessing
meillo@102	2038 .P
meillo@102	2039 The use of
meillo@101	2040 .Pn mhbuild
meillo@102	2041 composition drafts had one notable advantage over attachment headers
meillo@102	2042 from the programmer's point of view: The user provides the appropriate
meillo@102	2043 MIME types for files to include.
meillo@102	2044 The attachment system needs to find out the correct MIME type itself.
meillo@102	2045 This is a difficult task, yet it spares the user irritating work.
meillo@102	2046 Determining the correct MIME type of content is partly mechanical,
meillo@102	2047 partly intelligent work.
meillo@102	2048 Forcing the user to find out the correct MIME type,
meillo@102	2049 forces him to do partly mechanical work.
meillo@102	2050 Letting the computer do the work, can lead to bad choices for difficult
meillo@102	2051 content.
meillo@102	2052 For mmh, the latter option was chosen.
meillo@102	2053 .P
meillo@102	2054 Determining the MIME type by the suffix of the file name is a dumb
meillo@102	2055 approach, yet it is simple to implement and provides good results
meillo@102	2056 for the common cases.
meillo@102	2057 Mmh implements this approach in the
meillo@102	2058 .Pn print-mimetype
meillo@102	2059 script.
meillo@102	2060 Using it is the default choice.
meillo@102	2061 .P
meillo@102	2062 A far better but less portable approach is the use of
meillo@102	2063 .Pn file .
meillo@102	2064 This standard tool tries to determine the type of files.
meillo@102	2065 Unfortunately, its capabilities and accuracy varies from system to system.
meillo@102	2066 Additionally, its output was only intended for human beings,
meillo@102	2067 but not to be used by programs.
meillo@102	2068 It varies much.
meillo@102	2069 Nevertheless, modern versions of GNU
meillo@102	2070 .Pn file ,
meillo@102	2071 which is prevalent on the popular GNU/Linux systems,
meillo@102	2072 provides MIME type output in machine-readable form.
meillo@102	2073 Although this solution is highly system-dependent,
meillo@102	2074 it solves the difficult problem well.
meillo@102	2075 On systems where GNU
meillo@102	2076 .Pn file ,
meillo@102	2077 version 5.04 or higher, is available it should be used.
meillo@102	2078 One needs to specify the following profile entry to do so:
meillo@102	2079 .VS
meillo@102	2080 Mime-Type-Query: file -b --mime
meillo@102	2081 VE
meillo@102	2082 .LP
meillo@102	2083 Other versions of
meillo@102	2084 .Pn file
meillo@102	2085 might possibly be usable with wrapper scripts to reformat the output.
meillo@102	2086 The diversity among
meillo@102	2087 .Pn file
meillo@102	2088 implementations is great; one needs to check the local variant.
meillo@102	2089 .P
meillo@102	2090 If no MIME type can be determined, text content gets sent as
meillo@102	2091 `text/plain' and anything else under the generic fall-back type
meillo@102	2092 `application/octet-stream'.
meillo@102	2093 It is not possible in mmh to override the automatic MIME type guessing
meillo@102	2094 for a specific file.
meillo@102	2095 To do so, the user would need to know in advance for which file
meillo@102	2096 the automatic guessing does fail, or the system would require interaction.
meillo@102	2097 I consider both cases impractical.
meillo@102	2098 The existing solution should be sufficient.
meillo@102	2099 If not, the user may always fall back to
meillo@102	2100 .Pn mhbuild
meillo@102	2101 composition drafts and ignore the attachment system.
meillo@101	2102
meillo@102	2103
meillo@102	2104 .U3 "Storing Attachments
meillo@102	2105 .P
meillo@102	2106 FIXME
meillo@102	2107
meillo@102	2108
meillo@102	2109 .U3 "Showing MIME Messages
meillo@102	2110 .P
meillo@102	2111 FIXME
meillo@102	2112
meillo@58	2113
meillo@58	2114
meillo@58	2115 .H2 "Digital Cryptography
meillo@22	2116 .P
meillo@58	2117 Signing and encryption.
meillo@58	2118
meillo@58	2119
meillo@102	2120
meillo@102	2121 .H2 "Modern Defaults
meillo@22	2122 .P
meillo@102	2123 Just to give one example, for me it took one year of using nmh
meillo@102	2124 before I became aware of the existence of the attachment system.
meillo@102	2125 One could argue that this fact disqualifies my reading of the
meillo@102	2126 documentation.
meillo@102	2127 If I would have installed nmh from source back then, I could agree.
meillo@102	2128 Yet I had used a prepackaged version and had expected that it would
meillo@102	2129 just work.
meillo@58	2130
meillo@58	2131
meillo@58	2132
meillo@100	2133 .H1 "Code Style
meillo@22	2134 .P
meillo@58	2135 foo
meillo@58	2136
meillo@58	2137
meillo@58	2138 .H2 "Standard Code
meillo@22	2139 .P
meillo@58	2140 POSIX
meillo@22	2141
meillo@102	2142 .U3 "Converting to Standard Code
meillo@102	2143 .P
meillo@102	2144 One part of this task was converting obsolete code constructs
meillo@102	2145 to standard constructs.
meillo@102	2146 As I'm not even thirty years old and have no more than seven years of
meillo@102	2147 Unix experience, I needed to learn about the history in retrospective.
meillo@102	2148 Older people likely have used those ancient constructs themselves
meillo@102	2149 and have suffered from their incompatibilities and have longed for
meillo@102	2150 standardization.
meillo@102	2151 Unfortunately, I have only read that others had done so.
meillo@102	2152 This put me in a much more difficult positions when working on the old
meillo@102	2153 code.
meillo@102	2154 I needed to recherche what other would have known by heart from
meillo@102	2155 experience.
meillo@102	2156 All my programming experience comes from a time past ANSI C
meillo@102	2157 and past POSIX.
meillo@102	2158 Although I knew about the times before, I took the
meillo@102	2159 current state implicitly for granted most of the time.
meillo@102	2160 .P
meillo@102	2161 Being aware of
meillo@102	2162 these facts, I rather let people with more historic experience solve the
meillo@102	2163 task of converting the ancient code constructs to standardized ones.
meillo@102	2164 Luckily, Lyndon Nerenberg focused on this task at the nmh project.
meillo@102	2165 He converted large parts of the code to POSIX constructs, removing
meillo@102	2166 the conditionals compilation for now standardized features.
meillo@104	2167 I'm thankful for this task being solved.
meillo@104	2168 I only pulled the changes into
meillo@102	2169 mmh.
meillo@102	2170
meillo@102	2171
meillo@102	2172
meillo@22	2173
meillo@58	2174 .H2 "Separation
meillo@14	2175
meillo@58	2176 .U2 "MH Directory Split
meillo@0	2177 .P
meillo@19	2178 In MH and nmh, a personal setup had consisted of two parts:
meillo@19	2179 The MH profile, named
meillo@19	2180 .Fn \&.mh_profile
meillo@19	2181 and being located directly in the user's home directory.
meillo@19	2182 And the MH directory, where all his mail messages and also his personal
meillo@104	2183 forms, scan formats, other configuration files are stored.
meillo@104	2184 The location
meillo@104	2185 of this directory could be user-chosen.
meillo@104	2186 The default was to name it
meillo@19	2187 .Fn Mail
meillo@19	2188 and have it directly in the home directory.
meillo@19	2189 .P
meillo@19	2190 I've never liked the data storage and the configuration to be intermixed.
meillo@104	2191 They are different kinds of data.
meillo@104	2192 One part, are the messages,
meillo@104	2193 which are the data to operate on.
meillo@104	2194 The other part, are the personal
meillo@19	2195 configuration files, which are able to change the behavior of the operations.
meillo@19	2196 The actual operations are defined in the profile, however.
meillo@19	2197 .P
meillo@19	2198 When storing data, one should try to group data by its type.
meillo@19	2199 There's sense in the Unix file system hierarchy, where configuration
meillo@19	2200 file are stored separate (\c
meillo@19	2201 .Fn /etc )
meillo@19	2202 to the programs (\c
meillo@19	2203 .Fn /bin
meillo@19	2204 and
meillo@19	2205 .Fn /usr/bin )
meillo@19	2206 to their sources (\c
meillo@19	2207 .Fn /usr/src ).
meillo@19	2208 Such separation eases the backup management, for instance.
meillo@19	2209 .P
meillo@19	2210 In mmh, I've reorganized the file locations.
meillo@19	2211 Still there are two places:
meillo@19	2212 There's the mail storage directory, which, like in MH, contains all the
meillo@19	2213 messages, but, unlike in MH, nothing else.
meillo@19	2214 Its location still is user-chosen, with the default name
meillo@19	2215 .Fn Mail ,
meillo@104	2216 in the user's home directory.
meillo@104	2217 This is much similar to the case in nmh.
meillo@19	2218 The configuration files, however, are grouped together in the new directory
meillo@19	2219 .Fn \&.mmh
meillo@19	2220 in the user's home directory.
meillo@19	2221 The user's profile now is a file, named
meillo@19	2222 .Fn profile ,
meillo@19	2223 in this mmh directory.
meillo@19	2224 Consistently, the context file and all the personal forms, scan formats,
meillo@19	2225 and the like, are also there.
meillo@19	2226 .P
meillo@19	2227 The naming changed with the relocation.
meillo@19	2228 The directory where everything, except the profile, had been stored (\c
meillo@19	2229 .Fn $HOME/Mail ),
meillo@104	2230 used to be called \fIMH directory\fP.
meillo@104	2231 Now, this directory is called the
meillo@104	2232 user's \fImail storage\fP.
meillo@104	2233 The name \fImmh directory\fP is now given to
meillo@19	2234 the new directory
meillo@19	2235 (\c
meillo@19	2236 .Fn $HOME/.mmh ),
meillo@19	2237 containing all the personal configuration files.
meillo@19	2238 .P
meillo@19	2239 The separation of the files by type of content is logical and convenient.
meillo@19	2240 There are no functional differences as any possible setup known to me
meillo@19	2241 can be implemented with both approaches, although likely a bit easier
meillo@104	2242 with the new approach.
meillo@104	2243 The main goal of the change had been to provide
meillo@19	2244 sensible storage locations for any type of personal mmh file.
meillo@19	2245 .P
meillo@19	2246 In order for one user to have multiple MH setups, he can use the
meillo@19	2247 environment variable
meillo@19	2248 .Ev MH
meillo@19	2249 the point to a different profile file.
meillo@19	2250 The MH directory (mail storage plus personal configuration files) is
meillo@19	2251 defined by the
meillo@19	2252 .Pe Path
meillo@19	2253 profile entry.
meillo@19	2254 The context file could be defined by the
meillo@19	2255 .Pe context
meillo@19	2256 profile entry or by the
meillo@19	2257 .Ev MHCONTEXT
meillo@19	2258 environment variable.
meillo@19	2259 The latter is useful to have a distinct context (e.g. current folders)
meillo@19	2260 in each terminal window, for instance.
meillo@19	2261 In mmh, there are three environment variables now.
meillo@19	2262 .Ev MMH
meillo@19	2263 may be used to change the location of the mmh directory.
meillo@19	2264 .Ev MMHP
meillo@19	2265 and
meillo@19	2266 .Ev MMHC
meillo@19	2267 change the profile and context files, respectively.
meillo@19	2268 Besides providing a more consistent feel (which simply is the result
meillo@19	2269 of being designed anew), the set of personal configuration files can
meillo@19	2270 be chosen independently from the profile (including mail storage location)
meillo@104	2271 and context, now.
meillo@104	2272 Being it relevant for practical use or not, it
meillo@104	2273 de-facto is an improvement.
meillo@104	2274 However, the main achievement is the
meillo@19	2275 split between mail storage and personal configuration files.
meillo@17	2276
meillo@0	2277
meillo@58	2278 .H2 "Modularization
meillo@0	2279 .P
meillo@58	2280 whatnowproc
meillo@0	2281 .P
meillo@49	2282 The \fIMH library\fP
meillo@49	2283 .Fn libmh.a
meillo@49	2284 collects a bunch of standard functions that many of the MH tools need,
meillo@49	2285 like reading the profile or context files.
meillo@49	2286 This doesn't hurt the separation.
meillo@49	2287
meillo@58	2288
meillo@58	2289 .H2 "Style
meillo@58	2290 .P
meillo@58	2291 Code layout, goto, ...
meillo@58	2292
meillo@102	2293 .P
meillo@102	2294 anno rework
meillo@102	2295
meillo@58	2296
meillo@58	2297
meillo@58	2298
meillo@89	2299 .H1 "Concept Exploitation/Homogeneity
meillo@58	2300
meillo@58	2301
meillo@58	2302 .H2 "Draft Folder
meillo@58	2303 .P
meillo@58	2304 Historically, MH provided exactly one draft message, named
meillo@58	2305 .Fn draft
meillo@58	2306 and
meillo@104	2307 being located in the MH directory.
meillo@104	2308 When starting to compose another message
meillo@58	2309 before the former one was sent, the user had been questioned whether to use,
meillo@104	2310 refile or replace the old draft.
meillo@104	2311 Working on multiple drafts at the same time
meillo@104	2312 was impossible.
meillo@104	2313 One could only work on them in alteration by refiling the
meillo@104	2314 previous one to some directory and fetching some other one for reediting.
meillo@58	2315 This manual draft management needed to be done each time the user wanted
meillo@58	2316 to switch between editing one draft to editing another.
meillo@58	2317 .P
meillo@58	2318 To allow true parallel editing of drafts, in a straight forward way, the
meillo@104	2319 draft folder facility exists.
meillo@104	2320 It had been introduced already in July 1984
meillo@104	2321 by Marshall T. Rose.
meillo@104	2322 The facility was deactivated by default.
meillo@58	2323 Even in nmh, the draft folder facility remained deactivated by default.
meillo@58	2324 At least, Richard Coleman added the man page
meillo@58	2325 .Mp mh-draft(5)
meillo@58	2326 to document
meillo@58	2327 the feature well.
meillo@58	2328 .P
meillo@58	2329 The only advantage of not using the draft folder facility is the static
meillo@104	2330 name of the draft file.
meillo@104	2331 This could be an issue for MH front-ends like mh-e.
meillo@58	2332 But as they likely want to provide working on multiple drafts in parallel,
meillo@104	2333 the issue is only concerning compatibility.
meillo@104	2334 The aim of nmh to stay compatible
meillo@58	2335 prevented the default activation of the draft folder facility.
meillo@58	2336 .P
meillo@58	2337 On the other hand, a draft folder is the much more natural concept than
meillo@104	2338 a draft message.
meillo@104	2339 MH's mail storage consists of folders and messages,
meillo@104	2340 the messages named with ascending numbers.
meillo@104	2341 A draft message breaks with this
meillo@58	2342 concept by introducing a message in a file named
meillo@58	2343 .Fn draft .
meillo@58	2344 This draft
meillo@104	2345 message is special.
meillo@104	2346 It can not be simply listed with the available tools,
meillo@104	2347 but instead requires special switches.
meillo@104	2348 I.e. corner-cases were
meillo@104	2349 introduced.
meillo@104	2350 A draft folder, in contrast, does not introduce such
meillo@104	2351 corner-cases.
meillo@104	2352 The available tools can operate on the messages within that
meillo@104	2353 folder like on any messages within any mail folders.
meillo@104	2354 The only difference
meillo@58	2355 is the fact that the default folder for
meillo@58	2356 .Pn send
meillo@58	2357 is the draft folder,
meillo@58	2358 instead of the current folder, like for all other tools.
meillo@58	2359 .P
meillo@58	2360 The trivial part of the change was activating the draft folder facility
meillo@104	2361 by default and setting a default name for this folder.
meillo@104	2362 Obviously, I chose
meillo@58	2363 the name
meillo@58	2364 .Fn +drafts .
meillo@58	2365 This made the
meillo@82	2366 .Sw -draftfolder
meillo@58	2367 and
meillo@82	2368 .Sw -draftmessage
meillo@58	2369 switches useless, and I could remove them.
meillo@58	2370 The more difficult but also the part that showed the real improvement,
meillo@58	2371 was updating the tools to the new concept.
meillo@82	2372 .Sw -draft
meillo@58	2373 switches could
meillo@58	2374 be dropped, as operating on a draft message became indistinguishable to
meillo@58	2375 operating on any other message for the tools.
meillo@58	2376 .Pn comp
meillo@58	2377 still has its
meillo@82	2378 .Sw -use
meillo@58	2379 switch for switching between its two modes: (1) Compose a new
meillo@104	2380 draft, possibly by taking some existing message as a form.
meillo@104	2381 (2) Modify
meillo@104	2382 an existing draft.
meillo@104	2383 In either case, the behavior of
meillo@58	2384 .Pn comp is
meillo@104	2385 deterministic.
meillo@104	2386 There is no more need to query the user.
meillo@104	2387 I consider this
meillo@104	2388 a major improvement.
meillo@104	2389 By making
meillo@58	2390 .Pn send
meillo@58	2391 simply operate on the current
meillo@58	2392 message in the draft folder by default, with message and folder both
meillo@58	2393 overridable by specifying them on the command line, it is now possible
meillo@58	2394 to send a draft anywhere within the storage by simply specifying its folder
meillo@58	2395 and name.
meillo@58	2396 .P
meillo@58	2397 All theses changes converted special cases to regular cases, thus
meillo@58	2398 simplifying the tools and increasing the flexibility.
meillo@58	2399
meillo@58	2400
meillo@58	2401 .H2 "Trash Folder
meillo@58	2402 .P
meillo@58	2403 Similar to the situation for drafts is the situation for removed messages.
meillo@104	2404 Historically, a message was deleted by renaming.
meillo@104	2405 A specific
meillo@58	2406 \fIbackup prefix\fP, often comma (\c
meillo@58	2407 .Fn , )
meillo@58	2408 or hash (\c
meillo@58	2409 .Fn # ),
meillo@104	2410 being prepended to the file name.
meillo@104	2411 Thus, MH wouldn't recognize the file
meillo@58	2412 as a message anymore, as only files whose name consists of digits only
meillo@104	2413 are treated as messages.
meillo@104	2414 The removed messages remained as files in the
meillo@58	2415 same directory and needed some maintenance job to truly delete them after
meillo@104	2416 some grace time.
meillo@104	2417 Usually, by running a command similar to
meillo@82	2418 .VS
meillo@82	2419 find /home/user/Mail -ctime +7 -name ',*' \| xargs rm
meillo@82	2420 VE
meillo@104	2421 in a cron job.
meillo@104	2422 Within the grace time interval
meillo@58	2423 the original message could be restored by stripping the
meillo@104	2424 the backup prefix from the file name.
meillo@104	2425 If however, the last message of
meillo@58	2426 a folder is been removed \(en say message
meillo@58	2427 .Fn 6
meillo@58	2428 becomes file
meillo@58	2429 .Fn ,6
meillo@58	2430 \(en and a new message enters the same folder, thus the same
meillo@58	2431 numbered being given again \(en in our case
meillo@58	2432 .Fn 6
meillo@58	2433 \(en, if that one
meillo@58	2434 is removed too, then the backup of the former message gets overwritten.
meillo@58	2435 Thus, the ability to restore removed messages does not only depend on
meillo@58	2436 the ``sweeping cron job'' but also on the removing of further messages.
meillo@58	2437 This is undesirable, because the real mechanism is hidden from the user
meillo@58	2438 and the consequences of further removals are not always obvious.
meillo@58	2439 Further more, the backup files are scattered within the whole mail
meillo@58	2440 storage, instead of being collected at one place.
meillo@58	2441 .P
meillo@58	2442 To improve the situation, the profile entry
meillo@58	2443 .Pe rmmproc
meillo@58	2444 (previously named
meillo@58	2445 .Pe Delete-Prog )
meillo@58	2446 was introduced, very early.
meillo@58	2447 It could be set to any command, which would care for the mail removal
meillo@58	2448 instead of taking the default action, described above.
meillo@58	2449 Refiling the to-be-removed files to some garbage folder was a common
meillo@104	2450 example.
meillo@104	2451 Nmh's man page
meillo@58	2452 .Mp rmm(1)
meillo@58	2453 proposes
meillo@58	2454 .Cl "refile +d
meillo@58	2455 to move messages to the garbage folder and
meillo@58	2456 .Cl "rm `mhpath +d all`
meillo@58	2457 the empty the garbage folder.
meillo@104	2458 Managing the message removal this way is a sane approach.
meillo@104	2459 It keeps
meillo@58	2460 the removed messages in one place, makes it easy to remove the backup
meillo@58	2461 files, and, most important, enables the user to use the tools of MH
meillo@104	2462 itself to operate on the removed messages.
meillo@104	2463 One can
meillo@58	2464 .Pn scan
meillo@58	2465 them,
meillo@58	2466 .Pn show
meillo@58	2467 them, and restore them with
meillo@58	2468 .Pn refile .
meillo@58	2469 There's no more
meillo@58	2470 need to use
meillo@58	2471 .Pn mhpath
meillo@58	2472 to switch over from MH tools to Unix tools \(en MH can do it all itself.
meillo@58	2473 .P
meillo@58	2474 This approach matches perfect with the concepts of MH, thus making
meillo@104	2475 it powerful.
meillo@104	2476 Hence, I made it the default.
meillo@104	2477 And even more, I also
meillo@58	2478 removed the old backup prefix approach, as it is clearly less powerful.
meillo@58	2479 Keeping unused alternative in the code is a bad choice as they likely
meillo@104	2480 gather bugs, by not being constantly tested.
meillo@104	2481 Also, the increased code
meillo@104	2482 size and more conditions crease the maintenance costs.
meillo@104	2483 By strictly
meillo@58	2484 converting to the trash folder approach, I simplified the code base.
meillo@58	2485 .Pn rmm
meillo@58	2486 calls
meillo@58	2487 .Pn refile
meillo@58	2488 internally to move the to-be-removed
meillo@58	2489 message to the trash folder (\c
meillo@58	2490 .Fn +trash
meillo@104	2491 by default).
meillo@104	2492 Messages
meillo@58	2493 there can be operated on like on any other message in the storage.
meillo@58	2494 The sweep clean, one can use
meillo@82	2495 .Cl "rmm -unlink +trash a" ,
meillo@58	2496 where the
meillo@82	2497 .Sw -unlink
meillo@58	2498 switch causes the files to be truly unliked instead
meillo@58	2499 of moved to the trash folder.
meillo@58	2500
meillo@58	2501
meillo@58	2502 .H2 "Path Notations
meillo@58	2503 .P
meillo@58	2504 foo
meillo@58	2505
meillo@58	2506
meillo@58	2507 .H2 "MIME Integration
meillo@58	2508 .P
meillo@58	2509 user-visible access to whole messages and MIME parts are inherently
meillo@58	2510 different
meillo@58	2511
meillo@58	2512
meillo@58	2513 .H2 "Of One Cast
meillo@58	2514 .P