docs/master: ch03.roff annotate

docs/master

annotate ch03.roff @ 95:edac7e46a9f2

More text about switches.

author	markus schnalke <meillo@marmaro.de>
date	Sat, 16 Jun 2012 13:26:30 +0200
parents	093ccf39a45e
children	12348d620245

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@58	4 It is structured along the goals to achieve. The concrete work done
meillo@58	5 is described in the examples of how the general goals were achieved.
meillo@87	6 The discussion compares the current version of mmh with the state of
meillo@87	7 nmh just before the mmh project started, i.e. Fall 2011.
meillo@87	8 Current changes of nmh will be mentioned only as side notes.
meillo@87	9 .\" XXX where do I discuss the parallel development of nmh?
meillo@58	10
meillo@58	11
meillo@58	12
meillo@58	13 .H1 "Stream-lining
meillo@58	14
meillo@0	15 .P
meillo@58	16 MH had been considered an all-in-one system for mail handling.
meillo@58	17 The community around nmh has a similar understanding.
meillo@87	18 In fundamental difference, mmh shall be a MUA only.
meillo@87	19 I believe that the development of all-in-one mail systems is obsolete.
meillo@87	20 Today, email is too complex to be fully covered by single projects.
meillo@87	21 Such a project won't be able to excel in all aspects.
meillo@87	22 Instead, the aspects of email should be covered my multiple projects,
meillo@87	23 which then can be combined to form a complete system.
meillo@87	24 Excellent implementations for the various aspects of email exist already.
meillo@87	25 Just to name three examples: Postfix is a specialized MTA,
meillo@87	26 Procmail is a specialized MDA, and Fetchmail is a specialized MRA.
meillo@89	27 I believe that it is best to use such specialized tools instead of
meillo@87	28 providing the same function again as a side-component in the project.
meillo@58	29 .P
meillo@87	30 Doing something well, requires to focus on a small set of specific aspects.
meillo@87	31 Under the assumption that focused development produces better results
meillo@87	32 in the particular area, specialized projects will likely be superior
meillo@87	33 in their field of focus.
meillo@87	34 Hence, all-in-one mail system projects \(en no matter if monolithic
meillo@87	35 or modular \(en will never be the best choice in any of the fields.
meillo@87	36 Even in providing the best consistent all-in-one system they are likely
meillo@87	37 to be beaten by projects that focus only on integrating existing mail
meillo@89	38 components to a homogeneous system.
meillo@87	39 .P
meillo@87	40 The limiting resource in Free Software community development
meillo@87	41 is usually man power.
meillo@87	42 If the development power is spread over a large development area,
meillo@87	43 it becomes even more difficult to compete with the specialists in the
meillo@87	44 various fields.
meillo@87	45 The concrete situation for MH-based mail systems is even tougher,
meillo@87	46 given the small and aged community, including both developers and users,
meillo@87	47 it has.
meillo@87	48 .P
meillo@87	49 In consequence, I believe that the available development resources
meillo@87	50 should be focused on the point where MH is most unique.
meillo@87	51 This is clearly the user interface \(en the MUA.
meillo@87	52 Peripheral parts should be removed to stream-line mmh for the MUA task.
meillo@60	53
meillo@60	54
meillo@87	55 .H2 "Removal of the Mail Transfer Facilities
meillo@60	56 .P
meillo@60	57 In contrast to nmh, which also provides mail submission and mail retrieval
meillo@87	58 agents, mmh is a MUA only.
meillo@66	59 This general difference in the view on the character of nmh
meillo@76	60 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@66	64 The MSA is called \fIMessage Transfer Service\fP (MTS) in nmh.
meillo@76	65 The facility established network connections and spoke SMTP to submit
meillo@60	66 messages for relay to the outside world.
meillo@76	67 This part was implemented by the
meillo@60	68 .Pn post
meillo@60	69 command.
meillo@87	70 The changes in emailing in the last years
meillo@87	71 demanded changes in this part of nmh too.
meillo@89	72 Encryption and authentication for network connections
meillo@87	73 needed to be supported, hence TLS and SASL were introduced into nmh.
meillo@87	74 This added complexity to nmh without improving it in its core functions.
meillo@87	75 Also, keeping up with recent developments in the field of
meillo@87	76 mail transfer requires development power and specialists.
meillo@87	77 In mmh this whole facility was simply cut off.
meillo@76	78 .Ci f6aa95b724fd8c791164abe7ee5468bf5c34f226
meillo@76	79 .Ci fecd5d34f65597a4dfa16aeabea7d74b191532c3
meillo@76	80 .Ci 156d35f6425bea4c1ed3c4c79783dc613379c65b
meillo@87	81 Instead, mmh depends on an external MSA.
meillo@60	82 The only outgoing interface available to mmh is the
meillo@60	83 .Pn sendmail
meillo@87	84 command, which almost any MSA provides.
meillo@87	85 If not, a wrapper program can be written.
meillo@87	86 It must read the message from the standard input, extract the
meillo@87	87 recipient addresses from the message header, and hand the message
meillo@87	88 over to the MSA.
meillo@87	89 For example, a wrapper script for qmail would be:
meillo@87	90 .VS
meillo@87	91 #!/bin/sh
meillo@87	92 # ignore command line arguments
meillo@87	93 exec qmail-inject
meillo@87	94 VE
meillo@87	95 The requirement to parse the recipient addresses out of the message header
meillo@87	96 is likely to be removed in the future.
meillo@87	97 Then mmh would give the recipient addresses as command line arguments.
meillo@87	98 This is clearly the better interface, but mmh does not provide it yet.
meillo@87	99 .\" XXX implement it
meillo@60	100 .P
meillo@60	101 To retrieve mail, the
meillo@60	102 .Pn inc
meillo@76	103 command established network connections
meillo@76	104 and spoke POP3 to retrieve mail from remote servers.
meillo@76	105 As with mail submission, the network connections required encryption and
meillo@87	106 authentication, thus TLS and SASL were added.
meillo@87	107 Support for message retrieval through IMAP will become necessary
meillo@87	108 to be added soon, too, and so on for any changes in mail transfer.
meillo@76	109 Mmh has dropped the support for retrieving mail from remote locations.
meillo@76	110 .Ci ab7b48411962d26439f92f35ed084d3d6275459c
meillo@76	111 Instead, it depends on an external tool to cover this task.
meillo@87	112 In mmh there exist two paths for messages to enter mmh's mail storage:
meillo@87	113 (1) Mail can be incorporate with
meillo@60	114 .Pn inc
meillo@87	115 from the system maildrop, or (2) with
meillo@60	116 .Pn rcvstore
meillo@87	117 by reading them, one at a time, from the standard input.
meillo@60	118 .P
meillo@60	119 With the removal of the MSA and MRA, mmh converted from an all-in-one
meillo@87	120 mail system to being a MUA only.
meillo@87	121 Following the Unix philosophy, it now focuses on one job and
meillo@76	122 tries to do that one well.
meillo@76	123 Not only the programs follow that tenet but also the project itself does so.
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@87	140 Now, an MSA or MRA is more complex than a text pager
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@87	156 If it is conceptionally more elegant to have the MSA and MRA
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@76	167 (\c
meillo@60	168 .Pn /bin/mail
meillo@76	169 had once covered anything there was to email and still had been small
meillo@76	170 and simple.)
meillo@76	171 Then 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@87	177 RFCs started to introduce mail agents and separated the various tasks
meillo@87	178 because the existing tasks became more extensive and new tasks appeared.
meillo@87	179 Again, email systems grew, or they split parts off.
meillo@76	180 In nmh, for instance, the POP server, which the original MH had included,
meillo@76	181 was removed.
meillo@87	182 Now is the time to go one step further and remove the MSA and MRA, 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@87	186 There's 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@87	191 Function 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@87	210 Implementing complex functions originally in the project will add
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@60	252 .H2 "Removal of 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@87	259 On 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@62	285 Writing directly to a 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@87	315 It did distinguished between old and new mail, but
meillo@87	316 this detail information and can be retrieved with
meillo@76	317 .Pn stat (1),
meillo@62	318 too.
meillo@62	319 A very small shell script could be written to output 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@76	347 .P
meillo@76	348 Having less code (with equal readability, of course)
meillo@76	349 for the same functionality is an advantage.
meillo@63	350 Less code means less bugs and less maintenance work.
meillo@76	351 As
meillo@63	352 .Pn rcvtty
meillo@63	353 and
meillo@63	354 .Pn msgchk
meillo@87	355 are assumed to be rarely used and can be implemented in different ways,
meillo@87	356 why should one keep them?
meillo@76	357 Removing them stream-lines mmh.
meillo@63	358 .Pn viamail 's
meillo@63	359 use case is now partly obsolete and partly covered by
meillo@63	360 .Pn forw ,
meillo@76	361 hence there's no reason to still maintain it.
meillo@63	362 .Pn conflict
meillo@76	363 is not related to the mail client, and
meillo@63	364 .Pn msh
meillo@63	365 conflicts with the basic concept of MH.
meillo@76	366 Theses two tools might still be useful, but they should not be part of mmh.
meillo@63	367 .P
meillo@76	368 Finally, there's
meillo@76	369 .Pn slocal .
meillo@76	370 .Pn slocal
meillo@76	371 is an MDA and thus not directly MUA-related.
meillo@78	372 It should be removed, because including it is a violation
meillo@78	373 of the idea that mmh is a MUA only.
meillo@78	374 It should 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@87	382 technical area (cf. Sec. XXX),
meillo@87	383 still 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@87	393 The need to install a complete MH system to have
meillo@87	394 .Pn slocal
meillo@87	395 would be gone.
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@76	401 That's conceptionally the best solution.
meillo@76	402 Yet,
meillo@76	403 .Pn slocal
meillo@87	404 is not split off.
meillo@87	405 I feel unsure with removing it from mmh.
meillo@87	406 Hence, I defer the decision over
meillo@87	407 .Pn slocal .
meillo@87	408 In the meanwhile
meillo@78	409 .Pn slocal
meillo@87	410 does not hurt because it is unrelated to the rest of mmh.
meillo@0	411
meillo@58	412
meillo@76	413 .H2 "\fLshow\fP and \fPmhshow\fP
meillo@58	414 .P
meillo@69	415 Since the very beginning \(en already in the first concept paper \(en
meillo@58	416 .Pn show
meillo@62	417 had been MH's message display program.
meillo@58	418 .Pn show
meillo@76	419 mapped message numbers and sequences to files and invoked
meillo@58	420 .Pn mhl
meillo@89	421 to have the files formatted.
meillo@88	422 With MIME, this approach wasn't sufficient anymore.
meillo@58	423 MIME messages can consist of multiple parts, some of which aren't
meillo@88	424 directly displayable, further more text content might be encoded in
meillo@58	425 foreign charsets.
meillo@58	426 .Pn show 's
meillo@76	427 understanding of messages and
meillo@58	428 .Pn mhl 's
meillo@88	429 display capabilities couldn't cope with the task any longer.
meillo@62	430 .P
meillo@88	431 Instead of extending these tools, additional tools were written from
meillo@88	432 scratch and added to the MH tool chest.
meillo@88	433 Doing so is encouraged by the tool chest approach.
meillo@88	434 Modular design is a great advantage for extending a system,
meillo@88	435 as new tools can be added without interfering with existing ones.
meillo@62	436 First, the new MIME features were added in form of the single program
meillo@58	437 .Pn mhn .
meillo@58	438 The command
meillo@82	439 .Cl "mhn -show 42
meillo@58	440 would show the MIME message numbered 42.
meillo@58	441 With the 1.0 release of nmh in February 1999, Richard Coleman finished
meillo@58	442 the split of
meillo@58	443 .Pn mhn
meillo@88	444 into a set of specialized tools, which together covered the
meillo@88	445 multiple aspects of MIME.
meillo@88	446 One of them was
meillo@69	447 .Pn mhshow ,
meillo@88	448 which replaced
meillo@88	449 .Cl "mhn -show" .
meillo@88	450 It was capable of displaying MIME messages appropriately.
meillo@62	451 .P
meillo@88	452 From then on, two message display tools were part of nmh,
meillo@76	453 .Pn show
meillo@76	454 and
meillo@76	455 .Pn mhshow .
meillo@88	456 To ease the life of users,
meillo@69	457 .Pn show
meillo@69	458 was extended to automatically hand the job over to
meillo@69	459 .Pn mhshow
meillo@69	460 if displaying the message would be beyond
meillo@69	461 .Pn show 's
meillo@69	462 abilities.
meillo@88	463 In consequence, the user would simply invoke
meillo@69	464 .Pn show
meillo@69	465 (possibly through
meillo@69	466 .Pn next
meillo@69	467 or
meillo@69	468 .Pn prev )
meillo@69	469 and get the message printed with either
meillo@69	470 .Pn show
meillo@69	471 or
meillo@69	472 .Pn mhshow ,
meillo@69	473 whatever was more appropriate.
meillo@69	474 .P
meillo@69	475 Having two similar tools for essentially the same task is redundant.
meillo@88	476 Usually,
meillo@88	477 users wouldn't distinguish between
meillo@88	478 .Pn show
meillo@88	479 and
meillo@88	480 .Pn mhshow
meillo@88	481 in their daily mail reading.
meillo@88	482 Having two separate display programs was therefore mainly unnecessary
meillo@88	483 from a user's point of view.
meillo@88	484 Besides, the development of both programs needed to be in sync,
meillo@76	485 to ensure that the programs behaved in a similar way,
meillo@76	486 because they were used like a single tool.
meillo@76	487 Different behavior would have surprised the user.
meillo@69	488 .P
meillo@69	489 Today, non-MIME messages are rather seen to be a special case of
meillo@88	490 MIME messages, although it's the other way round.
meillo@69	491 As
meillo@69	492 .Pn mhshow
meillo@88	493 had already be able to display non-MIME messages, it appeared natural
meillo@69	494 to drop
meillo@69	495 .Pn show
meillo@69	496 in favor of using
meillo@69	497 .Pn mhshow
meillo@69	498 exclusively.
meillo@88	499 .Ci 4c1efddfd499300c7e74263e57d8aa137e84c853
meillo@88	500 Removing
meillo@88	501 .Pn show
meillo@88	502 is no loss in function, because functionally
meillo@88	503 .Pn mhshow
meillo@88	504 covers it completely.
meillo@88	505 The old behavior of
meillo@88	506 .Pn show
meillo@88	507 can still be emulated with the simple command line:
meillo@88	508 .VS
meillo@88	509 mhl `mhpath c`
meillo@88	510 VE
meillo@88	511 .P
meillo@76	512 For convenience,
meillo@76	513 .Pn mhshow
meillo@88	514 was renamed to
meillo@88	515 .Pn show
meillo@88	516 after
meillo@88	517 .Pn show
meillo@88	518 was gone.
meillo@88	519 It is clear that such a rename may confuse future developers when
meillo@88	520 trying to understand the history.
meillo@88	521 Nevertheless, I consider the convenience on the user's side,
meillo@88	522 to call
meillo@88	523 .Pn show
meillo@88	524 when they want a message to be displayed, to outweigh the inconvenience
meillo@88	525 on the developer's side when understanding the project history.
meillo@69	526 .P
meillo@88	527 To prepare for the transition,
meillo@69	528 .Pn mhshow
meillo@69	529 was reworked to behave more like
meillo@69	530 .Pn show
meillo@69	531 first.
meillo@88	532 (cf. Sec. XXX)
meillo@88	533 Once the tools behaved more alike, the replacing appeared to be
meillo@88	534 even more natural.
meillo@88	535 Today, mmh's new
meillo@69	536 .Pn show
meillo@88	537 became the one single message display program again, with the difference
meillo@88	538 that today it handles MIME messages as well as non-MIME messages.
meillo@88	539 The outcome of the transition is one program less to maintain,
meillo@88	540 no second display program for users to deal with,
meillo@88	541 and less system complexity.
meillo@69	542 .P
meillo@88	543 Still, removing the old
meillo@69	544 .Pn show
meillo@88	545 hurts in one regard: It had been such a simple program.
meillo@88	546 Its lean elegance is missing to the new
meillo@69	547 .Pn show .
meillo@88	548 But there is no chance;
meillo@88	549 supporting MIME demands for higher essential complexity.
meillo@58	550
meillo@58	551
meillo@58	552 .H2 "Removal of Configure Options
meillo@58	553 .P
meillo@76	554 Customization is a double-edged sword.
meillo@76	555 It allows better suiting setups, but not for free.
meillo@76	556 There is the cost of code complexity to be able to customize.
meillo@76	557 There is the cost of less tested setups, because there are
meillo@72	558 more possible setups and especially corner-cases.
meillo@76	559 And, there is the cost of choice itself.
meillo@76	560 The code complexity directly affects the developers.
meillo@72	561 Less tested code affects both, users and developers.
meillo@76	562 The problem of choice affects the users, for once by having to
meillo@76	563 choose, but also by complexer interfaces that require more documentation.
meillo@72	564 Whenever options add little advantages, they should be considered for
meillo@72	565 removal.
meillo@72	566 I have reduced the number of project-specific configure options from
meillo@72	567 fifteen to three.
meillo@74	568
meillo@76	569 .U3 "Mail Transfer Facilities
meillo@74	570 .P
meillo@85	571 With the removal of the mail transfer facilities five configure
meillo@85	572 options vanished:
meillo@85	573 .P
meillo@85	574 The switches
meillo@85	575 .Sw --with-tls
meillo@85	576 and
meillo@85	577 .Sw --with-cyrus-sasl
meillo@89	578 had activated the support for transfer encryption and authentication.
meillo@85	579 This is not needed anymore.
meillo@85	580 .Ci fecd5d34f65597a4dfa16aeabea7d74b191532c3
meillo@85	581 .Ci 156d35f6425bea4c1ed3c4c79783dc613379c65b
meillo@85	582 .P
meillo@85	583 The configure switch
meillo@85	584 .Sw --enable-pop
meillo@85	585 activated the message retrieval facility.
meillo@85	586 The code area that would be conditionally compiled in for TLS and SASL
meillo@85	587 support had been small.
meillo@85	588 The conditionally compiled code area for POP support had been much larger.
meillo@85	589 Whereas the code base changes would only slightly change on toggling
meillo@85	590 TLS or SASL support, it changed much on toggling POP support.
meillo@85	591 The changes in the code base could hardly be overviewed.
meillo@85	592 By having POP support togglable a second code base had been created,
meillo@85	593 one that needed to be tested.
meillo@85	594 This situation is basically similar for the conditional TLS and SASL
meillo@85	595 code, but there the changes are minor and can yet be overviewed.
meillo@85	596 Still, conditional compilation of a code base creates variations
meillo@85	597 of the original program.
meillo@85	598 More variations require more testing and maintenance work.
meillo@85	599 .P
meillo@85	600 Two other options only specified default configuration values:
meillo@85	601 .Sw --with-mts=[smtp\|sendmail]
meillo@85	602 defined the default transport service.
meillo@85	603 In mmh this fixed to
meillo@85	604 .Ar sendmail .
meillo@85	605 .Ci f6aa95b724fd8c791164abe7ee5468bf5c34f226
meillo@85	606 With
meillo@85	607 .Sw --with-smtpservers=[server1...]
meillo@85	608 default SMTP servers for the
meillo@85	609 .Ar smtp
meillo@85	610 transport service could be specified.
meillo@72	611 .Ci 128545e06224233b7e91fc4c83f8830252fe16c9
meillo@85	612 Both of them became irrelevant.
meillo@72	613
meillo@74	614 .U3 "Backup Prefix
meillo@74	615 .P
meillo@76	616 The backup prefix is the string that was prepended to message
meillo@76	617 filenames to tag them as deleted.
meillo@76	618 By default it had been the comma character `\f(CW,\fP'.
meillo@78	619 In July 2000, Kimmo Suominen introduced
meillo@78	620 the configure option
meillo@78	621 .Sw --with-hash-backup
meillo@78	622 to change the default to the hash symbol `\f(CW#\fP'.
meillo@78	623 The choice was probably personal preference, because first, the
meillo@78	624 option was named
meillo@78	625 .Sw --with-backup-prefix.
meillo@78	626 and had the prefix symbol as argument.
meillo@78	627 Because giving the hash symbol as argument caused to many problems
meillo@78	628 for configure,
meillo@78	629 the option was limited to use the hash symbol as the default prefix.
meillo@78	630 This makes me believe, that the choice for the hash was personal preference.
meillo@78	631 Being it related or not, words that start with the hash symbol
meillo@78	632 introduce a comment in the Unix shell.
meillo@72	633 Thus, the command line
meillo@72	634 .Cl "rm #13 #15
meillo@72	635 calls
meillo@72	636 .Pn rm
meillo@72	637 without arguments because the first hash symbol starts the comment
meillo@72	638 that reaches until the end of the line.
meillo@72	639 To delete the backup files,
meillo@72	640 .Cl "rm ./#13 ./#15"
meillo@72	641 needs to be used.
meillo@78	642 Using the hash as backup prefix can be seen as a precaution agains
meillo@78	643 data loss.
meillo@78	644 .P
meillo@72	645 I removed the configure option but added the profile entry
meillo@72	646 .Pe backup-prefix ,
meillo@72	647 which allows to specify an arbitrary string as backup prefix.
meillo@72	648 .Ci 6c40d481d661d532dd527eaf34cebb6d3f8ed086
meillo@76	649 Profile entries are the common method to change mmh's behavior.
meillo@76	650 This change did not remove the choice but moved it to a location where
meillo@72	651 it suited better.
meillo@76	652 .P
meillo@78	653 Eventually, however, the new trash folder concept
meillo@78	654 .Cf "Sec. XXX
meillo@78	655 obsoleted the concept of the backup prefix completely.
meillo@78	656 .Ci 8edc5aaf86f9f77124664f6801bc6c6cdf258173
meillo@72	657 (Well, there still are corner-cases to remove until the backup
meillo@89	658 prefix can be laid to rest, eventually.)
meillo@72	659 .\" FIXME: Do this work in the code!
meillo@76	660
meillo@76	661 .U3 "Editor and Pager
meillo@74	662 .P
meillo@74	663 The two configure options
meillo@74	664 .CW --with-editor=EDITOR
meillo@74	665 .CW --with-pager=PAGER
meillo@74	666 were used to specify the default editor and pager at configure time.
meillo@74	667 Doing so at configure time made sense in the Eighties,
meillo@76	668 when the set of available editors and pagers varied much across
meillo@76	669 different systems.
meillo@89	670 Today, the situation is more homogeneous.
meillo@74	671 The programs
meillo@74	672 .Pn vi
meillo@74	673 and
meillo@74	674 .Pn more
meillo@76	675 can be expected to be available on every Unix system,
meillo@74	676 as they are specified by POSIX since two decades.
meillo@74	677 (The specifications for
meillo@74	678 .Pn vi
meillo@74	679 and
meillo@74	680 .Pn more
meillo@74	681 appeared in
meillo@74	682 .[
meillo@74	683 posix 1987
meillo@74	684 .]
meillo@74	685 and,
meillo@74	686 .[
meillo@74	687 posix 1992
meillo@74	688 .]
meillo@74	689 respectively.)
meillo@74	690 As a first step, these two tools were hard-coded as defaults.
meillo@74	691 .Ci 5d43a99db70c12a673028c7758c20cbe3e13ef5f
meillo@74	692 Not changed were the
meillo@74	693 .Pe editor
meillo@74	694 and
meillo@74	695 .Pe moreproc
meillo@76	696 profile entries, which allowed the user to override the system defaults.
meillo@74	697 Later, the concept was reworked to respect the standard environment
meillo@74	698 variables
meillo@74	699 .Ev VISUAL
meillo@74	700 and
meillo@74	701 .Ev PAGER
meillo@76	702 if they are set.
meillo@74	703 Today, mmh determines the editor to use in the following order,
meillo@74	704 taking the first available and non-empty item:
meillo@74	705 .IP (1)
meillo@74	706 Environment variable
meillo@74	707 .Ev MMHEDITOR
meillo@74	708 .IP (2)
meillo@74	709 Profile entry
meillo@74	710 .Pe Editor
meillo@74	711 .IP (3)
meillo@74	712 Environment variable
meillo@74	713 .Ev VISUAL
meillo@74	714 .IP (4)
meillo@74	715 Environment variable
meillo@74	716 .Ev EDITOR
meillo@74	717 .IP (5)
meillo@74	718 Command
meillo@74	719 .Pn vi .
meillo@74	720 .P
meillo@76	721 .Ci f85f4b7ae62e3d05a945dcd46ead51f0a2a89a9b
meillo@76	722 .P
meillo@89	723 The pager to use is determined in a similar order,
meillo@74	724 also taking the first available and non-empty item:
meillo@74	725 .IP (1)
meillo@74	726 Environment variable
meillo@74	727 .Ev MMHPAGER
meillo@74	728 .IP (2)
meillo@74	729 Profile entry
meillo@74	730 .Pe Pager
meillo@74	731 (replaces
meillo@74	732 .Pe moreproc )
meillo@74	733 .IP (3)
meillo@74	734 Environment variable
meillo@74	735 .Ev PAGER
meillo@74	736 .IP (4)
meillo@74	737 Command
meillo@74	738 .Pn more .
meillo@74	739 .P
meillo@74	740 .Ci 0c4214ea2aec6497d0d67b436bbee9bc1d225f1e
meillo@74	741 .P
meillo@76	742 By respecting the
meillo@74	743 .Ev VISUAL /\c
meillo@74	744 .Ev EDITOR
meillo@74	745 and
meillo@74	746 .Ev PAGER
meillo@76	747 environment variables,
meillo@76	748 the new behavior confirms better to the common style on Unix systems.
meillo@76	749 Additionally, the new approach is more uniform and clearer to users.
meillo@72	750
meillo@74	751 .U3 "Locale
meillo@74	752 .P
meillo@74	753 The configure option
meillo@74	754 .Sw --disable-locale
meillo@85	755 was removed because POSIX provides locale support and there's
meillo@85	756 hardly any need to disable locale support.
meillo@74	757 .Ci ccf4f175ef4c4e7522f9510a4a1149c15d810dd9
meillo@72	758
meillo@76	759 .U3 "ndbm
meillo@72	760 .P
meillo@74	761 .Pn slocal
meillo@78	762 used to depend on
meillo@74	763 .I ndbm ,
meillo@74	764 a database library.
meillo@76	765 The database is used to store the `\fLMessage-ID\fP's of all
meillo@76	766 messages delivered.
meillo@74	767 This enables
meillo@74	768 .Pn slocal
meillo@74	769 to suppress delivering the same message to the same user twice.
meillo@74	770 (This features was enabled by the
meillo@74	771 .Sw -suppressdup
meillo@74	772 switch.)
meillo@74	773 .P
meillo@74	774 A variety of version of the database library exist.
meillo@78	775 .[
meillo@78	776 wolter unix incompat notes dbm
meillo@78	777 .]
meillo@74	778 Complicated autoconf code was needed to detect them correctly.
meillo@74	779 Further more, the configure switches
meillo@74	780 .Sw --with-ndbm=ARG
meillo@74	781 and
meillo@74	782 .Sw --with-ndbmheader=ARG
meillo@74	783 were added to help with difficult setups that would
meillo@78	784 not be detected automatically or correctly.
meillo@74	785 .P
meillo@74	786 By removing the suppress duplicates feature of
meillo@74	787 .Pn slocal ,
meillo@74	788 the dependency on
meillo@74	789 .I ndbm
meillo@78	790 vanished and 120 lines of complex autoconf code could be saved.
meillo@74	791 .Ci ecd6d6a20cb7a1507e3a20d6c4cb3a1cf14c6bbf
meillo@89	792 The change removed functionality too, but that is minor to the
meillo@78	793 improvement by dropping the dependency and the complex autoconf code.
meillo@72	794
meillo@74	795 .U3 "mh-e Support
meillo@72	796 .P
meillo@74	797 The configure option
meillo@74	798 .Sw --disable-mhe
meillo@74	799 was removed when the mh-e support was reworked.
meillo@74	800 Mh-e is the Emacs front-end to MH.
meillo@76	801 It requires MH to provide minor additional functions.
meillo@76	802 The
meillo@76	803 .Sw --disable-mhe
meillo@76	804 configure option could switch these extensions off.
meillo@76	805 After removing the support for old versions of mh-e,
meillo@74	806 only the
meillo@74	807 .Sw -build
meillo@76	808 switches of
meillo@74	809 .Pn forw
meillo@74	810 and
meillo@74	811 .Pn repl
meillo@76	812 are left to be mh-e extensions.
meillo@76	813 They are now always built in because they add little code and complexity.
meillo@76	814 In consequence, the
meillo@74	815 .Sw --disable-mhe
meillo@76	816 configure option was removed
meillo@72	817 .Ci a7ce7b4a580d77b6c2c4d980812beb589aa4c643
meillo@74	818 Removing the option removed a second code setup that would have
meillo@74	819 needed to be tested.
meillo@76	820 This change was first done in nmh and thereafter merged into mmh.
meillo@76	821 .P
meillo@76	822 The interface changes in mmh require mh-e to be adjusted in order
meillo@76	823 to be able to use mmh as back-end.
meillo@76	824 This will require minor changes to mh-e, but removing the
meillo@76	825 .Sw -build
meillo@76	826 switches would require more rework.
meillo@72	827
meillo@74	828 .U3 "Masquerading
meillo@72	829 .P
meillo@74	830 The configure option
meillo@74	831 .Sw --enable-masquerade
meillo@76	832 could take up to three arguments:
meillo@76	833 `draft_from', `mmailid', and `username_extension'.
meillo@74	834 They activated different types of address masquerading.
meillo@74	835 All of them were implemented in the SMTP-speaking
meillo@74	836 .Pn post
meillo@76	837 command, which provided an MSA.
meillo@76	838 Address masquerading is an MTA's task and mmh does not cover
meillo@76	839 this field anymore.
meillo@76	840 Hence, true masquerading needs to be implemented in the external MTA.
meillo@74	841 .P
meillo@74	842 The
meillo@74	843 .I mmailid
meillo@74	844 masquerading type is the oldest one of the three and the only one
meillo@74	845 available in the original MH.
meillo@74	846 It provided a
meillo@74	847 .I username
meillo@74	848 to
meillo@74	849 .I fakeusername
meillo@76	850 mapping, based on the password file's GECOS field.
meillo@74	851 The man page
meillo@74	852 .Mp mh-tailor(5)
meillo@74	853 described the use case as being the following:
meillo@74	854 .QP
meillo@74	855 This is useful if you want the messages you send to always
meillo@74	856 appear to come from the name of an MTA alias rather than your
meillo@74	857 actual account name. For instance, many organizations set up
meillo@74	858 `First.Last' sendmail aliases for all users. If this is
meillo@74	859 the case, the GECOS field for each user should look like:
meillo@74	860 ``First [Middle] Last <First.Last>''
meillo@74	861 .P
meillo@74	862 As mmh sends outgoing mail via the local MTA only,
meillo@76	863 the best location to do such global rewrites is there.
meillo@74	864 Besides, the MTA is conceptionally the right location because it
meillo@74	865 does the reverse mapping for incoming mail (aliasing), too.
meillo@76	866 Further more, masquerading set up there is readily available for all
meillo@74	867 mail software on the system.
meillo@76	868 Hence, mmailid masquerading was removed.
meillo@74	869 .Ci 0836c8000ccb34b59410ef1c15b1b7feac70ce5f
meillo@74	870 .P
meillo@74	871 The
meillo@74	872 .I username_extension
meillo@76	873 masquerading type did not replace the username but would append a suffix,
meillo@76	874 specified by the
meillo@74	875 .Ev USERNAME_EXTENSION
meillo@76	876 environment variable, to it.
meillo@76	877 This provided support for the
meillo@74	878 .I user-extension
meillo@74	879 feature of qmail and the similar
meillo@74	880 .I "plussed user
meillo@74	881 processing of sendmail.
meillo@74	882 The decision to remove this username_extension masquerading was
meillo@74	883 motivated by the fact that
meillo@74	884 .Pn spost
meillo@76	885 hadn't supported it already.
meillo@76	886 .Ci 2abae0bfd0ad5bf898461e50aa4b466d641f23d9
meillo@76	887 Username extensions are possible in mmh, but less convenient to use.
meillo@76	888 .\" XXX format file %(getenv USERNAME_EXTENSION)
meillo@74	889 .P
meillo@74	890 The
meillo@74	891 .I draft_from
meillo@74	892 masquerading type instructed
meillo@74	893 .Pn post
meillo@84	894 to use the value of the
meillo@84	895 .Hd From
meillo@84	896 header field as SMTP envelope sender.
meillo@76	897 Sender addresses could be replaced completely.
meillo@74	898 .Ci b14ea6073f77b4359aaf3fddd0e105989db9
meillo@76	899 Mmh offers a kind of masquerading similar in effect, but
meillo@74	900 with technical differences.
meillo@76	901 As mmh does not transfer messages itself, the local MTA has final control
meillo@76	902 over the sender's address. Any masquerading mmh introduces may be reverted
meillo@76	903 by the MTA.
meillo@76	904 In times of pedantic spam checking, an MTA will take care to use
meillo@76	905 sensible envelope sender addresses to keep its own reputation up.
meillo@84	906 Nonetheless, the MUA can set the
meillo@84	907 .Hd From
meillo@84	908 header field and thereby propose
meillo@76	909 a sender address to the MTA.
meillo@74	910 The MTA may then decide to take that one or generate the canonical sender
meillo@74	911 address for use as envelope sender address.
meillo@74	912 .P
meillo@74	913 In mmh, the MTA will always extract the recipient and sender from the
meillo@84	914 message header (\c
meillo@74	915 .Pn sendmail 's
meillo@74	916 .Sw -t
meillo@74	917 switch).
meillo@84	918 The
meillo@84	919 .Hd From
meillo@84	920 header field of the draft may be set arbitrary by the user.
meillo@74	921 If it is missing, the canonical sender address will be generated by the MTA.
meillo@74	922
meillo@74	923 .U3 "Remaining Options
meillo@74	924 .P
meillo@74	925 Two configure options remain in mmh.
meillo@74	926 One is the locking method to use:
meillo@74	927 .Sw --with-locking=[dot\|fcntl\|flock\|lockf] .
meillo@76	928 The idea of removing all methods except the portable dot locking
meillo@76	929 and having that one as the default is appealing, but this change
meillo@76	930 requires deeper technical investigation into the topic.
meillo@76	931 The other option,
meillo@74	932 .Sw --enable-debug ,
meillo@74	933 compiles the programs with debugging symbols and does not strip them.
meillo@74	934 This option is likely to stay.
meillo@72	935
meillo@72	936
meillo@58	937
meillo@63	938
meillo@93	939 .H2 "Removal of Switches
meillo@58	940 .P
meillo@93	941 The command line switches of MH tools follow the X Window style.
meillo@93	942 They are words, introduced by a single dash.
meillo@93	943 For example:
meillo@93	944 .Cl "-truncate" .
meillo@93	945 Every program in mmh has two generic switches:
meillo@93	946 .Sw -help ,
meillo@93	947 to print a short message on how to use the program, and
meillo@93	948 .Sw -Version ,
meillo@93	949 to tell what version of mmh the program belongs to.
meillo@93	950 .P
meillo@93	951 Switches change the behavior of programs.
meillo@93	952 Programs that do one thing in one way require no switches.
meillo@93	953 In most cases, doing something in exactly one way is too limiting.
meillo@93	954 If it is basically the same task to accomplish, but it should be done
meillo@93	955 in various ways, switches are a good approach to alter the behavior
meillo@93	956 of a program.
meillo@93	957 Changing the behavior of programs provides flexibility and customization
meillo@93	958 to users, but in the same way it complicates the code, documentation and
meillo@93	959 usage of the program.
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@93	968 .sp
meillo@93	969 .QP
meillo@93	970 A complaint often heard about systems which undergo substantial development
meillo@93	971 by many people over a number of years, is that more and more options are
meillo@93	972 introduced which add little to the functionality but greatly increase the
meillo@93	973 amount of information a user needs to know in order to get useful work done.
meillo@93	974 This is usually referred to as creeping featurism.
meillo@93	975 .QP
meillo@93	976 Unfortunately MH, having undergone six years of off-and-on development by
meillo@93	977 ten or so well-meaning programmers (the present authors included),
meillo@93	978 suffers mightily from this.
meillo@93	979 .sp
meillo@93	980 .P
meillo@93	981 Adding new switches only reluctantly is one part of the counter-action,
meillo@93	982 the other is removing hardly used switches.
meillo@93	983 Now that there are lots of switches already implemented,
meillo@93	984 removing some of them is more important.
meillo@93	985 Removing existing functionality is always difficult because it
meillo@93	986 breaks programs that use these functions.
meillo@93	987 Also, for every obsolete feature, there'll always be someone who still
meillo@93	988 uses it and thus opposes its removal.
meillo@93	989 This puts the developer into the position,
meillo@93	990 where sensible improvements to style are regarded as destructive acts.
meillo@93	991 Yet, living with the featurism is far worse, in my eyes.
meillo@93	992 Future needs will demand adding new features,
meillo@93	993 worsening the situation more and more.
meillo@93	994 Rose and Romine added in a footnote,
meillo@93	995 ``[...]
meillo@93	996 .Pn send
meillo@93	997 will no doubt acquire an endless number of switches in the years to come.''
meillo@93	998 Although clearly humorous, the comment displays the nature of
meillo@93	999 the problem.
meillo@93	1000 Though refusing to add any new switches would encounter the problem
meillo@93	1001 at its root, it is not practical.
meillo@93	1002 But removing obsolete switches is an effective approach to deal with the
meillo@93	1003 problem.
meillo@93	1004 Working on an experimental branch,
meillo@93	1005 eased this work because I had not to offend users.
meillo@93	1006 .P
meillo@93	1007 Rose and Romine counted 24 visible and 9 more hidden switches for
meillo@93	1008 .Pn send .
meillo@93	1009 At the beginning of mmh, it were 32 visible and 12 hidden ones.
meillo@93	1010 At the time of writing, mmh's
meillo@93	1011 .Pn send
meillo@93	1012 has 7 visible switches and 1 hidden switch.
meillo@93	1013 (In each of the examples, the two generic help and version switches
meillo@93	1014 are included.)
meillo@93	1015 .P
meillo@93	1016 Figure XXX
meillo@93	1017 .\" XXX Ref
meillo@93	1018 displays the number of switches for each of the tools that was not
meillo@93	1019 removed from or newly added to mmh.
meillo@93	1020 Both, visible and hidden switches, were counted, but
meillo@93	1021 not the generic help and version switches.
meillo@93	1022 Whereas in the beginning of the project, the average tool had 11 switches,
meillo@93	1023 now it has no more than 5 \(en only half as many.
meillo@93	1024 If the `no' switches and similar inverse variant are folded onto
meillo@93	1025 their counter-parts, the numbers are 8 in pre-mmh to 4 now.
meillo@93	1026 The total number of functional switches in mmh dropped from 465
meillo@93	1027 to 234.
meillo@58	1028
meillo@93	1029 .KS
meillo@93	1030 .in 1c
meillo@93	1031 .so input/switches.grap
meillo@93	1032 .KE
meillo@58	1033
meillo@93	1034 .P
meillo@93	1035 A part of the switches vanished after functions were removed.
meillo@93	1036 This was the case for network mail transfer, for instance.
meillo@93	1037 Sometimes the work flow was the other way:
meillo@93	1038 The trying to reduce the number of switches suggested the removal of
meillo@93	1039 functions.
meillo@58	1040
meillo@93	1041 .U3 "Draft Folder Facility
meillo@93	1042 .P
meillo@93	1043 A change early in the project was the completely transition from
meillo@93	1044 the single draft message to the draft folder facility.
meillo@93	1045 The draft folder facility was introduced in the mid-Eighties.
meillo@93	1046 (Rose and Romine called it a ``relatively new feature''
meillo@93	1047 .[
meillo@93	1048 rose romine real work
meillo@93	1049 .]
meillo@93	1050 in 1985.)
meillo@93	1051 Since then, the facility had existed but had remained deactive by default.
meillo@93	1052 The default activation and the related rework of the tools made it
meillo@93	1053 possible to remove the
meillo@93	1054 .Sw -[no]draftfolder ,
meillo@93	1055 and
meillo@93	1056 .Sw -draftmessage
meillo@93	1057 switches from
meillo@93	1058 .Pn comp ,
meillo@93	1059 .Pn repl ,
meillo@93	1060 .Pn forw ,
meillo@93	1061 .Pn dist ,
meillo@93	1062 .Pn whatnow ,
meillo@93	1063 and
meillo@93	1064 .Pn send .
meillo@93	1065 The only flexibility removed is having multiple draft folders
meillo@93	1066 within one profile.
meillo@93	1067 I consider this only a theoretical setup.
meillo@93	1068 In the same go, the
meillo@93	1069 .Sw -draft
meillo@93	1070 switch of
meillo@93	1071 .Pn anno ,
meillo@93	1072 .Pn refile ,
meillo@93	1073 and
meillo@93	1074 .Pn send
meillo@93	1075 was removed.
meillo@93	1076 The special-casing of `the' draft message became irrelevant after
meillo@93	1077 the rework of the draft system.
meillo@93	1078 (See Sec. XXX.)
meillo@95	1079 Equally,
meillo@95	1080 .Pn comp
meillo@95	1081 lost its
meillo@95	1082 .Sw -file
meillo@95	1083 switch.
meillo@95	1084 The draft folder facility, together with the
meillo@95	1085 .Sw -form
meillo@95	1086 switch, are sufficient.
meillo@93	1087
meillo@95	1088
meillo@95	1089 .U3 "Inplace Editing
meillo@93	1090 .P
meillo@93	1091 .Pn anno
meillo@93	1092 had the switches
meillo@93	1093 .Sw -[no]inplace
meillo@93	1094 to either annotate the message inplace and thus preserve hard links,
meillo@93	1095 or annotate a copy to replace the original message, breaking hard links.
meillo@93	1096 Following the assumption that linked messages are the same message,
meillo@93	1097 and annotating it should not break the link, the
meillo@93	1098 .Sw -[no]inplace
meillo@93	1099 switches were removed and the previous default
meillo@93	1100 .Sw -inplace
meillo@93	1101 was made the only behavior.
meillo@93	1102 The
meillo@93	1103 .Sw -[no]inplace
meillo@93	1104 switches of
meillo@93	1105 .Pn repl ,
meillo@93	1106 .Pn forw ,
meillo@93	1107 and
meillo@93	1108 .Pn dist
meillo@93	1109 could be removed, too, as they were simply passed through to
meillo@93	1110 .Pn anno .
meillo@93	1111 .P
meillo@93	1112 .Pn burst
meillo@93	1113 also had
meillo@93	1114 .Sw -[no]inplace
meillo@95	1115 switches, but with different meaning.
meillo@95	1116 With
meillo@95	1117 .Sw -inplace ,
meillo@95	1118 the digest had been replaced by the table of contents (i.e. the
meillo@95	1119 introduction text) and the bursted messages were placed right
meillo@95	1120 after this message, renumbering all following messages.
meillo@95	1121 Also, any trailing text of the digest was lost, though,
meillo@95	1122 in practice, it usually consists of an end-of-digest marker only.
meillo@95	1123 Nontheless, this behavior appeared less elegant than the
meillo@95	1124 .Sw -noinplace
meillo@95	1125 behavior, which already had been the default.
meillo@95	1126 Nmh's
meillo@95	1127 .Mp burst (1)
meillo@95	1128 man page reads:
meillo@95	1129 .sp \n(PDu
meillo@93	1130 .QP
meillo@93	1131 If -noinplace is given, each digest is preserved, no table
meillo@93	1132 of contents is produced, and the messages contained within
meillo@93	1133 the digest are placed at the end of the folder. Other messages
meillo@93	1134 are not tampered with in any way.
meillo@95	1135 .sp \n(PDu
meillo@95	1136 .LP
meillo@93	1137 The decision to drop the
meillo@93	1138 .Sw -inplace
meillo@95	1139 behavior was supported by the code complexity and the possible data loss
meillo@95	1140 it caused.
meillo@93	1141 .Sw -noinplace
meillo@95	1142 was chosen to be the definitive behavior.
meillo@93	1143
meillo@95	1144
meillo@95	1145 .U3 "Forms and Format Strings
meillo@93	1146 .P
meillo@95	1147 Historically, the tools that had
meillo@95	1148 .Sw -form
meillo@95	1149 switches to supply a form file had
meillo@95	1150 .Sw -format
meillo@95	1151 switches as well to supply the contents of a form file as a string
meillo@95	1152 on the command line directly.
meillo@95	1153 In consequence, the following two lines equaled:
meillo@95	1154 .VS
meillo@95	1155 scan -form scan.mailx
meillo@95	1156 scan -format "`cat .../scan.mailx`"
meillo@95	1157 VE
meillo@95	1158 The
meillo@95	1159 .Sw -format
meillo@95	1160 switches were dropped in favor for extending the
meillo@95	1161 .Sw -form
meillo@95	1162 switches.
meillo@95	1163 If their argument starts with an equal sign (`='),
meillo@95	1164 then the rest of the argument is taken as a format string,
meillo@95	1165 otherwise the arguments is treated as the name of a format file.
meillo@95	1166 Thus, now the following two lines equal:
meillo@95	1167 .VS
meillo@95	1168 scan -form scan.mailx
meillo@95	1169 scan -form "=`cat .../scan.mailx`"
meillo@95	1170 VE
meillo@95	1171 This rework removed the prefix collision between
meillo@95	1172 .Sw -form
meillo@95	1173 and
meillo@95	1174 .Sw -format .
meillo@95	1175 Now, typing
meillo@95	1176 .Sw -fo
meillo@95	1177 suffices to specify form or format string.
meillo@95	1178 .P
meillo@95	1179 The different meaning of
meillo@95	1180 .Sw -format
meillo@95	1181 for
meillo@95	1182 .Pn repl
meillo@95	1183 and
meillo@95	1184 .Pn forw
meillo@95	1185 was removed in mmh.
meillo@95	1186 .Pn forw
meillo@95	1187 was completely switched to MIME-type forwarding, thus removing the
meillo@95	1188 .Sw -[no]format .
meillo@95	1189 For
meillo@95	1190 .Pn repl ,
meillo@95	1191 the
meillo@95	1192 .Sw -[no]format
meillo@95	1193 switches were reworked to
meillo@95	1194 .Sw -[no]filter
meillo@95	1195 switches.
meillo@95	1196 The
meillo@95	1197 .Sw -format
meillo@95	1198 switches of
meillo@95	1199 .Pn send
meillo@95	1200 and
meillo@95	1201 .Pn post ,
meillo@95	1202 which had a third meaning,
meillo@95	1203 were removed likewise.
meillo@95	1204 Eventually, the ambiguity of the
meillo@95	1205 .Sw -format
meillo@95	1206 switches was resolved by not anymore having any such switch in mmh.
meillo@95	1207
meillo@95	1208
meillo@95	1209 .U3 "MIME Tools
meillo@95	1210 .P
meillo@95	1211 The MIME tools, which were once part of
meillo@95	1212 .Pn mhn ,
meillo@95	1213 had several switches that added little practical value to the programs.
meillo@95	1214 The
meillo@95	1215 .Sw -[no]realsize
meillo@95	1216 switches of
meillo@95	1217 .Pn mhbuild
meillo@95	1218 and
meillo@95	1219 .Pn mhlist
meillo@95	1220 were removed, doing real size calculations always now, as
meillo@95	1221 ``This provides an accurate count at the expense of a small delay.''
meillo@95	1222 This small delay is not noticable on modern systems.
meillo@95	1223 .P
meillo@95	1224 The
meillo@95	1225 .Sw -[no]check
meillo@95	1226 switches were removed together with the support for
meillo@95	1227 .Hd Content-MD5
meillo@95	1228 header fields.
meillo@95	1229 .[
meillo@95	1230 rfc 1864
meillo@95	1231 .]
meillo@95	1232 (See Sec. XXX)
meillo@95	1233 .P
meillo@95	1234 The
meillo@95	1235 .Sw -[no]ebcdicsafe
meillo@95	1236 and
meillo@95	1237 .Sw -[no]rfc934mode
meillo@95	1238 switches of
meillo@95	1239 .Pn mhbuild
meillo@95	1240 were removed because they are considered obsolete.
meillo@95	1241 .P
meillo@95	1242 Content caching of external MIME parts, activated with the
meillo@95	1243 .Sw -rcache
meillo@95	1244 and
meillo@95	1245 .Sw -wcache
meillo@95	1246 switches was completely removed.
meillo@95	1247 External MIME parts are truly rare today, having a caching facility
meillo@95	1248 for them is appeares to be unnecessary.
meillo@95	1249 .P
meillo@95	1250 In pre-MIME times,
meillo@95	1251 .Pn mhl
meillo@95	1252 had covered many tasks that are part of MIME handling today.
meillo@95	1253 Therefore,
meillo@95	1254 .Pn mhl
meillo@95	1255 could be simplified to a large extend, reducing the number of its
meillo@95	1256 switches from 21 to 6.
meillo@95	1257
meillo@95	1258
meillo@95	1259 .U3 "Mail Transfer Switches
meillo@95	1260 .P
meillo@95	1261 With the removal of the mail transfer facilities, a lot of switches
meillo@95	1262 vanished automatically.
meillo@95	1263 .Pn inc
meillo@95	1264 lost 9 switches, namely
meillo@95	1265 .Sw -host ,
meillo@95	1266 .Sw -port ,
meillo@95	1267 .Sw -user ,
meillo@95	1268 .Sw -proxy ,
meillo@95	1269 .Sw -snoop ,
meillo@95	1270 .Sw -[no]pack ,
meillo@95	1271 as well as
meillo@95	1272 .Sw -sasl
meillo@95	1273 and
meillo@95	1274 .Sw -saslmech .
meillo@95	1275 .Pn send
meillo@95	1276 and
meillo@95	1277 .Pn post
meillo@95	1278 lost 11 switches each, namely
meillo@95	1279 .Sw -server ,
meillo@95	1280 .Sw -port ,
meillo@95	1281 .Sw -client ,
meillo@95	1282 .Sw -user ,
meillo@95	1283 .Sw -mail ,
meillo@95	1284 .Sw -saml ,
meillo@95	1285 .Sw -send ,
meillo@95	1286 .Sw -soml ,
meillo@95	1287 .Sw -snoop ,
meillo@95	1288 as well as
meillo@95	1289 .Sw -sasl ,
meillo@95	1290 .Sw -saslmech ,
meillo@95	1291 and
meillo@95	1292 .Sw -tls .
meillo@95	1293 .Pn send
meillo@95	1294 had the switches only to pass them further to
meillo@95	1295 .Pn post ,
meillo@95	1296 because the user would invoke
meillo@95	1297 .Pn post
meillo@95	1298 not directly, but through
meillo@95	1299 .Pn send .
meillo@95	1300 All these switches, except
meillo@95	1301 .Sw -snoop
meillo@95	1302 were usually defined as default switches in the user's profile,
meillo@95	1303 but hardly given in interactive usage.
meillo@95	1304 .P
meillo@95	1305 Of course, those switches did not really ``vanish'', but the configuration
meillo@95	1306 they did was handed over to external MSAs and MRAs.
meillo@95	1307 Instead of setting up the mail transfer in mmh, it is set up in
meillo@95	1308 external tools.
meillo@95	1309 Yet, this simplifies mmh.
meillo@95	1310 Specialized external tools will likely have simple configuration files.
meillo@95	1311 Hence, instead of having one complicated central configuration file,
meillo@95	1312 the configuration of each domain is separate.
meillo@95	1313 Although the user needs to learn to configure each of the tools,
meillo@95	1314 each configuration is likely much simpler.
meillo@95	1315
meillo@95	1316
meillo@95	1317 .U3 "Maildrop Formats
meillo@95	1318 .P
meillo@95	1319 With the removal of MMDF maildrop format support,
meillo@95	1320 .Pn packf
meillo@95	1321 and
meillo@95	1322 .Pn rcvpack
meillo@95	1323 no longer needed their
meillo@95	1324 .Sw -mbox
meillo@95	1325 and
meillo@95	1326 .Sw -mmdf
meillo@95	1327 switches.
meillo@95	1328 .Sw -mbox
meillo@95	1329 is the sole behavior now.
meillo@95	1330 In the same go,
meillo@95	1331 .Pn packf
meillo@95	1332 was reworked (see Sec. XXX) and its
meillo@95	1333 .Sw -file
meillo@95	1334 switch became unnecessary.
meillo@95	1335
meillo@95	1336
meillo@95	1337 .U3 "Terminal Magic
meillo@95	1338 .P
meillo@95	1339 Mmh's tools will no longer clear the screen (\c
meillo@95	1340 .Pn scan 's
meillo@95	1341 and
meillo@95	1342 .Pn mhl 's
meillo@95	1343 .Sw -[no]clear
meillo@95	1344 switches).
meillo@95	1345 Neither will
meillo@95	1346 .Pn mhl
meillo@95	1347 ring the bell (\c
meillo@95	1348 .Sw -[no]bell )
meillo@95	1349 nor page the output itself (\c
meillo@95	1350 .Sw -length ).
meillo@95	1351 .P
meillo@95	1352 Generally, the pager to use is no longer specified with the
meillo@95	1353 .Sw -[no]moreproc
meillo@95	1354 command line switches for
meillo@95	1355 .Pn mhl
meillo@95	1356 and
meillo@95	1357 .Pn show /\c
meillo@95	1358 .Pn mhshow .
meillo@95	1359 .P
meillo@95	1360 .Pn prompter
meillo@95	1361 lost its
meillo@95	1362 .Sw -erase
meillo@95	1363 and
meillo@95	1364 .Sw -kill
meillo@95	1365 switches because today the terminal cares for the line editing keys.
meillo@95	1366
meillo@95	1367
meillo@95	1368 .U3 "Header Printing
meillo@95	1369 .P
meillo@95	1370 .Pn folder 's
meillo@95	1371 data output is self-explaining enough that
meillo@95	1372 displaying the header line makes few sense.
meillo@95	1373 Hence, the
meillo@95	1374 .Sw -[no]header
meillo@95	1375 switch was removed and headers are never printed.
meillo@95	1376 .P
meillo@95	1377 In
meillo@95	1378 .Pn mhlist ,
meillo@95	1379 the
meillo@95	1380 .Sw -[no]header
meillo@95	1381 switches were removed, too.
meillo@95	1382 But in this case headers are always printed,
meillo@95	1383 because the output is not self-explaining.
meillo@95	1384 .P
meillo@95	1385 .Pn scan
meillo@95	1386 also had
meillo@95	1387 .Sw -[no]header
meillo@95	1388 switches.
meillo@95	1389 Printing the header had been sensible until the introduction of
meillo@95	1390 format strings made it impossible to display the column headings.
meillo@95	1391 Only the folder name and the current date remained to be printed.
meillo@95	1392 As this information can be perfectly retrieved by
meillo@95	1393 .Pn folder
meillo@95	1394 and
meillo@95	1395 .Pn date ,
meillo@95	1396 consequently, the switches were removed.
meillo@95	1397 .P
meillo@95	1398 By removing all
meillo@95	1399 .Sw -header
meillo@95	1400 switches, the collision with
meillo@95	1401 .Sw -help
meillo@95	1402 on the first two letters was resolved.
meillo@95	1403 Currently,
meillo@95	1404 .Sw -h
meillo@95	1405 evaluates to
meillo@95	1406 .Sw -help
meillo@95	1407 for all tools of mmh.
meillo@95	1408
meillo@95	1409
meillo@95	1410 .U3 "Suppressing Edits or the WhatNow Shell
meillo@95	1411 .P
meillo@95	1412 The
meillo@95	1413 .Sw -noedit
meillo@95	1414 switches of
meillo@95	1415 .Pn comp ,
meillo@95	1416 .Pn repl ,
meillo@95	1417 .Pn forw ,
meillo@95	1418 .Pn dist ,
meillo@95	1419 and
meillo@95	1420 .Pn whatnow
meillo@95	1421 was removed, but it can now be replaced by specifying
meillo@95	1422 .Sw -editor
meillo@95	1423 with an empty argument.
meillo@95	1424 (Specifying
meillo@95	1425 .Cl "-editor true
meillo@95	1426 is nearly the same, only differing by the previous editor being set.)
meillo@95	1427 .P
meillo@95	1428 The more important change is the removal of the
meillo@95	1429 .Sw -nowhatnowproc
meillo@95	1430 switch.
meillo@95	1431 This switch had introduced an awkward behavior, as explained in nmh's
meillo@95	1432 man page for
meillo@95	1433 .Mp comp (1):
meillo@95	1434 .QP
meillo@95	1435 The \-editor editor switch indicates the editor to use for
meillo@95	1436 the initial edit. Upon exiting from the editor, comp will
meillo@95	1437 invoke the whatnow program. See whatnow(1) for a discussion
meillo@95	1438 of available options. The invocation of this program can be
meillo@95	1439 inhibited by using the \-nowhatnowproc switch. (In truth of
meillo@95	1440 fact, it is the whatnow program which starts the initial
meillo@95	1441 edit. Hence, \-nowhatnowproc will prevent any edit from
meillo@95	1442 occurring.)
meillo@95	1443 .P
meillo@95	1444 Effectively, the
meillo@95	1445 .Sw -nowhatnowproc
meillo@95	1446 switch stored a copy of the form file into the draft folder.
meillo@95	1447 As
meillo@95	1448 .Cl "-whatnowproc true
meillo@95	1449 causes the same behavior, the
meillo@95	1450 .Sw -nowhatnowproc
meillo@95	1451 switch was removed for being redundant.
meillo@95	1452 Likely, however, the intention for specifying
meillo@95	1453 .Sw -nowhatnowproc
meillo@95	1454 is sending a fully prepared form file at once.
meillo@95	1455 This can be done with
meillo@95	1456 .Cl "-whatnowproc send" .
meillo@95	1457
meillo@95	1458
meillo@95	1459 .U3 "Compatibility Switches
meillo@95	1460 .BU
meillo@95	1461 The hidden
meillo@95	1462 .Sw -[no]total
meillo@95	1463 switches of
meillo@95	1464 .Pn flist .
meillo@95	1465 They were simply the inverse of the visible
meillo@95	1466 .Sw -[no]fast
meillo@95	1467 switches:
meillo@95	1468 .Sw -total
meillo@95	1469 was
meillo@95	1470 .Sw -nofast
meillo@95	1471 and
meillo@95	1472 .Sw -nototal
meillo@95	1473 was
meillo@95	1474 .Sw -fast .
meillo@95	1475 I removed the
meillo@95	1476 .Sw -[no]total
meillo@95	1477 legacy.
meillo@95	1478 .BU
meillo@95	1479 The
meillo@95	1480 .Sw -subject
meillo@95	1481 switch of
meillo@95	1482 .Pn sortm
meillo@95	1483 existed for compatibility only.
meillo@95	1484 It can be fully replaced by
meillo@95	1485 .Cl "-textfield subject
meillo@95	1486 thus it was removed.
meillo@95	1487
meillo@95	1488
meillo@95	1489 .U3 "Various
meillo@95	1490 .BU
meillo@95	1491 In order to avoid prefix collisions amoung switch names, the
meillo@95	1492 .Sw -version
meillo@95	1493 switch was renamed to
meillo@95	1494 .Sw -Version
meillo@95	1495 (with capital `V').
meillo@95	1496 Every program has the
meillo@95	1497 .Sw -version
meillo@95	1498 switch but its first three letters collided with the
meillo@95	1499 .Sw -verbose
meillo@95	1500 switch, present in many programs.
meillo@95	1501 The rename solved this problem once for all.
meillo@95	1502 Although this rename breaks a basic interface, having the
meillo@95	1503 .Sw -V
meillo@95	1504 abbreviation to display the version information, isn't all too bad.
meillo@95	1505 .BU
meillo@95	1506 .Sw -[no]preserve
meillo@95	1507 of
meillo@95	1508 .Pn refile
meillo@95	1509 was removed because what use was it anyway?
meillo@95	1510 .QP
meillo@95	1511 Normally when a message is refiled, for each destination
meillo@95	1512 folder it is assigned the number which is one above the current
meillo@95	1513 highest message number in that folder. Use of the
meillo@95	1514 \-preserv [sic!] switch will override this message renaming, and try
meillo@95	1515 to preserve the number of the message. If a conflict for a
meillo@95	1516 particular folder occurs when using the \-preserve switch,
meillo@95	1517 then refile will use the next available message number which
meillo@95	1518 is above the message number you wish to preserve.
meillo@95	1519 .BU
meillo@95	1520 The removal of the
meillo@95	1521 .Sw -[no]reverse
meillo@95	1522 switches of
meillo@95	1523 .Pn scan
meillo@95	1524 is a bug fix, supported by the comments
meillo@95	1525 ``\-[no]reverse under #ifdef BERK (I really HATE this)''
meillo@95	1526 by Rose and
meillo@95	1527 ``Lists messages in reverse order with the `\-reverse' switch.
meillo@95	1528 This should be considered a bug.'' by Romine in the documentation.
meillo@95	1529 The question remaining is why neither Rose and Romine had fixed this
meillo@95	1530 bug in the Eighties when they wrote these comments nor has anyone
meillo@95	1531 thereafter.
meillo@93	1532
meillo@93	1533
meillo@93	1534 .ig
meillo@93	1535
meillo@95	1536 forw: [no]dashstuffing(mhl)
meillo@93	1537
meillo@95	1538 mhshow: [no]pause [no]serialonly
meillo@93	1539
meillo@93	1540 mhmail: resent queued
meillo@93	1541 inc: snoop, (pop)
meillo@93	1542
meillo@95	1543 mhl: [no]faceproc folder sleep
meillo@95	1544 [no]dashstuffing(forw) digest list volume number issue number
meillo@93	1545
meillo@95	1546 prompter: [no]doteof
meillo@93	1547
meillo@93	1548 refile: [no]preserve [no]unlink [no]rmmproc
meillo@93	1549
meillo@95	1550 send: [no]forward [no]mime [no]msgid
meillo@93	1551 [no]push split [no]unique (sasl) width snoop [no]dashstuffing
meillo@93	1552 attach attachformat
meillo@93	1553 whatnow: (noedit) attach
meillo@93	1554
meillo@93	1555 slocal: [no]suppressdups
meillo@93	1556
meillo@95	1557 spost: [no]filter [no]backup width [no]push idanno
meillo@93	1558 [no]check(whom) whom(whom)
meillo@93	1559
meillo@93	1560 whom: ???
meillo@93	1561
meillo@95	1562 ..
meillo@93	1563
meillo@93	1564
meillo@93	1565 .ig
meillo@93	1566
meillo@93	1567 .P
meillo@93	1568 To ease typing, the switches can be abbreviated as much as the remaining
meillo@93	1569 prefix remains unambiguous.
meillo@93	1570 If in our example no other switch would start with the letter `t', then
meillo@93	1571 .Cl "-truncate" ,
meillo@93	1572 .Cl "-trunc" ,
meillo@93	1573 .Cl "-tr" ,
meillo@93	1574 and
meillo@93	1575 .Cl "-t
meillo@93	1576 would all be the same.
meillo@93	1577 As a result, switches can neither be grouped (as in
meillo@93	1578 .Cl "ls -ltr" )
meillo@93	1579 nor can switch arguments be appended directly to the switch (as in
meillo@93	1580 .Cl "sendmail -q30m" ).
meillo@93	1581 .P
meillo@93	1582 Many switches have negating counter-parts, which start with `no'.
meillo@93	1583 For example
meillo@93	1584 .Cl "-notruncate
meillo@93	1585 inverts the
meillo@93	1586 .Cl "-truncate
meillo@93	1587 switch.
meillo@93	1588 They exist to undo the effect of default switches in the profile.
meillo@93	1589 If the user has chosen to change the default behavior of some tool
meillo@93	1590 by adding a default switch to the profile,
meillo@93	1591 he can still undo this change in behavior by specifiying the inverse
meillo@93	1592 switch on the command line.
meillo@93	1593 .P
meillo@93	1594 In the best case, all switches are unambiguous on the first character,
meillo@93	1595 or on the three-letter prefix for the `no' variants.
meillo@93	1596 Reducing switch prefix collisions, shortens the necessary prefix lenght
meillo@93	1597 the user must type.
meillo@93	1598 Having less switches helps best.
meillo@93	1599
meillo@93	1600 ..
meillo@58	1601
meillo@95	1602
meillo@95	1603
meillo@95	1604
meillo@74	1605 .H1 "Modernizing
meillo@58	1606
meillo@58	1607
meillo@58	1608 .H2 "Removal of Code Relicts
meillo@0	1609 .P
meillo@51	1610 The code base of mmh originates from the late Seventies,
meillo@51	1611 had been extensively
meillo@51	1612 worked on in the mid Eighties, and had been partly reorganized and extended
meillo@51	1613 in the Nineties. Relicts of all those times had gathered in the code base.
meillo@12	1614 My goal was to remove any ancient code parts. One part of the task was
meillo@12	1615 converting obsolete code constructs to standard constructs, the other part
meillo@12	1616 was dropping obsolete functions.
meillo@12	1617 .P
meillo@12	1618 As I'm not even thirty years old and have no more than seven years of
meillo@51	1619 Unix experience, I needed to learn about the history in retrospective.
meillo@51	1620 Older people likely have used those ancient constructs themselves
meillo@51	1621 and have suffered from their incompatibilities and have longed for
meillo@12	1622 standardization. Unfortunately, I have only read that others had done so.
meillo@12	1623 This put me in a much more difficult positions when working on the old
meillo@12	1624 code. I needed to recherche what other would have known by heart from
meillo@12	1625 experience. All my programming experience comes from a time past ANSI C
meillo@12	1626 and past POSIX. Although I knew about the times before, I took the
meillo@51	1627 current state implicitly for granted most of the time.
meillo@12	1628 .P
meillo@12	1629 Being aware of
meillo@12	1630 these facts, I rather let people with more historic experience solve the
meillo@12	1631 task of converting the ancient code constructs to standardized ones.
meillo@12	1632 Luckily, Lyndon Nerenberg focused on this task at the nmh project.
meillo@12	1633 He converted large parts of the code to POSIX constructs, removing
meillo@12	1634 the conditionals compilation for now standardized features.
meillo@12	1635 I'm thankful for this task being solved. I only pulled the changes into
meillo@12	1636 mmh.
meillo@12	1637 .P
meillo@20	1638 The other task \(en dropping ancient functionality to remove old code \(en
meillo@12	1639 I did myself, though. My position to strip mmh to the bare minimum of
meillo@12	1640 frequently used features is much more revolutional than the nmh community
meillo@20	1641 likes it. Without the need to justify my decisions, I was able to quickly
meillo@20	1642 remove functionality I considered ancient.
meillo@20	1643 The need to discuss my decisions with
meillo@20	1644 peers likely would have slowed this process down. Of course, I researched
meillo@12	1645 if a particular feature really should be dropped. Having not had any
meillo@12	1646 contact to this feature within my computer life was a first indicator to
meillo@12	1647 drop it, but I also asked others and searched the literature for modern
meillo@12	1648 usage of the feature. If it appeared to be truly ancient, I dropped it.
meillo@12	1649 The reason for dropping is always part of the commit message in the
meillo@12	1650 version control system. Thus, it is easy for others to check their
meillo@12	1651 view on the topic with mine and possibly to argue for reinclusion.
meillo@12	1652
meillo@12	1653 .U2 "MMDF maildrop support
meillo@12	1654 .P
meillo@12	1655 I did drop any support for the MMDF maildrop format. This type of format
meillo@12	1656 is conceptionally similar to the mbox format, but uses four bytes with
meillo@12	1657 value 1 (\fL^A^A^A^A\fP) as message delimiter,
meillo@18	1658 instead of the string ``\fLFrom\ \fP''.
meillo@12	1659 Due to the similarity and mbox being the de-facto standard maildrop
meillo@12	1660 format on Unix, but also due to the larger influence of Sendmail than MMDF,
meillo@12	1661 the MMDF maildrop format had vanished.
meillo@12	1662 .P
meillo@12	1663 The simplifications within the code were only moderate. Switches could
meillo@12	1664 be removed from tools like
meillo@12	1665 .L packf ,
meillo@12	1666 which generate packed mailboxes. Only one packed mailbox format remained:
meillo@12	1667 mbox.
meillo@12	1668 The most important changes affect the equally named mail parsing routine in
meillo@12	1669 .L sbr/m_getfld.c .
meillo@12	1670 The direct MMDF code had been removed, but as now only one packed mailbox
meillo@12	1671 format is left, code structure simplifications are likely possible.
meillo@12	1672 The reason why they are still outstanding is the heavily optimized code
meillo@18	1673 of
meillo@18	1674 .Fu m_getfld() .
meillo@18	1675 Changes beyond a small local scope \(en
meillo@12	1676 which restructuring in its core is \(en cause a high risk of damaging
meillo@12	1677 the intricate workings of the optimized code. This problem is know
meillo@12	1678 to the developers of nmh, too. They also avoid touching this minefield
meillo@12	1679 if possible.
meillo@12	1680
meillo@12	1681 .U2 "UUCP Bang Paths
meillo@12	1682 .P
meillo@12	1683 More questionably than the former topic is the removal of support for the
meillo@12	1684 UUCP bang path address style. However, the user may translate the bang
meillo@12	1685 paths on retrieval to Internet addresses and the other way on posting
meillo@12	1686 messages. The former can be done my an MDA like procmail; the latter
meillo@12	1687 by a sendmail wrapper. This would ensure that any address handling would
meillo@12	1688 work as expected. However, it might just work well without any
meillo@12	1689 such modifications, as mmh does not touch addresses much, in general.
meillo@12	1690 But I can't ensure as I have never used an environment with bang paths.
meillo@12	1691 Also, the behavior might break at any point in further development.
meillo@12	1692
meillo@12	1693 .U2 "Hardcopy terminal support
meillo@12	1694 .P
meillo@12	1695 More of a funny anecdote is the remaining of a check for printing to a
meillo@12	1696 hardcopy terminal until Spring 2012, when I finally removed it.
meillo@12	1697 I surely would be very happy to see such a terminal in action, maybe
meillo@12	1698 actually being able to work on it, but I fear my chances are null.
meillo@12	1699 .P
meillo@12	1700 The check only prevented a pager to be placed between the outputting
meillo@18	1701 program (\c
meillo@18	1702 .Pn mhl )
meillo@18	1703 and the terminal. This could have been ensured with
meillo@18	1704 the
meillo@82	1705 .Sw -nomoreproc
meillo@18	1706 at the command line statically, too.
meillo@12	1707
meillo@12	1708 .U2 "Removed support for header fields
meillo@12	1709 .P
meillo@84	1710 The
meillo@84	1711 .Hd Encrypted
meillo@84	1712 header field had been introduced by RFC\^822, but already
meillo@12	1713 marked legacy in RFC 2822. It was superseded by FIXME.
meillo@84	1714 Mmh does no more support this header field.
meillo@12	1715 .P
meillo@84	1716 Native support for
meillo@84	1717 .Hd Face
meillo@84	1718 header fields had been removed, as well.
meillo@84	1719 The feature is similar to the
meillo@84	1720 .Hd X-Face
meillo@84	1721 header field in its intent,
meillo@21	1722 but takes a different approach to store the image.
meillo@84	1723 Instead of encoding the image data directly into the header field,
meillo@84	1724 the it contains the hostname and UDP port where the image
meillo@21	1725 date could be retrieved.
meillo@84	1726 Neither
meillo@84	1727 .Hd X-Face
meillo@84	1728 nor the here described
meillo@84	1729 .Hd Face
meillo@84	1730 system
meillo@21	1731 \**
meillo@21	1732 .FS
meillo@21	1733 There is also a newer but different system, invented 2005,
meillo@84	1734 using
meillo@84	1735 .Hd Face
meillo@84	1736 headers.
meillo@84	1737 It is the successor of
meillo@84	1738 .Hd X-Face
meillo@84	1739 providing colored PNG images.
meillo@21	1740 .FE
meillo@21	1741 became well used in the large scale.
meillo@21	1742 It's still possible to use a Face systems,
meillo@21	1743 although mmh does not provide support for any of the different systems
meillo@21	1744 anymore. It's fairly easy to write a small shell script to
meillo@21	1745 extract the embedded or fetch the external Face data and display the image.
meillo@84	1746 Own
meillo@84	1747 .Hd Face
meillo@84	1748 header field can be added into the draft template files.
meillo@21	1749 .P
meillo@84	1750 .Hd Content-MD5
meillo@84	1751 header fields were introduced by RFC\^1864. They provide only
meillo@12	1752 a verification of data corruption during the transfer. By no means can
meillo@12	1753 they ensure verbatim end-to-end delivery of the contents. This is clearly
meillo@12	1754 stated in the RFC. The proper approach to provide verificationability
meillo@12	1755 of content in an end-to-end relationship is the use of digital cryptography
meillo@12	1756 (RFCs FIXME). On the other hand, transfer protocols should ensure the
meillo@12	1757 integrity of the transmission. In combinations these two approaches
meillo@84	1758 make the
meillo@84	1759 .Hd Content-MD5
meillo@84	1760 header field useless. In consequence, I removed
meillo@12	1761 the support for it. By this removal, MD5 computation is not needed
meillo@12	1762 anywhere in mmh. Hence, over 500 lines of code were removed by this one
meillo@84	1763 change. Even if the
meillo@84	1764 .Hd Content-MD5
meillo@84	1765 header field is useful sometimes,
meillo@89	1766 I value its usefulness less than the improvement in maintainability, caused
meillo@12	1767 by the removal.
meillo@12	1768
meillo@20	1769 .U2 "Prompter's Control Keys
meillo@20	1770 .P
meillo@20	1771 The program
meillo@20	1772 .Pn prompter
meillo@20	1773 queries the user to fill in a message form. When used by
meillo@20	1774 .Pn comp
meillo@20	1775 as:
meillo@82	1776 .VS
meillo@82	1777 comp -editor prompter
meillo@82	1778 VE
meillo@20	1779 the resulting behavior is similar to
meillo@20	1780 .Pn mailx .
meillo@51	1781 Apparently,
meillo@20	1782 .Pn prompter
meillo@20	1783 hadn't been touched lately. Otherwise it's hardly explainable why it
meillo@20	1784 still offered the switches
meillo@84	1785 .Sw -erase
meillo@84	1786 .Ar chr
meillo@20	1787 and
meillo@84	1788 .Sw -kill
meillo@84	1789 .Ar chr
meillo@20	1790 to name the characters for command line editing.
meillo@21	1791 The times when this had been necessary are long time gone.
meillo@20	1792 Today these things work out-of-the-box, and if not, are configured
meillo@20	1793 with the standard tool
meillo@20	1794 .Pn stty .
meillo@20	1795
meillo@21	1796 .U2 "Vfork and Retry Loops
meillo@21	1797 .P
meillo@51	1798 MH creates many processes, which is a consequence of the tool chest approach.
meillo@21	1799 In earlier times
meillo@21	1800 .Fu fork()
meillo@21	1801 had been an expensive system call, as the process's whole image needed
meillo@21	1802 to be duplicated. One common case is replacing the image with
meillo@21	1803 .Fu exec()
meillo@21	1804 right after having forked the child process.
meillo@21	1805 To speed up this case, the
meillo@21	1806 .Fu vfork()
meillo@21	1807 system call was invented at Berkeley. It completely omits copying the
meillo@21	1808 image. If the image gets replaced right afterwards then unnecessary
meillo@21	1809 work is omited. On old systems this results in large speed ups.
meillo@21	1810 MH uses
meillo@21	1811 .Fu vfork()
meillo@21	1812 whenever possible.
meillo@21	1813 .P
meillo@21	1814 Memory management units that support copy-on-write semantics make
meillo@21	1815 .Fu fork()
meillo@21	1816 almost as fast as
meillo@21	1817 .Fu vfork()
meillo@21	1818 in the cases when they can be exchanged.
meillo@21	1819 With
meillo@21	1820 .Fu vfork()
meillo@51	1821 being more error-prone and hardly faster, it's preferable to simply
meillo@21	1822 use
meillo@21	1823 .Fu fork()
meillo@21	1824 instead.
meillo@21	1825 .P
meillo@21	1826 Related to the costs of
meillo@21	1827 .Fu fork()
meillo@21	1828 is the probability of its success.
meillo@21	1829 Today on modern systems, the system call will succeed almost always.
meillo@51	1830 In the Eighties on heavy loaded systems, as they were common at
meillo@21	1831 universities, this had been different. Thus, many of the
meillo@21	1832 .Fu fork()
meillo@21	1833 calls were wrapped into loops to retry to fork several times in
meillo@21	1834 short intervals, in case of previous failure.
meillo@21	1835 In mmh, the program aborts at once if the fork failed.
meillo@21	1836 The user can reexecute the command then. This is expected to be a
meillo@21	1837 very rare case on modern systems, especially personal ones, which are
meillo@21	1838 common today.
meillo@21	1839
meillo@12	1840
meillo@58	1841 .H2 "Attachments
meillo@22	1842 .P
meillo@58	1843 MIME
meillo@58	1844
meillo@58	1845
meillo@58	1846 .H2 "Digital Cryptography
meillo@22	1847 .P
meillo@58	1848 Signing and encryption.
meillo@58	1849
meillo@58	1850
meillo@58	1851 .H2 "Good Defaults
meillo@22	1852 .P
meillo@58	1853 foo
meillo@58	1854
meillo@58	1855
meillo@58	1856
meillo@58	1857
meillo@58	1858 .H1 "Code style
meillo@22	1859 .P
meillo@58	1860 foo
meillo@58	1861
meillo@58	1862
meillo@58	1863 .H2 "Standard Code
meillo@22	1864 .P
meillo@58	1865 POSIX
meillo@22	1866
meillo@22	1867
meillo@58	1868 .H2 "Separation
meillo@14	1869
meillo@58	1870 .U2 "MH Directory Split
meillo@0	1871 .P
meillo@19	1872 In MH and nmh, a personal setup had consisted of two parts:
meillo@19	1873 The MH profile, named
meillo@19	1874 .Fn \&.mh_profile
meillo@19	1875 and being located directly in the user's home directory.
meillo@19	1876 And the MH directory, where all his mail messages and also his personal
meillo@19	1877 forms, scan formats, other configuration files are stored. The location
meillo@19	1878 of this directory could be user-chosen. The default was to name it
meillo@19	1879 .Fn Mail
meillo@19	1880 and have it directly in the home directory.
meillo@19	1881 .P
meillo@19	1882 I've never liked the data storage and the configuration to be intermixed.
meillo@19	1883 They are different kinds of data. One part, are the messages,
meillo@19	1884 which are the data to operate on. The other part, are the personal
meillo@19	1885 configuration files, which are able to change the behavior of the operations.
meillo@19	1886 The actual operations are defined in the profile, however.
meillo@19	1887 .P
meillo@19	1888 When storing data, one should try to group data by its type.
meillo@19	1889 There's sense in the Unix file system hierarchy, where configuration
meillo@19	1890 file are stored separate (\c
meillo@19	1891 .Fn /etc )
meillo@19	1892 to the programs (\c
meillo@19	1893 .Fn /bin
meillo@19	1894 and
meillo@19	1895 .Fn /usr/bin )
meillo@19	1896 to their sources (\c
meillo@19	1897 .Fn /usr/src ).
meillo@19	1898 Such separation eases the backup management, for instance.
meillo@19	1899 .P
meillo@19	1900 In mmh, I've reorganized the file locations.
meillo@19	1901 Still there are two places:
meillo@19	1902 There's the mail storage directory, which, like in MH, contains all the
meillo@19	1903 messages, but, unlike in MH, nothing else.
meillo@19	1904 Its location still is user-chosen, with the default name
meillo@19	1905 .Fn Mail ,
meillo@19	1906 in the user's home directory. This is much similar to the case in nmh.
meillo@19	1907 The configuration files, however, are grouped together in the new directory
meillo@19	1908 .Fn \&.mmh
meillo@19	1909 in the user's home directory.
meillo@19	1910 The user's profile now is a file, named
meillo@19	1911 .Fn profile ,
meillo@19	1912 in this mmh directory.
meillo@19	1913 Consistently, the context file and all the personal forms, scan formats,
meillo@19	1914 and the like, are also there.
meillo@19	1915 .P
meillo@19	1916 The naming changed with the relocation.
meillo@19	1917 The directory where everything, except the profile, had been stored (\c
meillo@19	1918 .Fn $HOME/Mail ),
meillo@19	1919 used to be called \fIMH directory\fP. Now, this directory is called the
meillo@19	1920 user's \fImail storage\fP. The name \fImmh directory\fP is now given to
meillo@19	1921 the new directory
meillo@19	1922 (\c
meillo@19	1923 .Fn $HOME/.mmh ),
meillo@19	1924 containing all the personal configuration files.
meillo@19	1925 .P
meillo@19	1926 The separation of the files by type of content is logical and convenient.
meillo@19	1927 There are no functional differences as any possible setup known to me
meillo@19	1928 can be implemented with both approaches, although likely a bit easier
meillo@19	1929 with the new approach. The main goal of the change had been to provide
meillo@19	1930 sensible storage locations for any type of personal mmh file.
meillo@19	1931 .P
meillo@19	1932 In order for one user to have multiple MH setups, he can use the
meillo@19	1933 environment variable
meillo@19	1934 .Ev MH
meillo@19	1935 the point to a different profile file.
meillo@19	1936 The MH directory (mail storage plus personal configuration files) is
meillo@19	1937 defined by the
meillo@19	1938 .Pe Path
meillo@19	1939 profile entry.
meillo@19	1940 The context file could be defined by the
meillo@19	1941 .Pe context
meillo@19	1942 profile entry or by the
meillo@19	1943 .Ev MHCONTEXT
meillo@19	1944 environment variable.
meillo@19	1945 The latter is useful to have a distinct context (e.g. current folders)
meillo@19	1946 in each terminal window, for instance.
meillo@19	1947 In mmh, there are three environment variables now.
meillo@19	1948 .Ev MMH
meillo@19	1949 may be used to change the location of the mmh directory.
meillo@19	1950 .Ev MMHP
meillo@19	1951 and
meillo@19	1952 .Ev MMHC
meillo@19	1953 change the profile and context files, respectively.
meillo@19	1954 Besides providing a more consistent feel (which simply is the result
meillo@19	1955 of being designed anew), the set of personal configuration files can
meillo@19	1956 be chosen independently from the profile (including mail storage location)
meillo@19	1957 and context, now. Being it relevant for practical use or not, it
meillo@19	1958 de-facto is an improvement. However, the main achievement is the
meillo@19	1959 split between mail storage and personal configuration files.
meillo@17	1960
meillo@0	1961
meillo@58	1962 .H2 "Modularization
meillo@0	1963 .P
meillo@58	1964 whatnowproc
meillo@0	1965 .P
meillo@49	1966 The \fIMH library\fP
meillo@49	1967 .Fn libmh.a
meillo@49	1968 collects a bunch of standard functions that many of the MH tools need,
meillo@49	1969 like reading the profile or context files.
meillo@49	1970 This doesn't hurt the separation.
meillo@49	1971
meillo@58	1972
meillo@58	1973 .H2 "Style
meillo@58	1974 .P
meillo@58	1975 Code layout, goto, ...
meillo@58	1976
meillo@58	1977
meillo@58	1978
meillo@58	1979
meillo@89	1980 .H1 "Concept Exploitation/Homogeneity
meillo@58	1981
meillo@58	1982
meillo@58	1983 .H2 "Draft Folder
meillo@58	1984 .P
meillo@58	1985 Historically, MH provided exactly one draft message, named
meillo@58	1986 .Fn draft
meillo@58	1987 and
meillo@58	1988 being located in the MH directory. When starting to compose another message
meillo@58	1989 before the former one was sent, the user had been questioned whether to use,
meillo@58	1990 refile or replace the old draft. Working on multiple drafts at the same time
meillo@58	1991 was impossible. One could only work on them in alteration by refiling the
meillo@58	1992 previous one to some directory and fetching some other one for reediting.
meillo@58	1993 This manual draft management needed to be done each time the user wanted
meillo@58	1994 to switch between editing one draft to editing another.
meillo@58	1995 .P
meillo@58	1996 To allow true parallel editing of drafts, in a straight forward way, the
meillo@58	1997 draft folder facility exists. It had been introduced already in July 1984
meillo@58	1998 by Marshall T. Rose. The facility was deactivated by default.
meillo@58	1999 Even in nmh, the draft folder facility remained deactivated by default.
meillo@58	2000 At least, Richard Coleman added the man page
meillo@58	2001 .Mp mh-draft(5)
meillo@58	2002 to document
meillo@58	2003 the feature well.
meillo@58	2004 .P
meillo@58	2005 The only advantage of not using the draft folder facility is the static
meillo@89	2006 name of the draft file. This could be an issue for MH front-ends like mh-e.
meillo@58	2007 But as they likely want to provide working on multiple drafts in parallel,
meillo@58	2008 the issue is only concerning compatibility. The aim of nmh to stay compatible
meillo@58	2009 prevented the default activation of the draft folder facility.
meillo@58	2010 .P
meillo@58	2011 On the other hand, a draft folder is the much more natural concept than
meillo@58	2012 a draft message. MH's mail storage consists of folders and messages,
meillo@58	2013 the messages named with ascending numbers. A draft message breaks with this
meillo@58	2014 concept by introducing a message in a file named
meillo@58	2015 .Fn draft .
meillo@58	2016 This draft
meillo@58	2017 message is special. It can not be simply listed with the available tools,
meillo@58	2018 but instead requires special switches. I.e. corner-cases were
meillo@58	2019 introduced. A draft folder, in contrast, does not introduce such
meillo@58	2020 corner-cases. The available tools can operate on the messages within that
meillo@58	2021 folder like on any messages within any mail folders. The only difference
meillo@58	2022 is the fact that the default folder for
meillo@58	2023 .Pn send
meillo@58	2024 is the draft folder,
meillo@58	2025 instead of the current folder, like for all other tools.
meillo@58	2026 .P
meillo@58	2027 The trivial part of the change was activating the draft folder facility
meillo@58	2028 by default and setting a default name for this folder. Obviously, I chose
meillo@58	2029 the name
meillo@58	2030 .Fn +drafts .
meillo@58	2031 This made the
meillo@82	2032 .Sw -draftfolder
meillo@58	2033 and
meillo@82	2034 .Sw -draftmessage
meillo@58	2035 switches useless, and I could remove them.
meillo@58	2036 The more difficult but also the part that showed the real improvement,
meillo@58	2037 was updating the tools to the new concept.
meillo@82	2038 .Sw -draft
meillo@58	2039 switches could
meillo@58	2040 be dropped, as operating on a draft message became indistinguishable to
meillo@58	2041 operating on any other message for the tools.
meillo@58	2042 .Pn comp
meillo@58	2043 still has its
meillo@82	2044 .Sw -use
meillo@58	2045 switch for switching between its two modes: (1) Compose a new
meillo@58	2046 draft, possibly by taking some existing message as a form. (2) Modify
meillo@58	2047 an existing draft. In either case, the behavior of
meillo@58	2048 .Pn comp is
meillo@58	2049 deterministic. There is no more need to query the user. I consider this
meillo@58	2050 a major improvement. By making
meillo@58	2051 .Pn send
meillo@58	2052 simply operate on the current
meillo@58	2053 message in the draft folder by default, with message and folder both
meillo@58	2054 overridable by specifying them on the command line, it is now possible
meillo@58	2055 to send a draft anywhere within the storage by simply specifying its folder
meillo@58	2056 and name.
meillo@58	2057 .P
meillo@58	2058 All theses changes converted special cases to regular cases, thus
meillo@58	2059 simplifying the tools and increasing the flexibility.
meillo@58	2060
meillo@58	2061
meillo@58	2062 .H2 "Trash Folder
meillo@58	2063 .P
meillo@58	2064 Similar to the situation for drafts is the situation for removed messages.
meillo@58	2065 Historically, a message was deleted by renaming. A specific
meillo@58	2066 \fIbackup prefix\fP, often comma (\c
meillo@58	2067 .Fn , )
meillo@58	2068 or hash (\c
meillo@58	2069 .Fn # ),
meillo@58	2070 being prepended to the file name. Thus, MH wouldn't recognize the file
meillo@58	2071 as a message anymore, as only files whose name consists of digits only
meillo@58	2072 are treated as messages. The removed messages remained as files in the
meillo@58	2073 same directory and needed some maintenance job to truly delete them after
meillo@58	2074 some grace time. Usually, by running a command similar to
meillo@82	2075 .VS
meillo@82	2076 find /home/user/Mail -ctime +7 -name ',*' \| xargs rm
meillo@82	2077 VE
meillo@58	2078 in a cron job. Within the grace time interval
meillo@58	2079 the original message could be restored by stripping the
meillo@58	2080 the backup prefix from the file name. If however, the last message of
meillo@58	2081 a folder is been removed \(en say message
meillo@58	2082 .Fn 6
meillo@58	2083 becomes file
meillo@58	2084 .Fn ,6
meillo@58	2085 \(en and a new message enters the same folder, thus the same
meillo@58	2086 numbered being given again \(en in our case
meillo@58	2087 .Fn 6
meillo@58	2088 \(en, if that one
meillo@58	2089 is removed too, then the backup of the former message gets overwritten.
meillo@58	2090 Thus, the ability to restore removed messages does not only depend on
meillo@58	2091 the ``sweeping cron job'' but also on the removing of further messages.
meillo@58	2092 This is undesirable, because the real mechanism is hidden from the user
meillo@58	2093 and the consequences of further removals are not always obvious.
meillo@58	2094 Further more, the backup files are scattered within the whole mail
meillo@58	2095 storage, instead of being collected at one place.
meillo@58	2096 .P
meillo@58	2097 To improve the situation, the profile entry
meillo@58	2098 .Pe rmmproc
meillo@58	2099 (previously named
meillo@58	2100 .Pe Delete-Prog )
meillo@58	2101 was introduced, very early.
meillo@58	2102 It could be set to any command, which would care for the mail removal
meillo@58	2103 instead of taking the default action, described above.
meillo@58	2104 Refiling the to-be-removed files to some garbage folder was a common
meillo@58	2105 example. Nmh's man page
meillo@58	2106 .Mp rmm(1)
meillo@58	2107 proposes
meillo@58	2108 .Cl "refile +d
meillo@58	2109 to move messages to the garbage folder and
meillo@58	2110 .Cl "rm `mhpath +d all`
meillo@58	2111 the empty the garbage folder.
meillo@58	2112 Managing the message removal this way is a sane approach. It keeps
meillo@58	2113 the removed messages in one place, makes it easy to remove the backup
meillo@58	2114 files, and, most important, enables the user to use the tools of MH
meillo@58	2115 itself to operate on the removed messages. One can
meillo@58	2116 .Pn scan
meillo@58	2117 them,
meillo@58	2118 .Pn show
meillo@58	2119 them, and restore them with
meillo@58	2120 .Pn refile .
meillo@58	2121 There's no more
meillo@58	2122 need to use
meillo@58	2123 .Pn mhpath
meillo@58	2124 to switch over from MH tools to Unix tools \(en MH can do it all itself.
meillo@58	2125 .P
meillo@58	2126 This approach matches perfect with the concepts of MH, thus making
meillo@58	2127 it powerful. Hence, I made it the default. And even more, I also
meillo@58	2128 removed the old backup prefix approach, as it is clearly less powerful.
meillo@58	2129 Keeping unused alternative in the code is a bad choice as they likely
meillo@58	2130 gather bugs, by not being constantly tested. Also, the increased code
meillo@58	2131 size and more conditions crease the maintenance costs. By strictly
meillo@58	2132 converting to the trash folder approach, I simplified the code base.
meillo@58	2133 .Pn rmm
meillo@58	2134 calls
meillo@58	2135 .Pn refile
meillo@58	2136 internally to move the to-be-removed
meillo@58	2137 message to the trash folder (\c
meillo@58	2138 .Fn +trash
meillo@58	2139 by default). Messages
meillo@58	2140 there can be operated on like on any other message in the storage.
meillo@58	2141 The sweep clean, one can use
meillo@82	2142 .Cl "rmm -unlink +trash a" ,
meillo@58	2143 where the
meillo@82	2144 .Sw -unlink
meillo@58	2145 switch causes the files to be truly unliked instead
meillo@58	2146 of moved to the trash folder.
meillo@58	2147
meillo@58	2148
meillo@58	2149 .H2 "Path Notations
meillo@58	2150 .P
meillo@58	2151 foo
meillo@58	2152
meillo@58	2153
meillo@58	2154 .H2 "MIME Integration
meillo@58	2155 .P
meillo@58	2156 user-visible access to whole messages and MIME parts are inherently
meillo@58	2157 different
meillo@58	2158
meillo@58	2159
meillo@58	2160 .H2 "Of One Cast
meillo@58	2161 .P