docs/master

annotate discussion.roff @ 107:9f672d3a25f9

Renamed the chapters to speaking names.
author markus schnalke <meillo@marmaro.de>
date Sat, 23 Jun 2012 22:12:14 +0200
parents ch03.roff@9ff356d84c57
children dd5620bf8659
rev   line source
meillo@58 1 .H0 "Discussion
meillo@0 2 .P
meillo@58 3 This main chapter discusses the practical work done in the mmh project.
meillo@104 4 It is structured along the goals to achieve.
meillo@104 5 The concrete work done
meillo@58 6 is described in the examples of how the general goals were achieved.
meillo@87 7 The discussion compares the current version of mmh with the state of
meillo@87 8 nmh just before the mmh project started, i.e. Fall 2011.
meillo@87 9 Current changes of nmh will be mentioned only as side notes.
meillo@87 10 .\" XXX where do I discuss the parallel development of nmh?
meillo@58 11
meillo@58 12
meillo@58 13
meillo@100 14 .H1 "Stream-Lining
meillo@58 15
meillo@0 16 .P
meillo@58 17 MH had been considered an all-in-one system for mail handling.
meillo@58 18 The community around nmh has a similar understanding.
meillo@87 19 In fundamental difference, mmh shall be a MUA only.
meillo@87 20 I believe that the development of all-in-one mail systems is obsolete.
meillo@87 21 Today, email is too complex to be fully covered by single projects.
meillo@87 22 Such a project won't be able to excel in all aspects.
meillo@87 23 Instead, the aspects of email should be covered my multiple projects,
meillo@87 24 which then can be combined to form a complete system.
meillo@87 25 Excellent implementations for the various aspects of email exist already.
meillo@87 26 Just to name three examples: Postfix is a specialized MTA,
meillo@87 27 Procmail is a specialized MDA, and Fetchmail is a specialized MRA.
meillo@89 28 I believe that it is best to use such specialized tools instead of
meillo@87 29 providing the same function again as a side-component in the project.
meillo@58 30 .P
meillo@87 31 Doing something well, requires to focus on a small set of specific aspects.
meillo@87 32 Under the assumption that focused development produces better results
meillo@100 33 in the particular area, specialized projects will be superior
meillo@87 34 in their field of focus.
meillo@87 35 Hence, all-in-one mail system projects \(en no matter if monolithic
meillo@87 36 or modular \(en will never be the best choice in any of the fields.
meillo@87 37 Even in providing the best consistent all-in-one system they are likely
meillo@87 38 to be beaten by projects that focus only on integrating existing mail
meillo@89 39 components to a homogeneous system.
meillo@87 40 .P
meillo@87 41 The limiting resource in Free Software community development
meillo@87 42 is usually man power.
meillo@87 43 If the development power is spread over a large development area,
meillo@87 44 it becomes even more difficult to compete with the specialists in the
meillo@87 45 various fields.
meillo@87 46 The concrete situation for MH-based mail systems is even tougher,
meillo@87 47 given the small and aged community, including both developers and users,
meillo@87 48 it has.
meillo@87 49 .P
meillo@87 50 In consequence, I believe that the available development resources
meillo@100 51 should focus on the point where MH is most unique.
meillo@87 52 This is clearly the user interface \(en the MUA.
meillo@87 53 Peripheral parts should be removed to stream-line mmh for the MUA task.
meillo@60 54
meillo@60 55
meillo@100 56 .H2 "Mail Transfer Facilities
meillo@60 57 .P
meillo@60 58 In contrast to nmh, which also provides mail submission and mail retrieval
meillo@87 59 agents, mmh is a MUA only.
meillo@100 60 This general difference initiated the development of mmh.
meillo@66 61 Removing the mail transfer facilities had been the first work task
meillo@76 62 in the mmh project.
meillo@60 63 .P
meillo@105 64 Focusing on one mail agent role only is motivated by Eric Allman's
meillo@105 65 experience with Sendmail.
meillo@105 66 He identified limiting Sendmail the MTA task had be one reason for
meillo@105 67 its success:
meillo@105 68 .[ [
meillo@105 69 costales sendmail
meillo@105 70 .], p. xviii]
meillo@105 71 .QS
meillo@105 72 Second, I limited myself to the routing function \(en
meillo@105 73 I wouldn't write user agents or delivery backends.
meillo@105 74 This was a departure of the dominant through of the time,
meillo@105 75 in which routing logic, local delivery, and often the network code
meillo@105 76 were incorporated directly into the user agents.
meillo@105 77 .QE
meillo@105 78 .P
meillo@105 79 In mmh, the Mail Submission Agent (MSA) is called
meillo@105 80 \fIMessage Transfer Service\fP (MTS).
meillo@105 81 This facility, implemented by the
meillo@105 82 .Pn post
meillo@105 83 command, established network connections and spoke SMTP to submit
meillo@60 84 messages for relay to the outside world.
meillo@105 85 The changes in email demanded changes in this part of nmh too.
meillo@89 86 Encryption and authentication for network connections
meillo@87 87 needed to be supported, hence TLS and SASL were introduced into nmh.
meillo@87 88 This added complexity to nmh without improving it in its core functions.
meillo@87 89 Also, keeping up with recent developments in the field of
meillo@87 90 mail transfer requires development power and specialists.
meillo@87 91 In mmh this whole facility was simply cut off.
meillo@76 92 .Ci f6aa95b724fd8c791164abe7ee5468bf5c34f226
meillo@76 93 .Ci fecd5d34f65597a4dfa16aeabea7d74b191532c3
meillo@76 94 .Ci 156d35f6425bea4c1ed3c4c79783dc613379c65b
meillo@87 95 Instead, mmh depends on an external MSA.
meillo@60 96 The only outgoing interface available to mmh is the
meillo@60 97 .Pn sendmail
meillo@87 98 command, which almost any MSA provides.
meillo@87 99 If not, a wrapper program can be written.
meillo@87 100 It must read the message from the standard input, extract the
meillo@87 101 recipient addresses from the message header, and hand the message
meillo@87 102 over to the MSA.
meillo@87 103 For example, a wrapper script for qmail would be:
meillo@87 104 .VS
meillo@87 105 #!/bin/sh
meillo@87 106 # ignore command line arguments
meillo@87 107 exec qmail-inject
meillo@87 108 VE
meillo@87 109 The requirement to parse the recipient addresses out of the message header
meillo@87 110 is likely to be removed in the future.
meillo@87 111 Then mmh would give the recipient addresses as command line arguments.
meillo@100 112 This appears to be the better interface.
meillo@87 113 .\" XXX implement it
meillo@60 114 .P
meillo@60 115 To retrieve mail, the
meillo@60 116 .Pn inc
meillo@100 117 command acted as Mail Retrieval Agent (MRA).
meillo@100 118 It established network connections
meillo@76 119 and spoke POP3 to retrieve mail from remote servers.
meillo@76 120 As with mail submission, the network connections required encryption and
meillo@87 121 authentication, thus TLS and SASL were added.
meillo@87 122 Support for message retrieval through IMAP will become necessary
meillo@100 123 to be added soon, too, and likewise for any other changes in mail transfer.
meillo@100 124 Not so for mmh because it has dropped the support for retrieving mail
meillo@100 125 from remote locations.
meillo@76 126 .Ci ab7b48411962d26439f92f35ed084d3d6275459c
meillo@76 127 Instead, it depends on an external tool to cover this task.
meillo@100 128 In mmh exist two paths for messages to enter mmh's mail storage:
meillo@100 129 (1) Mail can be incorporated with
meillo@60 130 .Pn inc
meillo@87 131 from the system maildrop, or (2) with
meillo@60 132 .Pn rcvstore
meillo@87 133 by reading them, one at a time, from the standard input.
meillo@60 134 .P
meillo@60 135 With the removal of the MSA and MRA, mmh converted from an all-in-one
meillo@87 136 mail system to being a MUA only.
meillo@60 137 Now, of course, mmh depends on third-party software.
meillo@87 138 An external MSA is required to transfer mail to the outside world;
meillo@60 139 an external MRA is required to retrieve mail from remote machines.
meillo@60 140 There exist excellent implementations of such software,
meillo@76 141 which do this specific task likely better than the internal
meillo@87 142 versions had done it.
meillo@87 143 Also, the best suiting programs can be freely chosen.
meillo@60 144 .P
meillo@60 145 As it had already been possible to use an external MSA or MRA,
meillo@60 146 why not keep the internal version for convenience?
meillo@76 147 The question whether there is sense in having a fall-back pager in all
meillo@76 148 the command line tools, for the cases when
meillo@60 149 .Pn more
meillo@60 150 or
meillo@60 151 .Pn less
meillo@76 152 aren't available, appears to be ridiculous.
meillo@100 153 Of course, MSAs and MRAs are more complex than text pagers
meillo@87 154 and not necessarily available but still the concept of orthogonal
meillo@87 155 design holds: ``Write programs that do one thing and do it well.''
meillo@87 156 .[
meillo@87 157 mcilroy unix phil
meillo@87 158 p. 53
meillo@87 159 .]
meillo@87 160 .[
meillo@87 161 mcilroy bstj foreword
meillo@87 162 .]
meillo@87 163 Here, this part of the Unix philosophy was applied not only
meillo@87 164 to the programs but to the project itself.
meillo@87 165 In other words:
meillo@87 166 ``Develop projects that focus on one thing and do it well.''
meillo@87 167 Projects grown complex should be split for the same reasons programs grown
meillo@87 168 complex should be split.
meillo@100 169 If it is conceptionally more elegant to have the MSA and MRA as
meillo@87 170 separate projects then they should be separated.
meillo@87 171 This is the case here, in my opinion.
meillo@87 172 The RFCs propose this separation by clearly distinguishing the different
meillo@87 173 mail handling tasks.
meillo@87 174 .[
meillo@87 175 rfc 821
meillo@87 176 .]
meillo@87 177 The small interfaces between the mail agents support the separation.
meillo@76 178 .P
meillo@87 179 In the beginning, email had been small and simple.
meillo@100 180 At that time,
meillo@60 181 .Pn /bin/mail
meillo@100 182 had covered anything there was to email and still had been small
meillo@100 183 and simple.
meillo@100 184 Later, the essential complexity of email increased.
meillo@87 185 (Essential complexity is the complexity defined by the problem itself.\0
meillo@87 186 .[[
meillo@87 187 brooks no silver bullet
meillo@87 188 .]])
meillo@87 189 Email systems reacted to this change: They grew.
meillo@100 190 RFCs started to introduce the concept of mail agents to separate the
meillo@100 191 various tasks because they became more extensive and new tasks appeared.
meillo@100 192 As the mail systems grew even more, parts were split off.
meillo@100 193 In nmh, for instance, the POP server, which was included in the original
meillo@100 194 MH, was removed.
meillo@100 195 Now is the time to go one step further and split the MSA and MRA off, too.
meillo@87 196 Not only does this decrease the code size of the project,
meillo@87 197 but, more important, it unburdens mmh of the whole field of
meillo@87 198 message transfer with all its implications for the project.
meillo@100 199 There is no more need to concern with changes in network transfer.
meillo@76 200 This independence is received by depending on an external program
meillo@76 201 that covers the field.
meillo@76 202 Today, this is a reasonable exchange.
meillo@60 203 .P
meillo@100 204 Functionality can be added in three different ways:
meillo@87 205 .BU
meillo@87 206 Implementing the function originally in the project.
meillo@87 207 .BU
meillo@87 208 Depending on a library that provides the function.
meillo@87 209 .BU
meillo@87 210 Depending on a program that provides the function.
meillo@87 211 .P
meillo@87 212 Whereas adding the function originally to the project increases the
meillo@76 213 code size most and requires most maintenance and development work,
meillo@87 214 it makes the project most independent of other software.
meillo@87 215 Using libraries or external programs require less maintenance work
meillo@87 216 but introduces dependencies on external software.
meillo@87 217 Programs have the smallest interfaces and provide the best separation
meillo@87 218 but possibly limit the information exchange.
meillo@87 219 External libraries are stronger connected than external programs,
meillo@87 220 thus information can be exchanged more flexible.
meillo@87 221 Adding code to a project increases maintenance work.
meillo@87 222 .\" XXX ref
meillo@100 223 Implementing complex functions originally in the project adds
meillo@87 224 a lot of code.
meillo@87 225 This should be avoided if possible.
meillo@66 226 Hence, the dependencies only change in kind, not in their existence.
meillo@66 227 In mmh, library dependencies on
meillo@66 228 .Pn libsasl2
meillo@66 229 and
meillo@66 230 .Pn libcrypto /\c
meillo@66 231 .Pn libssl
meillo@66 232 were treated against program dependencies on an MSA and an MRA.
meillo@87 233 This also meant treating build-time dependencies against run-time
meillo@87 234 dependencies.
meillo@66 235 Besides program dependencies providing the stronger separation
meillo@66 236 and being more flexible, they also allowed
meillo@66 237 over 6\|000 lines of code to be removed from mmh.
meillo@66 238 This made mmh's code base about 12\|% smaller.
meillo@87 239 Reducing the project's code size by such an amount without actually
meillo@87 240 losing functionality is a convincing argument.
meillo@87 241 Actually, as external MSAs and MRAs are likely superior to the
meillo@87 242 project's internal versions, the common user even gains functionality.
meillo@66 243 .P
meillo@76 244 Users of MH should not have problems to set up an external MSA and MRA.
meillo@60 245 Also, the popular MSAs and MRAs have large communities and a lot
meillo@60 246 of documentation available.
meillo@87 247 Choices for MSAs range from full-featured MTAs like
meillo@60 248 .I Postfix
meillo@87 249 over mid-size MTAs like
meillo@60 250 .I masqmail
meillo@60 251 and
meillo@60 252 .I dma
meillo@60 253 to small forwarders like
meillo@60 254 .I ssmtp
meillo@60 255 and
meillo@60 256 .I nullmailer .
meillo@60 257 Choices for MRAs include
meillo@60 258 .I fetchmail ,
meillo@60 259 .I getmail ,
meillo@60 260 .I mpop
meillo@60 261 and
meillo@60 262 .I fdm .
meillo@60 263
meillo@60 264
meillo@100 265 .H2 "Non-MUA Tools
meillo@60 266 .P
meillo@87 267 One goal of mmh is to remove the tools that are not part of the MUA's task.
meillo@89 268 Further more, any tools that don't improve the MUA's job significantly
meillo@87 269 should be removed.
meillo@87 270 Loosely related and rarely used tools distract from the lean appearance.
meillo@87 271 They require maintenance work without adding much to the core task.
meillo@100 272 By removing these tools, the project shall become more stream-lined
meillo@87 273 and focused.
meillo@76 274 In mmh the following tools are not available anymore:
meillo@62 275 .BU
meillo@58 276 .Pn conflict
meillo@87 277 was removed
meillo@76 278 .Ci 8b235097cbd11d728c07b966cf131aa7133ce5a9
meillo@87 279 because it is a mail system maintenance tool that is not MUA-related.
meillo@87 280 It even checked
meillo@58 281 .Fn /etc/passwd
meillo@58 282 and
meillo@58 283 .Fn /etc/group
meillo@87 284 for consistency, which is completely unrelated to email.
meillo@87 285 A tool like
meillo@87 286 .Pn conflict
meillo@87 287 is surely useful, but it should not be shipped with mmh.
meillo@76 288 .\" XXX historic reasons?
meillo@62 289 .BU
meillo@58 290 .Pn rcvtty
meillo@87 291 was removed
meillo@87 292 .Ci 14767c94b3827be7c867196467ed7aea5f6f49b0
meillo@89 293 because its use case of writing to the user's terminal
meillo@76 294 on receiving of mail is obsolete.
meillo@87 295 If users like to be informed of new mail, the shell's
meillo@58 296 .Ev MAILPATH
meillo@87 297 variable or graphical notifications are technically more appealing.
meillo@100 298 Writing directly to terminals is hardly ever wanted today.
meillo@62 299 If though one wants to have it this way, the standard tool
meillo@58 300 .Pn write
meillo@58 301 can be used in a way similar to:
meillo@82 302 .VS
meillo@58 303 scan -file - | write `id -un`
meillo@82 304 VE
meillo@62 305 .BU
meillo@58 306 .Pn viamail
meillo@87 307 was removed
meillo@87 308 .Ci eda72d6a7a7c20ff123043fb7f19c509ea01f932
meillo@87 309 when the new attachment system was activated, because
meillo@58 310 .Pn forw
meillo@76 311 could then cover the task itself.
meillo@62 312 The program
meillo@58 313 .Pn sendfiles
meillo@62 314 was rewritten as a shell script wrapper around
meillo@58 315 .Pn forw .
meillo@76 316 .Ci 0e82199cf3c991a173e0ac8aa776efdb3ded61e6
meillo@62 317 .BU
meillo@58 318 .Pn msgchk
meillo@87 319 was removed
meillo@87 320 .Ci bb9360ead7eb7a3fedcce2eeedfc660014e41dbe ,
meillo@87 321 because it lost its use case when POP support was removed.
meillo@76 322 A call to
meillo@58 323 .Pn msgchk
meillo@87 324 provided hardly more information than:
meillo@82 325 .VS
meillo@58 326 ls -l /var/mail/meillo
meillo@82 327 VE
meillo@100 328 It did distinguish between old and new mail, but
meillo@100 329 this detail information can be retrieved with
meillo@76 330 .Pn stat (1),
meillo@62 331 too.
meillo@100 332 A small shell script could be written to print the information
meillo@76 333 in a similar way, if truly necessary.
meillo@76 334 As mmh's
meillo@76 335 .Pn inc
meillo@87 336 only incorporates mail from the user's local maildrop,
meillo@62 337 and thus no data transfers over slow networks are involved,
meillo@76 338 there's hardly any need to check for new mail before incorporating it.
meillo@62 339 .BU
meillo@58 340 .Pn msh
meillo@87 341 was removed
meillo@76 342 .Ci 916690191222433a6923a4be54b0d8f6ac01bd02
meillo@87 343 because the tool was in conflict with the philosophy of MH.
meillo@76 344 It provided an interactive shell to access the features of MH,
meillo@76 345 but it wasn't just a shell, tailored to the needs of mail handling.
meillo@76 346 Instead it was one large program that had several MH tools built in.
meillo@76 347 This conflicts with the major feature of MH of being a tool chest.
meillo@76 348 .Pn msh 's
meillo@76 349 main use case had been accessing Bulletin Boards, which have seized to
meillo@62 350 be popular.
meillo@62 351 .P
meillo@62 352 Removing
meillo@58 353 .Pn msh ,
meillo@76 354 together with the truly archaic code relicts
meillo@58 355 .Pn vmh
meillo@58 356 and
meillo@58 357 .Pn wmh ,
meillo@62 358 saved more than 7\|000 lines of C code \(en
meillo@66 359 about 15\|% of the project's original source code amount.
meillo@100 360 Having less code \(en with equal readability, of course \(en
meillo@76 361 for the same functionality is an advantage.
meillo@63 362 Less code means less bugs and less maintenance work.
meillo@76 363 As
meillo@63 364 .Pn rcvtty
meillo@63 365 and
meillo@63 366 .Pn msgchk
meillo@87 367 are assumed to be rarely used and can be implemented in different ways,
meillo@87 368 why should one keep them?
meillo@76 369 Removing them stream-lines mmh.
meillo@63 370 .Pn viamail 's
meillo@63 371 use case is now partly obsolete and partly covered by
meillo@63 372 .Pn forw ,
meillo@76 373 hence there's no reason to still maintain it.
meillo@63 374 .Pn conflict
meillo@76 375 is not related to the mail client, and
meillo@63 376 .Pn msh
meillo@63 377 conflicts with the basic concept of MH.
meillo@76 378 Theses two tools might still be useful, but they should not be part of mmh.
meillo@63 379 .P
meillo@76 380 Finally, there's
meillo@76 381 .Pn slocal .
meillo@76 382 .Pn slocal
meillo@76 383 is an MDA and thus not directly MUA-related.
meillo@100 384 It should be removed from mmh, because including it conflicts with
meillo@100 385 the idea that mmh is a MUA only.
meillo@100 386 .Pn slocal
meillo@100 387 should rather become a separate project.
meillo@87 388 However,
meillo@76 389 .Pn slocal
meillo@76 390 provides rule-based processing of messages, like filing them into
meillo@76 391 different folders, which is otherwise not available in mmh.
meillo@87 392 Although
meillo@76 393 .Pn slocal
meillo@87 394 does neither pull in dependencies nor does it include a separate
meillo@100 395 technical area (cf. Sec. XXX), still,
meillo@100 396 it accounts for about 1\|000 lines of code that need to be maintained.
meillo@76 397 As
meillo@76 398 .Pn slocal
meillo@76 399 is almost self-standing, it should be split off into a separate project.
meillo@76 400 This would cut the strong connection between the MUA mmh and the MDA
meillo@76 401 .Pn slocal .
meillo@87 402 For anyone not using MH,
meillo@87 403 .Pn slocal
meillo@87 404 would become yet another independent MDA, like
meillo@87 405 .I procmail .
meillo@100 406 Then
meillo@87 407 .Pn slocal
meillo@100 408 could be installed without the complete MH system.
meillo@76 409 Likewise, mmh users could decide to use
meillo@76 410 .I procmail
meillo@87 411 without having a second, unused MDA,
meillo@87 412 .Pn slocal ,
meillo@76 413 installed.
meillo@100 414 That appears to be conceptionally the best solution.
meillo@76 415 Yet,
meillo@76 416 .Pn slocal
meillo@87 417 is not split off.
meillo@100 418 I defer the decision over
meillo@78 419 .Pn slocal
meillo@100 420 in need for deeper investigation.
meillo@100 421 In the meanwhile, it remains part of mmh.
meillo@100 422 That does not hurt because
meillo@100 423 .Pn slocal
meillo@100 424 is unrelated to the rest of the project.
meillo@0 425
meillo@58 426
meillo@76 427 .H2 "\fLshow\fP and \fPmhshow\fP
meillo@58 428 .P
meillo@69 429 Since the very beginning \(en already in the first concept paper \(en
meillo@58 430 .Pn show
meillo@62 431 had been MH's message display program.
meillo@58 432 .Pn show
meillo@76 433 mapped message numbers and sequences to files and invoked
meillo@58 434 .Pn mhl
meillo@89 435 to have the files formatted.
meillo@88 436 With MIME, this approach wasn't sufficient anymore.
meillo@100 437 MIME messages can consist of multiple parts. Some parts are not
meillo@100 438 directly displayable and text content might be encoded in
meillo@58 439 foreign charsets.
meillo@58 440 .Pn show 's
meillo@76 441 understanding of messages and
meillo@58 442 .Pn mhl 's
meillo@88 443 display capabilities couldn't cope with the task any longer.
meillo@62 444 .P
meillo@88 445 Instead of extending these tools, additional tools were written from
meillo@88 446 scratch and added to the MH tool chest.
meillo@88 447 Doing so is encouraged by the tool chest approach.
meillo@88 448 Modular design is a great advantage for extending a system,
meillo@88 449 as new tools can be added without interfering with existing ones.
meillo@62 450 First, the new MIME features were added in form of the single program
meillo@58 451 .Pn mhn .
meillo@58 452 The command
meillo@82 453 .Cl "mhn -show 42
meillo@58 454 would show the MIME message numbered 42.
meillo@58 455 With the 1.0 release of nmh in February 1999, Richard Coleman finished
meillo@58 456 the split of
meillo@58 457 .Pn mhn
meillo@88 458 into a set of specialized tools, which together covered the
meillo@88 459 multiple aspects of MIME.
meillo@88 460 One of them was
meillo@69 461 .Pn mhshow ,
meillo@88 462 which replaced
meillo@88 463 .Cl "mhn -show" .
meillo@88 464 It was capable of displaying MIME messages appropriately.
meillo@62 465 .P
meillo@88 466 From then on, two message display tools were part of nmh,
meillo@76 467 .Pn show
meillo@76 468 and
meillo@76 469 .Pn mhshow .
meillo@88 470 To ease the life of users,
meillo@69 471 .Pn show
meillo@69 472 was extended to automatically hand the job over to
meillo@69 473 .Pn mhshow
meillo@69 474 if displaying the message would be beyond
meillo@69 475 .Pn show 's
meillo@69 476 abilities.
meillo@88 477 In consequence, the user would simply invoke
meillo@69 478 .Pn show
meillo@69 479 (possibly through
meillo@69 480 .Pn next
meillo@69 481 or
meillo@69 482 .Pn prev )
meillo@69 483 and get the message printed with either
meillo@69 484 .Pn show
meillo@69 485 or
meillo@69 486 .Pn mhshow ,
meillo@69 487 whatever was more appropriate.
meillo@69 488 .P
meillo@69 489 Having two similar tools for essentially the same task is redundant.
meillo@88 490 Usually,
meillo@88 491 users wouldn't distinguish between
meillo@88 492 .Pn show
meillo@88 493 and
meillo@88 494 .Pn mhshow
meillo@88 495 in their daily mail reading.
meillo@88 496 Having two separate display programs was therefore mainly unnecessary
meillo@88 497 from a user's point of view.
meillo@88 498 Besides, the development of both programs needed to be in sync,
meillo@76 499 to ensure that the programs behaved in a similar way,
meillo@76 500 because they were used like a single tool.
meillo@76 501 Different behavior would have surprised the user.
meillo@69 502 .P
meillo@69 503 Today, non-MIME messages are rather seen to be a special case of
meillo@100 504 MIME messages, although it is the other way round.
meillo@69 505 As
meillo@69 506 .Pn mhshow
meillo@88 507 had already be able to display non-MIME messages, it appeared natural
meillo@69 508 to drop
meillo@69 509 .Pn show
meillo@69 510 in favor of using
meillo@69 511 .Pn mhshow
meillo@69 512 exclusively.
meillo@88 513 .Ci 4c1efddfd499300c7e74263e57d8aa137e84c853
meillo@88 514 Removing
meillo@88 515 .Pn show
meillo@88 516 is no loss in function, because functionally
meillo@88 517 .Pn mhshow
meillo@88 518 covers it completely.
meillo@88 519 The old behavior of
meillo@88 520 .Pn show
meillo@88 521 can still be emulated with the simple command line:
meillo@88 522 .VS
meillo@88 523 mhl `mhpath c`
meillo@88 524 VE
meillo@88 525 .P
meillo@76 526 For convenience,
meillo@76 527 .Pn mhshow
meillo@88 528 was renamed to
meillo@88 529 .Pn show
meillo@88 530 after
meillo@88 531 .Pn show
meillo@88 532 was gone.
meillo@88 533 It is clear that such a rename may confuse future developers when
meillo@88 534 trying to understand the history.
meillo@88 535 Nevertheless, I consider the convenience on the user's side,
meillo@88 536 to call
meillo@88 537 .Pn show
meillo@88 538 when they want a message to be displayed, to outweigh the inconvenience
meillo@88 539 on the developer's side when understanding the project history.
meillo@69 540 .P
meillo@88 541 To prepare for the transition,
meillo@69 542 .Pn mhshow
meillo@69 543 was reworked to behave more like
meillo@69 544 .Pn show
meillo@69 545 first.
meillo@88 546 (cf. Sec. XXX)
meillo@88 547 Once the tools behaved more alike, the replacing appeared to be
meillo@88 548 even more natural.
meillo@88 549 Today, mmh's new
meillo@69 550 .Pn show
meillo@88 551 became the one single message display program again, with the difference
meillo@88 552 that today it handles MIME messages as well as non-MIME messages.
meillo@88 553 The outcome of the transition is one program less to maintain,
meillo@88 554 no second display program for users to deal with,
meillo@88 555 and less system complexity.
meillo@69 556 .P
meillo@88 557 Still, removing the old
meillo@69 558 .Pn show
meillo@88 559 hurts in one regard: It had been such a simple program.
meillo@88 560 Its lean elegance is missing to the new
meillo@69 561 .Pn show .
meillo@88 562 But there is no chance;
meillo@88 563 supporting MIME demands for higher essential complexity.
meillo@58 564
meillo@58 565
meillo@100 566 .H2 "Configure Options
meillo@58 567 .P
meillo@76 568 Customization is a double-edged sword.
meillo@76 569 It allows better suiting setups, but not for free.
meillo@76 570 There is the cost of code complexity to be able to customize.
meillo@76 571 There is the cost of less tested setups, because there are
meillo@72 572 more possible setups and especially corner-cases.
meillo@76 573 And, there is the cost of choice itself.
meillo@76 574 The code complexity directly affects the developers.
meillo@72 575 Less tested code affects both, users and developers.
meillo@76 576 The problem of choice affects the users, for once by having to
meillo@100 577 choose, but also by more complex interfaces that require more documentation.
meillo@72 578 Whenever options add little advantages, they should be considered for
meillo@72 579 removal.
meillo@72 580 I have reduced the number of project-specific configure options from
meillo@72 581 fifteen to three.
meillo@74 582
meillo@76 583 .U3 "Mail Transfer Facilities
meillo@74 584 .P
meillo@85 585 With the removal of the mail transfer facilities five configure
meillo@85 586 options vanished:
meillo@85 587 .P
meillo@85 588 The switches
meillo@85 589 .Sw --with-tls
meillo@85 590 and
meillo@85 591 .Sw --with-cyrus-sasl
meillo@89 592 had activated the support for transfer encryption and authentication.
meillo@85 593 This is not needed anymore.
meillo@85 594 .Ci fecd5d34f65597a4dfa16aeabea7d74b191532c3
meillo@85 595 .Ci 156d35f6425bea4c1ed3c4c79783dc613379c65b
meillo@85 596 .P
meillo@85 597 The configure switch
meillo@85 598 .Sw --enable-pop
meillo@85 599 activated the message retrieval facility.
meillo@85 600 The code area that would be conditionally compiled in for TLS and SASL
meillo@85 601 support had been small.
meillo@85 602 The conditionally compiled code area for POP support had been much larger.
meillo@85 603 Whereas the code base changes would only slightly change on toggling
meillo@85 604 TLS or SASL support, it changed much on toggling POP support.
meillo@85 605 The changes in the code base could hardly be overviewed.
meillo@85 606 By having POP support togglable a second code base had been created,
meillo@85 607 one that needed to be tested.
meillo@85 608 This situation is basically similar for the conditional TLS and SASL
meillo@85 609 code, but there the changes are minor and can yet be overviewed.
meillo@85 610 Still, conditional compilation of a code base creates variations
meillo@85 611 of the original program.
meillo@85 612 More variations require more testing and maintenance work.
meillo@85 613 .P
meillo@85 614 Two other options only specified default configuration values:
meillo@100 615 .Sw --with-mts
meillo@100 616 defined the default transport service, either
meillo@100 617 .Ar smtp
meillo@100 618 or
meillo@100 619 .Ar sendmail .
meillo@85 620 In mmh this fixed to
meillo@85 621 .Ar sendmail .
meillo@85 622 .Ci f6aa95b724fd8c791164abe7ee5468bf5c34f226
meillo@85 623 With
meillo@100 624 .Sw --with-smtpservers
meillo@85 625 default SMTP servers for the
meillo@85 626 .Ar smtp
meillo@85 627 transport service could be specified.
meillo@72 628 .Ci 128545e06224233b7e91fc4c83f8830252fe16c9
meillo@85 629 Both of them became irrelevant.
meillo@72 630
meillo@74 631 .U3 "Backup Prefix
meillo@74 632 .P
meillo@76 633 The backup prefix is the string that was prepended to message
meillo@76 634 filenames to tag them as deleted.
meillo@76 635 By default it had been the comma character `\f(CW,\fP'.
meillo@78 636 In July 2000, Kimmo Suominen introduced
meillo@78 637 the configure option
meillo@78 638 .Sw --with-hash-backup
meillo@78 639 to change the default to the hash symbol `\f(CW#\fP'.
meillo@78 640 The choice was probably personal preference, because first, the
meillo@78 641 option was named
meillo@78 642 .Sw --with-backup-prefix.
meillo@78 643 and had the prefix symbol as argument.
meillo@100 644 But giving the hash symbol as argument caused too many problems
meillo@100 645 for Autoconf,
meillo@100 646 thus the option was limited to use the hash symbol as the default prefix.
meillo@100 647 This supports the assumption, that the choice for the hash was
meillo@100 648 personal preference only.
meillo@100 649 Being related or not, words that start with the hash symbol
meillo@78 650 introduce a comment in the Unix shell.
meillo@72 651 Thus, the command line
meillo@72 652 .Cl "rm #13 #15
meillo@72 653 calls
meillo@72 654 .Pn rm
meillo@72 655 without arguments because the first hash symbol starts the comment
meillo@72 656 that reaches until the end of the line.
meillo@72 657 To delete the backup files,
meillo@72 658 .Cl "rm ./#13 ./#15"
meillo@72 659 needs to be used.
meillo@100 660 Using the hash as backup prefix can be seen as a precaution against
meillo@78 661 data loss.
meillo@78 662 .P
meillo@72 663 I removed the configure option but added the profile entry
meillo@72 664 .Pe backup-prefix ,
meillo@72 665 which allows to specify an arbitrary string as backup prefix.
meillo@72 666 .Ci 6c40d481d661d532dd527eaf34cebb6d3f8ed086
meillo@76 667 Profile entries are the common method to change mmh's behavior.
meillo@76 668 This change did not remove the choice but moved it to a location where
meillo@72 669 it suited better.
meillo@76 670 .P
meillo@78 671 Eventually, however, the new trash folder concept
meillo@78 672 .Cf "Sec. XXX
meillo@78 673 obsoleted the concept of the backup prefix completely.
meillo@78 674 .Ci 8edc5aaf86f9f77124664f6801bc6c6cdf258173
meillo@100 675 .\" (Well, there still are corner-cases to remove until the backup
meillo@100 676 .\" prefix can be laid to rest, eventually.)
meillo@72 677 .\" FIXME: Do this work in the code!
meillo@76 678
meillo@76 679 .U3 "Editor and Pager
meillo@74 680 .P
meillo@74 681 The two configure options
meillo@74 682 .CW --with-editor=EDITOR
meillo@74 683 .CW --with-pager=PAGER
meillo@74 684 were used to specify the default editor and pager at configure time.
meillo@74 685 Doing so at configure time made sense in the Eighties,
meillo@76 686 when the set of available editors and pagers varied much across
meillo@76 687 different systems.
meillo@89 688 Today, the situation is more homogeneous.
meillo@74 689 The programs
meillo@74 690 .Pn vi
meillo@74 691 and
meillo@74 692 .Pn more
meillo@76 693 can be expected to be available on every Unix system,
meillo@74 694 as they are specified by POSIX since two decades.
meillo@74 695 (The specifications for
meillo@74 696 .Pn vi
meillo@74 697 and
meillo@74 698 .Pn more
meillo@74 699 appeared in
meillo@74 700 .[
meillo@74 701 posix 1987
meillo@74 702 .]
meillo@74 703 and,
meillo@74 704 .[
meillo@74 705 posix 1992
meillo@74 706 .]
meillo@74 707 respectively.)
meillo@74 708 As a first step, these two tools were hard-coded as defaults.
meillo@74 709 .Ci 5d43a99db70c12a673028c7758c20cbe3e13ef5f
meillo@74 710 Not changed were the
meillo@74 711 .Pe editor
meillo@74 712 and
meillo@74 713 .Pe moreproc
meillo@76 714 profile entries, which allowed the user to override the system defaults.
meillo@74 715 Later, the concept was reworked to respect the standard environment
meillo@74 716 variables
meillo@74 717 .Ev VISUAL
meillo@74 718 and
meillo@74 719 .Ev PAGER
meillo@76 720 if they are set.
meillo@74 721 Today, mmh determines the editor to use in the following order,
meillo@74 722 taking the first available and non-empty item:
meillo@74 723 .IP (1)
meillo@74 724 Environment variable
meillo@74 725 .Ev MMHEDITOR
meillo@74 726 .IP (2)
meillo@74 727 Profile entry
meillo@74 728 .Pe Editor
meillo@74 729 .IP (3)
meillo@74 730 Environment variable
meillo@74 731 .Ev VISUAL
meillo@74 732 .IP (4)
meillo@74 733 Environment variable
meillo@74 734 .Ev EDITOR
meillo@74 735 .IP (5)
meillo@74 736 Command
meillo@74 737 .Pn vi .
meillo@74 738 .P
meillo@76 739 .Ci f85f4b7ae62e3d05a945dcd46ead51f0a2a89a9b
meillo@76 740 .P
meillo@89 741 The pager to use is determined in a similar order,
meillo@74 742 also taking the first available and non-empty item:
meillo@74 743 .IP (1)
meillo@74 744 Environment variable
meillo@74 745 .Ev MMHPAGER
meillo@74 746 .IP (2)
meillo@74 747 Profile entry
meillo@74 748 .Pe Pager
meillo@74 749 (replaces
meillo@74 750 .Pe moreproc )
meillo@74 751 .IP (3)
meillo@74 752 Environment variable
meillo@74 753 .Ev PAGER
meillo@74 754 .IP (4)
meillo@74 755 Command
meillo@74 756 .Pn more .
meillo@74 757 .P
meillo@74 758 .Ci 0c4214ea2aec6497d0d67b436bbee9bc1d225f1e
meillo@74 759 .P
meillo@76 760 By respecting the
meillo@74 761 .Ev VISUAL /\c
meillo@74 762 .Ev EDITOR
meillo@74 763 and
meillo@74 764 .Ev PAGER
meillo@76 765 environment variables,
meillo@76 766 the new behavior confirms better to the common style on Unix systems.
meillo@76 767 Additionally, the new approach is more uniform and clearer to users.
meillo@72 768
meillo@72 769
meillo@76 770 .U3 "ndbm
meillo@72 771 .P
meillo@74 772 .Pn slocal
meillo@78 773 used to depend on
meillo@74 774 .I ndbm ,
meillo@74 775 a database library.
meillo@76 776 The database is used to store the `\fLMessage-ID\fP's of all
meillo@76 777 messages delivered.
meillo@74 778 This enables
meillo@74 779 .Pn slocal
meillo@74 780 to suppress delivering the same message to the same user twice.
meillo@74 781 (This features was enabled by the
meillo@74 782 .Sw -suppressdup
meillo@74 783 switch.)
meillo@74 784 .P
meillo@100 785 A variety of versions of the database library exist.
meillo@78 786 .[
meillo@78 787 wolter unix incompat notes dbm
meillo@78 788 .]
meillo@74 789 Complicated autoconf code was needed to detect them correctly.
meillo@74 790 Further more, the configure switches
meillo@74 791 .Sw --with-ndbm=ARG
meillo@74 792 and
meillo@74 793 .Sw --with-ndbmheader=ARG
meillo@74 794 were added to help with difficult setups that would
meillo@78 795 not be detected automatically or correctly.
meillo@74 796 .P
meillo@74 797 By removing the suppress duplicates feature of
meillo@74 798 .Pn slocal ,
meillo@74 799 the dependency on
meillo@74 800 .I ndbm
meillo@78 801 vanished and 120 lines of complex autoconf code could be saved.
meillo@74 802 .Ci ecd6d6a20cb7a1507e3a20d6c4cb3a1cf14c6bbf
meillo@89 803 The change removed functionality too, but that is minor to the
meillo@78 804 improvement by dropping the dependency and the complex autoconf code.
meillo@72 805
meillo@74 806 .U3 "mh-e Support
meillo@72 807 .P
meillo@74 808 The configure option
meillo@74 809 .Sw --disable-mhe
meillo@74 810 was removed when the mh-e support was reworked.
meillo@74 811 Mh-e is the Emacs front-end to MH.
meillo@76 812 It requires MH to provide minor additional functions.
meillo@76 813 The
meillo@76 814 .Sw --disable-mhe
meillo@76 815 configure option could switch these extensions off.
meillo@76 816 After removing the support for old versions of mh-e,
meillo@74 817 only the
meillo@74 818 .Sw -build
meillo@76 819 switches of
meillo@74 820 .Pn forw
meillo@74 821 and
meillo@74 822 .Pn repl
meillo@76 823 are left to be mh-e extensions.
meillo@76 824 They are now always built in because they add little code and complexity.
meillo@76 825 In consequence, the
meillo@74 826 .Sw --disable-mhe
meillo@76 827 configure option was removed
meillo@72 828 .Ci a7ce7b4a580d77b6c2c4d980812beb589aa4c643
meillo@74 829 Removing the option removed a second code setup that would have
meillo@74 830 needed to be tested.
meillo@76 831 This change was first done in nmh and thereafter merged into mmh.
meillo@76 832 .P
meillo@76 833 The interface changes in mmh require mh-e to be adjusted in order
meillo@76 834 to be able to use mmh as back-end.
meillo@76 835 This will require minor changes to mh-e, but removing the
meillo@76 836 .Sw -build
meillo@76 837 switches would require more rework.
meillo@72 838
meillo@74 839 .U3 "Masquerading
meillo@72 840 .P
meillo@74 841 The configure option
meillo@74 842 .Sw --enable-masquerade
meillo@76 843 could take up to three arguments:
meillo@76 844 `draft_from', `mmailid', and `username_extension'.
meillo@74 845 They activated different types of address masquerading.
meillo@74 846 All of them were implemented in the SMTP-speaking
meillo@74 847 .Pn post
meillo@76 848 command, which provided an MSA.
meillo@76 849 Address masquerading is an MTA's task and mmh does not cover
meillo@76 850 this field anymore.
meillo@76 851 Hence, true masquerading needs to be implemented in the external MTA.
meillo@74 852 .P
meillo@74 853 The
meillo@74 854 .I mmailid
meillo@74 855 masquerading type is the oldest one of the three and the only one
meillo@74 856 available in the original MH.
meillo@74 857 It provided a
meillo@74 858 .I username
meillo@74 859 to
meillo@74 860 .I fakeusername
meillo@76 861 mapping, based on the password file's GECOS field.
meillo@74 862 The man page
meillo@74 863 .Mp mh-tailor(5)
meillo@74 864 described the use case as being the following:
meillo@98 865 .QS
meillo@74 866 This is useful if you want the messages you send to always
meillo@74 867 appear to come from the name of an MTA alias rather than your
meillo@74 868 actual account name. For instance, many organizations set up
meillo@74 869 `First.Last' sendmail aliases for all users. If this is
meillo@74 870 the case, the GECOS field for each user should look like:
meillo@74 871 ``First [Middle] Last <First.Last>''
meillo@98 872 .QE
meillo@74 873 .P
meillo@74 874 As mmh sends outgoing mail via the local MTA only,
meillo@76 875 the best location to do such global rewrites is there.
meillo@74 876 Besides, the MTA is conceptionally the right location because it
meillo@74 877 does the reverse mapping for incoming mail (aliasing), too.
meillo@76 878 Further more, masquerading set up there is readily available for all
meillo@74 879 mail software on the system.
meillo@76 880 Hence, mmailid masquerading was removed.
meillo@74 881 .Ci 0836c8000ccb34b59410ef1c15b1b7feac70ce5f
meillo@74 882 .P
meillo@74 883 The
meillo@74 884 .I username_extension
meillo@76 885 masquerading type did not replace the username but would append a suffix,
meillo@76 886 specified by the
meillo@74 887 .Ev USERNAME_EXTENSION
meillo@76 888 environment variable, to it.
meillo@76 889 This provided support for the
meillo@74 890 .I user-extension
meillo@74 891 feature of qmail and the similar
meillo@74 892 .I "plussed user
meillo@74 893 processing of sendmail.
meillo@74 894 The decision to remove this username_extension masquerading was
meillo@74 895 motivated by the fact that
meillo@74 896 .Pn spost
meillo@76 897 hadn't supported it already.
meillo@76 898 .Ci 2abae0bfd0ad5bf898461e50aa4b466d641f23d9
meillo@76 899 Username extensions are possible in mmh, but less convenient to use.
meillo@76 900 .\" XXX format file %(getenv USERNAME_EXTENSION)
meillo@74 901 .P
meillo@74 902 The
meillo@74 903 .I draft_from
meillo@74 904 masquerading type instructed
meillo@74 905 .Pn post
meillo@84 906 to use the value of the
meillo@84 907 .Hd From
meillo@84 908 header field as SMTP envelope sender.
meillo@76 909 Sender addresses could be replaced completely.
meillo@74 910 .Ci b14ea6073f77b4359aaf3fddd0e105989db9
meillo@76 911 Mmh offers a kind of masquerading similar in effect, but
meillo@74 912 with technical differences.
meillo@76 913 As mmh does not transfer messages itself, the local MTA has final control
meillo@76 914 over the sender's address. Any masquerading mmh introduces may be reverted
meillo@76 915 by the MTA.
meillo@76 916 In times of pedantic spam checking, an MTA will take care to use
meillo@76 917 sensible envelope sender addresses to keep its own reputation up.
meillo@84 918 Nonetheless, the MUA can set the
meillo@84 919 .Hd From
meillo@84 920 header field and thereby propose
meillo@76 921 a sender address to the MTA.
meillo@74 922 The MTA may then decide to take that one or generate the canonical sender
meillo@74 923 address for use as envelope sender address.
meillo@74 924 .P
meillo@74 925 In mmh, the MTA will always extract the recipient and sender from the
meillo@84 926 message header (\c
meillo@74 927 .Pn sendmail 's
meillo@74 928 .Sw -t
meillo@74 929 switch).
meillo@84 930 The
meillo@84 931 .Hd From
meillo@84 932 header field of the draft may be set arbitrary by the user.
meillo@74 933 If it is missing, the canonical sender address will be generated by the MTA.
meillo@74 934
meillo@74 935 .U3 "Remaining Options
meillo@74 936 .P
meillo@74 937 Two configure options remain in mmh.
meillo@74 938 One is the locking method to use:
meillo@74 939 .Sw --with-locking=[dot|fcntl|flock|lockf] .
meillo@76 940 The idea of removing all methods except the portable dot locking
meillo@76 941 and having that one as the default is appealing, but this change
meillo@76 942 requires deeper technical investigation into the topic.
meillo@76 943 The other option,
meillo@74 944 .Sw --enable-debug ,
meillo@74 945 compiles the programs with debugging symbols and does not strip them.
meillo@74 946 This option is likely to stay.
meillo@72 947
meillo@72 948
meillo@58 949
meillo@63 950
meillo@100 951 .H2 "Command Line Switches
meillo@58 952 .P
meillo@93 953 The command line switches of MH tools follow the X Window style.
meillo@93 954 They are words, introduced by a single dash.
meillo@93 955 For example:
meillo@93 956 .Cl "-truncate" .
meillo@93 957 Every program in mmh has two generic switches:
meillo@93 958 .Sw -help ,
meillo@93 959 to print a short message on how to use the program, and
meillo@93 960 .Sw -Version ,
meillo@93 961 to tell what version of mmh the program belongs to.
meillo@93 962 .P
meillo@93 963 Switches change the behavior of programs.
meillo@93 964 Programs that do one thing in one way require no switches.
meillo@93 965 In most cases, doing something in exactly one way is too limiting.
meillo@97 966 If there is basically one task to accomplish, but it should be done
meillo@93 967 in various ways, switches are a good approach to alter the behavior
meillo@93 968 of a program.
meillo@93 969 Changing the behavior of programs provides flexibility and customization
meillo@97 970 to users, but at the same time it complicates the code, documentation and
meillo@93 971 usage of the program.
meillo@97 972 .\" XXX: Ref
meillo@93 973 Therefore, the number of switches should be kept small.
meillo@93 974 A small set of well-chosen switches does no harm.
meillo@93 975 But usually, the number of switches increases over time.
meillo@93 976 Already in 1985, Rose and Romine have identified this as a major
meillo@93 977 problem of MH:
meillo@93 978 .[ [
meillo@93 979 rose romine real work
meillo@93 980 .], p. 12]
meillo@98 981 .QS
meillo@93 982 A complaint often heard about systems which undergo substantial development
meillo@93 983 by many people over a number of years, is that more and more options are
meillo@93 984 introduced which add little to the functionality but greatly increase the
meillo@93 985 amount of information a user needs to know in order to get useful work done.
meillo@93 986 This is usually referred to as creeping featurism.
meillo@93 987 .QP
meillo@93 988 Unfortunately MH, having undergone six years of off-and-on development by
meillo@93 989 ten or so well-meaning programmers (the present authors included),
meillo@93 990 suffers mightily from this.
meillo@98 991 .QE
meillo@93 992 .P
meillo@97 993 Being reluctant to adding new switches \(en or `options',
meillo@97 994 as Rose and Romine call them \(en is one part of a counter-action,
meillo@97 995 the other part is removing hardly used switches.
meillo@97 996 Nmh's tools had lots of switches already implemented,
meillo@97 997 hence, cleaning up by removing some of them was the more important part
meillo@97 998 of the counter-action.
meillo@93 999 Removing existing functionality is always difficult because it
meillo@93 1000 breaks programs that use these functions.
meillo@93 1001 Also, for every obsolete feature, there'll always be someone who still
meillo@93 1002 uses it and thus opposes its removal.
meillo@93 1003 This puts the developer into the position,
meillo@93 1004 where sensible improvements to style are regarded as destructive acts.
meillo@97 1005 Yet, living with the featurism is far worse, in my eyes, because
meillo@97 1006 future needs will demand adding further features,
meillo@93 1007 worsening the situation more and more.
meillo@93 1008 Rose and Romine added in a footnote,
meillo@93 1009 ``[...]
meillo@93 1010 .Pn send
meillo@93 1011 will no doubt acquire an endless number of switches in the years to come.''
meillo@97 1012 Although clearly humorous, the comment points to the nature of the problem.
meillo@97 1013 Refusing to add any new switches would encounter the problem at its root,
meillo@97 1014 but this is not practical.
meillo@97 1015 New needs will require new switches and it would be unwise to block
meillo@97 1016 them strictly.
meillo@97 1017 Nevertheless, removing obsolete switches still is an effective approach
meillo@97 1018 to deal with the problem.
meillo@97 1019 Working on an experimental branch without an established user base,
meillo@97 1020 eased my work because I did not offend users when I removed existing
meillo@97 1021 funtions.
meillo@93 1022 .P
meillo@93 1023 Rose and Romine counted 24 visible and 9 more hidden switches for
meillo@93 1024 .Pn send .
meillo@97 1025 In nmh, they increased up to 32 visible and 12 hidden ones.
meillo@97 1026 At the time of writing, no more than 7 visible switches and 1 hidden switch
meillo@97 1027 have remained in mmh's
meillo@97 1028 .Pn send .
meillo@97 1029 (These numbers include two generic switches, help and version.)
meillo@93 1030 .P
meillo@97 1031 Fig. XXX
meillo@93 1032 .\" XXX Ref
meillo@97 1033 displays the number of switches for each of the tools that is available
meillo@97 1034 in both, nmh and mmh.
meillo@100 1035 The tools are sorted by the number of switches they had in nmh.
meillo@100 1036 Visible and hidden switches were counted,
meillo@97 1037 but not the generic help and version switches.
meillo@93 1038 Whereas in the beginning of the project, the average tool had 11 switches,
meillo@93 1039 now it has no more than 5 \(en only half as many.
meillo@93 1040 If the `no' switches and similar inverse variant are folded onto
meillo@100 1041 their counter-parts, the average tool had 8 switches in pre-mmh times and
meillo@100 1042 has 4 now.
meillo@93 1043 The total number of functional switches in mmh dropped from 465
meillo@93 1044 to 234.
meillo@58 1045
meillo@93 1046 .KS
meillo@93 1047 .in 1c
meillo@93 1048 .so input/switches.grap
meillo@93 1049 .KE
meillo@58 1050
meillo@93 1051 .P
meillo@93 1052 A part of the switches vanished after functions were removed.
meillo@93 1053 This was the case for network mail transfer, for instance.
meillo@97 1054 Sometimes, however, the work flow was the other way:
meillo@97 1055 I looked through the
meillo@97 1056 .Mp mh-chart (7)
meillo@97 1057 man page to identify the tools with apparently too many switches.
meillo@97 1058 Then considering the value of each of the switches by examining
meillo@97 1059 the tool's man page and source code, aided by recherche and testing.
meillo@97 1060 This way, the removal of functions was suggested by the aim to reduce
meillo@97 1061 the number of switches per command.
meillo@97 1062
meillo@58 1063
meillo@93 1064 .U3 "Draft Folder Facility
meillo@93 1065 .P
meillo@100 1066 A change early in the project was the complete transition from
meillo@93 1067 the single draft message to the draft folder facility.
meillo@97 1068 .Ci 337338b404931f06f0db2119c9e145e8ca5a9860
meillo@100 1069 The draft folder facility was introduced in the mid-Eighties, when
meillo@100 1070 Rose and Romine called it a ``relatively new feature''.
meillo@93 1071 .[
meillo@93 1072 rose romine real work
meillo@93 1073 .]
meillo@97 1074 Since then, the facility had existed but was deactivated by default.
meillo@93 1075 The default activation and the related rework of the tools made it
meillo@93 1076 possible to remove the
meillo@93 1077 .Sw -[no]draftfolder ,
meillo@93 1078 and
meillo@93 1079 .Sw -draftmessage
meillo@93 1080 switches from
meillo@93 1081 .Pn comp ,
meillo@93 1082 .Pn repl ,
meillo@93 1083 .Pn forw ,
meillo@93 1084 .Pn dist ,
meillo@93 1085 .Pn whatnow ,
meillo@93 1086 and
meillo@93 1087 .Pn send .
meillo@97 1088 .Ci 337338b404931f06f0db2119c9e145e8ca5a9860
meillo@97 1089 The only flexibility removed with this change is having multiple
meillo@97 1090 draft folders within one profile.
meillo@97 1091 I consider this a theoretical problem only.
meillo@93 1092 In the same go, the
meillo@93 1093 .Sw -draft
meillo@93 1094 switch of
meillo@93 1095 .Pn anno ,
meillo@93 1096 .Pn refile ,
meillo@93 1097 and
meillo@93 1098 .Pn send
meillo@93 1099 was removed.
meillo@93 1100 The special-casing of `the' draft message became irrelevant after
meillo@93 1101 the rework of the draft system.
meillo@93 1102 (See Sec. XXX.)
meillo@95 1103 Equally,
meillo@95 1104 .Pn comp
meillo@95 1105 lost its
meillo@95 1106 .Sw -file
meillo@95 1107 switch.
meillo@95 1108 The draft folder facility, together with the
meillo@95 1109 .Sw -form
meillo@95 1110 switch, are sufficient.
meillo@93 1111
meillo@95 1112
meillo@102 1113 .U3 "In Place Editing
meillo@93 1114 .P
meillo@93 1115 .Pn anno
meillo@93 1116 had the switches
meillo@93 1117 .Sw -[no]inplace
meillo@100 1118 to either annotate the message in place and thus preserve hard links,
meillo@93 1119 or annotate a copy to replace the original message, breaking hard links.
meillo@97 1120 Following the assumption that linked messages should truly be the
meillo@97 1121 same message, and annotating it should not break the link, the
meillo@93 1122 .Sw -[no]inplace
meillo@93 1123 switches were removed and the previous default
meillo@93 1124 .Sw -inplace
meillo@93 1125 was made the only behavior.
meillo@97 1126 .Ci c8195849d2e366c569271abb0f5f60f4ebf0b4d0
meillo@93 1127 The
meillo@93 1128 .Sw -[no]inplace
meillo@93 1129 switches of
meillo@93 1130 .Pn repl ,
meillo@93 1131 .Pn forw ,
meillo@93 1132 and
meillo@93 1133 .Pn dist
meillo@93 1134 could be removed, too, as they were simply passed through to
meillo@93 1135 .Pn anno .
meillo@93 1136 .P
meillo@93 1137 .Pn burst
meillo@93 1138 also had
meillo@93 1139 .Sw -[no]inplace
meillo@95 1140 switches, but with different meaning.
meillo@95 1141 With
meillo@95 1142 .Sw -inplace ,
meillo@95 1143 the digest had been replaced by the table of contents (i.e. the
meillo@95 1144 introduction text) and the bursted messages were placed right
meillo@95 1145 after this message, renumbering all following messages.
meillo@95 1146 Also, any trailing text of the digest was lost, though,
meillo@95 1147 in practice, it usually consists of an end-of-digest marker only.
meillo@95 1148 Nontheless, this behavior appeared less elegant than the
meillo@95 1149 .Sw -noinplace
meillo@95 1150 behavior, which already had been the default.
meillo@95 1151 Nmh's
meillo@95 1152 .Mp burst (1)
meillo@95 1153 man page reads:
meillo@95 1154 .sp \n(PDu
meillo@98 1155 .QS
meillo@93 1156 If -noinplace is given, each digest is preserved, no table
meillo@93 1157 of contents is produced, and the messages contained within
meillo@93 1158 the digest are placed at the end of the folder. Other messages
meillo@93 1159 are not tampered with in any way.
meillo@98 1160 .QE
meillo@95 1161 .LP
meillo@93 1162 The decision to drop the
meillo@93 1163 .Sw -inplace
meillo@95 1164 behavior was supported by the code complexity and the possible data loss
meillo@95 1165 it caused.
meillo@93 1166 .Sw -noinplace
meillo@95 1167 was chosen to be the definitive behavior.
meillo@97 1168 .Ci 68a686adeb39223a5e1ad35e4a24890ec053679d
meillo@93 1169
meillo@95 1170
meillo@95 1171 .U3 "Forms and Format Strings
meillo@93 1172 .P
meillo@95 1173 Historically, the tools that had
meillo@95 1174 .Sw -form
meillo@95 1175 switches to supply a form file had
meillo@95 1176 .Sw -format
meillo@95 1177 switches as well to supply the contents of a form file as a string
meillo@95 1178 on the command line directly.
meillo@95 1179 In consequence, the following two lines equaled:
meillo@95 1180 .VS
meillo@95 1181 scan -form scan.mailx
meillo@95 1182 scan -format "`cat .../scan.mailx`"
meillo@95 1183 VE
meillo@95 1184 The
meillo@95 1185 .Sw -format
meillo@95 1186 switches were dropped in favor for extending the
meillo@95 1187 .Sw -form
meillo@95 1188 switches.
meillo@97 1189 .Ci f51956be123db66b00138f80464d06f030dbb88d
meillo@95 1190 If their argument starts with an equal sign (`='),
meillo@95 1191 then the rest of the argument is taken as a format string,
meillo@95 1192 otherwise the arguments is treated as the name of a format file.
meillo@95 1193 Thus, now the following two lines equal:
meillo@95 1194 .VS
meillo@95 1195 scan -form scan.mailx
meillo@95 1196 scan -form "=`cat .../scan.mailx`"
meillo@95 1197 VE
meillo@95 1198 This rework removed the prefix collision between
meillo@95 1199 .Sw -form
meillo@95 1200 and
meillo@95 1201 .Sw -format .
meillo@95 1202 Now, typing
meillo@95 1203 .Sw -fo
meillo@95 1204 suffices to specify form or format string.
meillo@95 1205 .P
meillo@95 1206 The different meaning of
meillo@95 1207 .Sw -format
meillo@95 1208 for
meillo@95 1209 .Pn repl
meillo@95 1210 and
meillo@95 1211 .Pn forw
meillo@95 1212 was removed in mmh.
meillo@95 1213 .Pn forw
meillo@95 1214 was completely switched to MIME-type forwarding, thus removing the
meillo@95 1215 .Sw -[no]format .
meillo@97 1216 .Ci 6e271608b7b9c23771523f88d23a4d3593010cf1
meillo@95 1217 For
meillo@95 1218 .Pn repl ,
meillo@95 1219 the
meillo@95 1220 .Sw -[no]format
meillo@95 1221 switches were reworked to
meillo@95 1222 .Sw -[no]filter
meillo@95 1223 switches.
meillo@97 1224 .Ci 67411b1f95d6ec987b4c732459e1ba8a8ac192c6
meillo@95 1225 The
meillo@95 1226 .Sw -format
meillo@95 1227 switches of
meillo@95 1228 .Pn send
meillo@95 1229 and
meillo@95 1230 .Pn post ,
meillo@95 1231 which had a third meaning,
meillo@95 1232 were removed likewise.
meillo@97 1233 .Ci f3cb7cde0e6f10451b6848678d95860d512224b9
meillo@95 1234 Eventually, the ambiguity of the
meillo@95 1235 .Sw -format
meillo@95 1236 switches was resolved by not anymore having any such switch in mmh.
meillo@95 1237
meillo@95 1238
meillo@95 1239 .U3 "MIME Tools
meillo@95 1240 .P
meillo@95 1241 The MIME tools, which were once part of
meillo@100 1242 .Pn mhn
meillo@100 1243 [sic!],
meillo@95 1244 had several switches that added little practical value to the programs.
meillo@95 1245 The
meillo@95 1246 .Sw -[no]realsize
meillo@95 1247 switches of
meillo@95 1248 .Pn mhbuild
meillo@95 1249 and
meillo@95 1250 .Pn mhlist
meillo@97 1251 were removed, doing real size calculations always now
meillo@97 1252 .Ci 8d8f1c3abc586c005c904e52c4adbfe694d2201c ,
meillo@97 1253 as
meillo@95 1254 ``This provides an accurate count at the expense of a small delay.''
meillo@95 1255 This small delay is not noticable on modern systems.
meillo@95 1256 .P
meillo@95 1257 The
meillo@95 1258 .Sw -[no]check
meillo@95 1259 switches were removed together with the support for
meillo@95 1260 .Hd Content-MD5
meillo@95 1261 header fields.
meillo@95 1262 .[
meillo@95 1263 rfc 1864
meillo@95 1264 .]
meillo@97 1265 .Ci 31dc797eb5178970d68962ca8939da3fd9a8efda
meillo@95 1266 (See Sec. XXX)
meillo@95 1267 .P
meillo@95 1268 The
meillo@95 1269 .Sw -[no]ebcdicsafe
meillo@95 1270 and
meillo@95 1271 .Sw -[no]rfc934mode
meillo@95 1272 switches of
meillo@95 1273 .Pn mhbuild
meillo@95 1274 were removed because they are considered obsolete.
meillo@97 1275 .Ci 01a3480928da485b4d6109d36d751dfa71799d58
meillo@97 1276 .Ci 3363e2624dce0eb8164cf8b3f1ab385c8ff72e88
meillo@95 1277 .P
meillo@95 1278 Content caching of external MIME parts, activated with the
meillo@95 1279 .Sw -rcache
meillo@95 1280 and
meillo@95 1281 .Sw -wcache
meillo@95 1282 switches was completely removed.
meillo@97 1283 .Ci d1fefd9f614e4dc3cda16da6c69133c1b2005269
meillo@97 1284 External MIME parts are rare today, having a caching facility
meillo@96 1285 for them is appears to be unnecessary.
meillo@95 1286 .P
meillo@95 1287 In pre-MIME times,
meillo@95 1288 .Pn mhl
meillo@95 1289 had covered many tasks that are part of MIME handling today.
meillo@95 1290 Therefore,
meillo@95 1291 .Pn mhl
meillo@95 1292 could be simplified to a large extend, reducing the number of its
meillo@95 1293 switches from 21 to 6.
meillo@97 1294 .Ci 350ad6d3542a07639213cf2a4fe524e829c1e7b6
meillo@97 1295 .Ci 0e46503be3c855bddaeae3843e1b659279c35d70
meillo@95 1296
meillo@95 1297
meillo@95 1298 .U3 "Mail Transfer Switches
meillo@95 1299 .P
meillo@95 1300 With the removal of the mail transfer facilities, a lot of switches
meillo@95 1301 vanished automatically.
meillo@95 1302 .Pn inc
meillo@95 1303 lost 9 switches, namely
meillo@95 1304 .Sw -host ,
meillo@95 1305 .Sw -port ,
meillo@95 1306 .Sw -user ,
meillo@95 1307 .Sw -proxy ,
meillo@95 1308 .Sw -snoop ,
meillo@95 1309 .Sw -[no]pack ,
meillo@95 1310 as well as
meillo@95 1311 .Sw -sasl
meillo@95 1312 and
meillo@95 1313 .Sw -saslmech .
meillo@95 1314 .Pn send
meillo@95 1315 and
meillo@95 1316 .Pn post
meillo@95 1317 lost 11 switches each, namely
meillo@95 1318 .Sw -server ,
meillo@95 1319 .Sw -port ,
meillo@95 1320 .Sw -client ,
meillo@95 1321 .Sw -user ,
meillo@95 1322 .Sw -mail ,
meillo@95 1323 .Sw -saml ,
meillo@95 1324 .Sw -send ,
meillo@95 1325 .Sw -soml ,
meillo@95 1326 .Sw -snoop ,
meillo@95 1327 as well as
meillo@95 1328 .Sw -sasl ,
meillo@95 1329 .Sw -saslmech ,
meillo@95 1330 and
meillo@95 1331 .Sw -tls .
meillo@95 1332 .Pn send
meillo@95 1333 had the switches only to pass them further to
meillo@95 1334 .Pn post ,
meillo@95 1335 because the user would invoke
meillo@95 1336 .Pn post
meillo@95 1337 not directly, but through
meillo@95 1338 .Pn send .
meillo@95 1339 All these switches, except
meillo@95 1340 .Sw -snoop
meillo@95 1341 were usually defined as default switches in the user's profile,
meillo@95 1342 but hardly given in interactive usage.
meillo@95 1343 .P
meillo@95 1344 Of course, those switches did not really ``vanish'', but the configuration
meillo@95 1345 they did was handed over to external MSAs and MRAs.
meillo@95 1346 Instead of setting up the mail transfer in mmh, it is set up in
meillo@95 1347 external tools.
meillo@95 1348 Yet, this simplifies mmh.
meillo@95 1349 Specialized external tools will likely have simple configuration files.
meillo@95 1350 Hence, instead of having one complicated central configuration file,
meillo@95 1351 the configuration of each domain is separate.
meillo@95 1352 Although the user needs to learn to configure each of the tools,
meillo@95 1353 each configuration is likely much simpler.
meillo@95 1354
meillo@95 1355
meillo@95 1356 .U3 "Maildrop Formats
meillo@95 1357 .P
meillo@95 1358 With the removal of MMDF maildrop format support,
meillo@95 1359 .Pn packf
meillo@95 1360 and
meillo@95 1361 .Pn rcvpack
meillo@95 1362 no longer needed their
meillo@95 1363 .Sw -mbox
meillo@95 1364 and
meillo@95 1365 .Sw -mmdf
meillo@95 1366 switches.
meillo@95 1367 .Sw -mbox
meillo@95 1368 is the sole behavior now.
meillo@97 1369 .Ci 3916ab66ad5d183705ac12357621ea8661afd3c0
meillo@95 1370 In the same go,
meillo@95 1371 .Pn packf
meillo@97 1372 and
meillo@97 1373 .Pn rcvpack
meillo@97 1374 were reworked (see Sec. XXX) and their
meillo@95 1375 .Sw -file
meillo@95 1376 switch became unnecessary.
meillo@97 1377 .Ci ca1023716d4c2ab890696f3e41fa0d94267a940e
meillo@95 1378
meillo@95 1379
meillo@95 1380 .U3 "Terminal Magic
meillo@95 1381 .P
meillo@95 1382 Mmh's tools will no longer clear the screen (\c
meillo@95 1383 .Pn scan 's
meillo@95 1384 and
meillo@95 1385 .Pn mhl 's
meillo@95 1386 .Sw -[no]clear
meillo@97 1387 switches
meillo@97 1388 .Ci e57b17343dcb3ff373ef4dd089fbe778f0c7c270
meillo@97 1389 .Ci 943765e7ac5693ae177fd8d2b5a2440e53ce816e ).
meillo@95 1390 Neither will
meillo@95 1391 .Pn mhl
meillo@95 1392 ring the bell (\c
meillo@97 1393 .Sw -[no]bell
meillo@97 1394 .Ci e11983f44e59d8de236affa5b0d0d3067c192e24 )
meillo@95 1395 nor page the output itself (\c
meillo@97 1396 .Sw -length
meillo@97 1397 .Ci 5b9d883db0318ed2b84bb82dee880d7381f99188 ).
meillo@95 1398 .P
meillo@95 1399 Generally, the pager to use is no longer specified with the
meillo@95 1400 .Sw -[no]moreproc
meillo@95 1401 command line switches for
meillo@95 1402 .Pn mhl
meillo@95 1403 and
meillo@95 1404 .Pn show /\c
meillo@95 1405 .Pn mhshow .
meillo@97 1406 .Ci 39e87a75b5c2d3572ec72e717720b44af291e88a
meillo@95 1407 .P
meillo@95 1408 .Pn prompter
meillo@95 1409 lost its
meillo@95 1410 .Sw -erase
meillo@95 1411 and
meillo@95 1412 .Sw -kill
meillo@95 1413 switches because today the terminal cares for the line editing keys.
meillo@95 1414
meillo@95 1415
meillo@95 1416 .U3 "Header Printing
meillo@95 1417 .P
meillo@95 1418 .Pn folder 's
meillo@95 1419 data output is self-explaining enough that
meillo@95 1420 displaying the header line makes few sense.
meillo@95 1421 Hence, the
meillo@95 1422 .Sw -[no]header
meillo@95 1423 switch was removed and headers are never printed.
meillo@97 1424 .Ci 601cc73d1fa05ce96faa728f036d6c51b91701c7
meillo@95 1425 .P
meillo@95 1426 In
meillo@95 1427 .Pn mhlist ,
meillo@95 1428 the
meillo@95 1429 .Sw -[no]header
meillo@95 1430 switches were removed, too.
meillo@97 1431 .Ci b24f96523aaf60e44e04a3ffb1d22e69a13a602f
meillo@95 1432 But in this case headers are always printed,
meillo@95 1433 because the output is not self-explaining.
meillo@95 1434 .P
meillo@95 1435 .Pn scan
meillo@95 1436 also had
meillo@95 1437 .Sw -[no]header
meillo@95 1438 switches.
meillo@95 1439 Printing the header had been sensible until the introduction of
meillo@95 1440 format strings made it impossible to display the column headings.
meillo@95 1441 Only the folder name and the current date remained to be printed.
meillo@95 1442 As this information can be perfectly retrieved by
meillo@95 1443 .Pn folder
meillo@95 1444 and
meillo@95 1445 .Pn date ,
meillo@95 1446 consequently, the switches were removed.
meillo@97 1447 .Ci c477dc5d1d03fa6d9a8ab3dd3508c63cbddc044e
meillo@95 1448 .P
meillo@95 1449 By removing all
meillo@95 1450 .Sw -header
meillo@95 1451 switches, the collision with
meillo@95 1452 .Sw -help
meillo@95 1453 on the first two letters was resolved.
meillo@95 1454 Currently,
meillo@95 1455 .Sw -h
meillo@95 1456 evaluates to
meillo@95 1457 .Sw -help
meillo@95 1458 for all tools of mmh.
meillo@95 1459
meillo@95 1460
meillo@95 1461 .U3 "Suppressing Edits or the WhatNow Shell
meillo@95 1462 .P
meillo@95 1463 The
meillo@95 1464 .Sw -noedit
meillo@100 1465 switch of
meillo@95 1466 .Pn comp ,
meillo@95 1467 .Pn repl ,
meillo@95 1468 .Pn forw ,
meillo@95 1469 .Pn dist ,
meillo@95 1470 and
meillo@95 1471 .Pn whatnow
meillo@95 1472 was removed, but it can now be replaced by specifying
meillo@95 1473 .Sw -editor
meillo@95 1474 with an empty argument.
meillo@97 1475 .Ci 75fca31a5b9d5c1a99c74ab14c94438d8852fba9
meillo@95 1476 (Specifying
meillo@95 1477 .Cl "-editor true
meillo@95 1478 is nearly the same, only differing by the previous editor being set.)
meillo@95 1479 .P
meillo@95 1480 The more important change is the removal of the
meillo@95 1481 .Sw -nowhatnowproc
meillo@95 1482 switch.
meillo@97 1483 .Ci ee4f43cf2ef0084ec698e4e87159a94c01940622
meillo@95 1484 This switch had introduced an awkward behavior, as explained in nmh's
meillo@95 1485 man page for
meillo@95 1486 .Mp comp (1):
meillo@98 1487 .QS
meillo@98 1488 The \-editor editor switch indicates the editor to use for
meillo@98 1489 the initial edit. Upon exiting from the editor, comp will
meillo@98 1490 invoke the whatnow program. See whatnow(1) for a discussion
meillo@98 1491 of available options. The invocation of this program can be
meillo@98 1492 inhibited by using the \-nowhatnowproc switch. (In truth of
meillo@98 1493 fact, it is the whatnow program which starts the initial
meillo@98 1494 edit. Hence, \-nowhatnowproc will prevent any edit from
meillo@95 1495 occurring.)
meillo@98 1496 .QE
meillo@95 1497 .P
meillo@95 1498 Effectively, the
meillo@95 1499 .Sw -nowhatnowproc
meillo@100 1500 switch creates only a draft message.
meillo@95 1501 As
meillo@95 1502 .Cl "-whatnowproc true
meillo@95 1503 causes the same behavior, the
meillo@95 1504 .Sw -nowhatnowproc
meillo@95 1505 switch was removed for being redundant.
meillo@100 1506 Likely, the
meillo@95 1507 .Sw -nowhatnowproc
meillo@100 1508 switch was intended to be used by front-ends.
meillo@95 1509
meillo@95 1510
meillo@95 1511 .U3 "Compatibility Switches
meillo@95 1512 .BU
meillo@95 1513 The hidden
meillo@95 1514 .Sw -[no]total
meillo@95 1515 switches of
meillo@95 1516 .Pn flist .
meillo@95 1517 They were simply the inverse of the visible
meillo@95 1518 .Sw -[no]fast
meillo@95 1519 switches:
meillo@95 1520 .Sw -total
meillo@95 1521 was
meillo@95 1522 .Sw -nofast
meillo@95 1523 and
meillo@95 1524 .Sw -nototal
meillo@95 1525 was
meillo@95 1526 .Sw -fast .
meillo@95 1527 I removed the
meillo@95 1528 .Sw -[no]total
meillo@95 1529 legacy.
meillo@97 1530 .Ci ea21fe2c4bd23c639bef251398fae809875732ec
meillo@95 1531 .BU
meillo@95 1532 The
meillo@95 1533 .Sw -subject
meillo@95 1534 switch of
meillo@95 1535 .Pn sortm
meillo@95 1536 existed for compatibility only.
meillo@95 1537 It can be fully replaced by
meillo@95 1538 .Cl "-textfield subject
meillo@95 1539 thus it was removed.
meillo@97 1540 .Ci 00140a3c86e9def69d98ba2ffd4d6e50ef6326ea
meillo@95 1541
meillo@95 1542
meillo@95 1543 .U3 "Various
meillo@95 1544 .BU
meillo@96 1545 In order to avoid prefix collisions among switch names, the
meillo@95 1546 .Sw -version
meillo@95 1547 switch was renamed to
meillo@95 1548 .Sw -Version
meillo@95 1549 (with capital `V').
meillo@97 1550 .Ci 32b2354dbaf4bf934936eb5b102a4a3d2fdd209a
meillo@95 1551 Every program has the
meillo@95 1552 .Sw -version
meillo@95 1553 switch but its first three letters collided with the
meillo@95 1554 .Sw -verbose
meillo@95 1555 switch, present in many programs.
meillo@95 1556 The rename solved this problem once for all.
meillo@95 1557 Although this rename breaks a basic interface, having the
meillo@95 1558 .Sw -V
meillo@95 1559 abbreviation to display the version information, isn't all too bad.
meillo@95 1560 .BU
meillo@95 1561 .Sw -[no]preserve
meillo@95 1562 of
meillo@95 1563 .Pn refile
meillo@95 1564 was removed because what use was it anyway?
meillo@98 1565 .QS
meillo@95 1566 Normally when a message is refiled, for each destination
meillo@95 1567 folder it is assigned the number which is one above the current
meillo@95 1568 highest message number in that folder. Use of the
meillo@95 1569 \-preserv [sic!] switch will override this message renaming, and try
meillo@95 1570 to preserve the number of the message. If a conflict for a
meillo@95 1571 particular folder occurs when using the \-preserve switch,
meillo@95 1572 then refile will use the next available message number which
meillo@95 1573 is above the message number you wish to preserve.
meillo@98 1574 .QE
meillo@95 1575 .BU
meillo@95 1576 The removal of the
meillo@95 1577 .Sw -[no]reverse
meillo@95 1578 switches of
meillo@95 1579 .Pn scan
meillo@97 1580 .Ci 8edc5aaf86f9f77124664f6801bc6c6cdf258173
meillo@95 1581 is a bug fix, supported by the comments
meillo@95 1582 ``\-[no]reverse under #ifdef BERK (I really HATE this)''
meillo@95 1583 by Rose and
meillo@95 1584 ``Lists messages in reverse order with the `\-reverse' switch.
meillo@95 1585 This should be considered a bug.'' by Romine in the documentation.
meillo@97 1586 The question remains why neither Rose and Romine had fixed this
meillo@95 1587 bug in the Eighties when they wrote these comments nor has anyone
meillo@95 1588 thereafter.
meillo@93 1589
meillo@93 1590
meillo@93 1591 .ig
meillo@93 1592
meillo@95 1593 forw: [no]dashstuffing(mhl)
meillo@93 1594
meillo@95 1595 mhshow: [no]pause [no]serialonly
meillo@93 1596
meillo@93 1597 mhmail: resent queued
meillo@93 1598 inc: snoop, (pop)
meillo@93 1599
meillo@95 1600 mhl: [no]faceproc folder sleep
meillo@95 1601 [no]dashstuffing(forw) digest list volume number issue number
meillo@93 1602
meillo@95 1603 prompter: [no]doteof
meillo@93 1604
meillo@93 1605 refile: [no]preserve [no]unlink [no]rmmproc
meillo@93 1606
meillo@95 1607 send: [no]forward [no]mime [no]msgid
meillo@93 1608 [no]push split [no]unique (sasl) width snoop [no]dashstuffing
meillo@93 1609 attach attachformat
meillo@93 1610 whatnow: (noedit) attach
meillo@93 1611
meillo@93 1612 slocal: [no]suppressdups
meillo@93 1613
meillo@95 1614 spost: [no]filter [no]backup width [no]push idanno
meillo@93 1615 [no]check(whom) whom(whom)
meillo@93 1616
meillo@93 1617 whom: ???
meillo@93 1618
meillo@95 1619 ..
meillo@93 1620
meillo@93 1621
meillo@93 1622 .ig
meillo@93 1623
meillo@93 1624 .P
meillo@93 1625 In the best case, all switches are unambiguous on the first character,
meillo@93 1626 or on the three-letter prefix for the `no' variants.
meillo@96 1627 Reducing switch prefix collisions, shortens the necessary prefix length
meillo@93 1628 the user must type.
meillo@93 1629 Having less switches helps best.
meillo@93 1630
meillo@93 1631 ..
meillo@58 1632
meillo@95 1633
meillo@102 1634 .\" XXX: whatnow prompt commands
meillo@102 1635
meillo@102 1636
meillo@95 1637
meillo@95 1638
meillo@74 1639 .H1 "Modernizing
meillo@102 1640 .P
meillo@102 1641 The code base of mmh originates from the late Seventies.
meillo@102 1642 Through the Eighties, extensive work had been done on it.
meillo@102 1643 In the Nineties, it had been partly reorganized and extended.
meillo@102 1644 Relicts from each decade have gathered in the code base.
meillo@102 1645 My goal was to modernize the code base.
meillo@102 1646
meillo@102 1647 .P
meillo@102 1648 FIXME functional aspect only here
meillo@102 1649 .P
meillo@102 1650 FIXME ref to `code style' for non-functional aspects.
meillo@58 1651
meillo@58 1652
meillo@100 1653 .H2 "Code Relicts
meillo@0 1654 .P
meillo@102 1655 My position to drop obsolete functionality of mmh to remove old code
meillo@104 1656 is much more revolutional than the nmh community likes to have it.
meillo@104 1657 Working on an experimental version, I was able to quickly drop
meillo@104 1658 functionality I considered ancient.
meillo@104 1659 The need for consensus with peers would have slowed this process down.
meillo@104 1660 Without the need to justify my decisions, I was able to rush forward.
meillo@104 1661 In Dezember 2011, Paul Vixie motivated the nmh developers to just
meillo@104 1662 do the work:
meillo@104 1663 .[
meillo@104 1664 paul vixie edginess nmh-workers
meillo@104 1665 .]
meillo@104 1666 .QS
meillo@104 1667 let's stop walking on egg shells with this code base. there's no need to
meillo@104 1668 discuss whether to keep using vfork, just note in [sic!] passing, [...]
meillo@104 1669 we don't need a separate branch for removing vmh
meillo@104 1670 or ridding ourselves of #ifdef's or removing posix replacement functions
meillo@104 1671 or depending on pure ansi/posix "libc".
meillo@104 1672 .QP
meillo@104 1673 these things should each be a day or two of work and the "main branch"
meillo@104 1674 should just be modern. [...]
meillo@104 1675 let's push forward, aggressively.
meillo@104 1676 .QE
meillo@104 1677 .LP
meillo@104 1678 I did so already in the months before.
meillo@104 1679 I pushed forward.
meillo@104 1680 I simply dropped the cruft.
meillo@104 1681 .P
meillo@104 1682 The decision to drop a feature was based on literature research and
meillo@104 1683 careful thinking, but whether having had contact to this particular
meillo@104 1684 feature within my own computer life served as a rule of thumb.
meillo@104 1685 My reasons are always made clean in the commit message for the
meillo@102 1686 version control system.
meillo@104 1687 Hence, others can comprehend my view and argue for undoing the change
meillo@104 1688 if I have missed an important aspect.
meillo@12 1689
meillo@102 1690
meillo@104 1691 .U3 "Forking
meillo@12 1692 .P
meillo@104 1693 In being a tool chest, MH creates many processes.
meillo@104 1694 In earlier times
meillo@104 1695 .Fu fork()
meillo@104 1696 had been an expensive system call, because the process's image needed
meillo@104 1697 to be duplicated completely at once.
meillo@104 1698 This was especially painfull in the common case when the image gets
meillo@104 1699 replaced by a call to
meillo@104 1700 .Fu exec()
meillo@104 1701 right after having forked the child process.
meillo@104 1702 The
meillo@104 1703 .Fu vfork()
meillo@104 1704 system call was invented to speed up this particular case.
meillo@104 1705 It completely omits the duplication of the image.
meillo@104 1706 On old systems this resulted in significant speed ups.
meillo@104 1707 Therefore MH used
meillo@104 1708 .Fu vfork()
meillo@104 1709 whenever possible.
meillo@12 1710 .P
meillo@104 1711 Modern memory management units support copy-on-write semantics, which make
meillo@104 1712 .Fu fork()
meillo@104 1713 almost as fast as
meillo@104 1714 .Fu vfork() .
meillo@104 1715 The man page of
meillo@104 1716 .Mp vfork (2)
meillo@104 1717 in FreeBSD 8.0 states:
meillo@104 1718 .QS
meillo@104 1719 This system call will be eliminated when proper system sharing mechanisms
meillo@104 1720 are implemented. Users should not depend on the memory sharing semantics
meillo@104 1721 of vfork() as it will, in that case, be made synonymous to fork(2).
meillo@104 1722 .QE
meillo@104 1723 .LP
meillo@104 1724 Vixie supports the removal with the note that ``the last
meillo@104 1725 system on which fork was so slow that an mh user would notice it, was
meillo@104 1726 Eunice. that was 1987''.
meillo@104 1727 .[
meillo@104 1728 nmh-workers vixie edginess
meillo@104 1729 .]
meillo@104 1730 I replaced all calls to
meillo@104 1731 .Fu vfork()
meillo@104 1732 with calls to
meillo@104 1733 .Fu fork() .
meillo@104 1734 .P
meillo@104 1735 Related to the costs of
meillo@104 1736 .Fu fork()
meillo@104 1737 is the probability of its success.
meillo@104 1738 In the Eighties on heavy loaded systems, calls to
meillo@104 1739 .Fu fork()
meillo@104 1740 were prone to failure.
meillo@104 1741 Hence, many of the
meillo@104 1742 .Fu fork()
meillo@104 1743 calls in the code were wrapped into loops to retry the
meillo@104 1744 .Fu fork()
meillo@104 1745 several times, for higher changes to succeed, eventually.
meillo@104 1746 On modern systems, failing calls to
meillo@104 1747 .Fu fork()
meillo@104 1748 are unusual.
meillo@104 1749 Hence, in the rare case when
meillo@104 1750 .Fu fork()
meillo@104 1751 fails, mmh programs simply abort.
meillo@12 1752
meillo@12 1753
meillo@104 1754 .U3 "Obsolete Header Fields
meillo@104 1755 .BU
meillo@84 1756 The
meillo@84 1757 .Hd Encrypted
meillo@104 1758 header field was introduced by RFC\|822,
meillo@104 1759 but already marked legacy in RFC\|2822.
meillo@104 1760 OpenPGP provides the basis for standardized exchange of encrypted
meillo@104 1761 messages [RFC\|4880, RFC\|3156].
meillo@104 1762 The support for
meillo@104 1763 .Hd Encrypted
meillo@104 1764 header fields is removed in mmh.
meillo@104 1765 .BU
meillo@84 1766 Native support for
meillo@84 1767 .Hd Face
meillo@104 1768 header fields has been removed, as well.
meillo@104 1769 This feature is similar to the
meillo@84 1770 .Hd X-Face
meillo@84 1771 header field in its intent,
meillo@21 1772 but takes a different approach to store the image.
meillo@84 1773 Instead of encoding the image data directly into the header field,
meillo@84 1774 the it contains the hostname and UDP port where the image
meillo@21 1775 date could be retrieved.
meillo@104 1776 There is even a third system, invented in 2005.
meillo@104 1777 Although it re-uses the
meillo@104 1778 .Hd Face
meillo@104 1779 header field, it is the successor of
meillo@84 1780 .Hd X-Face
meillo@104 1781 with support for colored PNG images.
meillo@104 1782 None of the Face systems described here is popular today.
meillo@104 1783 Hence, mmh has no direct support for them.
meillo@104 1784 .BU
meillo@104 1785 The
meillo@104 1786 .Hd Content-MD5
meillo@104 1787 header field was introduced by RFC\|1864.
meillo@104 1788 It provides detection of data corruption during the transfer.
meillo@104 1789 But it can not ensure verbatim end-to-end delivery of the contents
meillo@104 1790 [RFC\|1864].
meillo@104 1791 The proper approach to verify content integrity in an
meillo@104 1792 end-to-end relationship is the use of digital cryptography.
meillo@104 1793 .\" XXX (RFCs FIXME).
meillo@104 1794 On the other hand, transfer protocols should detect corruption during
meillo@104 1795 each transmission. The TCP includes a checksum field therefore.
meillo@104 1796 These two approaches in combinations render the
meillo@104 1797 .Hd Content-MD5
meillo@104 1798 header field superfluous.
meillo@104 1799 The nmh-workers mailing list archive contains about 4\|200 messages,
meillo@104 1800 ranging from 1992 until today.
meillo@104 1801 Not a single one had a
meillo@104 1802 .Hd Content-MD5
meillo@104 1803 header field.
meillo@104 1804 Neither did any of the 60\|000 messages in my personal mail storage.
meillo@104 1805 Removing the support for this header field,
meillo@104 1806 removed the last place where MD5 computation was needed.
meillo@104 1807 Hence, the MD5 code could be removed as well.
meillo@104 1808 Over 500 lines of code vanished by this one change.
meillo@104 1809
meillo@104 1810
meillo@104 1811 .U3 "MMDF maildrop support
meillo@21 1812 .P
meillo@104 1813 This type of format is conceptionally similar to the mbox format,
meillo@104 1814 but uses a different message delimiter (`\fL^A^A^A^A\fP' instead of
meillo@104 1815 `\fLFrom\0\fP').
meillo@104 1816 Mbox is the de-facto standard maildrop format on Unix,
meillo@104 1817 whereas the MMDF maildrop format is hardly still known today.
meillo@104 1818 I did drop MMDF maildrop format support.
meillo@104 1819 .P
meillo@104 1820 The simplifications within the code were only moderate.
meillo@104 1821 Switches could be removed from
meillo@104 1822 .L packf
meillo@104 1823 and
meillo@104 1824 .L rcvpack ,
meillo@104 1825 which generate packed mailboxes.
meillo@104 1826 Only one packed mailbox format remained: mbox.
meillo@104 1827 The more important changes affected the equally named mail parsing
meillo@104 1828 routine in
meillo@104 1829 .Fn sbr/m_getfld.c .
meillo@104 1830 The MMDF code had been removed there, but as now only one packed mailbox
meillo@104 1831 format is left, further code structure simplifications may be possible.
meillo@104 1832 I have not worked on them yet because
meillo@104 1833 .Fu m_getfld()
meillo@104 1834 is heavily optimized and thus dangerous to touch.
meillo@104 1835 The risk of damaging the intricate workings of the optimized code is
meillo@104 1836 too high.
meillo@104 1837 .\" XXX: move somewhere else
meillo@104 1838 This problem is know to the developers of nmh, too.
meillo@104 1839 They also avoid touching this minefield if possible.
meillo@104 1840
meillo@12 1841
meillo@101 1842 .U3 "Prompter's Control Keys
meillo@20 1843 .P
meillo@20 1844 The program
meillo@20 1845 .Pn prompter
meillo@104 1846 queries the user to fill in a message form.
meillo@104 1847 When used by
meillo@20 1848 .Pn comp
meillo@104 1849 as
meillo@104 1850 .Cl "comp -editor prompter" ,
meillo@20 1851 the resulting behavior is similar to
meillo@20 1852 .Pn mailx .
meillo@51 1853 Apparently,
meillo@20 1854 .Pn prompter
meillo@104 1855 hadn't been touched lately.
meillo@104 1856 Otherwise it's hardly explainable why it
meillo@20 1857 still offered the switches
meillo@84 1858 .Sw -erase
meillo@84 1859 .Ar chr
meillo@20 1860 and
meillo@84 1861 .Sw -kill
meillo@84 1862 .Ar chr
meillo@20 1863 to name the characters for command line editing.
meillo@21 1864 The times when this had been necessary are long time gone.
meillo@20 1865 Today these things work out-of-the-box, and if not, are configured
meillo@20 1866 with the standard tool
meillo@20 1867 .Pn stty .
meillo@104 1868 The switches are removed now
meillo@104 1869 .Ci 0bd9750710cdbab80cfb4036dd87af20afe1552f .
meillo@20 1870
meillo@104 1871
meillo@104 1872 .U3 "Hardcopy terminal support
meillo@21 1873 .P
meillo@104 1874 More of a funny anecdote is a check for printing to a
meillo@104 1875 hardcopy terminal that remained in the code until Spring 2012,
meillo@104 1876 when I finally removed it
meillo@104 1877 .Ci b7764c4a6b71d37918a97594d866258f154017ca .
meillo@104 1878 I surely would be very happy to see such a terminal in action,
meillo@104 1879 maybe actually being able to work on it, but I fear my chances are null.
meillo@21 1880 .P
meillo@104 1881 The check only prevented a pager to be placed between the outputting
meillo@104 1882 program (\c
meillo@104 1883 .Pn mhl )
meillo@104 1884 and the terminal.
meillo@104 1885 In nmh, this could have been ensured with the
meillo@104 1886 .Sw -nomoreproc
meillo@104 1887 at the command line statically, too.
meillo@104 1888 In mmh, set the profile entry
meillo@104 1889 .Pe Pager
meillo@104 1890 or the environment variable
meillo@104 1891 .Ev PAGER
meillo@104 1892 to
meillo@104 1893 .Pn cat .
meillo@104 1894
meillo@104 1895
meillo@21 1896
meillo@12 1897
meillo@58 1898 .H2 "Attachments
meillo@22 1899 .P
meillo@101 1900 The mind model of email attachments is unrelated to MIME.
meillo@101 1901 Although the MIME RFCs (2045 through 2049) define the technical
meillo@101 1902 requirements for having attachments, they do not mention the the word
meillo@101 1903 ``attachment''.
meillo@101 1904 Instead of attachments, MIME talks about ``multi-part message bodies''
meillo@101 1905 [RFC\|2045], a more general concept.
meillo@101 1906 Multi-part messages are messages
meillo@101 1907 ``in which one or more different
meillo@101 1908 sets of data are combined in a single body''
meillo@101 1909 [RFC\|2046].
meillo@101 1910 MIME keeps its descriptions generic;
meillo@101 1911 it does not imply specific usage models.
meillo@101 1912 In email one usage model became prevalent: attachments.
meillo@101 1913 The idea is having a main text document with files of arbitrary kind
meillo@101 1914 attached to it.
meillo@101 1915 In MIME terms, this is a multi-part message having a text part first
meillo@101 1916 and parts of arbitray type following.
meillo@101 1917 .P
meillo@101 1918 MH's MIME support is a direct implementation of the RFCs.
meillo@101 1919 The perception of the topic described in the RFCs is clearly visible
meillo@101 1920 in MH's implementation.
meillo@101 1921 Thus, MH had all the MIME features but no idea of attachments.
meillo@101 1922 Today, however, users don't need all the MIME features but they want
meillo@101 1923 convenient attachment handling.
meillo@102 1924
meillo@102 1925 .U3 "Composing MIME Messages
meillo@102 1926 .P
meillo@102 1927 In order to improve the situation on the message composing side,
meillo@102 1928 Jon Steinhart had added an attachment system to nmh in 2002.
meillo@101 1929 .Ci 7480dbc14bc90f2d872d434205c0784704213252
meillo@102 1930 In the file
meillo@102 1931 .Fn docs/README-ATTACHMENTS ,
meillo@102 1932 he described his motivation to do so as such:
meillo@101 1933 .QS
meillo@101 1934 Although nmh contains the necessary functionality for MIME message handing,
meillo@101 1935 the interface to this functionality is pretty obtuse.
meillo@101 1936 There's no way that I'm ever going to convince my partner to write
meillo@101 1937 .Pn mhbuild
meillo@101 1938 composition files!
meillo@101 1939 .QE
meillo@102 1940 .LP
meillo@102 1941 With this change, the mind model of attachments entered nmh.
meillo@102 1942 In the same document:
meillo@101 1943 .QS
meillo@101 1944 These changes simplify the task of managing attachments on draft files.
meillo@101 1945 They allow attachments to be added, listed, and deleted.
meillo@101 1946 MIME messages are automatically created when drafts with attachments
meillo@101 1947 are sent.
meillo@101 1948 .QE
meillo@102 1949 .LP
meillo@102 1950 Unfortunately, the attachment system,
meillo@102 1951 like any new facilities in nmh,
meillo@102 1952 was deactive by default.
meillo@101 1953 .P
meillo@101 1954 During my work in Argentina, I tried to improve the attachment system.
meillo@102 1955 But, because of great opposition in the nmh community,
meillo@102 1956 my patch died as a proposal on the mailing list, after long discussions.
meillo@101 1957 .[
meillo@101 1958 nmh-workers attachment proposal
meillo@101 1959 .]
meillo@102 1960 In Januar 2012, I extended the patch and applied it to mmh.
meillo@101 1961 .Ci 8ff284ff9167eff8f5349481529332d59ed913b1
meillo@102 1962 In mmh, the attachment system is active by default.
meillo@102 1963 Instead of command line switches, the
meillo@102 1964 .Pe Attachment-Header
meillo@102 1965 profile entry is used to specify
meillo@102 1966 the name of the attachment header field.
meillo@102 1967 It is pre-defined to
meillo@102 1968 .Hd Attach .
meillo@101 1969 .P
meillo@101 1970 To add an attachment to a draft, simply add an attachment header:
meillo@101 1971 .VS
meillo@101 1972 To: bob
meillo@101 1973 Subject: The file you wanted
meillo@101 1974 Attach: /path/to/the/file-bob-wanted
meillo@101 1975 --------
meillo@101 1976 Here it is.
meillo@101 1977 VE
meillo@101 1978 The header field can be added to the draft manually in the editor,
meillo@102 1979 or by using the `attach' command at the WhatNow prompt, or
meillo@102 1980 non-interactively with
meillo@101 1981 .Pn anno :
meillo@101 1982 .VS
meillo@102 1983 anno -append -nodate -component Attach -text /path/to/attachment
meillo@101 1984 VE
meillo@102 1985 Drafts with attachment headers are converted to MIME automatically by
meillo@102 1986 .Pn send .
meillo@102 1987 The conversion to MIME is invisible to the user.
meillo@102 1988 The draft stored in the draft folder is always in source form, with
meillo@101 1989 attachment headers.
meillo@101 1990 If the MIMEification fails, for instance because the file to attach
meillo@101 1991 is not accessible, the original draft is not changed.
meillo@101 1992 .P
meillo@102 1993 The attachment system handles the forwarding of messages, too.
meillo@101 1994 If the attachment header value starts with a plus character (`+'),
meillo@101 1995 like in
meillo@101 1996 .Cl "Attach: +bob 30 42" ,
meillo@101 1997 The given messages in the specified folder will be attached.
meillo@101 1998 This allowed to simplify
meillo@101 1999 .Pn forw .
meillo@101 2000 .Ci f41f04cf4ceca7355232cf7413e59afafccc9550
meillo@101 2001 .P
meillo@101 2002 Closely related to attachments is non-ASCII text content,
meillo@101 2003 because it requires MIME too.
meillo@102 2004 In nmh, the user needed to call `mime' at the WhatNow prompt
meillo@101 2005 to have the draft converted to MIME.
meillo@102 2006 This was necessary whenever the draft contained non-ASCII characters.
meillo@101 2007 If the user did not call `mime', a broken message would be sent.
meillo@101 2008 Therefore, the
meillo@101 2009 .Pe automimeproc
meillo@101 2010 profile entry could be specified to have the `mime' command invoked
meillo@102 2011 automatically each time.
meillo@101 2012 Unfortunately, this approach conflicted with with attachment system
meillo@101 2013 because the draft would already be in MIME format at the time
meillo@101 2014 when the attachment system wanted to MIMEify it.
meillo@102 2015 To use nmh's attachment system, `mime' must not be called at the
meillo@102 2016 WhatNow prompt and
meillo@101 2017 .Pe automimeproc
meillo@102 2018 must not be set in the profile.
meillo@101 2019 But then the case of non-ASCII text without attachment headers was
meillo@101 2020 not caught.
meillo@102 2021 All in all, the solution was complex and irritating.
meillo@102 2022 My patch from December 2010 would have simplified the situation.
meillo@102 2023 .P
meillo@101 2024 Mmh's current solution is even more elaborate.
meillo@101 2025 Any necessary MIMEification is done automatically.
meillo@101 2026 There is no `mime' command at the WhatNow prompt anymore.
meillo@102 2027 The draft will be converted automatically to MIME when either an
meillo@102 2028 attachment header or non-ASCII text is present.
meillo@101 2029 Further more, the special meaning of the hash character (`#')
meillo@102 2030 at line beginnings in the draft message is removed.
meillo@102 2031 Users need not at all deal with the whole topic.
meillo@101 2032 .P
meillo@102 2033 Although the new approach does not anymore support arbitrary MIME
meillo@102 2034 compositions directly, the full power of
meillo@101 2035 .Pn mhbuild
meillo@101 2036 can still be accessed.
meillo@102 2037 Given no attachment headers are included, the user can create
meillo@101 2038 .Pn mhbuild
meillo@102 2039 composition drafts like in nmh.
meillo@101 2040 Then, at the WhatNow prompt, he needs to invoke
meillo@101 2041 .Cl "edit mhbuild
meillo@101 2042 to convert it to MIME.
meillo@102 2043 Because the resulting draft does neither contain non-aASCII characters
meillo@102 2044 nor has it attachment headers, the attachment system will not touch it.
meillo@101 2045 .P
meillo@101 2046 The approach taken in mmh is taylored towards todays most common case:
meillo@101 2047 a text part with possibly attachments.
meillo@102 2048 This case is simplified a lot for users.
meillo@102 2049
meillo@102 2050 .U3 "MIME Type Guessing
meillo@102 2051 .P
meillo@102 2052 The use of
meillo@101 2053 .Pn mhbuild
meillo@102 2054 composition drafts had one notable advantage over attachment headers
meillo@102 2055 from the programmer's point of view: The user provides the appropriate
meillo@102 2056 MIME types for files to include.
meillo@102 2057 The attachment system needs to find out the correct MIME type itself.
meillo@102 2058 This is a difficult task, yet it spares the user irritating work.
meillo@102 2059 Determining the correct MIME type of content is partly mechanical,
meillo@102 2060 partly intelligent work.
meillo@102 2061 Forcing the user to find out the correct MIME type,
meillo@102 2062 forces him to do partly mechanical work.
meillo@102 2063 Letting the computer do the work, can lead to bad choices for difficult
meillo@102 2064 content.
meillo@102 2065 For mmh, the latter option was chosen.
meillo@102 2066 .P
meillo@102 2067 Determining the MIME type by the suffix of the file name is a dumb
meillo@102 2068 approach, yet it is simple to implement and provides good results
meillo@102 2069 for the common cases.
meillo@102 2070 Mmh implements this approach in the
meillo@102 2071 .Pn print-mimetype
meillo@102 2072 script.
meillo@102 2073 Using it is the default choice.
meillo@102 2074 .P
meillo@102 2075 A far better but less portable approach is the use of
meillo@102 2076 .Pn file .
meillo@102 2077 This standard tool tries to determine the type of files.
meillo@102 2078 Unfortunately, its capabilities and accuracy varies from system to system.
meillo@102 2079 Additionally, its output was only intended for human beings,
meillo@102 2080 but not to be used by programs.
meillo@102 2081 It varies much.
meillo@102 2082 Nevertheless, modern versions of GNU
meillo@102 2083 .Pn file ,
meillo@102 2084 which is prevalent on the popular GNU/Linux systems,
meillo@102 2085 provides MIME type output in machine-readable form.
meillo@102 2086 Although this solution is highly system-dependent,
meillo@102 2087 it solves the difficult problem well.
meillo@102 2088 On systems where GNU
meillo@102 2089 .Pn file ,
meillo@102 2090 version 5.04 or higher, is available it should be used.
meillo@102 2091 One needs to specify the following profile entry to do so:
meillo@102 2092 .VS
meillo@102 2093 Mime-Type-Query: file -b --mime
meillo@102 2094 VE
meillo@102 2095 .LP
meillo@102 2096 Other versions of
meillo@102 2097 .Pn file
meillo@102 2098 might possibly be usable with wrapper scripts to reformat the output.
meillo@102 2099 The diversity among
meillo@102 2100 .Pn file
meillo@102 2101 implementations is great; one needs to check the local variant.
meillo@102 2102 .P
meillo@102 2103 If no MIME type can be determined, text content gets sent as
meillo@102 2104 `text/plain' and anything else under the generic fall-back type
meillo@102 2105 `application/octet-stream'.
meillo@102 2106 It is not possible in mmh to override the automatic MIME type guessing
meillo@102 2107 for a specific file.
meillo@102 2108 To do so, the user would need to know in advance for which file
meillo@102 2109 the automatic guessing does fail, or the system would require interaction.
meillo@102 2110 I consider both cases impractical.
meillo@102 2111 The existing solution should be sufficient.
meillo@102 2112 If not, the user may always fall back to
meillo@102 2113 .Pn mhbuild
meillo@102 2114 composition drafts and ignore the attachment system.
meillo@101 2115
meillo@102 2116
meillo@102 2117 .U3 "Storing Attachments
meillo@102 2118 .P
meillo@102 2119 FIXME
meillo@102 2120
meillo@102 2121
meillo@102 2122 .U3 "Showing MIME Messages
meillo@102 2123 .P
meillo@102 2124 FIXME
meillo@102 2125
meillo@58 2126
meillo@58 2127
meillo@58 2128 .H2 "Digital Cryptography
meillo@22 2129 .P
meillo@58 2130 Signing and encryption.
meillo@58 2131
meillo@58 2132
meillo@102 2133
meillo@102 2134 .H2 "Modern Defaults
meillo@22 2135 .P
meillo@102 2136 Just to give one example, for me it took one year of using nmh
meillo@102 2137 before I became aware of the existence of the attachment system.
meillo@102 2138 One could argue that this fact disqualifies my reading of the
meillo@102 2139 documentation.
meillo@102 2140 If I would have installed nmh from source back then, I could agree.
meillo@102 2141 Yet I had used a prepackaged version and had expected that it would
meillo@102 2142 just work.
meillo@58 2143
meillo@58 2144
meillo@58 2145
meillo@100 2146 .H1 "Code Style
meillo@22 2147 .P
meillo@58 2148 foo
meillo@58 2149
meillo@58 2150
meillo@58 2151 .H2 "Standard Code
meillo@22 2152 .P
meillo@58 2153 POSIX
meillo@22 2154
meillo@102 2155 .U3 "Converting to Standard Code
meillo@102 2156 .P
meillo@102 2157 One part of this task was converting obsolete code constructs
meillo@102 2158 to standard constructs.
meillo@102 2159 As I'm not even thirty years old and have no more than seven years of
meillo@102 2160 Unix experience, I needed to learn about the history in retrospective.
meillo@102 2161 Older people likely have used those ancient constructs themselves
meillo@102 2162 and have suffered from their incompatibilities and have longed for
meillo@102 2163 standardization.
meillo@102 2164 Unfortunately, I have only read that others had done so.
meillo@102 2165 This put me in a much more difficult positions when working on the old
meillo@102 2166 code.
meillo@102 2167 I needed to recherche what other would have known by heart from
meillo@102 2168 experience.
meillo@102 2169 All my programming experience comes from a time past ANSI C
meillo@102 2170 and past POSIX.
meillo@102 2171 Although I knew about the times before, I took the
meillo@102 2172 current state implicitly for granted most of the time.
meillo@102 2173 .P
meillo@102 2174 Being aware of
meillo@102 2175 these facts, I rather let people with more historic experience solve the
meillo@102 2176 task of converting the ancient code constructs to standardized ones.
meillo@102 2177 Luckily, Lyndon Nerenberg focused on this task at the nmh project.
meillo@102 2178 He converted large parts of the code to POSIX constructs, removing
meillo@102 2179 the conditionals compilation for now standardized features.
meillo@104 2180 I'm thankful for this task being solved.
meillo@104 2181 I only pulled the changes into
meillo@102 2182 mmh.
meillo@102 2183
meillo@102 2184
meillo@102 2185
meillo@22 2186
meillo@58 2187 .H2 "Separation
meillo@14 2188
meillo@58 2189 .U2 "MH Directory Split
meillo@0 2190 .P
meillo@19 2191 In MH and nmh, a personal setup had consisted of two parts:
meillo@19 2192 The MH profile, named
meillo@19 2193 .Fn \&.mh_profile
meillo@19 2194 and being located directly in the user's home directory.
meillo@19 2195 And the MH directory, where all his mail messages and also his personal
meillo@104 2196 forms, scan formats, other configuration files are stored.
meillo@104 2197 The location
meillo@104 2198 of this directory could be user-chosen.
meillo@104 2199 The default was to name it
meillo@19 2200 .Fn Mail
meillo@19 2201 and have it directly in the home directory.
meillo@19 2202 .P
meillo@19 2203 I've never liked the data storage and the configuration to be intermixed.
meillo@104 2204 They are different kinds of data.
meillo@104 2205 One part, are the messages,
meillo@104 2206 which are the data to operate on.
meillo@104 2207 The other part, are the personal
meillo@19 2208 configuration files, which are able to change the behavior of the operations.
meillo@19 2209 The actual operations are defined in the profile, however.
meillo@19 2210 .P
meillo@19 2211 When storing data, one should try to group data by its type.
meillo@19 2212 There's sense in the Unix file system hierarchy, where configuration
meillo@19 2213 file are stored separate (\c
meillo@19 2214 .Fn /etc )
meillo@19 2215 to the programs (\c
meillo@19 2216 .Fn /bin
meillo@19 2217 and
meillo@19 2218 .Fn /usr/bin )
meillo@19 2219 to their sources (\c
meillo@19 2220 .Fn /usr/src ).
meillo@19 2221 Such separation eases the backup management, for instance.
meillo@19 2222 .P
meillo@19 2223 In mmh, I've reorganized the file locations.
meillo@19 2224 Still there are two places:
meillo@19 2225 There's the mail storage directory, which, like in MH, contains all the
meillo@19 2226 messages, but, unlike in MH, nothing else.
meillo@19 2227 Its location still is user-chosen, with the default name
meillo@19 2228 .Fn Mail ,
meillo@104 2229 in the user's home directory.
meillo@104 2230 This is much similar to the case in nmh.
meillo@19 2231 The configuration files, however, are grouped together in the new directory
meillo@19 2232 .Fn \&.mmh
meillo@19 2233 in the user's home directory.
meillo@19 2234 The user's profile now is a file, named
meillo@19 2235 .Fn profile ,
meillo@19 2236 in this mmh directory.
meillo@19 2237 Consistently, the context file and all the personal forms, scan formats,
meillo@19 2238 and the like, are also there.
meillo@19 2239 .P
meillo@19 2240 The naming changed with the relocation.
meillo@19 2241 The directory where everything, except the profile, had been stored (\c
meillo@19 2242 .Fn $HOME/Mail ),
meillo@104 2243 used to be called \fIMH directory\fP.
meillo@104 2244 Now, this directory is called the
meillo@104 2245 user's \fImail storage\fP.
meillo@104 2246 The name \fImmh directory\fP is now given to
meillo@19 2247 the new directory
meillo@19 2248 (\c
meillo@19 2249 .Fn $HOME/.mmh ),
meillo@19 2250 containing all the personal configuration files.
meillo@19 2251 .P
meillo@19 2252 The separation of the files by type of content is logical and convenient.
meillo@19 2253 There are no functional differences as any possible setup known to me
meillo@19 2254 can be implemented with both approaches, although likely a bit easier
meillo@104 2255 with the new approach.
meillo@104 2256 The main goal of the change had been to provide
meillo@19 2257 sensible storage locations for any type of personal mmh file.
meillo@19 2258 .P
meillo@19 2259 In order for one user to have multiple MH setups, he can use the
meillo@19 2260 environment variable
meillo@19 2261 .Ev MH
meillo@19 2262 the point to a different profile file.
meillo@19 2263 The MH directory (mail storage plus personal configuration files) is
meillo@19 2264 defined by the
meillo@19 2265 .Pe Path
meillo@19 2266 profile entry.
meillo@19 2267 The context file could be defined by the
meillo@19 2268 .Pe context
meillo@19 2269 profile entry or by the
meillo@19 2270 .Ev MHCONTEXT
meillo@19 2271 environment variable.
meillo@19 2272 The latter is useful to have a distinct context (e.g. current folders)
meillo@19 2273 in each terminal window, for instance.
meillo@19 2274 In mmh, there are three environment variables now.
meillo@19 2275 .Ev MMH
meillo@19 2276 may be used to change the location of the mmh directory.
meillo@19 2277 .Ev MMHP
meillo@19 2278 and
meillo@19 2279 .Ev MMHC
meillo@19 2280 change the profile and context files, respectively.
meillo@19 2281 Besides providing a more consistent feel (which simply is the result
meillo@19 2282 of being designed anew), the set of personal configuration files can
meillo@19 2283 be chosen independently from the profile (including mail storage location)
meillo@104 2284 and context, now.
meillo@104 2285 Being it relevant for practical use or not, it
meillo@104 2286 de-facto is an improvement.
meillo@104 2287 However, the main achievement is the
meillo@19 2288 split between mail storage and personal configuration files.
meillo@17 2289
meillo@0 2290
meillo@58 2291 .H2 "Modularization
meillo@0 2292 .P
meillo@58 2293 whatnowproc
meillo@0 2294 .P
meillo@49 2295 The \fIMH library\fP
meillo@49 2296 .Fn libmh.a
meillo@49 2297 collects a bunch of standard functions that many of the MH tools need,
meillo@49 2298 like reading the profile or context files.
meillo@49 2299 This doesn't hurt the separation.
meillo@49 2300
meillo@58 2301
meillo@58 2302 .H2 "Style
meillo@58 2303 .P
meillo@58 2304 Code layout, goto, ...
meillo@58 2305
meillo@102 2306 .P
meillo@102 2307 anno rework
meillo@102 2308
meillo@58 2309
meillo@58 2310
meillo@58 2311
meillo@89 2312 .H1 "Concept Exploitation/Homogeneity
meillo@58 2313
meillo@58 2314
meillo@58 2315 .H2 "Draft Folder
meillo@58 2316 .P
meillo@58 2317 Historically, MH provided exactly one draft message, named
meillo@58 2318 .Fn draft
meillo@58 2319 and
meillo@104 2320 being located in the MH directory.
meillo@104 2321 When starting to compose another message
meillo@58 2322 before the former one was sent, the user had been questioned whether to use,
meillo@104 2323 refile or replace the old draft.
meillo@104 2324 Working on multiple drafts at the same time
meillo@104 2325 was impossible.
meillo@104 2326 One could only work on them in alteration by refiling the
meillo@104 2327 previous one to some directory and fetching some other one for reediting.
meillo@58 2328 This manual draft management needed to be done each time the user wanted
meillo@58 2329 to switch between editing one draft to editing another.
meillo@58 2330 .P
meillo@58 2331 To allow true parallel editing of drafts, in a straight forward way, the
meillo@104 2332 draft folder facility exists.
meillo@104 2333 It had been introduced already in July 1984
meillo@104 2334 by Marshall T. Rose.
meillo@104 2335 The facility was deactivated by default.
meillo@58 2336 Even in nmh, the draft folder facility remained deactivated by default.
meillo@58 2337 At least, Richard Coleman added the man page
meillo@58 2338 .Mp mh-draft(5)
meillo@58 2339 to document
meillo@58 2340 the feature well.
meillo@58 2341 .P
meillo@58 2342 The only advantage of not using the draft folder facility is the static
meillo@104 2343 name of the draft file.
meillo@104 2344 This could be an issue for MH front-ends like mh-e.
meillo@58 2345 But as they likely want to provide working on multiple drafts in parallel,
meillo@104 2346 the issue is only concerning compatibility.
meillo@104 2347 The aim of nmh to stay compatible
meillo@58 2348 prevented the default activation of the draft folder facility.
meillo@58 2349 .P
meillo@58 2350 On the other hand, a draft folder is the much more natural concept than
meillo@104 2351 a draft message.
meillo@104 2352 MH's mail storage consists of folders and messages,
meillo@104 2353 the messages named with ascending numbers.
meillo@104 2354 A draft message breaks with this
meillo@58 2355 concept by introducing a message in a file named
meillo@58 2356 .Fn draft .
meillo@58 2357 This draft
meillo@104 2358 message is special.
meillo@104 2359 It can not be simply listed with the available tools,
meillo@104 2360 but instead requires special switches.
meillo@104 2361 I.e. corner-cases were
meillo@104 2362 introduced.
meillo@104 2363 A draft folder, in contrast, does not introduce such
meillo@104 2364 corner-cases.
meillo@104 2365 The available tools can operate on the messages within that
meillo@104 2366 folder like on any messages within any mail folders.
meillo@104 2367 The only difference
meillo@58 2368 is the fact that the default folder for
meillo@58 2369 .Pn send
meillo@58 2370 is the draft folder,
meillo@58 2371 instead of the current folder, like for all other tools.
meillo@58 2372 .P
meillo@58 2373 The trivial part of the change was activating the draft folder facility
meillo@104 2374 by default and setting a default name for this folder.
meillo@104 2375 Obviously, I chose
meillo@58 2376 the name
meillo@58 2377 .Fn +drafts .
meillo@58 2378 This made the
meillo@82 2379 .Sw -draftfolder
meillo@58 2380 and
meillo@82 2381 .Sw -draftmessage
meillo@58 2382 switches useless, and I could remove them.
meillo@58 2383 The more difficult but also the part that showed the real improvement,
meillo@58 2384 was updating the tools to the new concept.
meillo@82 2385 .Sw -draft
meillo@58 2386 switches could
meillo@58 2387 be dropped, as operating on a draft message became indistinguishable to
meillo@58 2388 operating on any other message for the tools.
meillo@58 2389 .Pn comp
meillo@58 2390 still has its
meillo@82 2391 .Sw -use
meillo@58 2392 switch for switching between its two modes: (1) Compose a new
meillo@104 2393 draft, possibly by taking some existing message as a form.
meillo@104 2394 (2) Modify
meillo@104 2395 an existing draft.
meillo@104 2396 In either case, the behavior of
meillo@58 2397 .Pn comp is
meillo@104 2398 deterministic.
meillo@104 2399 There is no more need to query the user.
meillo@104 2400 I consider this
meillo@104 2401 a major improvement.
meillo@104 2402 By making
meillo@58 2403 .Pn send
meillo@58 2404 simply operate on the current
meillo@58 2405 message in the draft folder by default, with message and folder both
meillo@58 2406 overridable by specifying them on the command line, it is now possible
meillo@58 2407 to send a draft anywhere within the storage by simply specifying its folder
meillo@58 2408 and name.
meillo@58 2409 .P
meillo@58 2410 All theses changes converted special cases to regular cases, thus
meillo@58 2411 simplifying the tools and increasing the flexibility.
meillo@58 2412
meillo@58 2413
meillo@58 2414 .H2 "Trash Folder
meillo@58 2415 .P
meillo@58 2416 Similar to the situation for drafts is the situation for removed messages.
meillo@104 2417 Historically, a message was deleted by renaming.
meillo@104 2418 A specific
meillo@58 2419 \fIbackup prefix\fP, often comma (\c
meillo@58 2420 .Fn , )
meillo@58 2421 or hash (\c
meillo@58 2422 .Fn # ),
meillo@104 2423 being prepended to the file name.
meillo@104 2424 Thus, MH wouldn't recognize the file
meillo@58 2425 as a message anymore, as only files whose name consists of digits only
meillo@104 2426 are treated as messages.
meillo@104 2427 The removed messages remained as files in the
meillo@58 2428 same directory and needed some maintenance job to truly delete them after
meillo@104 2429 some grace time.
meillo@104 2430 Usually, by running a command similar to
meillo@82 2431 .VS
meillo@82 2432 find /home/user/Mail -ctime +7 -name ',*' | xargs rm
meillo@82 2433 VE
meillo@104 2434 in a cron job.
meillo@104 2435 Within the grace time interval
meillo@58 2436 the original message could be restored by stripping the
meillo@104 2437 the backup prefix from the file name.
meillo@104 2438 If however, the last message of
meillo@58 2439 a folder is been removed \(en say message
meillo@58 2440 .Fn 6
meillo@58 2441 becomes file
meillo@58 2442 .Fn ,6
meillo@58 2443 \(en and a new message enters the same folder, thus the same
meillo@58 2444 numbered being given again \(en in our case
meillo@58 2445 .Fn 6
meillo@58 2446 \(en, if that one
meillo@58 2447 is removed too, then the backup of the former message gets overwritten.
meillo@58 2448 Thus, the ability to restore removed messages does not only depend on
meillo@58 2449 the ``sweeping cron job'' but also on the removing of further messages.
meillo@58 2450 This is undesirable, because the real mechanism is hidden from the user
meillo@58 2451 and the consequences of further removals are not always obvious.
meillo@58 2452 Further more, the backup files are scattered within the whole mail
meillo@58 2453 storage, instead of being collected at one place.
meillo@58 2454 .P
meillo@58 2455 To improve the situation, the profile entry
meillo@58 2456 .Pe rmmproc
meillo@58 2457 (previously named
meillo@58 2458 .Pe Delete-Prog )
meillo@58 2459 was introduced, very early.
meillo@58 2460 It could be set to any command, which would care for the mail removal
meillo@58 2461 instead of taking the default action, described above.
meillo@58 2462 Refiling the to-be-removed files to some garbage folder was a common
meillo@104 2463 example.
meillo@104 2464 Nmh's man page
meillo@58 2465 .Mp rmm(1)
meillo@58 2466 proposes
meillo@58 2467 .Cl "refile +d
meillo@58 2468 to move messages to the garbage folder and
meillo@58 2469 .Cl "rm `mhpath +d all`
meillo@58 2470 the empty the garbage folder.
meillo@104 2471 Managing the message removal this way is a sane approach.
meillo@104 2472 It keeps
meillo@58 2473 the removed messages in one place, makes it easy to remove the backup
meillo@58 2474 files, and, most important, enables the user to use the tools of MH
meillo@104 2475 itself to operate on the removed messages.
meillo@104 2476 One can
meillo@58 2477 .Pn scan
meillo@58 2478 them,
meillo@58 2479 .Pn show
meillo@58 2480 them, and restore them with
meillo@58 2481 .Pn refile .
meillo@58 2482 There's no more
meillo@58 2483 need to use
meillo@58 2484 .Pn mhpath
meillo@58 2485 to switch over from MH tools to Unix tools \(en MH can do it all itself.
meillo@58 2486 .P
meillo@58 2487 This approach matches perfect with the concepts of MH, thus making
meillo@104 2488 it powerful.
meillo@104 2489 Hence, I made it the default.
meillo@104 2490 And even more, I also
meillo@58 2491 removed the old backup prefix approach, as it is clearly less powerful.
meillo@58 2492 Keeping unused alternative in the code is a bad choice as they likely
meillo@104 2493 gather bugs, by not being constantly tested.
meillo@104 2494 Also, the increased code
meillo@104 2495 size and more conditions crease the maintenance costs.
meillo@104 2496 By strictly
meillo@58 2497 converting to the trash folder approach, I simplified the code base.
meillo@58 2498 .Pn rmm
meillo@58 2499 calls
meillo@58 2500 .Pn refile
meillo@58 2501 internally to move the to-be-removed
meillo@58 2502 message to the trash folder (\c
meillo@58 2503 .Fn +trash
meillo@104 2504 by default).
meillo@104 2505 Messages
meillo@58 2506 there can be operated on like on any other message in the storage.
meillo@58 2507 The sweep clean, one can use
meillo@82 2508 .Cl "rmm -unlink +trash a" ,
meillo@58 2509 where the
meillo@82 2510 .Sw -unlink
meillo@58 2511 switch causes the files to be truly unliked instead
meillo@58 2512 of moved to the trash folder.
meillo@58 2513
meillo@58 2514
meillo@58 2515 .H2 "Path Notations
meillo@58 2516 .P
meillo@58 2517 foo
meillo@58 2518
meillo@58 2519
meillo@58 2520 .H2 "MIME Integration
meillo@58 2521 .P
meillo@58 2522 user-visible access to whole messages and MIME parts are inherently
meillo@58 2523 different
meillo@58 2524
meillo@58 2525
meillo@58 2526 .H2 "Of One Cast
meillo@58 2527 .P