docs/master

annotate ch03.roff @ 102:a782488c85f5

More text about attachments mainly, plus some rearrangements.
author markus schnalke <meillo@marmaro.de>
date Wed, 20 Jun 2012 17:57:37 +0200
parents e8e6adb14beb
children 2818ca27d24c
rev   line source
meillo@58 1 .H0 "Discussion
meillo@0 2 .P
meillo@58 3 This main chapter discusses the practical work done in the mmh project.
meillo@58 4 It is structured along the goals to achieve. The concrete work done
meillo@58 5 is described in the examples of how the general goals were achieved.
meillo@87 6 The discussion compares the current version of mmh with the state of
meillo@87 7 nmh just before the mmh project started, i.e. Fall 2011.
meillo@87 8 Current changes of nmh will be mentioned only as side notes.
meillo@87 9 .\" XXX where do I discuss the parallel development of nmh?
meillo@58 10
meillo@58 11
meillo@58 12
meillo@100 13 .H1 "Stream-Lining
meillo@58 14
meillo@0 15 .P
meillo@58 16 MH had been considered an all-in-one system for mail handling.
meillo@58 17 The community around nmh has a similar understanding.
meillo@87 18 In fundamental difference, mmh shall be a MUA only.
meillo@87 19 I believe that the development of all-in-one mail systems is obsolete.
meillo@87 20 Today, email is too complex to be fully covered by single projects.
meillo@87 21 Such a project won't be able to excel in all aspects.
meillo@87 22 Instead, the aspects of email should be covered my multiple projects,
meillo@87 23 which then can be combined to form a complete system.
meillo@87 24 Excellent implementations for the various aspects of email exist already.
meillo@87 25 Just to name three examples: Postfix is a specialized MTA,
meillo@87 26 Procmail is a specialized MDA, and Fetchmail is a specialized MRA.
meillo@89 27 I believe that it is best to use such specialized tools instead of
meillo@87 28 providing the same function again as a side-component in the project.
meillo@58 29 .P
meillo@87 30 Doing something well, requires to focus on a small set of specific aspects.
meillo@87 31 Under the assumption that focused development produces better results
meillo@100 32 in the particular area, specialized projects will be superior
meillo@87 33 in their field of focus.
meillo@87 34 Hence, all-in-one mail system projects \(en no matter if monolithic
meillo@87 35 or modular \(en will never be the best choice in any of the fields.
meillo@87 36 Even in providing the best consistent all-in-one system they are likely
meillo@87 37 to be beaten by projects that focus only on integrating existing mail
meillo@89 38 components to a homogeneous system.
meillo@87 39 .P
meillo@87 40 The limiting resource in Free Software community development
meillo@87 41 is usually man power.
meillo@87 42 If the development power is spread over a large development area,
meillo@87 43 it becomes even more difficult to compete with the specialists in the
meillo@87 44 various fields.
meillo@87 45 The concrete situation for MH-based mail systems is even tougher,
meillo@87 46 given the small and aged community, including both developers and users,
meillo@87 47 it has.
meillo@87 48 .P
meillo@87 49 In consequence, I believe that the available development resources
meillo@100 50 should focus on the point where MH is most unique.
meillo@87 51 This is clearly the user interface \(en the MUA.
meillo@87 52 Peripheral parts should be removed to stream-line mmh for the MUA task.
meillo@60 53
meillo@60 54
meillo@100 55 .H2 "Mail Transfer Facilities
meillo@60 56 .P
meillo@60 57 In contrast to nmh, which also provides mail submission and mail retrieval
meillo@87 58 agents, mmh is a MUA only.
meillo@100 59 This general difference initiated the development of mmh.
meillo@66 60 Removing the mail transfer facilities had been the first work task
meillo@76 61 in the mmh project.
meillo@60 62 .P
meillo@100 63 The Mail Submission Agent (MSA) is called
meillo@100 64 \fIMessage Transfer Service\fP (MTS) in nmh.
meillo@76 65 The facility established network connections and spoke SMTP to submit
meillo@60 66 messages for relay to the outside world.
meillo@76 67 This part was implemented by the
meillo@60 68 .Pn post
meillo@60 69 command.
meillo@96 70 The changes in email in the last years
meillo@87 71 demanded changes in this part of nmh too.
meillo@89 72 Encryption and authentication for network connections
meillo@87 73 needed to be supported, hence TLS and SASL were introduced into nmh.
meillo@87 74 This added complexity to nmh without improving it in its core functions.
meillo@87 75 Also, keeping up with recent developments in the field of
meillo@87 76 mail transfer requires development power and specialists.
meillo@87 77 In mmh this whole facility was simply cut off.
meillo@76 78 .Ci f6aa95b724fd8c791164abe7ee5468bf5c34f226
meillo@76 79 .Ci fecd5d34f65597a4dfa16aeabea7d74b191532c3
meillo@76 80 .Ci 156d35f6425bea4c1ed3c4c79783dc613379c65b
meillo@87 81 Instead, mmh depends on an external MSA.
meillo@60 82 The only outgoing interface available to mmh is the
meillo@60 83 .Pn sendmail
meillo@87 84 command, which almost any MSA provides.
meillo@87 85 If not, a wrapper program can be written.
meillo@87 86 It must read the message from the standard input, extract the
meillo@87 87 recipient addresses from the message header, and hand the message
meillo@87 88 over to the MSA.
meillo@87 89 For example, a wrapper script for qmail would be:
meillo@87 90 .VS
meillo@87 91 #!/bin/sh
meillo@87 92 # ignore command line arguments
meillo@87 93 exec qmail-inject
meillo@87 94 VE
meillo@87 95 The requirement to parse the recipient addresses out of the message header
meillo@87 96 is likely to be removed in the future.
meillo@87 97 Then mmh would give the recipient addresses as command line arguments.
meillo@100 98 This appears to be the better interface.
meillo@87 99 .\" XXX implement it
meillo@60 100 .P
meillo@60 101 To retrieve mail, the
meillo@60 102 .Pn inc
meillo@100 103 command acted as Mail Retrieval Agent (MRA).
meillo@100 104 It established network connections
meillo@76 105 and spoke POP3 to retrieve mail from remote servers.
meillo@76 106 As with mail submission, the network connections required encryption and
meillo@87 107 authentication, thus TLS and SASL were added.
meillo@87 108 Support for message retrieval through IMAP will become necessary
meillo@100 109 to be added soon, too, and likewise for any other changes in mail transfer.
meillo@100 110 Not so for mmh because it has dropped the support for retrieving mail
meillo@100 111 from remote locations.
meillo@76 112 .Ci ab7b48411962d26439f92f35ed084d3d6275459c
meillo@76 113 Instead, it depends on an external tool to cover this task.
meillo@100 114 In mmh exist two paths for messages to enter mmh's mail storage:
meillo@100 115 (1) Mail can be incorporated with
meillo@60 116 .Pn inc
meillo@87 117 from the system maildrop, or (2) with
meillo@60 118 .Pn rcvstore
meillo@87 119 by reading them, one at a time, from the standard input.
meillo@60 120 .P
meillo@60 121 With the removal of the MSA and MRA, mmh converted from an all-in-one
meillo@87 122 mail system to being a MUA only.
meillo@60 123 Now, of course, mmh depends on third-party software.
meillo@87 124 An external MSA is required to transfer mail to the outside world;
meillo@60 125 an external MRA is required to retrieve mail from remote machines.
meillo@60 126 There exist excellent implementations of such software,
meillo@76 127 which do this specific task likely better than the internal
meillo@87 128 versions had done it.
meillo@87 129 Also, the best suiting programs can be freely chosen.
meillo@60 130 .P
meillo@60 131 As it had already been possible to use an external MSA or MRA,
meillo@60 132 why not keep the internal version for convenience?
meillo@76 133 The question whether there is sense in having a fall-back pager in all
meillo@76 134 the command line tools, for the cases when
meillo@60 135 .Pn more
meillo@60 136 or
meillo@60 137 .Pn less
meillo@76 138 aren't available, appears to be ridiculous.
meillo@100 139 Of course, MSAs and MRAs are more complex than text pagers
meillo@87 140 and not necessarily available but still the concept of orthogonal
meillo@87 141 design holds: ``Write programs that do one thing and do it well.''
meillo@87 142 .[
meillo@87 143 mcilroy unix phil
meillo@87 144 p. 53
meillo@87 145 .]
meillo@87 146 .[
meillo@87 147 mcilroy bstj foreword
meillo@87 148 .]
meillo@87 149 Here, this part of the Unix philosophy was applied not only
meillo@87 150 to the programs but to the project itself.
meillo@87 151 In other words:
meillo@87 152 ``Develop projects that focus on one thing and do it well.''
meillo@87 153 Projects grown complex should be split for the same reasons programs grown
meillo@87 154 complex should be split.
meillo@100 155 If it is conceptionally more elegant to have the MSA and MRA as
meillo@87 156 separate projects then they should be separated.
meillo@87 157 This is the case here, in my opinion.
meillo@87 158 The RFCs propose this separation by clearly distinguishing the different
meillo@87 159 mail handling tasks.
meillo@87 160 .[
meillo@87 161 rfc 821
meillo@87 162 .]
meillo@87 163 The small interfaces between the mail agents support the separation.
meillo@76 164 .P
meillo@87 165 In the beginning, email had been small and simple.
meillo@100 166 At that time,
meillo@60 167 .Pn /bin/mail
meillo@100 168 had covered anything there was to email and still had been small
meillo@100 169 and simple.
meillo@100 170 Later, the essential complexity of email increased.
meillo@87 171 (Essential complexity is the complexity defined by the problem itself.\0
meillo@87 172 .[[
meillo@87 173 brooks no silver bullet
meillo@87 174 .]])
meillo@87 175 Email systems reacted to this change: They grew.
meillo@100 176 RFCs started to introduce the concept of mail agents to separate the
meillo@100 177 various tasks because they became more extensive and new tasks appeared.
meillo@100 178 As the mail systems grew even more, parts were split off.
meillo@100 179 In nmh, for instance, the POP server, which was included in the original
meillo@100 180 MH, was removed.
meillo@100 181 Now is the time to go one step further and split the MSA and MRA off, too.
meillo@87 182 Not only does this decrease the code size of the project,
meillo@87 183 but, more important, it unburdens mmh of the whole field of
meillo@87 184 message transfer with all its implications for the project.
meillo@100 185 There is no more need to concern with changes in network transfer.
meillo@76 186 This independence is received by depending on an external program
meillo@76 187 that covers the field.
meillo@76 188 Today, this is a reasonable exchange.
meillo@60 189 .P
meillo@100 190 Functionality can be added in three different ways:
meillo@87 191 .BU
meillo@87 192 Implementing the function originally in the project.
meillo@87 193 .BU
meillo@87 194 Depending on a library that provides the function.
meillo@87 195 .BU
meillo@87 196 Depending on a program that provides the function.
meillo@87 197 .P
meillo@87 198 Whereas adding the function originally to the project increases the
meillo@76 199 code size most and requires most maintenance and development work,
meillo@87 200 it makes the project most independent of other software.
meillo@87 201 Using libraries or external programs require less maintenance work
meillo@87 202 but introduces dependencies on external software.
meillo@87 203 Programs have the smallest interfaces and provide the best separation
meillo@87 204 but possibly limit the information exchange.
meillo@87 205 External libraries are stronger connected than external programs,
meillo@87 206 thus information can be exchanged more flexible.
meillo@87 207 Adding code to a project increases maintenance work.
meillo@87 208 .\" XXX ref
meillo@100 209 Implementing complex functions originally in the project adds
meillo@87 210 a lot of code.
meillo@87 211 This should be avoided if possible.
meillo@66 212 Hence, the dependencies only change in kind, not in their existence.
meillo@66 213 In mmh, library dependencies on
meillo@66 214 .Pn libsasl2
meillo@66 215 and
meillo@66 216 .Pn libcrypto /\c
meillo@66 217 .Pn libssl
meillo@66 218 were treated against program dependencies on an MSA and an MRA.
meillo@87 219 This also meant treating build-time dependencies against run-time
meillo@87 220 dependencies.
meillo@66 221 Besides program dependencies providing the stronger separation
meillo@66 222 and being more flexible, they also allowed
meillo@66 223 over 6\|000 lines of code to be removed from mmh.
meillo@66 224 This made mmh's code base about 12\|% smaller.
meillo@87 225 Reducing the project's code size by such an amount without actually
meillo@87 226 losing functionality is a convincing argument.
meillo@87 227 Actually, as external MSAs and MRAs are likely superior to the
meillo@87 228 project's internal versions, the common user even gains functionality.
meillo@66 229 .P
meillo@76 230 Users of MH should not have problems to set up an external MSA and MRA.
meillo@60 231 Also, the popular MSAs and MRAs have large communities and a lot
meillo@60 232 of documentation available.
meillo@87 233 Choices for MSAs range from full-featured MTAs like
meillo@60 234 .I Postfix
meillo@87 235 over mid-size MTAs like
meillo@60 236 .I masqmail
meillo@60 237 and
meillo@60 238 .I dma
meillo@60 239 to small forwarders like
meillo@60 240 .I ssmtp
meillo@60 241 and
meillo@60 242 .I nullmailer .
meillo@60 243 Choices for MRAs include
meillo@60 244 .I fetchmail ,
meillo@60 245 .I getmail ,
meillo@60 246 .I mpop
meillo@60 247 and
meillo@60 248 .I fdm .
meillo@60 249
meillo@60 250
meillo@100 251 .H2 "Non-MUA Tools
meillo@60 252 .P
meillo@87 253 One goal of mmh is to remove the tools that are not part of the MUA's task.
meillo@89 254 Further more, any tools that don't improve the MUA's job significantly
meillo@87 255 should be removed.
meillo@87 256 Loosely related and rarely used tools distract from the lean appearance.
meillo@87 257 They require maintenance work without adding much to the core task.
meillo@100 258 By removing these tools, the project shall become more stream-lined
meillo@87 259 and focused.
meillo@76 260 In mmh the following tools are not available anymore:
meillo@62 261 .BU
meillo@58 262 .Pn conflict
meillo@87 263 was removed
meillo@76 264 .Ci 8b235097cbd11d728c07b966cf131aa7133ce5a9
meillo@87 265 because it is a mail system maintenance tool that is not MUA-related.
meillo@87 266 It even checked
meillo@58 267 .Fn /etc/passwd
meillo@58 268 and
meillo@58 269 .Fn /etc/group
meillo@87 270 for consistency, which is completely unrelated to email.
meillo@87 271 A tool like
meillo@87 272 .Pn conflict
meillo@87 273 is surely useful, but it should not be shipped with mmh.
meillo@76 274 .\" XXX historic reasons?
meillo@62 275 .BU
meillo@58 276 .Pn rcvtty
meillo@87 277 was removed
meillo@87 278 .Ci 14767c94b3827be7c867196467ed7aea5f6f49b0
meillo@89 279 because its use case of writing to the user's terminal
meillo@76 280 on receiving of mail is obsolete.
meillo@87 281 If users like to be informed of new mail, the shell's
meillo@58 282 .Ev MAILPATH
meillo@87 283 variable or graphical notifications are technically more appealing.
meillo@100 284 Writing directly to terminals is hardly ever wanted today.
meillo@62 285 If though one wants to have it this way, the standard tool
meillo@58 286 .Pn write
meillo@58 287 can be used in a way similar to:
meillo@82 288 .VS
meillo@58 289 scan -file - | write `id -un`
meillo@82 290 VE
meillo@62 291 .BU
meillo@58 292 .Pn viamail
meillo@87 293 was removed
meillo@87 294 .Ci eda72d6a7a7c20ff123043fb7f19c509ea01f932
meillo@87 295 when the new attachment system was activated, because
meillo@58 296 .Pn forw
meillo@76 297 could then cover the task itself.
meillo@62 298 The program
meillo@58 299 .Pn sendfiles
meillo@62 300 was rewritten as a shell script wrapper around
meillo@58 301 .Pn forw .
meillo@76 302 .Ci 0e82199cf3c991a173e0ac8aa776efdb3ded61e6
meillo@62 303 .BU
meillo@58 304 .Pn msgchk
meillo@87 305 was removed
meillo@87 306 .Ci bb9360ead7eb7a3fedcce2eeedfc660014e41dbe ,
meillo@87 307 because it lost its use case when POP support was removed.
meillo@76 308 A call to
meillo@58 309 .Pn msgchk
meillo@87 310 provided hardly more information than:
meillo@82 311 .VS
meillo@58 312 ls -l /var/mail/meillo
meillo@82 313 VE
meillo@100 314 It did distinguish between old and new mail, but
meillo@100 315 this detail information can be retrieved with
meillo@76 316 .Pn stat (1),
meillo@62 317 too.
meillo@100 318 A small shell script could be written to print the information
meillo@76 319 in a similar way, if truly necessary.
meillo@76 320 As mmh's
meillo@76 321 .Pn inc
meillo@87 322 only incorporates mail from the user's local maildrop,
meillo@62 323 and thus no data transfers over slow networks are involved,
meillo@76 324 there's hardly any need to check for new mail before incorporating it.
meillo@62 325 .BU
meillo@58 326 .Pn msh
meillo@87 327 was removed
meillo@76 328 .Ci 916690191222433a6923a4be54b0d8f6ac01bd02
meillo@87 329 because the tool was in conflict with the philosophy of MH.
meillo@76 330 It provided an interactive shell to access the features of MH,
meillo@76 331 but it wasn't just a shell, tailored to the needs of mail handling.
meillo@76 332 Instead it was one large program that had several MH tools built in.
meillo@76 333 This conflicts with the major feature of MH of being a tool chest.
meillo@76 334 .Pn msh 's
meillo@76 335 main use case had been accessing Bulletin Boards, which have seized to
meillo@62 336 be popular.
meillo@62 337 .P
meillo@62 338 Removing
meillo@58 339 .Pn msh ,
meillo@76 340 together with the truly archaic code relicts
meillo@58 341 .Pn vmh
meillo@58 342 and
meillo@58 343 .Pn wmh ,
meillo@62 344 saved more than 7\|000 lines of C code \(en
meillo@66 345 about 15\|% of the project's original source code amount.
meillo@100 346 Having less code \(en with equal readability, of course \(en
meillo@76 347 for the same functionality is an advantage.
meillo@63 348 Less code means less bugs and less maintenance work.
meillo@76 349 As
meillo@63 350 .Pn rcvtty
meillo@63 351 and
meillo@63 352 .Pn msgchk
meillo@87 353 are assumed to be rarely used and can be implemented in different ways,
meillo@87 354 why should one keep them?
meillo@76 355 Removing them stream-lines mmh.
meillo@63 356 .Pn viamail 's
meillo@63 357 use case is now partly obsolete and partly covered by
meillo@63 358 .Pn forw ,
meillo@76 359 hence there's no reason to still maintain it.
meillo@63 360 .Pn conflict
meillo@76 361 is not related to the mail client, and
meillo@63 362 .Pn msh
meillo@63 363 conflicts with the basic concept of MH.
meillo@76 364 Theses two tools might still be useful, but they should not be part of mmh.
meillo@63 365 .P
meillo@76 366 Finally, there's
meillo@76 367 .Pn slocal .
meillo@76 368 .Pn slocal
meillo@76 369 is an MDA and thus not directly MUA-related.
meillo@100 370 It should be removed from mmh, because including it conflicts with
meillo@100 371 the idea that mmh is a MUA only.
meillo@100 372 .Pn slocal
meillo@100 373 should rather become a separate project.
meillo@87 374 However,
meillo@76 375 .Pn slocal
meillo@76 376 provides rule-based processing of messages, like filing them into
meillo@76 377 different folders, which is otherwise not available in mmh.
meillo@87 378 Although
meillo@76 379 .Pn slocal
meillo@87 380 does neither pull in dependencies nor does it include a separate
meillo@100 381 technical area (cf. Sec. XXX), still,
meillo@100 382 it accounts for about 1\|000 lines of code that need to be maintained.
meillo@76 383 As
meillo@76 384 .Pn slocal
meillo@76 385 is almost self-standing, it should be split off into a separate project.
meillo@76 386 This would cut the strong connection between the MUA mmh and the MDA
meillo@76 387 .Pn slocal .
meillo@87 388 For anyone not using MH,
meillo@87 389 .Pn slocal
meillo@87 390 would become yet another independent MDA, like
meillo@87 391 .I procmail .
meillo@100 392 Then
meillo@87 393 .Pn slocal
meillo@100 394 could be installed without the complete MH system.
meillo@76 395 Likewise, mmh users could decide to use
meillo@76 396 .I procmail
meillo@87 397 without having a second, unused MDA,
meillo@87 398 .Pn slocal ,
meillo@76 399 installed.
meillo@100 400 That appears to be conceptionally the best solution.
meillo@76 401 Yet,
meillo@76 402 .Pn slocal
meillo@87 403 is not split off.
meillo@100 404 I defer the decision over
meillo@78 405 .Pn slocal
meillo@100 406 in need for deeper investigation.
meillo@100 407 In the meanwhile, it remains part of mmh.
meillo@100 408 That does not hurt because
meillo@100 409 .Pn slocal
meillo@100 410 is unrelated to the rest of the project.
meillo@0 411
meillo@58 412
meillo@76 413 .H2 "\fLshow\fP and \fPmhshow\fP
meillo@58 414 .P
meillo@69 415 Since the very beginning \(en already in the first concept paper \(en
meillo@58 416 .Pn show
meillo@62 417 had been MH's message display program.
meillo@58 418 .Pn show
meillo@76 419 mapped message numbers and sequences to files and invoked
meillo@58 420 .Pn mhl
meillo@89 421 to have the files formatted.
meillo@88 422 With MIME, this approach wasn't sufficient anymore.
meillo@100 423 MIME messages can consist of multiple parts. Some parts are not
meillo@100 424 directly displayable and text content might be encoded in
meillo@58 425 foreign charsets.
meillo@58 426 .Pn show 's
meillo@76 427 understanding of messages and
meillo@58 428 .Pn mhl 's
meillo@88 429 display capabilities couldn't cope with the task any longer.
meillo@62 430 .P
meillo@88 431 Instead of extending these tools, additional tools were written from
meillo@88 432 scratch and added to the MH tool chest.
meillo@88 433 Doing so is encouraged by the tool chest approach.
meillo@88 434 Modular design is a great advantage for extending a system,
meillo@88 435 as new tools can be added without interfering with existing ones.
meillo@62 436 First, the new MIME features were added in form of the single program
meillo@58 437 .Pn mhn .
meillo@58 438 The command
meillo@82 439 .Cl "mhn -show 42
meillo@58 440 would show the MIME message numbered 42.
meillo@58 441 With the 1.0 release of nmh in February 1999, Richard Coleman finished
meillo@58 442 the split of
meillo@58 443 .Pn mhn
meillo@88 444 into a set of specialized tools, which together covered the
meillo@88 445 multiple aspects of MIME.
meillo@88 446 One of them was
meillo@69 447 .Pn mhshow ,
meillo@88 448 which replaced
meillo@88 449 .Cl "mhn -show" .
meillo@88 450 It was capable of displaying MIME messages appropriately.
meillo@62 451 .P
meillo@88 452 From then on, two message display tools were part of nmh,
meillo@76 453 .Pn show
meillo@76 454 and
meillo@76 455 .Pn mhshow .
meillo@88 456 To ease the life of users,
meillo@69 457 .Pn show
meillo@69 458 was extended to automatically hand the job over to
meillo@69 459 .Pn mhshow
meillo@69 460 if displaying the message would be beyond
meillo@69 461 .Pn show 's
meillo@69 462 abilities.
meillo@88 463 In consequence, the user would simply invoke
meillo@69 464 .Pn show
meillo@69 465 (possibly through
meillo@69 466 .Pn next
meillo@69 467 or
meillo@69 468 .Pn prev )
meillo@69 469 and get the message printed with either
meillo@69 470 .Pn show
meillo@69 471 or
meillo@69 472 .Pn mhshow ,
meillo@69 473 whatever was more appropriate.
meillo@69 474 .P
meillo@69 475 Having two similar tools for essentially the same task is redundant.
meillo@88 476 Usually,
meillo@88 477 users wouldn't distinguish between
meillo@88 478 .Pn show
meillo@88 479 and
meillo@88 480 .Pn mhshow
meillo@88 481 in their daily mail reading.
meillo@88 482 Having two separate display programs was therefore mainly unnecessary
meillo@88 483 from a user's point of view.
meillo@88 484 Besides, the development of both programs needed to be in sync,
meillo@76 485 to ensure that the programs behaved in a similar way,
meillo@76 486 because they were used like a single tool.
meillo@76 487 Different behavior would have surprised the user.
meillo@69 488 .P
meillo@69 489 Today, non-MIME messages are rather seen to be a special case of
meillo@100 490 MIME messages, although it is the other way round.
meillo@69 491 As
meillo@69 492 .Pn mhshow
meillo@88 493 had already be able to display non-MIME messages, it appeared natural
meillo@69 494 to drop
meillo@69 495 .Pn show
meillo@69 496 in favor of using
meillo@69 497 .Pn mhshow
meillo@69 498 exclusively.
meillo@88 499 .Ci 4c1efddfd499300c7e74263e57d8aa137e84c853
meillo@88 500 Removing
meillo@88 501 .Pn show
meillo@88 502 is no loss in function, because functionally
meillo@88 503 .Pn mhshow
meillo@88 504 covers it completely.
meillo@88 505 The old behavior of
meillo@88 506 .Pn show
meillo@88 507 can still be emulated with the simple command line:
meillo@88 508 .VS
meillo@88 509 mhl `mhpath c`
meillo@88 510 VE
meillo@88 511 .P
meillo@76 512 For convenience,
meillo@76 513 .Pn mhshow
meillo@88 514 was renamed to
meillo@88 515 .Pn show
meillo@88 516 after
meillo@88 517 .Pn show
meillo@88 518 was gone.
meillo@88 519 It is clear that such a rename may confuse future developers when
meillo@88 520 trying to understand the history.
meillo@88 521 Nevertheless, I consider the convenience on the user's side,
meillo@88 522 to call
meillo@88 523 .Pn show
meillo@88 524 when they want a message to be displayed, to outweigh the inconvenience
meillo@88 525 on the developer's side when understanding the project history.
meillo@69 526 .P
meillo@88 527 To prepare for the transition,
meillo@69 528 .Pn mhshow
meillo@69 529 was reworked to behave more like
meillo@69 530 .Pn show
meillo@69 531 first.
meillo@88 532 (cf. Sec. XXX)
meillo@88 533 Once the tools behaved more alike, the replacing appeared to be
meillo@88 534 even more natural.
meillo@88 535 Today, mmh's new
meillo@69 536 .Pn show
meillo@88 537 became the one single message display program again, with the difference
meillo@88 538 that today it handles MIME messages as well as non-MIME messages.
meillo@88 539 The outcome of the transition is one program less to maintain,
meillo@88 540 no second display program for users to deal with,
meillo@88 541 and less system complexity.
meillo@69 542 .P
meillo@88 543 Still, removing the old
meillo@69 544 .Pn show
meillo@88 545 hurts in one regard: It had been such a simple program.
meillo@88 546 Its lean elegance is missing to the new
meillo@69 547 .Pn show .
meillo@88 548 But there is no chance;
meillo@88 549 supporting MIME demands for higher essential complexity.
meillo@58 550
meillo@58 551
meillo@100 552 .H2 "Configure Options
meillo@58 553 .P
meillo@76 554 Customization is a double-edged sword.
meillo@76 555 It allows better suiting setups, but not for free.
meillo@76 556 There is the cost of code complexity to be able to customize.
meillo@76 557 There is the cost of less tested setups, because there are
meillo@72 558 more possible setups and especially corner-cases.
meillo@76 559 And, there is the cost of choice itself.
meillo@76 560 The code complexity directly affects the developers.
meillo@72 561 Less tested code affects both, users and developers.
meillo@76 562 The problem of choice affects the users, for once by having to
meillo@100 563 choose, but also by more complex interfaces that require more documentation.
meillo@72 564 Whenever options add little advantages, they should be considered for
meillo@72 565 removal.
meillo@72 566 I have reduced the number of project-specific configure options from
meillo@72 567 fifteen to three.
meillo@74 568
meillo@76 569 .U3 "Mail Transfer Facilities
meillo@74 570 .P
meillo@85 571 With the removal of the mail transfer facilities five configure
meillo@85 572 options vanished:
meillo@85 573 .P
meillo@85 574 The switches
meillo@85 575 .Sw --with-tls
meillo@85 576 and
meillo@85 577 .Sw --with-cyrus-sasl
meillo@89 578 had activated the support for transfer encryption and authentication.
meillo@85 579 This is not needed anymore.
meillo@85 580 .Ci fecd5d34f65597a4dfa16aeabea7d74b191532c3
meillo@85 581 .Ci 156d35f6425bea4c1ed3c4c79783dc613379c65b
meillo@85 582 .P
meillo@85 583 The configure switch
meillo@85 584 .Sw --enable-pop
meillo@85 585 activated the message retrieval facility.
meillo@85 586 The code area that would be conditionally compiled in for TLS and SASL
meillo@85 587 support had been small.
meillo@85 588 The conditionally compiled code area for POP support had been much larger.
meillo@85 589 Whereas the code base changes would only slightly change on toggling
meillo@85 590 TLS or SASL support, it changed much on toggling POP support.
meillo@85 591 The changes in the code base could hardly be overviewed.
meillo@85 592 By having POP support togglable a second code base had been created,
meillo@85 593 one that needed to be tested.
meillo@85 594 This situation is basically similar for the conditional TLS and SASL
meillo@85 595 code, but there the changes are minor and can yet be overviewed.
meillo@85 596 Still, conditional compilation of a code base creates variations
meillo@85 597 of the original program.
meillo@85 598 More variations require more testing and maintenance work.
meillo@85 599 .P
meillo@85 600 Two other options only specified default configuration values:
meillo@100 601 .Sw --with-mts
meillo@100 602 defined the default transport service, either
meillo@100 603 .Ar smtp
meillo@100 604 or
meillo@100 605 .Ar sendmail .
meillo@85 606 In mmh this fixed to
meillo@85 607 .Ar sendmail .
meillo@85 608 .Ci f6aa95b724fd8c791164abe7ee5468bf5c34f226
meillo@85 609 With
meillo@100 610 .Sw --with-smtpservers
meillo@85 611 default SMTP servers for the
meillo@85 612 .Ar smtp
meillo@85 613 transport service could be specified.
meillo@72 614 .Ci 128545e06224233b7e91fc4c83f8830252fe16c9
meillo@85 615 Both of them became irrelevant.
meillo@72 616
meillo@74 617 .U3 "Backup Prefix
meillo@74 618 .P
meillo@76 619 The backup prefix is the string that was prepended to message
meillo@76 620 filenames to tag them as deleted.
meillo@76 621 By default it had been the comma character `\f(CW,\fP'.
meillo@78 622 In July 2000, Kimmo Suominen introduced
meillo@78 623 the configure option
meillo@78 624 .Sw --with-hash-backup
meillo@78 625 to change the default to the hash symbol `\f(CW#\fP'.
meillo@78 626 The choice was probably personal preference, because first, the
meillo@78 627 option was named
meillo@78 628 .Sw --with-backup-prefix.
meillo@78 629 and had the prefix symbol as argument.
meillo@100 630 But giving the hash symbol as argument caused too many problems
meillo@100 631 for Autoconf,
meillo@100 632 thus the option was limited to use the hash symbol as the default prefix.
meillo@100 633 This supports the assumption, that the choice for the hash was
meillo@100 634 personal preference only.
meillo@100 635 Being related or not, words that start with the hash symbol
meillo@78 636 introduce a comment in the Unix shell.
meillo@72 637 Thus, the command line
meillo@72 638 .Cl "rm #13 #15
meillo@72 639 calls
meillo@72 640 .Pn rm
meillo@72 641 without arguments because the first hash symbol starts the comment
meillo@72 642 that reaches until the end of the line.
meillo@72 643 To delete the backup files,
meillo@72 644 .Cl "rm ./#13 ./#15"
meillo@72 645 needs to be used.
meillo@100 646 Using the hash as backup prefix can be seen as a precaution against
meillo@78 647 data loss.
meillo@78 648 .P
meillo@72 649 I removed the configure option but added the profile entry
meillo@72 650 .Pe backup-prefix ,
meillo@72 651 which allows to specify an arbitrary string as backup prefix.
meillo@72 652 .Ci 6c40d481d661d532dd527eaf34cebb6d3f8ed086
meillo@76 653 Profile entries are the common method to change mmh's behavior.
meillo@76 654 This change did not remove the choice but moved it to a location where
meillo@72 655 it suited better.
meillo@76 656 .P
meillo@78 657 Eventually, however, the new trash folder concept
meillo@78 658 .Cf "Sec. XXX
meillo@78 659 obsoleted the concept of the backup prefix completely.
meillo@78 660 .Ci 8edc5aaf86f9f77124664f6801bc6c6cdf258173
meillo@100 661 .\" (Well, there still are corner-cases to remove until the backup
meillo@100 662 .\" prefix can be laid to rest, eventually.)
meillo@72 663 .\" FIXME: Do this work in the code!
meillo@76 664
meillo@76 665 .U3 "Editor and Pager
meillo@74 666 .P
meillo@74 667 The two configure options
meillo@74 668 .CW --with-editor=EDITOR
meillo@74 669 .CW --with-pager=PAGER
meillo@74 670 were used to specify the default editor and pager at configure time.
meillo@74 671 Doing so at configure time made sense in the Eighties,
meillo@76 672 when the set of available editors and pagers varied much across
meillo@76 673 different systems.
meillo@89 674 Today, the situation is more homogeneous.
meillo@74 675 The programs
meillo@74 676 .Pn vi
meillo@74 677 and
meillo@74 678 .Pn more
meillo@76 679 can be expected to be available on every Unix system,
meillo@74 680 as they are specified by POSIX since two decades.
meillo@74 681 (The specifications for
meillo@74 682 .Pn vi
meillo@74 683 and
meillo@74 684 .Pn more
meillo@74 685 appeared in
meillo@74 686 .[
meillo@74 687 posix 1987
meillo@74 688 .]
meillo@74 689 and,
meillo@74 690 .[
meillo@74 691 posix 1992
meillo@74 692 .]
meillo@74 693 respectively.)
meillo@74 694 As a first step, these two tools were hard-coded as defaults.
meillo@74 695 .Ci 5d43a99db70c12a673028c7758c20cbe3e13ef5f
meillo@74 696 Not changed were the
meillo@74 697 .Pe editor
meillo@74 698 and
meillo@74 699 .Pe moreproc
meillo@76 700 profile entries, which allowed the user to override the system defaults.
meillo@74 701 Later, the concept was reworked to respect the standard environment
meillo@74 702 variables
meillo@74 703 .Ev VISUAL
meillo@74 704 and
meillo@74 705 .Ev PAGER
meillo@76 706 if they are set.
meillo@74 707 Today, mmh determines the editor to use in the following order,
meillo@74 708 taking the first available and non-empty item:
meillo@74 709 .IP (1)
meillo@74 710 Environment variable
meillo@74 711 .Ev MMHEDITOR
meillo@74 712 .IP (2)
meillo@74 713 Profile entry
meillo@74 714 .Pe Editor
meillo@74 715 .IP (3)
meillo@74 716 Environment variable
meillo@74 717 .Ev VISUAL
meillo@74 718 .IP (4)
meillo@74 719 Environment variable
meillo@74 720 .Ev EDITOR
meillo@74 721 .IP (5)
meillo@74 722 Command
meillo@74 723 .Pn vi .
meillo@74 724 .P
meillo@76 725 .Ci f85f4b7ae62e3d05a945dcd46ead51f0a2a89a9b
meillo@76 726 .P
meillo@89 727 The pager to use is determined in a similar order,
meillo@74 728 also taking the first available and non-empty item:
meillo@74 729 .IP (1)
meillo@74 730 Environment variable
meillo@74 731 .Ev MMHPAGER
meillo@74 732 .IP (2)
meillo@74 733 Profile entry
meillo@74 734 .Pe Pager
meillo@74 735 (replaces
meillo@74 736 .Pe moreproc )
meillo@74 737 .IP (3)
meillo@74 738 Environment variable
meillo@74 739 .Ev PAGER
meillo@74 740 .IP (4)
meillo@74 741 Command
meillo@74 742 .Pn more .
meillo@74 743 .P
meillo@74 744 .Ci 0c4214ea2aec6497d0d67b436bbee9bc1d225f1e
meillo@74 745 .P
meillo@76 746 By respecting the
meillo@74 747 .Ev VISUAL /\c
meillo@74 748 .Ev EDITOR
meillo@74 749 and
meillo@74 750 .Ev PAGER
meillo@76 751 environment variables,
meillo@76 752 the new behavior confirms better to the common style on Unix systems.
meillo@76 753 Additionally, the new approach is more uniform and clearer to users.
meillo@72 754
meillo@72 755
meillo@76 756 .U3 "ndbm
meillo@72 757 .P
meillo@74 758 .Pn slocal
meillo@78 759 used to depend on
meillo@74 760 .I ndbm ,
meillo@74 761 a database library.
meillo@76 762 The database is used to store the `\fLMessage-ID\fP's of all
meillo@76 763 messages delivered.
meillo@74 764 This enables
meillo@74 765 .Pn slocal
meillo@74 766 to suppress delivering the same message to the same user twice.
meillo@74 767 (This features was enabled by the
meillo@74 768 .Sw -suppressdup
meillo@74 769 switch.)
meillo@74 770 .P
meillo@100 771 A variety of versions of the database library exist.
meillo@78 772 .[
meillo@78 773 wolter unix incompat notes dbm
meillo@78 774 .]
meillo@74 775 Complicated autoconf code was needed to detect them correctly.
meillo@74 776 Further more, the configure switches
meillo@74 777 .Sw --with-ndbm=ARG
meillo@74 778 and
meillo@74 779 .Sw --with-ndbmheader=ARG
meillo@74 780 were added to help with difficult setups that would
meillo@78 781 not be detected automatically or correctly.
meillo@74 782 .P
meillo@74 783 By removing the suppress duplicates feature of
meillo@74 784 .Pn slocal ,
meillo@74 785 the dependency on
meillo@74 786 .I ndbm
meillo@78 787 vanished and 120 lines of complex autoconf code could be saved.
meillo@74 788 .Ci ecd6d6a20cb7a1507e3a20d6c4cb3a1cf14c6bbf
meillo@89 789 The change removed functionality too, but that is minor to the
meillo@78 790 improvement by dropping the dependency and the complex autoconf code.
meillo@72 791
meillo@74 792 .U3 "mh-e Support
meillo@72 793 .P
meillo@74 794 The configure option
meillo@74 795 .Sw --disable-mhe
meillo@74 796 was removed when the mh-e support was reworked.
meillo@74 797 Mh-e is the Emacs front-end to MH.
meillo@76 798 It requires MH to provide minor additional functions.
meillo@76 799 The
meillo@76 800 .Sw --disable-mhe
meillo@76 801 configure option could switch these extensions off.
meillo@76 802 After removing the support for old versions of mh-e,
meillo@74 803 only the
meillo@74 804 .Sw -build
meillo@76 805 switches of
meillo@74 806 .Pn forw
meillo@74 807 and
meillo@74 808 .Pn repl
meillo@76 809 are left to be mh-e extensions.
meillo@76 810 They are now always built in because they add little code and complexity.
meillo@76 811 In consequence, the
meillo@74 812 .Sw --disable-mhe
meillo@76 813 configure option was removed
meillo@72 814 .Ci a7ce7b4a580d77b6c2c4d980812beb589aa4c643
meillo@74 815 Removing the option removed a second code setup that would have
meillo@74 816 needed to be tested.
meillo@76 817 This change was first done in nmh and thereafter merged into mmh.
meillo@76 818 .P
meillo@76 819 The interface changes in mmh require mh-e to be adjusted in order
meillo@76 820 to be able to use mmh as back-end.
meillo@76 821 This will require minor changes to mh-e, but removing the
meillo@76 822 .Sw -build
meillo@76 823 switches would require more rework.
meillo@72 824
meillo@74 825 .U3 "Masquerading
meillo@72 826 .P
meillo@74 827 The configure option
meillo@74 828 .Sw --enable-masquerade
meillo@76 829 could take up to three arguments:
meillo@76 830 `draft_from', `mmailid', and `username_extension'.
meillo@74 831 They activated different types of address masquerading.
meillo@74 832 All of them were implemented in the SMTP-speaking
meillo@74 833 .Pn post
meillo@76 834 command, which provided an MSA.
meillo@76 835 Address masquerading is an MTA's task and mmh does not cover
meillo@76 836 this field anymore.
meillo@76 837 Hence, true masquerading needs to be implemented in the external MTA.
meillo@74 838 .P
meillo@74 839 The
meillo@74 840 .I mmailid
meillo@74 841 masquerading type is the oldest one of the three and the only one
meillo@74 842 available in the original MH.
meillo@74 843 It provided a
meillo@74 844 .I username
meillo@74 845 to
meillo@74 846 .I fakeusername
meillo@76 847 mapping, based on the password file's GECOS field.
meillo@74 848 The man page
meillo@74 849 .Mp mh-tailor(5)
meillo@74 850 described the use case as being the following:
meillo@98 851 .QS
meillo@74 852 This is useful if you want the messages you send to always
meillo@74 853 appear to come from the name of an MTA alias rather than your
meillo@74 854 actual account name. For instance, many organizations set up
meillo@74 855 `First.Last' sendmail aliases for all users. If this is
meillo@74 856 the case, the GECOS field for each user should look like:
meillo@74 857 ``First [Middle] Last <First.Last>''
meillo@98 858 .QE
meillo@74 859 .P
meillo@74 860 As mmh sends outgoing mail via the local MTA only,
meillo@76 861 the best location to do such global rewrites is there.
meillo@74 862 Besides, the MTA is conceptionally the right location because it
meillo@74 863 does the reverse mapping for incoming mail (aliasing), too.
meillo@76 864 Further more, masquerading set up there is readily available for all
meillo@74 865 mail software on the system.
meillo@76 866 Hence, mmailid masquerading was removed.
meillo@74 867 .Ci 0836c8000ccb34b59410ef1c15b1b7feac70ce5f
meillo@74 868 .P
meillo@74 869 The
meillo@74 870 .I username_extension
meillo@76 871 masquerading type did not replace the username but would append a suffix,
meillo@76 872 specified by the
meillo@74 873 .Ev USERNAME_EXTENSION
meillo@76 874 environment variable, to it.
meillo@76 875 This provided support for the
meillo@74 876 .I user-extension
meillo@74 877 feature of qmail and the similar
meillo@74 878 .I "plussed user
meillo@74 879 processing of sendmail.
meillo@74 880 The decision to remove this username_extension masquerading was
meillo@74 881 motivated by the fact that
meillo@74 882 .Pn spost
meillo@76 883 hadn't supported it already.
meillo@76 884 .Ci 2abae0bfd0ad5bf898461e50aa4b466d641f23d9
meillo@76 885 Username extensions are possible in mmh, but less convenient to use.
meillo@76 886 .\" XXX format file %(getenv USERNAME_EXTENSION)
meillo@74 887 .P
meillo@74 888 The
meillo@74 889 .I draft_from
meillo@74 890 masquerading type instructed
meillo@74 891 .Pn post
meillo@84 892 to use the value of the
meillo@84 893 .Hd From
meillo@84 894 header field as SMTP envelope sender.
meillo@76 895 Sender addresses could be replaced completely.
meillo@74 896 .Ci b14ea6073f77b4359aaf3fddd0e105989db9
meillo@76 897 Mmh offers a kind of masquerading similar in effect, but
meillo@74 898 with technical differences.
meillo@76 899 As mmh does not transfer messages itself, the local MTA has final control
meillo@76 900 over the sender's address. Any masquerading mmh introduces may be reverted
meillo@76 901 by the MTA.
meillo@76 902 In times of pedantic spam checking, an MTA will take care to use
meillo@76 903 sensible envelope sender addresses to keep its own reputation up.
meillo@84 904 Nonetheless, the MUA can set the
meillo@84 905 .Hd From
meillo@84 906 header field and thereby propose
meillo@76 907 a sender address to the MTA.
meillo@74 908 The MTA may then decide to take that one or generate the canonical sender
meillo@74 909 address for use as envelope sender address.
meillo@74 910 .P
meillo@74 911 In mmh, the MTA will always extract the recipient and sender from the
meillo@84 912 message header (\c
meillo@74 913 .Pn sendmail 's
meillo@74 914 .Sw -t
meillo@74 915 switch).
meillo@84 916 The
meillo@84 917 .Hd From
meillo@84 918 header field of the draft may be set arbitrary by the user.
meillo@74 919 If it is missing, the canonical sender address will be generated by the MTA.
meillo@74 920
meillo@74 921 .U3 "Remaining Options
meillo@74 922 .P
meillo@74 923 Two configure options remain in mmh.
meillo@74 924 One is the locking method to use:
meillo@74 925 .Sw --with-locking=[dot|fcntl|flock|lockf] .
meillo@76 926 The idea of removing all methods except the portable dot locking
meillo@76 927 and having that one as the default is appealing, but this change
meillo@76 928 requires deeper technical investigation into the topic.
meillo@76 929 The other option,
meillo@74 930 .Sw --enable-debug ,
meillo@74 931 compiles the programs with debugging symbols and does not strip them.
meillo@74 932 This option is likely to stay.
meillo@72 933
meillo@72 934
meillo@58 935
meillo@63 936
meillo@100 937 .H2 "Command Line Switches
meillo@58 938 .P
meillo@93 939 The command line switches of MH tools follow the X Window style.
meillo@93 940 They are words, introduced by a single dash.
meillo@93 941 For example:
meillo@93 942 .Cl "-truncate" .
meillo@93 943 Every program in mmh has two generic switches:
meillo@93 944 .Sw -help ,
meillo@93 945 to print a short message on how to use the program, and
meillo@93 946 .Sw -Version ,
meillo@93 947 to tell what version of mmh the program belongs to.
meillo@93 948 .P
meillo@93 949 Switches change the behavior of programs.
meillo@93 950 Programs that do one thing in one way require no switches.
meillo@93 951 In most cases, doing something in exactly one way is too limiting.
meillo@97 952 If there is basically one task to accomplish, but it should be done
meillo@93 953 in various ways, switches are a good approach to alter the behavior
meillo@93 954 of a program.
meillo@93 955 Changing the behavior of programs provides flexibility and customization
meillo@97 956 to users, but at the same time it complicates the code, documentation and
meillo@93 957 usage of the program.
meillo@97 958 .\" XXX: Ref
meillo@93 959 Therefore, the number of switches should be kept small.
meillo@93 960 A small set of well-chosen switches does no harm.
meillo@93 961 But usually, the number of switches increases over time.
meillo@93 962 Already in 1985, Rose and Romine have identified this as a major
meillo@93 963 problem of MH:
meillo@93 964 .[ [
meillo@93 965 rose romine real work
meillo@93 966 .], p. 12]
meillo@98 967 .QS
meillo@93 968 A complaint often heard about systems which undergo substantial development
meillo@93 969 by many people over a number of years, is that more and more options are
meillo@93 970 introduced which add little to the functionality but greatly increase the
meillo@93 971 amount of information a user needs to know in order to get useful work done.
meillo@93 972 This is usually referred to as creeping featurism.
meillo@93 973 .QP
meillo@93 974 Unfortunately MH, having undergone six years of off-and-on development by
meillo@93 975 ten or so well-meaning programmers (the present authors included),
meillo@93 976 suffers mightily from this.
meillo@98 977 .QE
meillo@93 978 .P
meillo@97 979 Being reluctant to adding new switches \(en or `options',
meillo@97 980 as Rose and Romine call them \(en is one part of a counter-action,
meillo@97 981 the other part is removing hardly used switches.
meillo@97 982 Nmh's tools had lots of switches already implemented,
meillo@97 983 hence, cleaning up by removing some of them was the more important part
meillo@97 984 of the counter-action.
meillo@93 985 Removing existing functionality is always difficult because it
meillo@93 986 breaks programs that use these functions.
meillo@93 987 Also, for every obsolete feature, there'll always be someone who still
meillo@93 988 uses it and thus opposes its removal.
meillo@93 989 This puts the developer into the position,
meillo@93 990 where sensible improvements to style are regarded as destructive acts.
meillo@97 991 Yet, living with the featurism is far worse, in my eyes, because
meillo@97 992 future needs will demand adding further features,
meillo@93 993 worsening the situation more and more.
meillo@93 994 Rose and Romine added in a footnote,
meillo@93 995 ``[...]
meillo@93 996 .Pn send
meillo@93 997 will no doubt acquire an endless number of switches in the years to come.''
meillo@97 998 Although clearly humorous, the comment points to the nature of the problem.
meillo@97 999 Refusing to add any new switches would encounter the problem at its root,
meillo@97 1000 but this is not practical.
meillo@97 1001 New needs will require new switches and it would be unwise to block
meillo@97 1002 them strictly.
meillo@97 1003 Nevertheless, removing obsolete switches still is an effective approach
meillo@97 1004 to deal with the problem.
meillo@97 1005 Working on an experimental branch without an established user base,
meillo@97 1006 eased my work because I did not offend users when I removed existing
meillo@97 1007 funtions.
meillo@93 1008 .P
meillo@93 1009 Rose and Romine counted 24 visible and 9 more hidden switches for
meillo@93 1010 .Pn send .
meillo@97 1011 In nmh, they increased up to 32 visible and 12 hidden ones.
meillo@97 1012 At the time of writing, no more than 7 visible switches and 1 hidden switch
meillo@97 1013 have remained in mmh's
meillo@97 1014 .Pn send .
meillo@97 1015 (These numbers include two generic switches, help and version.)
meillo@93 1016 .P
meillo@97 1017 Fig. XXX
meillo@93 1018 .\" XXX Ref
meillo@97 1019 displays the number of switches for each of the tools that is available
meillo@97 1020 in both, nmh and mmh.
meillo@100 1021 The tools are sorted by the number of switches they had in nmh.
meillo@100 1022 Visible and hidden switches were counted,
meillo@97 1023 but not the generic help and version switches.
meillo@93 1024 Whereas in the beginning of the project, the average tool had 11 switches,
meillo@93 1025 now it has no more than 5 \(en only half as many.
meillo@93 1026 If the `no' switches and similar inverse variant are folded onto
meillo@100 1027 their counter-parts, the average tool had 8 switches in pre-mmh times and
meillo@100 1028 has 4 now.
meillo@93 1029 The total number of functional switches in mmh dropped from 465
meillo@93 1030 to 234.
meillo@58 1031
meillo@93 1032 .KS
meillo@93 1033 .in 1c
meillo@93 1034 .so input/switches.grap
meillo@93 1035 .KE
meillo@58 1036
meillo@93 1037 .P
meillo@93 1038 A part of the switches vanished after functions were removed.
meillo@93 1039 This was the case for network mail transfer, for instance.
meillo@97 1040 Sometimes, however, the work flow was the other way:
meillo@97 1041 I looked through the
meillo@97 1042 .Mp mh-chart (7)
meillo@97 1043 man page to identify the tools with apparently too many switches.
meillo@97 1044 Then considering the value of each of the switches by examining
meillo@97 1045 the tool's man page and source code, aided by recherche and testing.
meillo@97 1046 This way, the removal of functions was suggested by the aim to reduce
meillo@97 1047 the number of switches per command.
meillo@97 1048
meillo@58 1049
meillo@93 1050 .U3 "Draft Folder Facility
meillo@93 1051 .P
meillo@100 1052 A change early in the project was the complete transition from
meillo@93 1053 the single draft message to the draft folder facility.
meillo@97 1054 .Ci 337338b404931f06f0db2119c9e145e8ca5a9860
meillo@100 1055 The draft folder facility was introduced in the mid-Eighties, when
meillo@100 1056 Rose and Romine called it a ``relatively new feature''.
meillo@93 1057 .[
meillo@93 1058 rose romine real work
meillo@93 1059 .]
meillo@97 1060 Since then, the facility had existed but was deactivated by default.
meillo@93 1061 The default activation and the related rework of the tools made it
meillo@93 1062 possible to remove the
meillo@93 1063 .Sw -[no]draftfolder ,
meillo@93 1064 and
meillo@93 1065 .Sw -draftmessage
meillo@93 1066 switches from
meillo@93 1067 .Pn comp ,
meillo@93 1068 .Pn repl ,
meillo@93 1069 .Pn forw ,
meillo@93 1070 .Pn dist ,
meillo@93 1071 .Pn whatnow ,
meillo@93 1072 and
meillo@93 1073 .Pn send .
meillo@97 1074 .Ci 337338b404931f06f0db2119c9e145e8ca5a9860
meillo@97 1075 The only flexibility removed with this change is having multiple
meillo@97 1076 draft folders within one profile.
meillo@97 1077 I consider this a theoretical problem only.
meillo@93 1078 In the same go, the
meillo@93 1079 .Sw -draft
meillo@93 1080 switch of
meillo@93 1081 .Pn anno ,
meillo@93 1082 .Pn refile ,
meillo@93 1083 and
meillo@93 1084 .Pn send
meillo@93 1085 was removed.
meillo@93 1086 The special-casing of `the' draft message became irrelevant after
meillo@93 1087 the rework of the draft system.
meillo@93 1088 (See Sec. XXX.)
meillo@95 1089 Equally,
meillo@95 1090 .Pn comp
meillo@95 1091 lost its
meillo@95 1092 .Sw -file
meillo@95 1093 switch.
meillo@95 1094 The draft folder facility, together with the
meillo@95 1095 .Sw -form
meillo@95 1096 switch, are sufficient.
meillo@93 1097
meillo@95 1098
meillo@102 1099 .U3 "In Place Editing
meillo@93 1100 .P
meillo@93 1101 .Pn anno
meillo@93 1102 had the switches
meillo@93 1103 .Sw -[no]inplace
meillo@100 1104 to either annotate the message in place and thus preserve hard links,
meillo@93 1105 or annotate a copy to replace the original message, breaking hard links.
meillo@97 1106 Following the assumption that linked messages should truly be the
meillo@97 1107 same message, and annotating it should not break the link, the
meillo@93 1108 .Sw -[no]inplace
meillo@93 1109 switches were removed and the previous default
meillo@93 1110 .Sw -inplace
meillo@93 1111 was made the only behavior.
meillo@97 1112 .Ci c8195849d2e366c569271abb0f5f60f4ebf0b4d0
meillo@93 1113 The
meillo@93 1114 .Sw -[no]inplace
meillo@93 1115 switches of
meillo@93 1116 .Pn repl ,
meillo@93 1117 .Pn forw ,
meillo@93 1118 and
meillo@93 1119 .Pn dist
meillo@93 1120 could be removed, too, as they were simply passed through to
meillo@93 1121 .Pn anno .
meillo@93 1122 .P
meillo@93 1123 .Pn burst
meillo@93 1124 also had
meillo@93 1125 .Sw -[no]inplace
meillo@95 1126 switches, but with different meaning.
meillo@95 1127 With
meillo@95 1128 .Sw -inplace ,
meillo@95 1129 the digest had been replaced by the table of contents (i.e. the
meillo@95 1130 introduction text) and the bursted messages were placed right
meillo@95 1131 after this message, renumbering all following messages.
meillo@95 1132 Also, any trailing text of the digest was lost, though,
meillo@95 1133 in practice, it usually consists of an end-of-digest marker only.
meillo@95 1134 Nontheless, this behavior appeared less elegant than the
meillo@95 1135 .Sw -noinplace
meillo@95 1136 behavior, which already had been the default.
meillo@95 1137 Nmh's
meillo@95 1138 .Mp burst (1)
meillo@95 1139 man page reads:
meillo@95 1140 .sp \n(PDu
meillo@98 1141 .QS
meillo@93 1142 If -noinplace is given, each digest is preserved, no table
meillo@93 1143 of contents is produced, and the messages contained within
meillo@93 1144 the digest are placed at the end of the folder. Other messages
meillo@93 1145 are not tampered with in any way.
meillo@98 1146 .QE
meillo@95 1147 .LP
meillo@93 1148 The decision to drop the
meillo@93 1149 .Sw -inplace
meillo@95 1150 behavior was supported by the code complexity and the possible data loss
meillo@95 1151 it caused.
meillo@93 1152 .Sw -noinplace
meillo@95 1153 was chosen to be the definitive behavior.
meillo@97 1154 .Ci 68a686adeb39223a5e1ad35e4a24890ec053679d
meillo@93 1155
meillo@95 1156
meillo@95 1157 .U3 "Forms and Format Strings
meillo@93 1158 .P
meillo@95 1159 Historically, the tools that had
meillo@95 1160 .Sw -form
meillo@95 1161 switches to supply a form file had
meillo@95 1162 .Sw -format
meillo@95 1163 switches as well to supply the contents of a form file as a string
meillo@95 1164 on the command line directly.
meillo@95 1165 In consequence, the following two lines equaled:
meillo@95 1166 .VS
meillo@95 1167 scan -form scan.mailx
meillo@95 1168 scan -format "`cat .../scan.mailx`"
meillo@95 1169 VE
meillo@95 1170 The
meillo@95 1171 .Sw -format
meillo@95 1172 switches were dropped in favor for extending the
meillo@95 1173 .Sw -form
meillo@95 1174 switches.
meillo@97 1175 .Ci f51956be123db66b00138f80464d06f030dbb88d
meillo@95 1176 If their argument starts with an equal sign (`='),
meillo@95 1177 then the rest of the argument is taken as a format string,
meillo@95 1178 otherwise the arguments is treated as the name of a format file.
meillo@95 1179 Thus, now the following two lines equal:
meillo@95 1180 .VS
meillo@95 1181 scan -form scan.mailx
meillo@95 1182 scan -form "=`cat .../scan.mailx`"
meillo@95 1183 VE
meillo@95 1184 This rework removed the prefix collision between
meillo@95 1185 .Sw -form
meillo@95 1186 and
meillo@95 1187 .Sw -format .
meillo@95 1188 Now, typing
meillo@95 1189 .Sw -fo
meillo@95 1190 suffices to specify form or format string.
meillo@95 1191 .P
meillo@95 1192 The different meaning of
meillo@95 1193 .Sw -format
meillo@95 1194 for
meillo@95 1195 .Pn repl
meillo@95 1196 and
meillo@95 1197 .Pn forw
meillo@95 1198 was removed in mmh.
meillo@95 1199 .Pn forw
meillo@95 1200 was completely switched to MIME-type forwarding, thus removing the
meillo@95 1201 .Sw -[no]format .
meillo@97 1202 .Ci 6e271608b7b9c23771523f88d23a4d3593010cf1
meillo@95 1203 For
meillo@95 1204 .Pn repl ,
meillo@95 1205 the
meillo@95 1206 .Sw -[no]format
meillo@95 1207 switches were reworked to
meillo@95 1208 .Sw -[no]filter
meillo@95 1209 switches.
meillo@97 1210 .Ci 67411b1f95d6ec987b4c732459e1ba8a8ac192c6
meillo@95 1211 The
meillo@95 1212 .Sw -format
meillo@95 1213 switches of
meillo@95 1214 .Pn send
meillo@95 1215 and
meillo@95 1216 .Pn post ,
meillo@95 1217 which had a third meaning,
meillo@95 1218 were removed likewise.
meillo@97 1219 .Ci f3cb7cde0e6f10451b6848678d95860d512224b9
meillo@95 1220 Eventually, the ambiguity of the
meillo@95 1221 .Sw -format
meillo@95 1222 switches was resolved by not anymore having any such switch in mmh.
meillo@95 1223
meillo@95 1224
meillo@95 1225 .U3 "MIME Tools
meillo@95 1226 .P
meillo@95 1227 The MIME tools, which were once part of
meillo@100 1228 .Pn mhn
meillo@100 1229 [sic!],
meillo@95 1230 had several switches that added little practical value to the programs.
meillo@95 1231 The
meillo@95 1232 .Sw -[no]realsize
meillo@95 1233 switches of
meillo@95 1234 .Pn mhbuild
meillo@95 1235 and
meillo@95 1236 .Pn mhlist
meillo@97 1237 were removed, doing real size calculations always now
meillo@97 1238 .Ci 8d8f1c3abc586c005c904e52c4adbfe694d2201c ,
meillo@97 1239 as
meillo@95 1240 ``This provides an accurate count at the expense of a small delay.''
meillo@95 1241 This small delay is not noticable on modern systems.
meillo@95 1242 .P
meillo@95 1243 The
meillo@95 1244 .Sw -[no]check
meillo@95 1245 switches were removed together with the support for
meillo@95 1246 .Hd Content-MD5
meillo@95 1247 header fields.
meillo@95 1248 .[
meillo@95 1249 rfc 1864
meillo@95 1250 .]
meillo@97 1251 .Ci 31dc797eb5178970d68962ca8939da3fd9a8efda
meillo@95 1252 (See Sec. XXX)
meillo@95 1253 .P
meillo@95 1254 The
meillo@95 1255 .Sw -[no]ebcdicsafe
meillo@95 1256 and
meillo@95 1257 .Sw -[no]rfc934mode
meillo@95 1258 switches of
meillo@95 1259 .Pn mhbuild
meillo@95 1260 were removed because they are considered obsolete.
meillo@97 1261 .Ci 01a3480928da485b4d6109d36d751dfa71799d58
meillo@97 1262 .Ci 3363e2624dce0eb8164cf8b3f1ab385c8ff72e88
meillo@95 1263 .P
meillo@95 1264 Content caching of external MIME parts, activated with the
meillo@95 1265 .Sw -rcache
meillo@95 1266 and
meillo@95 1267 .Sw -wcache
meillo@95 1268 switches was completely removed.
meillo@97 1269 .Ci d1fefd9f614e4dc3cda16da6c69133c1b2005269
meillo@97 1270 External MIME parts are rare today, having a caching facility
meillo@96 1271 for them is appears to be unnecessary.
meillo@95 1272 .P
meillo@95 1273 In pre-MIME times,
meillo@95 1274 .Pn mhl
meillo@95 1275 had covered many tasks that are part of MIME handling today.
meillo@95 1276 Therefore,
meillo@95 1277 .Pn mhl
meillo@95 1278 could be simplified to a large extend, reducing the number of its
meillo@95 1279 switches from 21 to 6.
meillo@97 1280 .Ci 350ad6d3542a07639213cf2a4fe524e829c1e7b6
meillo@97 1281 .Ci 0e46503be3c855bddaeae3843e1b659279c35d70
meillo@95 1282
meillo@95 1283
meillo@95 1284 .U3 "Mail Transfer Switches
meillo@95 1285 .P
meillo@95 1286 With the removal of the mail transfer facilities, a lot of switches
meillo@95 1287 vanished automatically.
meillo@95 1288 .Pn inc
meillo@95 1289 lost 9 switches, namely
meillo@95 1290 .Sw -host ,
meillo@95 1291 .Sw -port ,
meillo@95 1292 .Sw -user ,
meillo@95 1293 .Sw -proxy ,
meillo@95 1294 .Sw -snoop ,
meillo@95 1295 .Sw -[no]pack ,
meillo@95 1296 as well as
meillo@95 1297 .Sw -sasl
meillo@95 1298 and
meillo@95 1299 .Sw -saslmech .
meillo@95 1300 .Pn send
meillo@95 1301 and
meillo@95 1302 .Pn post
meillo@95 1303 lost 11 switches each, namely
meillo@95 1304 .Sw -server ,
meillo@95 1305 .Sw -port ,
meillo@95 1306 .Sw -client ,
meillo@95 1307 .Sw -user ,
meillo@95 1308 .Sw -mail ,
meillo@95 1309 .Sw -saml ,
meillo@95 1310 .Sw -send ,
meillo@95 1311 .Sw -soml ,
meillo@95 1312 .Sw -snoop ,
meillo@95 1313 as well as
meillo@95 1314 .Sw -sasl ,
meillo@95 1315 .Sw -saslmech ,
meillo@95 1316 and
meillo@95 1317 .Sw -tls .
meillo@95 1318 .Pn send
meillo@95 1319 had the switches only to pass them further to
meillo@95 1320 .Pn post ,
meillo@95 1321 because the user would invoke
meillo@95 1322 .Pn post
meillo@95 1323 not directly, but through
meillo@95 1324 .Pn send .
meillo@95 1325 All these switches, except
meillo@95 1326 .Sw -snoop
meillo@95 1327 were usually defined as default switches in the user's profile,
meillo@95 1328 but hardly given in interactive usage.
meillo@95 1329 .P
meillo@95 1330 Of course, those switches did not really ``vanish'', but the configuration
meillo@95 1331 they did was handed over to external MSAs and MRAs.
meillo@95 1332 Instead of setting up the mail transfer in mmh, it is set up in
meillo@95 1333 external tools.
meillo@95 1334 Yet, this simplifies mmh.
meillo@95 1335 Specialized external tools will likely have simple configuration files.
meillo@95 1336 Hence, instead of having one complicated central configuration file,
meillo@95 1337 the configuration of each domain is separate.
meillo@95 1338 Although the user needs to learn to configure each of the tools,
meillo@95 1339 each configuration is likely much simpler.
meillo@95 1340
meillo@95 1341
meillo@95 1342 .U3 "Maildrop Formats
meillo@95 1343 .P
meillo@95 1344 With the removal of MMDF maildrop format support,
meillo@95 1345 .Pn packf
meillo@95 1346 and
meillo@95 1347 .Pn rcvpack
meillo@95 1348 no longer needed their
meillo@95 1349 .Sw -mbox
meillo@95 1350 and
meillo@95 1351 .Sw -mmdf
meillo@95 1352 switches.
meillo@95 1353 .Sw -mbox
meillo@95 1354 is the sole behavior now.
meillo@97 1355 .Ci 3916ab66ad5d183705ac12357621ea8661afd3c0
meillo@95 1356 In the same go,
meillo@95 1357 .Pn packf
meillo@97 1358 and
meillo@97 1359 .Pn rcvpack
meillo@97 1360 were reworked (see Sec. XXX) and their
meillo@95 1361 .Sw -file
meillo@95 1362 switch became unnecessary.
meillo@97 1363 .Ci ca1023716d4c2ab890696f3e41fa0d94267a940e
meillo@95 1364
meillo@95 1365
meillo@95 1366 .U3 "Terminal Magic
meillo@95 1367 .P
meillo@95 1368 Mmh's tools will no longer clear the screen (\c
meillo@95 1369 .Pn scan 's
meillo@95 1370 and
meillo@95 1371 .Pn mhl 's
meillo@95 1372 .Sw -[no]clear
meillo@97 1373 switches
meillo@97 1374 .Ci e57b17343dcb3ff373ef4dd089fbe778f0c7c270
meillo@97 1375 .Ci 943765e7ac5693ae177fd8d2b5a2440e53ce816e ).
meillo@95 1376 Neither will
meillo@95 1377 .Pn mhl
meillo@95 1378 ring the bell (\c
meillo@97 1379 .Sw -[no]bell
meillo@97 1380 .Ci e11983f44e59d8de236affa5b0d0d3067c192e24 )
meillo@95 1381 nor page the output itself (\c
meillo@97 1382 .Sw -length
meillo@97 1383 .Ci 5b9d883db0318ed2b84bb82dee880d7381f99188 ).
meillo@95 1384 .P
meillo@95 1385 Generally, the pager to use is no longer specified with the
meillo@95 1386 .Sw -[no]moreproc
meillo@95 1387 command line switches for
meillo@95 1388 .Pn mhl
meillo@95 1389 and
meillo@95 1390 .Pn show /\c
meillo@95 1391 .Pn mhshow .
meillo@97 1392 .Ci 39e87a75b5c2d3572ec72e717720b44af291e88a
meillo@95 1393 .P
meillo@95 1394 .Pn prompter
meillo@95 1395 lost its
meillo@95 1396 .Sw -erase
meillo@95 1397 and
meillo@95 1398 .Sw -kill
meillo@95 1399 switches because today the terminal cares for the line editing keys.
meillo@95 1400
meillo@95 1401
meillo@95 1402 .U3 "Header Printing
meillo@95 1403 .P
meillo@95 1404 .Pn folder 's
meillo@95 1405 data output is self-explaining enough that
meillo@95 1406 displaying the header line makes few sense.
meillo@95 1407 Hence, the
meillo@95 1408 .Sw -[no]header
meillo@95 1409 switch was removed and headers are never printed.
meillo@97 1410 .Ci 601cc73d1fa05ce96faa728f036d6c51b91701c7
meillo@95 1411 .P
meillo@95 1412 In
meillo@95 1413 .Pn mhlist ,
meillo@95 1414 the
meillo@95 1415 .Sw -[no]header
meillo@95 1416 switches were removed, too.
meillo@97 1417 .Ci b24f96523aaf60e44e04a3ffb1d22e69a13a602f
meillo@95 1418 But in this case headers are always printed,
meillo@95 1419 because the output is not self-explaining.
meillo@95 1420 .P
meillo@95 1421 .Pn scan
meillo@95 1422 also had
meillo@95 1423 .Sw -[no]header
meillo@95 1424 switches.
meillo@95 1425 Printing the header had been sensible until the introduction of
meillo@95 1426 format strings made it impossible to display the column headings.
meillo@95 1427 Only the folder name and the current date remained to be printed.
meillo@95 1428 As this information can be perfectly retrieved by
meillo@95 1429 .Pn folder
meillo@95 1430 and
meillo@95 1431 .Pn date ,
meillo@95 1432 consequently, the switches were removed.
meillo@97 1433 .Ci c477dc5d1d03fa6d9a8ab3dd3508c63cbddc044e
meillo@95 1434 .P
meillo@95 1435 By removing all
meillo@95 1436 .Sw -header
meillo@95 1437 switches, the collision with
meillo@95 1438 .Sw -help
meillo@95 1439 on the first two letters was resolved.
meillo@95 1440 Currently,
meillo@95 1441 .Sw -h
meillo@95 1442 evaluates to
meillo@95 1443 .Sw -help
meillo@95 1444 for all tools of mmh.
meillo@95 1445
meillo@95 1446
meillo@95 1447 .U3 "Suppressing Edits or the WhatNow Shell
meillo@95 1448 .P
meillo@95 1449 The
meillo@95 1450 .Sw -noedit
meillo@100 1451 switch of
meillo@95 1452 .Pn comp ,
meillo@95 1453 .Pn repl ,
meillo@95 1454 .Pn forw ,
meillo@95 1455 .Pn dist ,
meillo@95 1456 and
meillo@95 1457 .Pn whatnow
meillo@95 1458 was removed, but it can now be replaced by specifying
meillo@95 1459 .Sw -editor
meillo@95 1460 with an empty argument.
meillo@97 1461 .Ci 75fca31a5b9d5c1a99c74ab14c94438d8852fba9
meillo@95 1462 (Specifying
meillo@95 1463 .Cl "-editor true
meillo@95 1464 is nearly the same, only differing by the previous editor being set.)
meillo@95 1465 .P
meillo@95 1466 The more important change is the removal of the
meillo@95 1467 .Sw -nowhatnowproc
meillo@95 1468 switch.
meillo@97 1469 .Ci ee4f43cf2ef0084ec698e4e87159a94c01940622
meillo@95 1470 This switch had introduced an awkward behavior, as explained in nmh's
meillo@95 1471 man page for
meillo@95 1472 .Mp comp (1):
meillo@98 1473 .QS
meillo@98 1474 The \-editor editor switch indicates the editor to use for
meillo@98 1475 the initial edit. Upon exiting from the editor, comp will
meillo@98 1476 invoke the whatnow program. See whatnow(1) for a discussion
meillo@98 1477 of available options. The invocation of this program can be
meillo@98 1478 inhibited by using the \-nowhatnowproc switch. (In truth of
meillo@98 1479 fact, it is the whatnow program which starts the initial
meillo@98 1480 edit. Hence, \-nowhatnowproc will prevent any edit from
meillo@95 1481 occurring.)
meillo@98 1482 .QE
meillo@95 1483 .P
meillo@95 1484 Effectively, the
meillo@95 1485 .Sw -nowhatnowproc
meillo@100 1486 switch creates only a draft message.
meillo@95 1487 As
meillo@95 1488 .Cl "-whatnowproc true
meillo@95 1489 causes the same behavior, the
meillo@95 1490 .Sw -nowhatnowproc
meillo@95 1491 switch was removed for being redundant.
meillo@100 1492 Likely, the
meillo@95 1493 .Sw -nowhatnowproc
meillo@100 1494 switch was intended to be used by front-ends.
meillo@95 1495
meillo@95 1496
meillo@95 1497 .U3 "Compatibility Switches
meillo@95 1498 .BU
meillo@95 1499 The hidden
meillo@95 1500 .Sw -[no]total
meillo@95 1501 switches of
meillo@95 1502 .Pn flist .
meillo@95 1503 They were simply the inverse of the visible
meillo@95 1504 .Sw -[no]fast
meillo@95 1505 switches:
meillo@95 1506 .Sw -total
meillo@95 1507 was
meillo@95 1508 .Sw -nofast
meillo@95 1509 and
meillo@95 1510 .Sw -nototal
meillo@95 1511 was
meillo@95 1512 .Sw -fast .
meillo@95 1513 I removed the
meillo@95 1514 .Sw -[no]total
meillo@95 1515 legacy.
meillo@97 1516 .Ci ea21fe2c4bd23c639bef251398fae809875732ec
meillo@95 1517 .BU
meillo@95 1518 The
meillo@95 1519 .Sw -subject
meillo@95 1520 switch of
meillo@95 1521 .Pn sortm
meillo@95 1522 existed for compatibility only.
meillo@95 1523 It can be fully replaced by
meillo@95 1524 .Cl "-textfield subject
meillo@95 1525 thus it was removed.
meillo@97 1526 .Ci 00140a3c86e9def69d98ba2ffd4d6e50ef6326ea
meillo@95 1527
meillo@95 1528
meillo@95 1529 .U3 "Various
meillo@95 1530 .BU
meillo@96 1531 In order to avoid prefix collisions among switch names, the
meillo@95 1532 .Sw -version
meillo@95 1533 switch was renamed to
meillo@95 1534 .Sw -Version
meillo@95 1535 (with capital `V').
meillo@97 1536 .Ci 32b2354dbaf4bf934936eb5b102a4a3d2fdd209a
meillo@95 1537 Every program has the
meillo@95 1538 .Sw -version
meillo@95 1539 switch but its first three letters collided with the
meillo@95 1540 .Sw -verbose
meillo@95 1541 switch, present in many programs.
meillo@95 1542 The rename solved this problem once for all.
meillo@95 1543 Although this rename breaks a basic interface, having the
meillo@95 1544 .Sw -V
meillo@95 1545 abbreviation to display the version information, isn't all too bad.
meillo@95 1546 .BU
meillo@95 1547 .Sw -[no]preserve
meillo@95 1548 of
meillo@95 1549 .Pn refile
meillo@95 1550 was removed because what use was it anyway?
meillo@98 1551 .QS
meillo@95 1552 Normally when a message is refiled, for each destination
meillo@95 1553 folder it is assigned the number which is one above the current
meillo@95 1554 highest message number in that folder. Use of the
meillo@95 1555 \-preserv [sic!] switch will override this message renaming, and try
meillo@95 1556 to preserve the number of the message. If a conflict for a
meillo@95 1557 particular folder occurs when using the \-preserve switch,
meillo@95 1558 then refile will use the next available message number which
meillo@95 1559 is above the message number you wish to preserve.
meillo@98 1560 .QE
meillo@95 1561 .BU
meillo@95 1562 The removal of the
meillo@95 1563 .Sw -[no]reverse
meillo@95 1564 switches of
meillo@95 1565 .Pn scan
meillo@97 1566 .Ci 8edc5aaf86f9f77124664f6801bc6c6cdf258173
meillo@95 1567 is a bug fix, supported by the comments
meillo@95 1568 ``\-[no]reverse under #ifdef BERK (I really HATE this)''
meillo@95 1569 by Rose and
meillo@95 1570 ``Lists messages in reverse order with the `\-reverse' switch.
meillo@95 1571 This should be considered a bug.'' by Romine in the documentation.
meillo@97 1572 The question remains why neither Rose and Romine had fixed this
meillo@95 1573 bug in the Eighties when they wrote these comments nor has anyone
meillo@95 1574 thereafter.
meillo@93 1575
meillo@93 1576
meillo@93 1577 .ig
meillo@93 1578
meillo@95 1579 forw: [no]dashstuffing(mhl)
meillo@93 1580
meillo@95 1581 mhshow: [no]pause [no]serialonly
meillo@93 1582
meillo@93 1583 mhmail: resent queued
meillo@93 1584 inc: snoop, (pop)
meillo@93 1585
meillo@95 1586 mhl: [no]faceproc folder sleep
meillo@95 1587 [no]dashstuffing(forw) digest list volume number issue number
meillo@93 1588
meillo@95 1589 prompter: [no]doteof
meillo@93 1590
meillo@93 1591 refile: [no]preserve [no]unlink [no]rmmproc
meillo@93 1592
meillo@95 1593 send: [no]forward [no]mime [no]msgid
meillo@93 1594 [no]push split [no]unique (sasl) width snoop [no]dashstuffing
meillo@93 1595 attach attachformat
meillo@93 1596 whatnow: (noedit) attach
meillo@93 1597
meillo@93 1598 slocal: [no]suppressdups
meillo@93 1599
meillo@95 1600 spost: [no]filter [no]backup width [no]push idanno
meillo@93 1601 [no]check(whom) whom(whom)
meillo@93 1602
meillo@93 1603 whom: ???
meillo@93 1604
meillo@95 1605 ..
meillo@93 1606
meillo@93 1607
meillo@93 1608 .ig
meillo@93 1609
meillo@93 1610 .P
meillo@93 1611 In the best case, all switches are unambiguous on the first character,
meillo@93 1612 or on the three-letter prefix for the `no' variants.
meillo@96 1613 Reducing switch prefix collisions, shortens the necessary prefix length
meillo@93 1614 the user must type.
meillo@93 1615 Having less switches helps best.
meillo@93 1616
meillo@93 1617 ..
meillo@58 1618
meillo@95 1619
meillo@102 1620 .\" XXX: whatnow prompt commands
meillo@102 1621
meillo@102 1622
meillo@95 1623
meillo@95 1624
meillo@74 1625 .H1 "Modernizing
meillo@102 1626 .P
meillo@102 1627 The code base of mmh originates from the late Seventies.
meillo@102 1628 Through the Eighties, extensive work had been done on it.
meillo@102 1629 In the Nineties, it had been partly reorganized and extended.
meillo@102 1630 Relicts from each decade have gathered in the code base.
meillo@102 1631 My goal was to modernize the code base.
meillo@102 1632
meillo@102 1633 .P
meillo@102 1634 FIXME functional aspect only here
meillo@102 1635 .P
meillo@102 1636 FIXME ref to `code style' for non-functional aspects.
meillo@58 1637
meillo@58 1638
meillo@100 1639 .H2 "Code Relicts
meillo@0 1640 .P
meillo@102 1641 My position to drop obsolete functionality of mmh to remove old code
meillo@102 1642 is much more revolutional than the nmh community likes it.
meillo@102 1643 Without the need to justify my decisions, I was able to quickly
meillo@20 1644 remove functionality I considered ancient.
meillo@20 1645 The need to discuss my decisions with
meillo@102 1646 peers likely would have slowed this process down.
meillo@102 1647 Of course, I researched if a particular feature really should be dropped.
meillo@102 1648 Having not had any
meillo@12 1649 contact to this feature within my computer life was a first indicator to
meillo@12 1650 drop it, but I also asked others and searched the literature for modern
meillo@102 1651 usage of the feature.
meillo@102 1652 If it appeared to be truly ancient, I dropped it.
meillo@12 1653 The reason for dropping is always part of the commit message in the
meillo@102 1654 version control system.
meillo@102 1655 Thus, it is easy for others to check their
meillo@12 1656 view on the topic with mine and possibly to argue for reinclusion.
meillo@12 1657
meillo@102 1658
meillo@101 1659 .U3 "MMDF maildrop support
meillo@12 1660 .P
meillo@102 1661 I did drop any support for the MMDF maildrop format.
meillo@102 1662 This type of format
meillo@12 1663 is conceptionally similar to the mbox format, but uses four bytes with
meillo@12 1664 value 1 (\fL^A^A^A^A\fP) as message delimiter,
meillo@18 1665 instead of the string ``\fLFrom\ \fP''.
meillo@12 1666 Due to the similarity and mbox being the de-facto standard maildrop
meillo@12 1667 format on Unix, but also due to the larger influence of Sendmail than MMDF,
meillo@12 1668 the MMDF maildrop format had vanished.
meillo@12 1669 .P
meillo@102 1670 The simplifications within the code were only moderate.
meillo@102 1671 Switches could be removed from tools like
meillo@12 1672 .L packf ,
meillo@102 1673 which generate packed mailboxes.
meillo@102 1674 Only one packed mailbox format remained: mbox.
meillo@12 1675 The most important changes affect the equally named mail parsing routine in
meillo@12 1676 .L sbr/m_getfld.c .
meillo@12 1677 The direct MMDF code had been removed, but as now only one packed mailbox
meillo@12 1678 format is left, code structure simplifications are likely possible.
meillo@12 1679 The reason why they are still outstanding is the heavily optimized code
meillo@18 1680 of
meillo@18 1681 .Fu m_getfld() .
meillo@18 1682 Changes beyond a small local scope \(en
meillo@12 1683 which restructuring in its core is \(en cause a high risk of damaging
meillo@102 1684 the intricate workings of the optimized code.
meillo@102 1685 This problem is know to the developers of nmh, too.
meillo@102 1686 They also avoid touching this minefield if possible.
meillo@12 1687
meillo@101 1688 .U3 "UUCP Bang Paths
meillo@12 1689 .P
meillo@12 1690 More questionably than the former topic is the removal of support for the
meillo@102 1691 UUCP bang path address style.
meillo@102 1692 However, the user may translate the bang
meillo@12 1693 paths on retrieval to Internet addresses and the other way on posting
meillo@102 1694 messages.
meillo@102 1695 The former can be done my an MDA like procmail; the latter
meillo@102 1696 by a sendmail wrapper.
meillo@102 1697 This would ensure that any address handling would work as expected.
meillo@102 1698 However, it might just work well without any
meillo@12 1699 such modifications, as mmh does not touch addresses much, in general.
meillo@12 1700 But I can't ensure as I have never used an environment with bang paths.
meillo@12 1701 Also, the behavior might break at any point in further development.
meillo@12 1702
meillo@101 1703 .U3 "Hardcopy terminal support
meillo@12 1704 .P
meillo@12 1705 More of a funny anecdote is the remaining of a check for printing to a
meillo@12 1706 hardcopy terminal until Spring 2012, when I finally removed it.
meillo@12 1707 I surely would be very happy to see such a terminal in action, maybe
meillo@12 1708 actually being able to work on it, but I fear my chances are null.
meillo@12 1709 .P
meillo@12 1710 The check only prevented a pager to be placed between the outputting
meillo@18 1711 program (\c
meillo@18 1712 .Pn mhl )
meillo@102 1713 and the terminal.
meillo@102 1714 This could have been ensured with the
meillo@82 1715 .Sw -nomoreproc
meillo@18 1716 at the command line statically, too.
meillo@12 1717
meillo@101 1718 .U3 "Removed support for header fields
meillo@12 1719 .P
meillo@84 1720 The
meillo@84 1721 .Hd Encrypted
meillo@84 1722 header field had been introduced by RFC\^822, but already
meillo@102 1723 marked legacy in RFC 2822.
meillo@102 1724 It was superseded by FIXME.
meillo@84 1725 Mmh does no more support this header field.
meillo@12 1726 .P
meillo@84 1727 Native support for
meillo@84 1728 .Hd Face
meillo@84 1729 header fields had been removed, as well.
meillo@84 1730 The feature is similar to the
meillo@84 1731 .Hd X-Face
meillo@84 1732 header field in its intent,
meillo@21 1733 but takes a different approach to store the image.
meillo@84 1734 Instead of encoding the image data directly into the header field,
meillo@84 1735 the it contains the hostname and UDP port where the image
meillo@21 1736 date could be retrieved.
meillo@84 1737 Neither
meillo@84 1738 .Hd X-Face
meillo@84 1739 nor the here described
meillo@84 1740 .Hd Face
meillo@84 1741 system
meillo@21 1742 \**
meillo@21 1743 .FS
meillo@21 1744 There is also a newer but different system, invented 2005,
meillo@84 1745 using
meillo@84 1746 .Hd Face
meillo@84 1747 headers.
meillo@84 1748 It is the successor of
meillo@84 1749 .Hd X-Face
meillo@84 1750 providing colored PNG images.
meillo@21 1751 .FE
meillo@21 1752 became well used in the large scale.
meillo@21 1753 It's still possible to use a Face systems,
meillo@21 1754 although mmh does not provide support for any of the different systems
meillo@21 1755 anymore. It's fairly easy to write a small shell script to
meillo@21 1756 extract the embedded or fetch the external Face data and display the image.
meillo@84 1757 Own
meillo@84 1758 .Hd Face
meillo@84 1759 header field can be added into the draft template files.
meillo@21 1760 .P
meillo@84 1761 .Hd Content-MD5
meillo@84 1762 header fields were introduced by RFC\^1864. They provide only
meillo@12 1763 a verification of data corruption during the transfer. By no means can
meillo@12 1764 they ensure verbatim end-to-end delivery of the contents. This is clearly
meillo@12 1765 stated in the RFC. The proper approach to provide verificationability
meillo@12 1766 of content in an end-to-end relationship is the use of digital cryptography
meillo@12 1767 (RFCs FIXME). On the other hand, transfer protocols should ensure the
meillo@12 1768 integrity of the transmission. In combinations these two approaches
meillo@84 1769 make the
meillo@84 1770 .Hd Content-MD5
meillo@84 1771 header field useless. In consequence, I removed
meillo@12 1772 the support for it. By this removal, MD5 computation is not needed
meillo@12 1773 anywhere in mmh. Hence, over 500 lines of code were removed by this one
meillo@84 1774 change. Even if the
meillo@84 1775 .Hd Content-MD5
meillo@84 1776 header field is useful sometimes,
meillo@89 1777 I value its usefulness less than the improvement in maintainability, caused
meillo@12 1778 by the removal.
meillo@12 1779
meillo@101 1780 .U3 "Prompter's Control Keys
meillo@20 1781 .P
meillo@20 1782 The program
meillo@20 1783 .Pn prompter
meillo@20 1784 queries the user to fill in a message form. When used by
meillo@20 1785 .Pn comp
meillo@20 1786 as:
meillo@82 1787 .VS
meillo@82 1788 comp -editor prompter
meillo@82 1789 VE
meillo@20 1790 the resulting behavior is similar to
meillo@20 1791 .Pn mailx .
meillo@51 1792 Apparently,
meillo@20 1793 .Pn prompter
meillo@20 1794 hadn't been touched lately. Otherwise it's hardly explainable why it
meillo@20 1795 still offered the switches
meillo@84 1796 .Sw -erase
meillo@84 1797 .Ar chr
meillo@20 1798 and
meillo@84 1799 .Sw -kill
meillo@84 1800 .Ar chr
meillo@20 1801 to name the characters for command line editing.
meillo@21 1802 The times when this had been necessary are long time gone.
meillo@20 1803 Today these things work out-of-the-box, and if not, are configured
meillo@20 1804 with the standard tool
meillo@20 1805 .Pn stty .
meillo@20 1806
meillo@101 1807 .U3 "Vfork and Retry Loops
meillo@21 1808 .P
meillo@51 1809 MH creates many processes, which is a consequence of the tool chest approach.
meillo@21 1810 In earlier times
meillo@21 1811 .Fu fork()
meillo@21 1812 had been an expensive system call, as the process's whole image needed
meillo@21 1813 to be duplicated. One common case is replacing the image with
meillo@21 1814 .Fu exec()
meillo@21 1815 right after having forked the child process.
meillo@21 1816 To speed up this case, the
meillo@21 1817 .Fu vfork()
meillo@21 1818 system call was invented at Berkeley. It completely omits copying the
meillo@21 1819 image. If the image gets replaced right afterwards then unnecessary
meillo@21 1820 work is omited. On old systems this results in large speed ups.
meillo@21 1821 MH uses
meillo@21 1822 .Fu vfork()
meillo@21 1823 whenever possible.
meillo@21 1824 .P
meillo@21 1825 Memory management units that support copy-on-write semantics make
meillo@21 1826 .Fu fork()
meillo@21 1827 almost as fast as
meillo@21 1828 .Fu vfork()
meillo@21 1829 in the cases when they can be exchanged.
meillo@21 1830 With
meillo@21 1831 .Fu vfork()
meillo@51 1832 being more error-prone and hardly faster, it's preferable to simply
meillo@21 1833 use
meillo@21 1834 .Fu fork()
meillo@21 1835 instead.
meillo@21 1836 .P
meillo@21 1837 Related to the costs of
meillo@21 1838 .Fu fork()
meillo@21 1839 is the probability of its success.
meillo@21 1840 Today on modern systems, the system call will succeed almost always.
meillo@51 1841 In the Eighties on heavy loaded systems, as they were common at
meillo@21 1842 universities, this had been different. Thus, many of the
meillo@21 1843 .Fu fork()
meillo@21 1844 calls were wrapped into loops to retry to fork several times in
meillo@21 1845 short intervals, in case of previous failure.
meillo@21 1846 In mmh, the program aborts at once if the fork failed.
meillo@21 1847 The user can reexecute the command then. This is expected to be a
meillo@21 1848 very rare case on modern systems, especially personal ones, which are
meillo@21 1849 common today.
meillo@21 1850
meillo@12 1851
meillo@58 1852 .H2 "Attachments
meillo@22 1853 .P
meillo@101 1854 The mind model of email attachments is unrelated to MIME.
meillo@101 1855 Although the MIME RFCs (2045 through 2049) define the technical
meillo@101 1856 requirements for having attachments, they do not mention the the word
meillo@101 1857 ``attachment''.
meillo@101 1858 Instead of attachments, MIME talks about ``multi-part message bodies''
meillo@101 1859 [RFC\|2045], a more general concept.
meillo@101 1860 Multi-part messages are messages
meillo@101 1861 ``in which one or more different
meillo@101 1862 sets of data are combined in a single body''
meillo@101 1863 [RFC\|2046].
meillo@101 1864 MIME keeps its descriptions generic;
meillo@101 1865 it does not imply specific usage models.
meillo@101 1866 In email one usage model became prevalent: attachments.
meillo@101 1867 The idea is having a main text document with files of arbitrary kind
meillo@101 1868 attached to it.
meillo@101 1869 In MIME terms, this is a multi-part message having a text part first
meillo@101 1870 and parts of arbitray type following.
meillo@101 1871 .P
meillo@101 1872 MH's MIME support is a direct implementation of the RFCs.
meillo@101 1873 The perception of the topic described in the RFCs is clearly visible
meillo@101 1874 in MH's implementation.
meillo@101 1875 Thus, MH had all the MIME features but no idea of attachments.
meillo@101 1876 Today, however, users don't need all the MIME features but they want
meillo@101 1877 convenient attachment handling.
meillo@102 1878
meillo@102 1879 .U3 "Composing MIME Messages
meillo@102 1880 .P
meillo@102 1881 In order to improve the situation on the message composing side,
meillo@102 1882 Jon Steinhart had added an attachment system to nmh in 2002.
meillo@101 1883 .Ci 7480dbc14bc90f2d872d434205c0784704213252
meillo@102 1884 In the file
meillo@102 1885 .Fn docs/README-ATTACHMENTS ,
meillo@102 1886 he described his motivation to do so as such:
meillo@101 1887 .QS
meillo@101 1888 Although nmh contains the necessary functionality for MIME message handing,
meillo@101 1889 the interface to this functionality is pretty obtuse.
meillo@101 1890 There's no way that I'm ever going to convince my partner to write
meillo@101 1891 .Pn mhbuild
meillo@101 1892 composition files!
meillo@101 1893 .QE
meillo@102 1894 .LP
meillo@102 1895 With this change, the mind model of attachments entered nmh.
meillo@102 1896 In the same document:
meillo@101 1897 .QS
meillo@101 1898 These changes simplify the task of managing attachments on draft files.
meillo@101 1899 They allow attachments to be added, listed, and deleted.
meillo@101 1900 MIME messages are automatically created when drafts with attachments
meillo@101 1901 are sent.
meillo@101 1902 .QE
meillo@102 1903 .LP
meillo@102 1904 Unfortunately, the attachment system,
meillo@102 1905 like any new facilities in nmh,
meillo@102 1906 was deactive by default.
meillo@101 1907 .P
meillo@101 1908 During my work in Argentina, I tried to improve the attachment system.
meillo@102 1909 But, because of great opposition in the nmh community,
meillo@102 1910 my patch died as a proposal on the mailing list, after long discussions.
meillo@101 1911 .[
meillo@101 1912 nmh-workers attachment proposal
meillo@101 1913 .]
meillo@102 1914 In Januar 2012, I extended the patch and applied it to mmh.
meillo@101 1915 .Ci 8ff284ff9167eff8f5349481529332d59ed913b1
meillo@102 1916 In mmh, the attachment system is active by default.
meillo@102 1917 Instead of command line switches, the
meillo@102 1918 .Pe Attachment-Header
meillo@102 1919 profile entry is used to specify
meillo@102 1920 the name of the attachment header field.
meillo@102 1921 It is pre-defined to
meillo@102 1922 .Hd Attach .
meillo@101 1923 .P
meillo@101 1924 To add an attachment to a draft, simply add an attachment header:
meillo@101 1925 .VS
meillo@101 1926 To: bob
meillo@101 1927 Subject: The file you wanted
meillo@101 1928 Attach: /path/to/the/file-bob-wanted
meillo@101 1929 --------
meillo@101 1930 Here it is.
meillo@101 1931 VE
meillo@101 1932 The header field can be added to the draft manually in the editor,
meillo@102 1933 or by using the `attach' command at the WhatNow prompt, or
meillo@102 1934 non-interactively with
meillo@101 1935 .Pn anno :
meillo@101 1936 .VS
meillo@102 1937 anno -append -nodate -component Attach -text /path/to/attachment
meillo@101 1938 VE
meillo@102 1939 Drafts with attachment headers are converted to MIME automatically by
meillo@102 1940 .Pn send .
meillo@102 1941 The conversion to MIME is invisible to the user.
meillo@102 1942 The draft stored in the draft folder is always in source form, with
meillo@101 1943 attachment headers.
meillo@101 1944 If the MIMEification fails, for instance because the file to attach
meillo@101 1945 is not accessible, the original draft is not changed.
meillo@101 1946 .P
meillo@102 1947 The attachment system handles the forwarding of messages, too.
meillo@101 1948 If the attachment header value starts with a plus character (`+'),
meillo@101 1949 like in
meillo@101 1950 .Cl "Attach: +bob 30 42" ,
meillo@101 1951 The given messages in the specified folder will be attached.
meillo@101 1952 This allowed to simplify
meillo@101 1953 .Pn forw .
meillo@101 1954 .Ci f41f04cf4ceca7355232cf7413e59afafccc9550
meillo@101 1955 .P
meillo@101 1956 Closely related to attachments is non-ASCII text content,
meillo@101 1957 because it requires MIME too.
meillo@102 1958 In nmh, the user needed to call `mime' at the WhatNow prompt
meillo@101 1959 to have the draft converted to MIME.
meillo@102 1960 This was necessary whenever the draft contained non-ASCII characters.
meillo@101 1961 If the user did not call `mime', a broken message would be sent.
meillo@101 1962 Therefore, the
meillo@101 1963 .Pe automimeproc
meillo@101 1964 profile entry could be specified to have the `mime' command invoked
meillo@102 1965 automatically each time.
meillo@101 1966 Unfortunately, this approach conflicted with with attachment system
meillo@101 1967 because the draft would already be in MIME format at the time
meillo@101 1968 when the attachment system wanted to MIMEify it.
meillo@102 1969 To use nmh's attachment system, `mime' must not be called at the
meillo@102 1970 WhatNow prompt and
meillo@101 1971 .Pe automimeproc
meillo@102 1972 must not be set in the profile.
meillo@101 1973 But then the case of non-ASCII text without attachment headers was
meillo@101 1974 not caught.
meillo@102 1975 All in all, the solution was complex and irritating.
meillo@102 1976 My patch from December 2010 would have simplified the situation.
meillo@102 1977 .P
meillo@101 1978 Mmh's current solution is even more elaborate.
meillo@101 1979 Any necessary MIMEification is done automatically.
meillo@101 1980 There is no `mime' command at the WhatNow prompt anymore.
meillo@102 1981 The draft will be converted automatically to MIME when either an
meillo@102 1982 attachment header or non-ASCII text is present.
meillo@101 1983 Further more, the special meaning of the hash character (`#')
meillo@102 1984 at line beginnings in the draft message is removed.
meillo@102 1985 Users need not at all deal with the whole topic.
meillo@101 1986 .P
meillo@102 1987 Although the new approach does not anymore support arbitrary MIME
meillo@102 1988 compositions directly, the full power of
meillo@101 1989 .Pn mhbuild
meillo@101 1990 can still be accessed.
meillo@102 1991 Given no attachment headers are included, the user can create
meillo@101 1992 .Pn mhbuild
meillo@102 1993 composition drafts like in nmh.
meillo@101 1994 Then, at the WhatNow prompt, he needs to invoke
meillo@101 1995 .Cl "edit mhbuild
meillo@101 1996 to convert it to MIME.
meillo@102 1997 Because the resulting draft does neither contain non-aASCII characters
meillo@102 1998 nor has it attachment headers, the attachment system will not touch it.
meillo@101 1999 .P
meillo@101 2000 The approach taken in mmh is taylored towards todays most common case:
meillo@101 2001 a text part with possibly attachments.
meillo@102 2002 This case is simplified a lot for users.
meillo@102 2003
meillo@102 2004 .U3 "MIME Type Guessing
meillo@102 2005 .P
meillo@102 2006 The use of
meillo@101 2007 .Pn mhbuild
meillo@102 2008 composition drafts had one notable advantage over attachment headers
meillo@102 2009 from the programmer's point of view: The user provides the appropriate
meillo@102 2010 MIME types for files to include.
meillo@102 2011 The attachment system needs to find out the correct MIME type itself.
meillo@102 2012 This is a difficult task, yet it spares the user irritating work.
meillo@102 2013 Determining the correct MIME type of content is partly mechanical,
meillo@102 2014 partly intelligent work.
meillo@102 2015 Forcing the user to find out the correct MIME type,
meillo@102 2016 forces him to do partly mechanical work.
meillo@102 2017 Letting the computer do the work, can lead to bad choices for difficult
meillo@102 2018 content.
meillo@102 2019 For mmh, the latter option was chosen.
meillo@102 2020 .P
meillo@102 2021 Determining the MIME type by the suffix of the file name is a dumb
meillo@102 2022 approach, yet it is simple to implement and provides good results
meillo@102 2023 for the common cases.
meillo@102 2024 Mmh implements this approach in the
meillo@102 2025 .Pn print-mimetype
meillo@102 2026 script.
meillo@102 2027 Using it is the default choice.
meillo@102 2028 .P
meillo@102 2029 A far better but less portable approach is the use of
meillo@102 2030 .Pn file .
meillo@102 2031 This standard tool tries to determine the type of files.
meillo@102 2032 Unfortunately, its capabilities and accuracy varies from system to system.
meillo@102 2033 Additionally, its output was only intended for human beings,
meillo@102 2034 but not to be used by programs.
meillo@102 2035 It varies much.
meillo@102 2036 Nevertheless, modern versions of GNU
meillo@102 2037 .Pn file ,
meillo@102 2038 which is prevalent on the popular GNU/Linux systems,
meillo@102 2039 provides MIME type output in machine-readable form.
meillo@102 2040 Although this solution is highly system-dependent,
meillo@102 2041 it solves the difficult problem well.
meillo@102 2042 On systems where GNU
meillo@102 2043 .Pn file ,
meillo@102 2044 version 5.04 or higher, is available it should be used.
meillo@102 2045 One needs to specify the following profile entry to do so:
meillo@102 2046 .VS
meillo@102 2047 Mime-Type-Query: file -b --mime
meillo@102 2048 VE
meillo@102 2049 .LP
meillo@102 2050 Other versions of
meillo@102 2051 .Pn file
meillo@102 2052 might possibly be usable with wrapper scripts to reformat the output.
meillo@102 2053 The diversity among
meillo@102 2054 .Pn file
meillo@102 2055 implementations is great; one needs to check the local variant.
meillo@102 2056 .P
meillo@102 2057 If no MIME type can be determined, text content gets sent as
meillo@102 2058 `text/plain' and anything else under the generic fall-back type
meillo@102 2059 `application/octet-stream'.
meillo@102 2060 It is not possible in mmh to override the automatic MIME type guessing
meillo@102 2061 for a specific file.
meillo@102 2062 To do so, the user would need to know in advance for which file
meillo@102 2063 the automatic guessing does fail, or the system would require interaction.
meillo@102 2064 I consider both cases impractical.
meillo@102 2065 The existing solution should be sufficient.
meillo@102 2066 If not, the user may always fall back to
meillo@102 2067 .Pn mhbuild
meillo@102 2068 composition drafts and ignore the attachment system.
meillo@101 2069
meillo@102 2070
meillo@102 2071 .U3 "Storing Attachments
meillo@102 2072 .P
meillo@102 2073 FIXME
meillo@102 2074
meillo@102 2075
meillo@102 2076 .U3 "Showing MIME Messages
meillo@102 2077 .P
meillo@102 2078 FIXME
meillo@102 2079
meillo@58 2080
meillo@58 2081
meillo@58 2082 .H2 "Digital Cryptography
meillo@22 2083 .P
meillo@58 2084 Signing and encryption.
meillo@58 2085
meillo@58 2086
meillo@102 2087
meillo@102 2088 .H2 "Modern Defaults
meillo@22 2089 .P
meillo@102 2090 Just to give one example, for me it took one year of using nmh
meillo@102 2091 before I became aware of the existence of the attachment system.
meillo@102 2092 One could argue that this fact disqualifies my reading of the
meillo@102 2093 documentation.
meillo@102 2094 If I would have installed nmh from source back then, I could agree.
meillo@102 2095 Yet I had used a prepackaged version and had expected that it would
meillo@102 2096 just work.
meillo@58 2097
meillo@58 2098
meillo@58 2099
meillo@100 2100 .H1 "Code Style
meillo@22 2101 .P
meillo@58 2102 foo
meillo@58 2103
meillo@58 2104
meillo@58 2105 .H2 "Standard Code
meillo@22 2106 .P
meillo@58 2107 POSIX
meillo@22 2108
meillo@102 2109 .U3 "Converting to Standard Code
meillo@102 2110 .P
meillo@102 2111 One part of this task was converting obsolete code constructs
meillo@102 2112 to standard constructs.
meillo@102 2113 As I'm not even thirty years old and have no more than seven years of
meillo@102 2114 Unix experience, I needed to learn about the history in retrospective.
meillo@102 2115 Older people likely have used those ancient constructs themselves
meillo@102 2116 and have suffered from their incompatibilities and have longed for
meillo@102 2117 standardization.
meillo@102 2118 Unfortunately, I have only read that others had done so.
meillo@102 2119 This put me in a much more difficult positions when working on the old
meillo@102 2120 code.
meillo@102 2121 I needed to recherche what other would have known by heart from
meillo@102 2122 experience.
meillo@102 2123 All my programming experience comes from a time past ANSI C
meillo@102 2124 and past POSIX.
meillo@102 2125 Although I knew about the times before, I took the
meillo@102 2126 current state implicitly for granted most of the time.
meillo@102 2127 .P
meillo@102 2128 Being aware of
meillo@102 2129 these facts, I rather let people with more historic experience solve the
meillo@102 2130 task of converting the ancient code constructs to standardized ones.
meillo@102 2131 Luckily, Lyndon Nerenberg focused on this task at the nmh project.
meillo@102 2132 He converted large parts of the code to POSIX constructs, removing
meillo@102 2133 the conditionals compilation for now standardized features.
meillo@102 2134 I'm thankful for this task being solved. I only pulled the changes into
meillo@102 2135 mmh.
meillo@102 2136
meillo@102 2137
meillo@102 2138
meillo@22 2139
meillo@58 2140 .H2 "Separation
meillo@14 2141
meillo@58 2142 .U2 "MH Directory Split
meillo@0 2143 .P
meillo@19 2144 In MH and nmh, a personal setup had consisted of two parts:
meillo@19 2145 The MH profile, named
meillo@19 2146 .Fn \&.mh_profile
meillo@19 2147 and being located directly in the user's home directory.
meillo@19 2148 And the MH directory, where all his mail messages and also his personal
meillo@19 2149 forms, scan formats, other configuration files are stored. The location
meillo@19 2150 of this directory could be user-chosen. The default was to name it
meillo@19 2151 .Fn Mail
meillo@19 2152 and have it directly in the home directory.
meillo@19 2153 .P
meillo@19 2154 I've never liked the data storage and the configuration to be intermixed.
meillo@19 2155 They are different kinds of data. One part, are the messages,
meillo@19 2156 which are the data to operate on. The other part, are the personal
meillo@19 2157 configuration files, which are able to change the behavior of the operations.
meillo@19 2158 The actual operations are defined in the profile, however.
meillo@19 2159 .P
meillo@19 2160 When storing data, one should try to group data by its type.
meillo@19 2161 There's sense in the Unix file system hierarchy, where configuration
meillo@19 2162 file are stored separate (\c
meillo@19 2163 .Fn /etc )
meillo@19 2164 to the programs (\c
meillo@19 2165 .Fn /bin
meillo@19 2166 and
meillo@19 2167 .Fn /usr/bin )
meillo@19 2168 to their sources (\c
meillo@19 2169 .Fn /usr/src ).
meillo@19 2170 Such separation eases the backup management, for instance.
meillo@19 2171 .P
meillo@19 2172 In mmh, I've reorganized the file locations.
meillo@19 2173 Still there are two places:
meillo@19 2174 There's the mail storage directory, which, like in MH, contains all the
meillo@19 2175 messages, but, unlike in MH, nothing else.
meillo@19 2176 Its location still is user-chosen, with the default name
meillo@19 2177 .Fn Mail ,
meillo@19 2178 in the user's home directory. This is much similar to the case in nmh.
meillo@19 2179 The configuration files, however, are grouped together in the new directory
meillo@19 2180 .Fn \&.mmh
meillo@19 2181 in the user's home directory.
meillo@19 2182 The user's profile now is a file, named
meillo@19 2183 .Fn profile ,
meillo@19 2184 in this mmh directory.
meillo@19 2185 Consistently, the context file and all the personal forms, scan formats,
meillo@19 2186 and the like, are also there.
meillo@19 2187 .P
meillo@19 2188 The naming changed with the relocation.
meillo@19 2189 The directory where everything, except the profile, had been stored (\c
meillo@19 2190 .Fn $HOME/Mail ),
meillo@19 2191 used to be called \fIMH directory\fP. Now, this directory is called the
meillo@19 2192 user's \fImail storage\fP. The name \fImmh directory\fP is now given to
meillo@19 2193 the new directory
meillo@19 2194 (\c
meillo@19 2195 .Fn $HOME/.mmh ),
meillo@19 2196 containing all the personal configuration files.
meillo@19 2197 .P
meillo@19 2198 The separation of the files by type of content is logical and convenient.
meillo@19 2199 There are no functional differences as any possible setup known to me
meillo@19 2200 can be implemented with both approaches, although likely a bit easier
meillo@19 2201 with the new approach. The main goal of the change had been to provide
meillo@19 2202 sensible storage locations for any type of personal mmh file.
meillo@19 2203 .P
meillo@19 2204 In order for one user to have multiple MH setups, he can use the
meillo@19 2205 environment variable
meillo@19 2206 .Ev MH
meillo@19 2207 the point to a different profile file.
meillo@19 2208 The MH directory (mail storage plus personal configuration files) is
meillo@19 2209 defined by the
meillo@19 2210 .Pe Path
meillo@19 2211 profile entry.
meillo@19 2212 The context file could be defined by the
meillo@19 2213 .Pe context
meillo@19 2214 profile entry or by the
meillo@19 2215 .Ev MHCONTEXT
meillo@19 2216 environment variable.
meillo@19 2217 The latter is useful to have a distinct context (e.g. current folders)
meillo@19 2218 in each terminal window, for instance.
meillo@19 2219 In mmh, there are three environment variables now.
meillo@19 2220 .Ev MMH
meillo@19 2221 may be used to change the location of the mmh directory.
meillo@19 2222 .Ev MMHP
meillo@19 2223 and
meillo@19 2224 .Ev MMHC
meillo@19 2225 change the profile and context files, respectively.
meillo@19 2226 Besides providing a more consistent feel (which simply is the result
meillo@19 2227 of being designed anew), the set of personal configuration files can
meillo@19 2228 be chosen independently from the profile (including mail storage location)
meillo@19 2229 and context, now. Being it relevant for practical use or not, it
meillo@19 2230 de-facto is an improvement. However, the main achievement is the
meillo@19 2231 split between mail storage and personal configuration files.
meillo@17 2232
meillo@0 2233
meillo@58 2234 .H2 "Modularization
meillo@0 2235 .P
meillo@58 2236 whatnowproc
meillo@0 2237 .P
meillo@49 2238 The \fIMH library\fP
meillo@49 2239 .Fn libmh.a
meillo@49 2240 collects a bunch of standard functions that many of the MH tools need,
meillo@49 2241 like reading the profile or context files.
meillo@49 2242 This doesn't hurt the separation.
meillo@49 2243
meillo@58 2244
meillo@58 2245 .H2 "Style
meillo@58 2246 .P
meillo@58 2247 Code layout, goto, ...
meillo@58 2248
meillo@102 2249 .P
meillo@102 2250 anno rework
meillo@102 2251
meillo@58 2252
meillo@58 2253
meillo@58 2254
meillo@89 2255 .H1 "Concept Exploitation/Homogeneity
meillo@58 2256
meillo@58 2257
meillo@58 2258 .H2 "Draft Folder
meillo@58 2259 .P
meillo@58 2260 Historically, MH provided exactly one draft message, named
meillo@58 2261 .Fn draft
meillo@58 2262 and
meillo@58 2263 being located in the MH directory. When starting to compose another message
meillo@58 2264 before the former one was sent, the user had been questioned whether to use,
meillo@58 2265 refile or replace the old draft. Working on multiple drafts at the same time
meillo@58 2266 was impossible. One could only work on them in alteration by refiling the
meillo@58 2267 previous one to some directory and fetching some other one for reediting.
meillo@58 2268 This manual draft management needed to be done each time the user wanted
meillo@58 2269 to switch between editing one draft to editing another.
meillo@58 2270 .P
meillo@58 2271 To allow true parallel editing of drafts, in a straight forward way, the
meillo@58 2272 draft folder facility exists. It had been introduced already in July 1984
meillo@58 2273 by Marshall T. Rose. The facility was deactivated by default.
meillo@58 2274 Even in nmh, the draft folder facility remained deactivated by default.
meillo@58 2275 At least, Richard Coleman added the man page
meillo@58 2276 .Mp mh-draft(5)
meillo@58 2277 to document
meillo@58 2278 the feature well.
meillo@58 2279 .P
meillo@58 2280 The only advantage of not using the draft folder facility is the static
meillo@89 2281 name of the draft file. This could be an issue for MH front-ends like mh-e.
meillo@58 2282 But as they likely want to provide working on multiple drafts in parallel,
meillo@58 2283 the issue is only concerning compatibility. The aim of nmh to stay compatible
meillo@58 2284 prevented the default activation of the draft folder facility.
meillo@58 2285 .P
meillo@58 2286 On the other hand, a draft folder is the much more natural concept than
meillo@58 2287 a draft message. MH's mail storage consists of folders and messages,
meillo@58 2288 the messages named with ascending numbers. A draft message breaks with this
meillo@58 2289 concept by introducing a message in a file named
meillo@58 2290 .Fn draft .
meillo@58 2291 This draft
meillo@58 2292 message is special. It can not be simply listed with the available tools,
meillo@58 2293 but instead requires special switches. I.e. corner-cases were
meillo@58 2294 introduced. A draft folder, in contrast, does not introduce such
meillo@58 2295 corner-cases. The available tools can operate on the messages within that
meillo@58 2296 folder like on any messages within any mail folders. The only difference
meillo@58 2297 is the fact that the default folder for
meillo@58 2298 .Pn send
meillo@58 2299 is the draft folder,
meillo@58 2300 instead of the current folder, like for all other tools.
meillo@58 2301 .P
meillo@58 2302 The trivial part of the change was activating the draft folder facility
meillo@58 2303 by default and setting a default name for this folder. Obviously, I chose
meillo@58 2304 the name
meillo@58 2305 .Fn +drafts .
meillo@58 2306 This made the
meillo@82 2307 .Sw -draftfolder
meillo@58 2308 and
meillo@82 2309 .Sw -draftmessage
meillo@58 2310 switches useless, and I could remove them.
meillo@58 2311 The more difficult but also the part that showed the real improvement,
meillo@58 2312 was updating the tools to the new concept.
meillo@82 2313 .Sw -draft
meillo@58 2314 switches could
meillo@58 2315 be dropped, as operating on a draft message became indistinguishable to
meillo@58 2316 operating on any other message for the tools.
meillo@58 2317 .Pn comp
meillo@58 2318 still has its
meillo@82 2319 .Sw -use
meillo@58 2320 switch for switching between its two modes: (1) Compose a new
meillo@58 2321 draft, possibly by taking some existing message as a form. (2) Modify
meillo@58 2322 an existing draft. In either case, the behavior of
meillo@58 2323 .Pn comp is
meillo@58 2324 deterministic. There is no more need to query the user. I consider this
meillo@58 2325 a major improvement. By making
meillo@58 2326 .Pn send
meillo@58 2327 simply operate on the current
meillo@58 2328 message in the draft folder by default, with message and folder both
meillo@58 2329 overridable by specifying them on the command line, it is now possible
meillo@58 2330 to send a draft anywhere within the storage by simply specifying its folder
meillo@58 2331 and name.
meillo@58 2332 .P
meillo@58 2333 All theses changes converted special cases to regular cases, thus
meillo@58 2334 simplifying the tools and increasing the flexibility.
meillo@58 2335
meillo@58 2336
meillo@58 2337 .H2 "Trash Folder
meillo@58 2338 .P
meillo@58 2339 Similar to the situation for drafts is the situation for removed messages.
meillo@58 2340 Historically, a message was deleted by renaming. A specific
meillo@58 2341 \fIbackup prefix\fP, often comma (\c
meillo@58 2342 .Fn , )
meillo@58 2343 or hash (\c
meillo@58 2344 .Fn # ),
meillo@58 2345 being prepended to the file name. Thus, MH wouldn't recognize the file
meillo@58 2346 as a message anymore, as only files whose name consists of digits only
meillo@58 2347 are treated as messages. The removed messages remained as files in the
meillo@58 2348 same directory and needed some maintenance job to truly delete them after
meillo@58 2349 some grace time. Usually, by running a command similar to
meillo@82 2350 .VS
meillo@82 2351 find /home/user/Mail -ctime +7 -name ',*' | xargs rm
meillo@82 2352 VE
meillo@58 2353 in a cron job. Within the grace time interval
meillo@58 2354 the original message could be restored by stripping the
meillo@58 2355 the backup prefix from the file name. If however, the last message of
meillo@58 2356 a folder is been removed \(en say message
meillo@58 2357 .Fn 6
meillo@58 2358 becomes file
meillo@58 2359 .Fn ,6
meillo@58 2360 \(en and a new message enters the same folder, thus the same
meillo@58 2361 numbered being given again \(en in our case
meillo@58 2362 .Fn 6
meillo@58 2363 \(en, if that one
meillo@58 2364 is removed too, then the backup of the former message gets overwritten.
meillo@58 2365 Thus, the ability to restore removed messages does not only depend on
meillo@58 2366 the ``sweeping cron job'' but also on the removing of further messages.
meillo@58 2367 This is undesirable, because the real mechanism is hidden from the user
meillo@58 2368 and the consequences of further removals are not always obvious.
meillo@58 2369 Further more, the backup files are scattered within the whole mail
meillo@58 2370 storage, instead of being collected at one place.
meillo@58 2371 .P
meillo@58 2372 To improve the situation, the profile entry
meillo@58 2373 .Pe rmmproc
meillo@58 2374 (previously named
meillo@58 2375 .Pe Delete-Prog )
meillo@58 2376 was introduced, very early.
meillo@58 2377 It could be set to any command, which would care for the mail removal
meillo@58 2378 instead of taking the default action, described above.
meillo@58 2379 Refiling the to-be-removed files to some garbage folder was a common
meillo@58 2380 example. Nmh's man page
meillo@58 2381 .Mp rmm(1)
meillo@58 2382 proposes
meillo@58 2383 .Cl "refile +d
meillo@58 2384 to move messages to the garbage folder and
meillo@58 2385 .Cl "rm `mhpath +d all`
meillo@58 2386 the empty the garbage folder.
meillo@58 2387 Managing the message removal this way is a sane approach. It keeps
meillo@58 2388 the removed messages in one place, makes it easy to remove the backup
meillo@58 2389 files, and, most important, enables the user to use the tools of MH
meillo@58 2390 itself to operate on the removed messages. One can
meillo@58 2391 .Pn scan
meillo@58 2392 them,
meillo@58 2393 .Pn show
meillo@58 2394 them, and restore them with
meillo@58 2395 .Pn refile .
meillo@58 2396 There's no more
meillo@58 2397 need to use
meillo@58 2398 .Pn mhpath
meillo@58 2399 to switch over from MH tools to Unix tools \(en MH can do it all itself.
meillo@58 2400 .P
meillo@58 2401 This approach matches perfect with the concepts of MH, thus making
meillo@58 2402 it powerful. Hence, I made it the default. And even more, I also
meillo@58 2403 removed the old backup prefix approach, as it is clearly less powerful.
meillo@58 2404 Keeping unused alternative in the code is a bad choice as they likely
meillo@58 2405 gather bugs, by not being constantly tested. Also, the increased code
meillo@58 2406 size and more conditions crease the maintenance costs. By strictly
meillo@58 2407 converting to the trash folder approach, I simplified the code base.
meillo@58 2408 .Pn rmm
meillo@58 2409 calls
meillo@58 2410 .Pn refile
meillo@58 2411 internally to move the to-be-removed
meillo@58 2412 message to the trash folder (\c
meillo@58 2413 .Fn +trash
meillo@58 2414 by default). Messages
meillo@58 2415 there can be operated on like on any other message in the storage.
meillo@58 2416 The sweep clean, one can use
meillo@82 2417 .Cl "rmm -unlink +trash a" ,
meillo@58 2418 where the
meillo@82 2419 .Sw -unlink
meillo@58 2420 switch causes the files to be truly unliked instead
meillo@58 2421 of moved to the trash folder.
meillo@58 2422
meillo@58 2423
meillo@58 2424 .H2 "Path Notations
meillo@58 2425 .P
meillo@58 2426 foo
meillo@58 2427
meillo@58 2428
meillo@58 2429 .H2 "MIME Integration
meillo@58 2430 .P
meillo@58 2431 user-visible access to whole messages and MIME parts are inherently
meillo@58 2432 different
meillo@58 2433
meillo@58 2434
meillo@58 2435 .H2 "Of One Cast
meillo@58 2436 .P