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1 .H0 "Discussion
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2 .P
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3 This main chapter discusses the practical work done in the mmh project.
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4 It is structured along the goals to achieve.
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5 The concrete work done
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6 is described in the examples of how the general goals were achieved.
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7 The discussion compares the current version of mmh with the state of
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8 nmh just before the mmh project started, i.e. Fall 2011.
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9 Current changes of nmh will be mentioned only as side notes.
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10 .\" XXX where do I discuss the parallel development of nmh?
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11
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12
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13
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14 .H1 "Stream-Lining
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15
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16 .P
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17 MH had been considered an all-in-one system for mail handling.
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18 The community around nmh has a similar understanding.
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19 In fundamental difference, mmh shall be a MUA only.
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20 I believe that the development of all-in-one mail systems is obsolete.
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21 Today, email is too complex to be fully covered by single projects.
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22 Such a project won't be able to excel in all aspects.
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23 Instead, the aspects of email should be covered my multiple projects,
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24 which then can be combined to form a complete system.
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25 Excellent implementations for the various aspects of email exist already.
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26 Just to name three examples: Postfix is a specialized MTA,
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27 Procmail is a specialized MDA, and Fetchmail is a specialized MRA.
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28 I believe that it is best to use such specialized tools instead of
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29 providing the same function again as a side-component in the project.
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30 .P
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31 Doing something well, requires to focus on a small set of specific aspects.
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32 Under the assumption that focused development produces better results
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33 in the particular area, specialized projects will be superior
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34 in their field of focus.
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35 Hence, all-in-one mail system projects \(en no matter if monolithic
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36 or modular \(en will never be the best choice in any of the fields.
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37 Even in providing the best consistent all-in-one system they are likely
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38 to be beaten by projects that focus only on integrating existing mail
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39 components to a homogeneous system.
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40 .P
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41 The limiting resource in Free Software community development
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42 is usually man power.
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43 If the development power is spread over a large development area,
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44 it becomes even more difficult to compete with the specialists in the
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45 various fields.
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46 The concrete situation for MH-based mail systems is even tougher,
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47 given the small and aged community, including both developers and users,
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48 it has.
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49 .P
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50 In consequence, I believe that the available development resources
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51 should focus on the point where MH is most unique.
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52 This is clearly the user interface \(en the MUA.
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53 Peripheral parts should be removed to stream-line mmh for the MUA task.
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54
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55
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56 .H2 "Mail Transfer Facilities
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57 .P
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58 In contrast to nmh, which also provides mail submission and mail retrieval
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59 agents, mmh is a MUA only.
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60 This general difference initiated the development of mmh.
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61 Removing the mail transfer facilities had been the first work task
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62 in the mmh project.
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63 .P
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64 Focusing on one mail agent role only is motivated by Eric Allman's
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65 experience with Sendmail.
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66 He identified limiting Sendmail the MTA task had be one reason for
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67 its success:
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68 .[ [
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69 costales sendmail
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70 .], p. xviii]
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71 .QS
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72 Second, I limited myself to the routing function \(en
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73 I wouldn't write user agents or delivery back-ends.
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74 This was a departure of the dominant through of the time,
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75 in which routing logic, local delivery, and often the network code
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76 were incorporated directly into the user agents.
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77 .QE
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78 .P
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79 In mmh, the Mail Submission Agent (MSA) is called
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80 \fIMessage Transfer Service\fP (MTS).
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81 This facility, implemented by the
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82 .Pn post
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83 command, established network connections and spoke SMTP to submit
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84 messages for relay to the outside world.
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85 The changes in email demanded changes in this part of nmh too.
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86 Encryption and authentication for network connections
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87 needed to be supported, hence TLS and SASL were introduced into nmh.
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88 This added complexity to nmh without improving it in its core functions.
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89 Also, keeping up with recent developments in the field of
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90 mail transfer requires development power and specialists.
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91 In mmh this whole facility was simply cut off.
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92 .Ci f6aa95b724fd8c791164abe7ee5468bf5c34f226
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93 .Ci fecd5d34f65597a4dfa16aeabea7d74b191532c3
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94 .Ci 156d35f6425bea4c1ed3c4c79783dc613379c65b
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95 Instead, mmh depends on an external MSA.
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96 The only outgoing interface available to mmh is the
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97 .Pn sendmail
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98 command, which almost any MSA provides.
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99 If not, a wrapper program can be written.
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100 It must read the message from the standard input, extract the
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101 recipient addresses from the message header, and hand the message
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102 over to the MSA.
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103 For example, a wrapper script for qmail would be:
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104 .VS
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105 #!/bin/sh
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106 # ignore command line arguments
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107 exec qmail-inject
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108 VE
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109 The requirement to parse the recipient addresses out of the message header
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110 is likely to be removed in the future.
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111 Then mmh would give the recipient addresses as command line arguments.
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112 This appears to be the better interface.
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113 .\" XXX implement it
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114 .P
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115 To retrieve mail, the
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116 .Pn inc
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117 command acted as Mail Retrieval Agent (MRA).
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118 It established network connections
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119 and spoke POP3 to retrieve mail from remote servers.
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120 As with mail submission, the network connections required encryption and
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121 authentication, thus TLS and SASL were added.
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122 Support for message retrieval through IMAP will become necessary
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123 to be added soon, too, and likewise for any other changes in mail transfer.
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124 Not so for mmh because it has dropped the support for retrieving mail
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125 from remote locations.
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126 .Ci ab7b48411962d26439f92f35ed084d3d6275459c
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127 Instead, it depends on an external tool to cover this task.
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128 In mmh exist two paths for messages to enter mmh's mail storage:
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129 (1) Mail can be incorporated with
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130 .Pn inc
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131 from the system maildrop, or (2) with
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132 .Pn rcvstore
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133 by reading them, one at a time, from the standard input.
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134 .P
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135 With the removal of the MSA and MRA, mmh converted from an all-in-one
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136 mail system to being a MUA only.
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137 Now, of course, mmh depends on third-party software.
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138 An external MSA is required to transfer mail to the outside world;
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139 an external MRA is required to retrieve mail from remote machines.
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140 There exist excellent implementations of such software,
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141 which do this specific task likely better than the internal
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142 versions had done it.
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143 Also, the best suiting programs can be freely chosen.
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144 .P
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145 As it had already been possible to use an external MSA or MRA,
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146 why not keep the internal version for convenience?
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147 The question whether there is sense in having a fall-back pager in all
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148 the command line tools, for the cases when
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149 .Pn more
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150 or
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151 .Pn less
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152 aren't available, appears to be ridiculous.
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153 Of course, MSAs and MRAs are more complex than text pagers
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154 and not necessarily available but still the concept of orthogonal
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155 design holds: ``Write programs that do one thing and do it well.''
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156 .[
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157 mcilroy unix phil
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158 p. 53
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159 .]
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160 .[
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161 mcilroy bstj foreword
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162 .]
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163 Here, this part of the Unix philosophy was applied not only
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164 to the programs but to the project itself.
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165 In other words:
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166 ``Develop projects that focus on one thing and do it well.''
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167 Projects grown complex should be split for the same reasons programs grown
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168 complex should be split.
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169 If it is conceptionally more elegant to have the MSA and MRA as
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170 separate projects then they should be separated.
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171 This is the case here, in my opinion.
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172 The RFCs propose this separation by clearly distinguishing the different
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173 mail handling tasks.
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174 .[
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175 rfc 821
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176 .]
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177 The small interfaces between the mail agents support the separation.
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178 .P
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179 In the beginning, email had been small and simple.
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180 At that time,
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181 .Pn /bin/mail
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182 had covered anything there was to email and still had been small
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183 and simple.
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184 Later, the essential complexity of email increased.
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185 (Essential complexity is the complexity defined by the problem itself.\0
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186 .[[
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187 brooks no silver bullet
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188 .]])
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189 Email systems reacted to this change: They grew.
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190 RFCs started to introduce the concept of mail agents to separate the
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191 various tasks because they became more extensive and new tasks appeared.
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192 As the mail systems grew even more, parts were split off.
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193 In nmh, for instance, the POP server, which was included in the original
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194 MH, was removed.
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195 Now is the time to go one step further and split the MSA and MRA off, too.
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196 Not only does this decrease the code size of the project,
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197 but, more important, it unburdens mmh of the whole field of
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198 message transfer with all its implications for the project.
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199 There is no more need to concern with changes in network transfer.
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200 This independence is received by depending on an external program
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201 that covers the field.
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202 Today, this is a reasonable exchange.
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203 .P
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204 Functionality can be added in three different ways:
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205 .BU
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206 Implementing the function originally in the project.
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207 .BU
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208 Depending on a library that provides the function.
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209 .BU
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210 Depending on a program that provides the function.
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211 .P
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212 Whereas adding the function originally to the project increases the
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213 code size most and requires most maintenance and development work,
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214 it makes the project most independent of other software.
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215 Using libraries or external programs require less maintenance work
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216 but introduces dependencies on external software.
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217 Programs have the smallest interfaces and provide the best separation
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218 but possibly limit the information exchange.
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219 External libraries are stronger connected than external programs,
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220 thus information can be exchanged more flexible.
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221 Adding code to a project increases maintenance work.
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222 .\" XXX ref
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223 Implementing complex functions originally in the project adds
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224 a lot of code.
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225 This should be avoided if possible.
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226 Hence, the dependencies only change in kind, not in their existence.
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227 In mmh, library dependencies on
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228 .Pn libsasl2
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229 and
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230 .Pn libcrypto /\c
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231 .Pn libssl
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232 were treated against program dependencies on an MSA and an MRA.
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233 This also meant treating build-time dependencies against run-time
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234 dependencies.
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235 Besides program dependencies providing the stronger separation
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236 and being more flexible, they also allowed
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237 over 6\|000 lines of code to be removed from mmh.
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238 This made mmh's code base about 12\|% smaller.
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239 Reducing the project's code size by such an amount without actually
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240 losing functionality is a convincing argument.
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241 Actually, as external MSAs and MRAs are likely superior to the
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242 project's internal versions, the common user even gains functionality.
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243 .P
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244 Users of MH should not have problems to set up an external MSA and MRA.
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245 Also, the popular MSAs and MRAs have large communities and a lot
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246 of documentation available.
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247 Choices for MSAs range from full-featured MTAs like
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248 .I Postfix
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249 over mid-size MTAs like
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250 .I masqmail
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251 and
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252 .I dma
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253 to small forwarders like
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254 .I ssmtp
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255 and
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256 .I nullmailer .
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257 Choices for MRAs include
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258 .I fetchmail ,
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259 .I getmail ,
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260 .I mpop
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261 and
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262 .I fdm .
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263
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264
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265 .H2 "Non-MUA Tools
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266 .P
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267 One goal of mmh is to remove the tools that are not part of the MUA's task.
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268 Further more, any tools that don't improve the MUA's job significantly
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269 should be removed.
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270 Loosely related and rarely used tools distract from the lean appearance.
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271 They require maintenance work without adding much to the core task.
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272 By removing these tools, the project shall become more stream-lined
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273 and focused.
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274 In mmh the following tools are not available anymore:
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275 .BU
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276 .Pn conflict
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277 was removed
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278 .Ci 8b235097cbd11d728c07b966cf131aa7133ce5a9
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279 because it is a mail system maintenance tool that is not MUA-related.
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280 It even checked
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281 .Fn /etc/passwd
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282 and
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283 .Fn /etc/group
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284 for consistency, which is completely unrelated to email.
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285 A tool like
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286 .Pn conflict
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287 is surely useful, but it should not be shipped with mmh.
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288 .\" XXX historic reasons?
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289 .BU
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290 .Pn rcvtty
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291 was removed
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292 .Ci 14767c94b3827be7c867196467ed7aea5f6f49b0
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293 because its use case of writing to the user's terminal
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294 on receiving of mail is obsolete.
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295 If users like to be informed of new mail, the shell's
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296 .Ev MAILPATH
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297 variable or graphical notifications are technically more appealing.
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298 Writing directly to terminals is hardly ever wanted today.
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299 If though one wants to have it this way, the standard tool
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300 .Pn write
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301 can be used in a way similar to:
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302 .VS
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303 scan -file - | write `id -un`
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304 VE
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305 .BU
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306 .Pn viamail
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307 was removed
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308 .Ci eda72d6a7a7c20ff123043fb7f19c509ea01f932
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309 when the new attachment system was activated, because
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310 .Pn forw
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311 could then cover the task itself.
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312 The program
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313 .Pn sendfiles
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314 was rewritten as a shell script wrapper around
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315 .Pn forw .
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316 .Ci 0e82199cf3c991a173e0ac8aa776efdb3ded61e6
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317 .BU
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318 .Pn msgchk
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319 was removed
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320 .Ci bb9360ead7eb7a3fedcce2eeedfc660014e41dbe ,
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321 because it lost its use case when POP support was removed.
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322 A call to
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323 .Pn msgchk
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324 provided hardly more information than:
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325 .VS
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326 ls -l /var/mail/meillo
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327 VE
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328 It did distinguish between old and new mail, but
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329 this detail information can be retrieved with
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330 .Pn stat (1),
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331 too.
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332 A small shell script could be written to print the information
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333 in a similar way, if truly necessary.
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334 As mmh's
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335 .Pn inc
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336 only incorporates mail from the user's local maildrop,
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337 and thus no data transfers over slow networks are involved,
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338 there's hardly any need to check for new mail before incorporating it.
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339 .BU
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340 .Pn msh
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341 was removed
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342 .Ci 916690191222433a6923a4be54b0d8f6ac01bd02
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343 because the tool was in conflict with the philosophy of MH.
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344 It provided an interactive shell to access the features of MH,
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345 but it wasn't just a shell, tailored to the needs of mail handling.
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346 Instead it was one large program that had several MH tools built in.
|
meillo@76
|
347 This conflicts with the major feature of MH of being a tool chest.
|
meillo@76
|
348 .Pn msh 's
|
meillo@76
|
349 main use case had been accessing Bulletin Boards, which have seized to
|
meillo@62
|
350 be popular.
|
meillo@62
|
351 .P
|
meillo@62
|
352 Removing
|
meillo@58
|
353 .Pn msh ,
|
meillo@76
|
354 together with the truly archaic code relicts
|
meillo@58
|
355 .Pn vmh
|
meillo@58
|
356 and
|
meillo@58
|
357 .Pn wmh ,
|
meillo@62
|
358 saved more than 7\|000 lines of C code \(en
|
meillo@66
|
359 about 15\|% of the project's original source code amount.
|
meillo@100
|
360 Having less code \(en with equal readability, of course \(en
|
meillo@76
|
361 for the same functionality is an advantage.
|
meillo@63
|
362 Less code means less bugs and less maintenance work.
|
meillo@76
|
363 As
|
meillo@63
|
364 .Pn rcvtty
|
meillo@63
|
365 and
|
meillo@63
|
366 .Pn msgchk
|
meillo@87
|
367 are assumed to be rarely used and can be implemented in different ways,
|
meillo@87
|
368 why should one keep them?
|
meillo@76
|
369 Removing them stream-lines mmh.
|
meillo@63
|
370 .Pn viamail 's
|
meillo@63
|
371 use case is now partly obsolete and partly covered by
|
meillo@63
|
372 .Pn forw ,
|
meillo@76
|
373 hence there's no reason to still maintain it.
|
meillo@63
|
374 .Pn conflict
|
meillo@76
|
375 is not related to the mail client, and
|
meillo@63
|
376 .Pn msh
|
meillo@63
|
377 conflicts with the basic concept of MH.
|
meillo@76
|
378 Theses two tools might still be useful, but they should not be part of mmh.
|
meillo@63
|
379 .P
|
meillo@76
|
380 Finally, there's
|
meillo@76
|
381 .Pn slocal .
|
meillo@76
|
382 .Pn slocal
|
meillo@76
|
383 is an MDA and thus not directly MUA-related.
|
meillo@100
|
384 It should be removed from mmh, because including it conflicts with
|
meillo@100
|
385 the idea that mmh is a MUA only.
|
meillo@100
|
386 .Pn slocal
|
meillo@100
|
387 should rather become a separate project.
|
meillo@87
|
388 However,
|
meillo@76
|
389 .Pn slocal
|
meillo@76
|
390 provides rule-based processing of messages, like filing them into
|
meillo@76
|
391 different folders, which is otherwise not available in mmh.
|
meillo@87
|
392 Although
|
meillo@76
|
393 .Pn slocal
|
meillo@87
|
394 does neither pull in dependencies nor does it include a separate
|
meillo@100
|
395 technical area (cf. Sec. XXX), still,
|
meillo@100
|
396 it accounts for about 1\|000 lines of code that need to be maintained.
|
meillo@76
|
397 As
|
meillo@76
|
398 .Pn slocal
|
meillo@76
|
399 is almost self-standing, it should be split off into a separate project.
|
meillo@76
|
400 This would cut the strong connection between the MUA mmh and the MDA
|
meillo@76
|
401 .Pn slocal .
|
meillo@87
|
402 For anyone not using MH,
|
meillo@87
|
403 .Pn slocal
|
meillo@87
|
404 would become yet another independent MDA, like
|
meillo@87
|
405 .I procmail .
|
meillo@100
|
406 Then
|
meillo@87
|
407 .Pn slocal
|
meillo@100
|
408 could be installed without the complete MH system.
|
meillo@76
|
409 Likewise, mmh users could decide to use
|
meillo@76
|
410 .I procmail
|
meillo@87
|
411 without having a second, unused MDA,
|
meillo@87
|
412 .Pn slocal ,
|
meillo@76
|
413 installed.
|
meillo@100
|
414 That appears to be conceptionally the best solution.
|
meillo@76
|
415 Yet,
|
meillo@76
|
416 .Pn slocal
|
meillo@87
|
417 is not split off.
|
meillo@100
|
418 I defer the decision over
|
meillo@78
|
419 .Pn slocal
|
meillo@100
|
420 in need for deeper investigation.
|
meillo@100
|
421 In the meanwhile, it remains part of mmh.
|
meillo@100
|
422 That does not hurt because
|
meillo@100
|
423 .Pn slocal
|
meillo@100
|
424 is unrelated to the rest of the project.
|
meillo@0
|
425
|
meillo@58
|
426
|
meillo@76
|
427 .H2 "\fLshow\fP and \fPmhshow\fP
|
meillo@58
|
428 .P
|
meillo@69
|
429 Since the very beginning \(en already in the first concept paper \(en
|
meillo@58
|
430 .Pn show
|
meillo@62
|
431 had been MH's message display program.
|
meillo@58
|
432 .Pn show
|
meillo@76
|
433 mapped message numbers and sequences to files and invoked
|
meillo@58
|
434 .Pn mhl
|
meillo@89
|
435 to have the files formatted.
|
meillo@88
|
436 With MIME, this approach wasn't sufficient anymore.
|
meillo@100
|
437 MIME messages can consist of multiple parts. Some parts are not
|
meillo@100
|
438 directly displayable and text content might be encoded in
|
meillo@58
|
439 foreign charsets.
|
meillo@58
|
440 .Pn show 's
|
meillo@76
|
441 understanding of messages and
|
meillo@58
|
442 .Pn mhl 's
|
meillo@88
|
443 display capabilities couldn't cope with the task any longer.
|
meillo@62
|
444 .P
|
meillo@88
|
445 Instead of extending these tools, additional tools were written from
|
meillo@88
|
446 scratch and added to the MH tool chest.
|
meillo@88
|
447 Doing so is encouraged by the tool chest approach.
|
meillo@88
|
448 Modular design is a great advantage for extending a system,
|
meillo@88
|
449 as new tools can be added without interfering with existing ones.
|
meillo@62
|
450 First, the new MIME features were added in form of the single program
|
meillo@58
|
451 .Pn mhn .
|
meillo@58
|
452 The command
|
meillo@82
|
453 .Cl "mhn -show 42
|
meillo@58
|
454 would show the MIME message numbered 42.
|
meillo@58
|
455 With the 1.0 release of nmh in February 1999, Richard Coleman finished
|
meillo@58
|
456 the split of
|
meillo@58
|
457 .Pn mhn
|
meillo@88
|
458 into a set of specialized tools, which together covered the
|
meillo@88
|
459 multiple aspects of MIME.
|
meillo@88
|
460 One of them was
|
meillo@69
|
461 .Pn mhshow ,
|
meillo@88
|
462 which replaced
|
meillo@88
|
463 .Cl "mhn -show" .
|
meillo@88
|
464 It was capable of displaying MIME messages appropriately.
|
meillo@62
|
465 .P
|
meillo@88
|
466 From then on, two message display tools were part of nmh,
|
meillo@76
|
467 .Pn show
|
meillo@76
|
468 and
|
meillo@76
|
469 .Pn mhshow .
|
meillo@88
|
470 To ease the life of users,
|
meillo@69
|
471 .Pn show
|
meillo@69
|
472 was extended to automatically hand the job over to
|
meillo@69
|
473 .Pn mhshow
|
meillo@69
|
474 if displaying the message would be beyond
|
meillo@69
|
475 .Pn show 's
|
meillo@69
|
476 abilities.
|
meillo@88
|
477 In consequence, the user would simply invoke
|
meillo@69
|
478 .Pn show
|
meillo@69
|
479 (possibly through
|
meillo@69
|
480 .Pn next
|
meillo@69
|
481 or
|
meillo@69
|
482 .Pn prev )
|
meillo@69
|
483 and get the message printed with either
|
meillo@69
|
484 .Pn show
|
meillo@69
|
485 or
|
meillo@69
|
486 .Pn mhshow ,
|
meillo@69
|
487 whatever was more appropriate.
|
meillo@69
|
488 .P
|
meillo@69
|
489 Having two similar tools for essentially the same task is redundant.
|
meillo@88
|
490 Usually,
|
meillo@88
|
491 users wouldn't distinguish between
|
meillo@88
|
492 .Pn show
|
meillo@88
|
493 and
|
meillo@88
|
494 .Pn mhshow
|
meillo@88
|
495 in their daily mail reading.
|
meillo@88
|
496 Having two separate display programs was therefore mainly unnecessary
|
meillo@88
|
497 from a user's point of view.
|
meillo@88
|
498 Besides, the development of both programs needed to be in sync,
|
meillo@76
|
499 to ensure that the programs behaved in a similar way,
|
meillo@76
|
500 because they were used like a single tool.
|
meillo@76
|
501 Different behavior would have surprised the user.
|
meillo@69
|
502 .P
|
meillo@69
|
503 Today, non-MIME messages are rather seen to be a special case of
|
meillo@100
|
504 MIME messages, although it is the other way round.
|
meillo@69
|
505 As
|
meillo@69
|
506 .Pn mhshow
|
meillo@88
|
507 had already be able to display non-MIME messages, it appeared natural
|
meillo@69
|
508 to drop
|
meillo@69
|
509 .Pn show
|
meillo@69
|
510 in favor of using
|
meillo@69
|
511 .Pn mhshow
|
meillo@69
|
512 exclusively.
|
meillo@88
|
513 .Ci 4c1efddfd499300c7e74263e57d8aa137e84c853
|
meillo@88
|
514 Removing
|
meillo@88
|
515 .Pn show
|
meillo@88
|
516 is no loss in function, because functionally
|
meillo@88
|
517 .Pn mhshow
|
meillo@88
|
518 covers it completely.
|
meillo@88
|
519 The old behavior of
|
meillo@88
|
520 .Pn show
|
meillo@88
|
521 can still be emulated with the simple command line:
|
meillo@88
|
522 .VS
|
meillo@88
|
523 mhl `mhpath c`
|
meillo@88
|
524 VE
|
meillo@88
|
525 .P
|
meillo@76
|
526 For convenience,
|
meillo@76
|
527 .Pn mhshow
|
meillo@88
|
528 was renamed to
|
meillo@88
|
529 .Pn show
|
meillo@88
|
530 after
|
meillo@88
|
531 .Pn show
|
meillo@88
|
532 was gone.
|
meillo@88
|
533 It is clear that such a rename may confuse future developers when
|
meillo@88
|
534 trying to understand the history.
|
meillo@88
|
535 Nevertheless, I consider the convenience on the user's side,
|
meillo@88
|
536 to call
|
meillo@88
|
537 .Pn show
|
meillo@88
|
538 when they want a message to be displayed, to outweigh the inconvenience
|
meillo@88
|
539 on the developer's side when understanding the project history.
|
meillo@69
|
540 .P
|
meillo@88
|
541 To prepare for the transition,
|
meillo@69
|
542 .Pn mhshow
|
meillo@69
|
543 was reworked to behave more like
|
meillo@69
|
544 .Pn show
|
meillo@69
|
545 first.
|
meillo@88
|
546 (cf. Sec. XXX)
|
meillo@88
|
547 Once the tools behaved more alike, the replacing appeared to be
|
meillo@88
|
548 even more natural.
|
meillo@88
|
549 Today, mmh's new
|
meillo@69
|
550 .Pn show
|
meillo@88
|
551 became the one single message display program again, with the difference
|
meillo@88
|
552 that today it handles MIME messages as well as non-MIME messages.
|
meillo@88
|
553 The outcome of the transition is one program less to maintain,
|
meillo@88
|
554 no second display program for users to deal with,
|
meillo@88
|
555 and less system complexity.
|
meillo@69
|
556 .P
|
meillo@88
|
557 Still, removing the old
|
meillo@69
|
558 .Pn show
|
meillo@88
|
559 hurts in one regard: It had been such a simple program.
|
meillo@88
|
560 Its lean elegance is missing to the new
|
meillo@69
|
561 .Pn show .
|
meillo@88
|
562 But there is no chance;
|
meillo@88
|
563 supporting MIME demands for higher essential complexity.
|
meillo@58
|
564
|
meillo@58
|
565
|
meillo@100
|
566 .H2 "Configure Options
|
meillo@58
|
567 .P
|
meillo@76
|
568 Customization is a double-edged sword.
|
meillo@76
|
569 It allows better suiting setups, but not for free.
|
meillo@76
|
570 There is the cost of code complexity to be able to customize.
|
meillo@76
|
571 There is the cost of less tested setups, because there are
|
meillo@72
|
572 more possible setups and especially corner-cases.
|
meillo@76
|
573 And, there is the cost of choice itself.
|
meillo@76
|
574 The code complexity directly affects the developers.
|
meillo@72
|
575 Less tested code affects both, users and developers.
|
meillo@76
|
576 The problem of choice affects the users, for once by having to
|
meillo@100
|
577 choose, but also by more complex interfaces that require more documentation.
|
meillo@72
|
578 Whenever options add little advantages, they should be considered for
|
meillo@72
|
579 removal.
|
meillo@72
|
580 I have reduced the number of project-specific configure options from
|
meillo@72
|
581 fifteen to three.
|
meillo@74
|
582
|
meillo@76
|
583 .U3 "Mail Transfer Facilities
|
meillo@74
|
584 .P
|
meillo@85
|
585 With the removal of the mail transfer facilities five configure
|
meillo@85
|
586 options vanished:
|
meillo@85
|
587 .P
|
meillo@85
|
588 The switches
|
meillo@85
|
589 .Sw --with-tls
|
meillo@85
|
590 and
|
meillo@85
|
591 .Sw --with-cyrus-sasl
|
meillo@89
|
592 had activated the support for transfer encryption and authentication.
|
meillo@85
|
593 This is not needed anymore.
|
meillo@85
|
594 .Ci fecd5d34f65597a4dfa16aeabea7d74b191532c3
|
meillo@85
|
595 .Ci 156d35f6425bea4c1ed3c4c79783dc613379c65b
|
meillo@85
|
596 .P
|
meillo@85
|
597 The configure switch
|
meillo@85
|
598 .Sw --enable-pop
|
meillo@85
|
599 activated the message retrieval facility.
|
meillo@85
|
600 The code area that would be conditionally compiled in for TLS and SASL
|
meillo@85
|
601 support had been small.
|
meillo@85
|
602 The conditionally compiled code area for POP support had been much larger.
|
meillo@85
|
603 Whereas the code base changes would only slightly change on toggling
|
meillo@85
|
604 TLS or SASL support, it changed much on toggling POP support.
|
meillo@85
|
605 The changes in the code base could hardly be overviewed.
|
meillo@85
|
606 By having POP support togglable a second code base had been created,
|
meillo@85
|
607 one that needed to be tested.
|
meillo@85
|
608 This situation is basically similar for the conditional TLS and SASL
|
meillo@85
|
609 code, but there the changes are minor and can yet be overviewed.
|
meillo@85
|
610 Still, conditional compilation of a code base creates variations
|
meillo@85
|
611 of the original program.
|
meillo@85
|
612 More variations require more testing and maintenance work.
|
meillo@85
|
613 .P
|
meillo@85
|
614 Two other options only specified default configuration values:
|
meillo@100
|
615 .Sw --with-mts
|
meillo@100
|
616 defined the default transport service, either
|
meillo@100
|
617 .Ar smtp
|
meillo@100
|
618 or
|
meillo@100
|
619 .Ar sendmail .
|
meillo@85
|
620 In mmh this fixed to
|
meillo@85
|
621 .Ar sendmail .
|
meillo@85
|
622 .Ci f6aa95b724fd8c791164abe7ee5468bf5c34f226
|
meillo@85
|
623 With
|
meillo@100
|
624 .Sw --with-smtpservers
|
meillo@85
|
625 default SMTP servers for the
|
meillo@85
|
626 .Ar smtp
|
meillo@85
|
627 transport service could be specified.
|
meillo@72
|
628 .Ci 128545e06224233b7e91fc4c83f8830252fe16c9
|
meillo@85
|
629 Both of them became irrelevant.
|
meillo@72
|
630
|
meillo@74
|
631 .U3 "Backup Prefix
|
meillo@74
|
632 .P
|
meillo@76
|
633 The backup prefix is the string that was prepended to message
|
meillo@76
|
634 filenames to tag them as deleted.
|
meillo@76
|
635 By default it had been the comma character `\f(CW,\fP'.
|
meillo@78
|
636 In July 2000, Kimmo Suominen introduced
|
meillo@78
|
637 the configure option
|
meillo@78
|
638 .Sw --with-hash-backup
|
meillo@78
|
639 to change the default to the hash symbol `\f(CW#\fP'.
|
meillo@78
|
640 The choice was probably personal preference, because first, the
|
meillo@78
|
641 option was named
|
meillo@78
|
642 .Sw --with-backup-prefix.
|
meillo@78
|
643 and had the prefix symbol as argument.
|
meillo@100
|
644 But giving the hash symbol as argument caused too many problems
|
meillo@100
|
645 for Autoconf,
|
meillo@100
|
646 thus the option was limited to use the hash symbol as the default prefix.
|
meillo@100
|
647 This supports the assumption, that the choice for the hash was
|
meillo@100
|
648 personal preference only.
|
meillo@100
|
649 Being related or not, words that start with the hash symbol
|
meillo@78
|
650 introduce a comment in the Unix shell.
|
meillo@72
|
651 Thus, the command line
|
meillo@72
|
652 .Cl "rm #13 #15
|
meillo@72
|
653 calls
|
meillo@72
|
654 .Pn rm
|
meillo@72
|
655 without arguments because the first hash symbol starts the comment
|
meillo@72
|
656 that reaches until the end of the line.
|
meillo@72
|
657 To delete the backup files,
|
meillo@72
|
658 .Cl "rm ./#13 ./#15"
|
meillo@72
|
659 needs to be used.
|
meillo@100
|
660 Using the hash as backup prefix can be seen as a precaution against
|
meillo@78
|
661 data loss.
|
meillo@78
|
662 .P
|
meillo@72
|
663 I removed the configure option but added the profile entry
|
meillo@72
|
664 .Pe backup-prefix ,
|
meillo@72
|
665 which allows to specify an arbitrary string as backup prefix.
|
meillo@72
|
666 .Ci 6c40d481d661d532dd527eaf34cebb6d3f8ed086
|
meillo@76
|
667 Profile entries are the common method to change mmh's behavior.
|
meillo@76
|
668 This change did not remove the choice but moved it to a location where
|
meillo@72
|
669 it suited better.
|
meillo@76
|
670 .P
|
meillo@78
|
671 Eventually, however, the new trash folder concept
|
meillo@78
|
672 .Cf "Sec. XXX
|
meillo@78
|
673 obsoleted the concept of the backup prefix completely.
|
meillo@78
|
674 .Ci 8edc5aaf86f9f77124664f6801bc6c6cdf258173
|
meillo@100
|
675 .\" (Well, there still are corner-cases to remove until the backup
|
meillo@100
|
676 .\" prefix can be laid to rest, eventually.)
|
meillo@72
|
677 .\" FIXME: Do this work in the code!
|
meillo@76
|
678
|
meillo@76
|
679 .U3 "Editor and Pager
|
meillo@74
|
680 .P
|
meillo@74
|
681 The two configure options
|
meillo@74
|
682 .CW --with-editor=EDITOR
|
meillo@74
|
683 .CW --with-pager=PAGER
|
meillo@74
|
684 were used to specify the default editor and pager at configure time.
|
meillo@109
|
685 Doing so at configure time made sense in the eighties,
|
meillo@76
|
686 when the set of available editors and pagers varied much across
|
meillo@76
|
687 different systems.
|
meillo@89
|
688 Today, the situation is more homogeneous.
|
meillo@74
|
689 The programs
|
meillo@74
|
690 .Pn vi
|
meillo@74
|
691 and
|
meillo@74
|
692 .Pn more
|
meillo@76
|
693 can be expected to be available on every Unix system,
|
meillo@74
|
694 as they are specified by POSIX since two decades.
|
meillo@74
|
695 (The specifications for
|
meillo@74
|
696 .Pn vi
|
meillo@74
|
697 and
|
meillo@74
|
698 .Pn more
|
meillo@74
|
699 appeared in
|
meillo@74
|
700 .[
|
meillo@74
|
701 posix 1987
|
meillo@74
|
702 .]
|
meillo@74
|
703 and,
|
meillo@74
|
704 .[
|
meillo@74
|
705 posix 1992
|
meillo@74
|
706 .]
|
meillo@74
|
707 respectively.)
|
meillo@74
|
708 As a first step, these two tools were hard-coded as defaults.
|
meillo@74
|
709 .Ci 5d43a99db70c12a673028c7758c20cbe3e13ef5f
|
meillo@74
|
710 Not changed were the
|
meillo@74
|
711 .Pe editor
|
meillo@74
|
712 and
|
meillo@74
|
713 .Pe moreproc
|
meillo@76
|
714 profile entries, which allowed the user to override the system defaults.
|
meillo@74
|
715 Later, the concept was reworked to respect the standard environment
|
meillo@74
|
716 variables
|
meillo@74
|
717 .Ev VISUAL
|
meillo@74
|
718 and
|
meillo@74
|
719 .Ev PAGER
|
meillo@76
|
720 if they are set.
|
meillo@74
|
721 Today, mmh determines the editor to use in the following order,
|
meillo@74
|
722 taking the first available and non-empty item:
|
meillo@74
|
723 .IP (1)
|
meillo@74
|
724 Environment variable
|
meillo@74
|
725 .Ev MMHEDITOR
|
meillo@74
|
726 .IP (2)
|
meillo@74
|
727 Profile entry
|
meillo@74
|
728 .Pe Editor
|
meillo@74
|
729 .IP (3)
|
meillo@74
|
730 Environment variable
|
meillo@74
|
731 .Ev VISUAL
|
meillo@74
|
732 .IP (4)
|
meillo@74
|
733 Environment variable
|
meillo@74
|
734 .Ev EDITOR
|
meillo@74
|
735 .IP (5)
|
meillo@74
|
736 Command
|
meillo@74
|
737 .Pn vi .
|
meillo@74
|
738 .P
|
meillo@76
|
739 .Ci f85f4b7ae62e3d05a945dcd46ead51f0a2a89a9b
|
meillo@76
|
740 .P
|
meillo@89
|
741 The pager to use is determined in a similar order,
|
meillo@74
|
742 also taking the first available and non-empty item:
|
meillo@74
|
743 .IP (1)
|
meillo@74
|
744 Environment variable
|
meillo@74
|
745 .Ev MMHPAGER
|
meillo@74
|
746 .IP (2)
|
meillo@74
|
747 Profile entry
|
meillo@74
|
748 .Pe Pager
|
meillo@74
|
749 (replaces
|
meillo@74
|
750 .Pe moreproc )
|
meillo@74
|
751 .IP (3)
|
meillo@74
|
752 Environment variable
|
meillo@74
|
753 .Ev PAGER
|
meillo@74
|
754 .IP (4)
|
meillo@74
|
755 Command
|
meillo@74
|
756 .Pn more .
|
meillo@74
|
757 .P
|
meillo@74
|
758 .Ci 0c4214ea2aec6497d0d67b436bbee9bc1d225f1e
|
meillo@74
|
759 .P
|
meillo@76
|
760 By respecting the
|
meillo@74
|
761 .Ev VISUAL /\c
|
meillo@74
|
762 .Ev EDITOR
|
meillo@74
|
763 and
|
meillo@74
|
764 .Ev PAGER
|
meillo@76
|
765 environment variables,
|
meillo@76
|
766 the new behavior confirms better to the common style on Unix systems.
|
meillo@76
|
767 Additionally, the new approach is more uniform and clearer to users.
|
meillo@72
|
768
|
meillo@72
|
769
|
meillo@76
|
770 .U3 "ndbm
|
meillo@72
|
771 .P
|
meillo@74
|
772 .Pn slocal
|
meillo@78
|
773 used to depend on
|
meillo@74
|
774 .I ndbm ,
|
meillo@74
|
775 a database library.
|
meillo@76
|
776 The database is used to store the `\fLMessage-ID\fP's of all
|
meillo@76
|
777 messages delivered.
|
meillo@74
|
778 This enables
|
meillo@74
|
779 .Pn slocal
|
meillo@74
|
780 to suppress delivering the same message to the same user twice.
|
meillo@74
|
781 (This features was enabled by the
|
meillo@74
|
782 .Sw -suppressdup
|
meillo@74
|
783 switch.)
|
meillo@74
|
784 .P
|
meillo@100
|
785 A variety of versions of the database library exist.
|
meillo@78
|
786 .[
|
meillo@78
|
787 wolter unix incompat notes dbm
|
meillo@78
|
788 .]
|
meillo@74
|
789 Complicated autoconf code was needed to detect them correctly.
|
meillo@74
|
790 Further more, the configure switches
|
meillo@74
|
791 .Sw --with-ndbm=ARG
|
meillo@74
|
792 and
|
meillo@74
|
793 .Sw --with-ndbmheader=ARG
|
meillo@74
|
794 were added to help with difficult setups that would
|
meillo@78
|
795 not be detected automatically or correctly.
|
meillo@74
|
796 .P
|
meillo@74
|
797 By removing the suppress duplicates feature of
|
meillo@74
|
798 .Pn slocal ,
|
meillo@74
|
799 the dependency on
|
meillo@74
|
800 .I ndbm
|
meillo@78
|
801 vanished and 120 lines of complex autoconf code could be saved.
|
meillo@74
|
802 .Ci ecd6d6a20cb7a1507e3a20d6c4cb3a1cf14c6bbf
|
meillo@89
|
803 The change removed functionality too, but that is minor to the
|
meillo@78
|
804 improvement by dropping the dependency and the complex autoconf code.
|
meillo@72
|
805
|
meillo@74
|
806 .U3 "mh-e Support
|
meillo@72
|
807 .P
|
meillo@74
|
808 The configure option
|
meillo@74
|
809 .Sw --disable-mhe
|
meillo@74
|
810 was removed when the mh-e support was reworked.
|
meillo@74
|
811 Mh-e is the Emacs front-end to MH.
|
meillo@76
|
812 It requires MH to provide minor additional functions.
|
meillo@76
|
813 The
|
meillo@76
|
814 .Sw --disable-mhe
|
meillo@76
|
815 configure option could switch these extensions off.
|
meillo@76
|
816 After removing the support for old versions of mh-e,
|
meillo@74
|
817 only the
|
meillo@74
|
818 .Sw -build
|
meillo@76
|
819 switches of
|
meillo@74
|
820 .Pn forw
|
meillo@74
|
821 and
|
meillo@74
|
822 .Pn repl
|
meillo@76
|
823 are left to be mh-e extensions.
|
meillo@76
|
824 They are now always built in because they add little code and complexity.
|
meillo@76
|
825 In consequence, the
|
meillo@74
|
826 .Sw --disable-mhe
|
meillo@76
|
827 configure option was removed
|
meillo@72
|
828 .Ci a7ce7b4a580d77b6c2c4d980812beb589aa4c643
|
meillo@74
|
829 Removing the option removed a second code setup that would have
|
meillo@74
|
830 needed to be tested.
|
meillo@76
|
831 This change was first done in nmh and thereafter merged into mmh.
|
meillo@76
|
832 .P
|
meillo@76
|
833 The interface changes in mmh require mh-e to be adjusted in order
|
meillo@76
|
834 to be able to use mmh as back-end.
|
meillo@76
|
835 This will require minor changes to mh-e, but removing the
|
meillo@76
|
836 .Sw -build
|
meillo@76
|
837 switches would require more rework.
|
meillo@72
|
838
|
meillo@74
|
839 .U3 "Masquerading
|
meillo@72
|
840 .P
|
meillo@74
|
841 The configure option
|
meillo@74
|
842 .Sw --enable-masquerade
|
meillo@76
|
843 could take up to three arguments:
|
meillo@76
|
844 `draft_from', `mmailid', and `username_extension'.
|
meillo@74
|
845 They activated different types of address masquerading.
|
meillo@74
|
846 All of them were implemented in the SMTP-speaking
|
meillo@74
|
847 .Pn post
|
meillo@76
|
848 command, which provided an MSA.
|
meillo@76
|
849 Address masquerading is an MTA's task and mmh does not cover
|
meillo@76
|
850 this field anymore.
|
meillo@76
|
851 Hence, true masquerading needs to be implemented in the external MTA.
|
meillo@74
|
852 .P
|
meillo@74
|
853 The
|
meillo@74
|
854 .I mmailid
|
meillo@74
|
855 masquerading type is the oldest one of the three and the only one
|
meillo@74
|
856 available in the original MH.
|
meillo@74
|
857 It provided a
|
meillo@74
|
858 .I username
|
meillo@74
|
859 to
|
meillo@74
|
860 .I fakeusername
|
meillo@76
|
861 mapping, based on the password file's GECOS field.
|
meillo@74
|
862 The man page
|
meillo@74
|
863 .Mp mh-tailor(5)
|
meillo@74
|
864 described the use case as being the following:
|
meillo@98
|
865 .QS
|
meillo@74
|
866 This is useful if you want the messages you send to always
|
meillo@74
|
867 appear to come from the name of an MTA alias rather than your
|
meillo@74
|
868 actual account name. For instance, many organizations set up
|
meillo@74
|
869 `First.Last' sendmail aliases for all users. If this is
|
meillo@74
|
870 the case, the GECOS field for each user should look like:
|
meillo@74
|
871 ``First [Middle] Last <First.Last>''
|
meillo@98
|
872 .QE
|
meillo@74
|
873 .P
|
meillo@74
|
874 As mmh sends outgoing mail via the local MTA only,
|
meillo@76
|
875 the best location to do such global rewrites is there.
|
meillo@74
|
876 Besides, the MTA is conceptionally the right location because it
|
meillo@74
|
877 does the reverse mapping for incoming mail (aliasing), too.
|
meillo@76
|
878 Further more, masquerading set up there is readily available for all
|
meillo@74
|
879 mail software on the system.
|
meillo@76
|
880 Hence, mmailid masquerading was removed.
|
meillo@74
|
881 .Ci 0836c8000ccb34b59410ef1c15b1b7feac70ce5f
|
meillo@74
|
882 .P
|
meillo@74
|
883 The
|
meillo@74
|
884 .I username_extension
|
meillo@76
|
885 masquerading type did not replace the username but would append a suffix,
|
meillo@76
|
886 specified by the
|
meillo@74
|
887 .Ev USERNAME_EXTENSION
|
meillo@76
|
888 environment variable, to it.
|
meillo@76
|
889 This provided support for the
|
meillo@74
|
890 .I user-extension
|
meillo@74
|
891 feature of qmail and the similar
|
meillo@74
|
892 .I "plussed user
|
meillo@74
|
893 processing of sendmail.
|
meillo@74
|
894 The decision to remove this username_extension masquerading was
|
meillo@74
|
895 motivated by the fact that
|
meillo@74
|
896 .Pn spost
|
meillo@76
|
897 hadn't supported it already.
|
meillo@76
|
898 .Ci 2abae0bfd0ad5bf898461e50aa4b466d641f23d9
|
meillo@76
|
899 Username extensions are possible in mmh, but less convenient to use.
|
meillo@76
|
900 .\" XXX format file %(getenv USERNAME_EXTENSION)
|
meillo@74
|
901 .P
|
meillo@74
|
902 The
|
meillo@74
|
903 .I draft_from
|
meillo@74
|
904 masquerading type instructed
|
meillo@74
|
905 .Pn post
|
meillo@84
|
906 to use the value of the
|
meillo@84
|
907 .Hd From
|
meillo@84
|
908 header field as SMTP envelope sender.
|
meillo@76
|
909 Sender addresses could be replaced completely.
|
meillo@74
|
910 .Ci b14ea6073f77b4359aaf3fddd0e105989db9
|
meillo@76
|
911 Mmh offers a kind of masquerading similar in effect, but
|
meillo@74
|
912 with technical differences.
|
meillo@76
|
913 As mmh does not transfer messages itself, the local MTA has final control
|
meillo@76
|
914 over the sender's address. Any masquerading mmh introduces may be reverted
|
meillo@76
|
915 by the MTA.
|
meillo@76
|
916 In times of pedantic spam checking, an MTA will take care to use
|
meillo@76
|
917 sensible envelope sender addresses to keep its own reputation up.
|
meillo@84
|
918 Nonetheless, the MUA can set the
|
meillo@84
|
919 .Hd From
|
meillo@84
|
920 header field and thereby propose
|
meillo@76
|
921 a sender address to the MTA.
|
meillo@74
|
922 The MTA may then decide to take that one or generate the canonical sender
|
meillo@74
|
923 address for use as envelope sender address.
|
meillo@74
|
924 .P
|
meillo@74
|
925 In mmh, the MTA will always extract the recipient and sender from the
|
meillo@84
|
926 message header (\c
|
meillo@74
|
927 .Pn sendmail 's
|
meillo@74
|
928 .Sw -t
|
meillo@74
|
929 switch).
|
meillo@84
|
930 The
|
meillo@84
|
931 .Hd From
|
meillo@84
|
932 header field of the draft may be set arbitrary by the user.
|
meillo@74
|
933 If it is missing, the canonical sender address will be generated by the MTA.
|
meillo@74
|
934
|
meillo@74
|
935 .U3 "Remaining Options
|
meillo@74
|
936 .P
|
meillo@74
|
937 Two configure options remain in mmh.
|
meillo@74
|
938 One is the locking method to use:
|
meillo@74
|
939 .Sw --with-locking=[dot|fcntl|flock|lockf] .
|
meillo@76
|
940 The idea of removing all methods except the portable dot locking
|
meillo@76
|
941 and having that one as the default is appealing, but this change
|
meillo@76
|
942 requires deeper technical investigation into the topic.
|
meillo@76
|
943 The other option,
|
meillo@74
|
944 .Sw --enable-debug ,
|
meillo@74
|
945 compiles the programs with debugging symbols and does not strip them.
|
meillo@74
|
946 This option is likely to stay.
|
meillo@72
|
947
|
meillo@72
|
948
|
meillo@58
|
949
|
meillo@63
|
950
|
meillo@100
|
951 .H2 "Command Line Switches
|
meillo@58
|
952 .P
|
meillo@93
|
953 The command line switches of MH tools follow the X Window style.
|
meillo@93
|
954 They are words, introduced by a single dash.
|
meillo@93
|
955 For example:
|
meillo@93
|
956 .Cl "-truncate" .
|
meillo@93
|
957 Every program in mmh has two generic switches:
|
meillo@93
|
958 .Sw -help ,
|
meillo@93
|
959 to print a short message on how to use the program, and
|
meillo@93
|
960 .Sw -Version ,
|
meillo@93
|
961 to tell what version of mmh the program belongs to.
|
meillo@93
|
962 .P
|
meillo@93
|
963 Switches change the behavior of programs.
|
meillo@93
|
964 Programs that do one thing in one way require no switches.
|
meillo@93
|
965 In most cases, doing something in exactly one way is too limiting.
|
meillo@97
|
966 If there is basically one task to accomplish, but it should be done
|
meillo@93
|
967 in various ways, switches are a good approach to alter the behavior
|
meillo@93
|
968 of a program.
|
meillo@93
|
969 Changing the behavior of programs provides flexibility and customization
|
meillo@97
|
970 to users, but at the same time it complicates the code, documentation and
|
meillo@93
|
971 usage of the program.
|
meillo@97
|
972 .\" XXX: Ref
|
meillo@93
|
973 Therefore, the number of switches should be kept small.
|
meillo@93
|
974 A small set of well-chosen switches does no harm.
|
meillo@93
|
975 But usually, the number of switches increases over time.
|
meillo@93
|
976 Already in 1985, Rose and Romine have identified this as a major
|
meillo@93
|
977 problem of MH:
|
meillo@93
|
978 .[ [
|
meillo@93
|
979 rose romine real work
|
meillo@93
|
980 .], p. 12]
|
meillo@98
|
981 .QS
|
meillo@93
|
982 A complaint often heard about systems which undergo substantial development
|
meillo@93
|
983 by many people over a number of years, is that more and more options are
|
meillo@93
|
984 introduced which add little to the functionality but greatly increase the
|
meillo@93
|
985 amount of information a user needs to know in order to get useful work done.
|
meillo@93
|
986 This is usually referred to as creeping featurism.
|
meillo@93
|
987 .QP
|
meillo@93
|
988 Unfortunately MH, having undergone six years of off-and-on development by
|
meillo@93
|
989 ten or so well-meaning programmers (the present authors included),
|
meillo@93
|
990 suffers mightily from this.
|
meillo@98
|
991 .QE
|
meillo@93
|
992 .P
|
meillo@97
|
993 Being reluctant to adding new switches \(en or `options',
|
meillo@97
|
994 as Rose and Romine call them \(en is one part of a counter-action,
|
meillo@97
|
995 the other part is removing hardly used switches.
|
meillo@97
|
996 Nmh's tools had lots of switches already implemented,
|
meillo@97
|
997 hence, cleaning up by removing some of them was the more important part
|
meillo@97
|
998 of the counter-action.
|
meillo@93
|
999 Removing existing functionality is always difficult because it
|
meillo@93
|
1000 breaks programs that use these functions.
|
meillo@93
|
1001 Also, for every obsolete feature, there'll always be someone who still
|
meillo@93
|
1002 uses it and thus opposes its removal.
|
meillo@93
|
1003 This puts the developer into the position,
|
meillo@93
|
1004 where sensible improvements to style are regarded as destructive acts.
|
meillo@97
|
1005 Yet, living with the featurism is far worse, in my eyes, because
|
meillo@97
|
1006 future needs will demand adding further features,
|
meillo@93
|
1007 worsening the situation more and more.
|
meillo@93
|
1008 Rose and Romine added in a footnote,
|
meillo@93
|
1009 ``[...]
|
meillo@93
|
1010 .Pn send
|
meillo@93
|
1011 will no doubt acquire an endless number of switches in the years to come.''
|
meillo@97
|
1012 Although clearly humorous, the comment points to the nature of the problem.
|
meillo@97
|
1013 Refusing to add any new switches would encounter the problem at its root,
|
meillo@97
|
1014 but this is not practical.
|
meillo@97
|
1015 New needs will require new switches and it would be unwise to block
|
meillo@97
|
1016 them strictly.
|
meillo@97
|
1017 Nevertheless, removing obsolete switches still is an effective approach
|
meillo@97
|
1018 to deal with the problem.
|
meillo@97
|
1019 Working on an experimental branch without an established user base,
|
meillo@97
|
1020 eased my work because I did not offend users when I removed existing
|
meillo@110
|
1021 functions.
|
meillo@93
|
1022 .P
|
meillo@93
|
1023 Rose and Romine counted 24 visible and 9 more hidden switches for
|
meillo@93
|
1024 .Pn send .
|
meillo@97
|
1025 In nmh, they increased up to 32 visible and 12 hidden ones.
|
meillo@97
|
1026 At the time of writing, no more than 7 visible switches and 1 hidden switch
|
meillo@97
|
1027 have remained in mmh's
|
meillo@97
|
1028 .Pn send .
|
meillo@97
|
1029 (These numbers include two generic switches, help and version.)
|
meillo@93
|
1030 .P
|
meillo@97
|
1031 Fig. XXX
|
meillo@93
|
1032 .\" XXX Ref
|
meillo@97
|
1033 displays the number of switches for each of the tools that is available
|
meillo@97
|
1034 in both, nmh and mmh.
|
meillo@100
|
1035 The tools are sorted by the number of switches they had in nmh.
|
meillo@100
|
1036 Visible and hidden switches were counted,
|
meillo@97
|
1037 but not the generic help and version switches.
|
meillo@93
|
1038 Whereas in the beginning of the project, the average tool had 11 switches,
|
meillo@93
|
1039 now it has no more than 5 \(en only half as many.
|
meillo@93
|
1040 If the `no' switches and similar inverse variant are folded onto
|
meillo@100
|
1041 their counter-parts, the average tool had 8 switches in pre-mmh times and
|
meillo@100
|
1042 has 4 now.
|
meillo@93
|
1043 The total number of functional switches in mmh dropped from 465
|
meillo@93
|
1044 to 234.
|
meillo@58
|
1045
|
meillo@93
|
1046 .KS
|
meillo@93
|
1047 .in 1c
|
meillo@93
|
1048 .so input/switches.grap
|
meillo@93
|
1049 .KE
|
meillo@58
|
1050
|
meillo@93
|
1051 .P
|
meillo@93
|
1052 A part of the switches vanished after functions were removed.
|
meillo@93
|
1053 This was the case for network mail transfer, for instance.
|
meillo@97
|
1054 Sometimes, however, the work flow was the other way:
|
meillo@97
|
1055 I looked through the
|
meillo@97
|
1056 .Mp mh-chart (7)
|
meillo@97
|
1057 man page to identify the tools with apparently too many switches.
|
meillo@97
|
1058 Then considering the value of each of the switches by examining
|
meillo@97
|
1059 the tool's man page and source code, aided by recherche and testing.
|
meillo@97
|
1060 This way, the removal of functions was suggested by the aim to reduce
|
meillo@97
|
1061 the number of switches per command.
|
meillo@97
|
1062
|
meillo@58
|
1063
|
meillo@93
|
1064 .U3 "Draft Folder Facility
|
meillo@93
|
1065 .P
|
meillo@100
|
1066 A change early in the project was the complete transition from
|
meillo@93
|
1067 the single draft message to the draft folder facility.
|
meillo@97
|
1068 .Ci 337338b404931f06f0db2119c9e145e8ca5a9860
|
meillo@109
|
1069 The draft folder facility was introduced in the mid-eighties, when
|
meillo@100
|
1070 Rose and Romine called it a ``relatively new feature''.
|
meillo@93
|
1071 .[
|
meillo@93
|
1072 rose romine real work
|
meillo@93
|
1073 .]
|
meillo@110
|
1074 Since then, the facility had existed but was inactive by default.
|
meillo@93
|
1075 The default activation and the related rework of the tools made it
|
meillo@93
|
1076 possible to remove the
|
meillo@93
|
1077 .Sw -[no]draftfolder ,
|
meillo@93
|
1078 and
|
meillo@93
|
1079 .Sw -draftmessage
|
meillo@93
|
1080 switches from
|
meillo@93
|
1081 .Pn comp ,
|
meillo@93
|
1082 .Pn repl ,
|
meillo@93
|
1083 .Pn forw ,
|
meillo@93
|
1084 .Pn dist ,
|
meillo@93
|
1085 .Pn whatnow ,
|
meillo@93
|
1086 and
|
meillo@93
|
1087 .Pn send .
|
meillo@97
|
1088 .Ci 337338b404931f06f0db2119c9e145e8ca5a9860
|
meillo@97
|
1089 The only flexibility removed with this change is having multiple
|
meillo@97
|
1090 draft folders within one profile.
|
meillo@97
|
1091 I consider this a theoretical problem only.
|
meillo@93
|
1092 In the same go, the
|
meillo@93
|
1093 .Sw -draft
|
meillo@93
|
1094 switch of
|
meillo@93
|
1095 .Pn anno ,
|
meillo@93
|
1096 .Pn refile ,
|
meillo@93
|
1097 and
|
meillo@93
|
1098 .Pn send
|
meillo@93
|
1099 was removed.
|
meillo@93
|
1100 The special-casing of `the' draft message became irrelevant after
|
meillo@93
|
1101 the rework of the draft system.
|
meillo@93
|
1102 (See Sec. XXX.)
|
meillo@95
|
1103 Equally,
|
meillo@95
|
1104 .Pn comp
|
meillo@95
|
1105 lost its
|
meillo@95
|
1106 .Sw -file
|
meillo@95
|
1107 switch.
|
meillo@95
|
1108 The draft folder facility, together with the
|
meillo@95
|
1109 .Sw -form
|
meillo@95
|
1110 switch, are sufficient.
|
meillo@93
|
1111
|
meillo@95
|
1112
|
meillo@102
|
1113 .U3 "In Place Editing
|
meillo@93
|
1114 .P
|
meillo@93
|
1115 .Pn anno
|
meillo@93
|
1116 had the switches
|
meillo@93
|
1117 .Sw -[no]inplace
|
meillo@100
|
1118 to either annotate the message in place and thus preserve hard links,
|
meillo@93
|
1119 or annotate a copy to replace the original message, breaking hard links.
|
meillo@97
|
1120 Following the assumption that linked messages should truly be the
|
meillo@97
|
1121 same message, and annotating it should not break the link, the
|
meillo@93
|
1122 .Sw -[no]inplace
|
meillo@93
|
1123 switches were removed and the previous default
|
meillo@93
|
1124 .Sw -inplace
|
meillo@93
|
1125 was made the only behavior.
|
meillo@97
|
1126 .Ci c8195849d2e366c569271abb0f5f60f4ebf0b4d0
|
meillo@93
|
1127 The
|
meillo@93
|
1128 .Sw -[no]inplace
|
meillo@93
|
1129 switches of
|
meillo@93
|
1130 .Pn repl ,
|
meillo@93
|
1131 .Pn forw ,
|
meillo@93
|
1132 and
|
meillo@93
|
1133 .Pn dist
|
meillo@93
|
1134 could be removed, too, as they were simply passed through to
|
meillo@93
|
1135 .Pn anno .
|
meillo@93
|
1136 .P
|
meillo@93
|
1137 .Pn burst
|
meillo@93
|
1138 also had
|
meillo@93
|
1139 .Sw -[no]inplace
|
meillo@95
|
1140 switches, but with different meaning.
|
meillo@95
|
1141 With
|
meillo@95
|
1142 .Sw -inplace ,
|
meillo@95
|
1143 the digest had been replaced by the table of contents (i.e. the
|
meillo@110
|
1144 introduction text) and the burst messages were placed right
|
meillo@95
|
1145 after this message, renumbering all following messages.
|
meillo@95
|
1146 Also, any trailing text of the digest was lost, though,
|
meillo@95
|
1147 in practice, it usually consists of an end-of-digest marker only.
|
meillo@95
|
1148 Nontheless, this behavior appeared less elegant than the
|
meillo@95
|
1149 .Sw -noinplace
|
meillo@95
|
1150 behavior, which already had been the default.
|
meillo@95
|
1151 Nmh's
|
meillo@95
|
1152 .Mp burst (1)
|
meillo@95
|
1153 man page reads:
|
meillo@95
|
1154 .sp \n(PDu
|
meillo@98
|
1155 .QS
|
meillo@93
|
1156 If -noinplace is given, each digest is preserved, no table
|
meillo@93
|
1157 of contents is produced, and the messages contained within
|
meillo@93
|
1158 the digest are placed at the end of the folder. Other messages
|
meillo@93
|
1159 are not tampered with in any way.
|
meillo@98
|
1160 .QE
|
meillo@95
|
1161 .LP
|
meillo@93
|
1162 The decision to drop the
|
meillo@93
|
1163 .Sw -inplace
|
meillo@95
|
1164 behavior was supported by the code complexity and the possible data loss
|
meillo@95
|
1165 it caused.
|
meillo@93
|
1166 .Sw -noinplace
|
meillo@95
|
1167 was chosen to be the definitive behavior.
|
meillo@97
|
1168 .Ci 68a686adeb39223a5e1ad35e4a24890ec053679d
|
meillo@93
|
1169
|
meillo@95
|
1170
|
meillo@95
|
1171 .U3 "Forms and Format Strings
|
meillo@93
|
1172 .P
|
meillo@95
|
1173 Historically, the tools that had
|
meillo@95
|
1174 .Sw -form
|
meillo@95
|
1175 switches to supply a form file had
|
meillo@95
|
1176 .Sw -format
|
meillo@95
|
1177 switches as well to supply the contents of a form file as a string
|
meillo@95
|
1178 on the command line directly.
|
meillo@95
|
1179 In consequence, the following two lines equaled:
|
meillo@95
|
1180 .VS
|
meillo@95
|
1181 scan -form scan.mailx
|
meillo@95
|
1182 scan -format "`cat .../scan.mailx`"
|
meillo@95
|
1183 VE
|
meillo@95
|
1184 The
|
meillo@95
|
1185 .Sw -format
|
meillo@95
|
1186 switches were dropped in favor for extending the
|
meillo@95
|
1187 .Sw -form
|
meillo@95
|
1188 switches.
|
meillo@97
|
1189 .Ci f51956be123db66b00138f80464d06f030dbb88d
|
meillo@95
|
1190 If their argument starts with an equal sign (`='),
|
meillo@95
|
1191 then the rest of the argument is taken as a format string,
|
meillo@95
|
1192 otherwise the arguments is treated as the name of a format file.
|
meillo@95
|
1193 Thus, now the following two lines equal:
|
meillo@95
|
1194 .VS
|
meillo@95
|
1195 scan -form scan.mailx
|
meillo@95
|
1196 scan -form "=`cat .../scan.mailx`"
|
meillo@95
|
1197 VE
|
meillo@95
|
1198 This rework removed the prefix collision between
|
meillo@95
|
1199 .Sw -form
|
meillo@95
|
1200 and
|
meillo@95
|
1201 .Sw -format .
|
meillo@95
|
1202 Now, typing
|
meillo@95
|
1203 .Sw -fo
|
meillo@95
|
1204 suffices to specify form or format string.
|
meillo@95
|
1205 .P
|
meillo@95
|
1206 The different meaning of
|
meillo@95
|
1207 .Sw -format
|
meillo@95
|
1208 for
|
meillo@95
|
1209 .Pn repl
|
meillo@95
|
1210 and
|
meillo@95
|
1211 .Pn forw
|
meillo@95
|
1212 was removed in mmh.
|
meillo@95
|
1213 .Pn forw
|
meillo@95
|
1214 was completely switched to MIME-type forwarding, thus removing the
|
meillo@95
|
1215 .Sw -[no]format .
|
meillo@97
|
1216 .Ci 6e271608b7b9c23771523f88d23a4d3593010cf1
|
meillo@95
|
1217 For
|
meillo@95
|
1218 .Pn repl ,
|
meillo@95
|
1219 the
|
meillo@95
|
1220 .Sw -[no]format
|
meillo@95
|
1221 switches were reworked to
|
meillo@95
|
1222 .Sw -[no]filter
|
meillo@95
|
1223 switches.
|
meillo@97
|
1224 .Ci 67411b1f95d6ec987b4c732459e1ba8a8ac192c6
|
meillo@95
|
1225 The
|
meillo@95
|
1226 .Sw -format
|
meillo@95
|
1227 switches of
|
meillo@95
|
1228 .Pn send
|
meillo@95
|
1229 and
|
meillo@95
|
1230 .Pn post ,
|
meillo@95
|
1231 which had a third meaning,
|
meillo@95
|
1232 were removed likewise.
|
meillo@97
|
1233 .Ci f3cb7cde0e6f10451b6848678d95860d512224b9
|
meillo@95
|
1234 Eventually, the ambiguity of the
|
meillo@95
|
1235 .Sw -format
|
meillo@95
|
1236 switches was resolved by not anymore having any such switch in mmh.
|
meillo@95
|
1237
|
meillo@95
|
1238
|
meillo@95
|
1239 .U3 "MIME Tools
|
meillo@95
|
1240 .P
|
meillo@95
|
1241 The MIME tools, which were once part of
|
meillo@100
|
1242 .Pn mhn
|
meillo@100
|
1243 [sic!],
|
meillo@95
|
1244 had several switches that added little practical value to the programs.
|
meillo@95
|
1245 The
|
meillo@95
|
1246 .Sw -[no]realsize
|
meillo@95
|
1247 switches of
|
meillo@95
|
1248 .Pn mhbuild
|
meillo@95
|
1249 and
|
meillo@95
|
1250 .Pn mhlist
|
meillo@97
|
1251 were removed, doing real size calculations always now
|
meillo@97
|
1252 .Ci 8d8f1c3abc586c005c904e52c4adbfe694d2201c ,
|
meillo@97
|
1253 as
|
meillo@95
|
1254 ``This provides an accurate count at the expense of a small delay.''
|
meillo@95
|
1255 This small delay is not noticable on modern systems.
|
meillo@95
|
1256 .P
|
meillo@95
|
1257 The
|
meillo@95
|
1258 .Sw -[no]check
|
meillo@95
|
1259 switches were removed together with the support for
|
meillo@95
|
1260 .Hd Content-MD5
|
meillo@95
|
1261 header fields.
|
meillo@95
|
1262 .[
|
meillo@95
|
1263 rfc 1864
|
meillo@95
|
1264 .]
|
meillo@97
|
1265 .Ci 31dc797eb5178970d68962ca8939da3fd9a8efda
|
meillo@95
|
1266 (See Sec. XXX)
|
meillo@95
|
1267 .P
|
meillo@95
|
1268 The
|
meillo@95
|
1269 .Sw -[no]ebcdicsafe
|
meillo@95
|
1270 and
|
meillo@95
|
1271 .Sw -[no]rfc934mode
|
meillo@95
|
1272 switches of
|
meillo@95
|
1273 .Pn mhbuild
|
meillo@95
|
1274 were removed because they are considered obsolete.
|
meillo@97
|
1275 .Ci 01a3480928da485b4d6109d36d751dfa71799d58
|
meillo@97
|
1276 .Ci 3363e2624dce0eb8164cf8b3f1ab385c8ff72e88
|
meillo@95
|
1277 .P
|
meillo@95
|
1278 Content caching of external MIME parts, activated with the
|
meillo@95
|
1279 .Sw -rcache
|
meillo@95
|
1280 and
|
meillo@95
|
1281 .Sw -wcache
|
meillo@95
|
1282 switches was completely removed.
|
meillo@97
|
1283 .Ci d1fefd9f614e4dc3cda16da6c69133c1b2005269
|
meillo@97
|
1284 External MIME parts are rare today, having a caching facility
|
meillo@96
|
1285 for them is appears to be unnecessary.
|
meillo@95
|
1286 .P
|
meillo@95
|
1287 In pre-MIME times,
|
meillo@95
|
1288 .Pn mhl
|
meillo@95
|
1289 had covered many tasks that are part of MIME handling today.
|
meillo@95
|
1290 Therefore,
|
meillo@95
|
1291 .Pn mhl
|
meillo@95
|
1292 could be simplified to a large extend, reducing the number of its
|
meillo@95
|
1293 switches from 21 to 6.
|
meillo@97
|
1294 .Ci 350ad6d3542a07639213cf2a4fe524e829c1e7b6
|
meillo@97
|
1295 .Ci 0e46503be3c855bddaeae3843e1b659279c35d70
|
meillo@95
|
1296
|
meillo@95
|
1297
|
meillo@95
|
1298 .U3 "Mail Transfer Switches
|
meillo@95
|
1299 .P
|
meillo@95
|
1300 With the removal of the mail transfer facilities, a lot of switches
|
meillo@95
|
1301 vanished automatically.
|
meillo@95
|
1302 .Pn inc
|
meillo@95
|
1303 lost 9 switches, namely
|
meillo@95
|
1304 .Sw -host ,
|
meillo@95
|
1305 .Sw -port ,
|
meillo@95
|
1306 .Sw -user ,
|
meillo@95
|
1307 .Sw -proxy ,
|
meillo@95
|
1308 .Sw -snoop ,
|
meillo@95
|
1309 .Sw -[no]pack ,
|
meillo@95
|
1310 as well as
|
meillo@95
|
1311 .Sw -sasl
|
meillo@95
|
1312 and
|
meillo@95
|
1313 .Sw -saslmech .
|
meillo@95
|
1314 .Pn send
|
meillo@95
|
1315 and
|
meillo@95
|
1316 .Pn post
|
meillo@95
|
1317 lost 11 switches each, namely
|
meillo@95
|
1318 .Sw -server ,
|
meillo@95
|
1319 .Sw -port ,
|
meillo@95
|
1320 .Sw -client ,
|
meillo@95
|
1321 .Sw -user ,
|
meillo@95
|
1322 .Sw -mail ,
|
meillo@95
|
1323 .Sw -saml ,
|
meillo@95
|
1324 .Sw -send ,
|
meillo@95
|
1325 .Sw -soml ,
|
meillo@95
|
1326 .Sw -snoop ,
|
meillo@95
|
1327 as well as
|
meillo@95
|
1328 .Sw -sasl ,
|
meillo@95
|
1329 .Sw -saslmech ,
|
meillo@95
|
1330 and
|
meillo@95
|
1331 .Sw -tls .
|
meillo@95
|
1332 .Pn send
|
meillo@95
|
1333 had the switches only to pass them further to
|
meillo@95
|
1334 .Pn post ,
|
meillo@95
|
1335 because the user would invoke
|
meillo@95
|
1336 .Pn post
|
meillo@95
|
1337 not directly, but through
|
meillo@95
|
1338 .Pn send .
|
meillo@95
|
1339 All these switches, except
|
meillo@95
|
1340 .Sw -snoop
|
meillo@95
|
1341 were usually defined as default switches in the user's profile,
|
meillo@95
|
1342 but hardly given in interactive usage.
|
meillo@95
|
1343 .P
|
meillo@95
|
1344 Of course, those switches did not really ``vanish'', but the configuration
|
meillo@95
|
1345 they did was handed over to external MSAs and MRAs.
|
meillo@95
|
1346 Instead of setting up the mail transfer in mmh, it is set up in
|
meillo@95
|
1347 external tools.
|
meillo@95
|
1348 Yet, this simplifies mmh.
|
meillo@95
|
1349 Specialized external tools will likely have simple configuration files.
|
meillo@95
|
1350 Hence, instead of having one complicated central configuration file,
|
meillo@95
|
1351 the configuration of each domain is separate.
|
meillo@95
|
1352 Although the user needs to learn to configure each of the tools,
|
meillo@95
|
1353 each configuration is likely much simpler.
|
meillo@95
|
1354
|
meillo@95
|
1355
|
meillo@95
|
1356 .U3 "Maildrop Formats
|
meillo@95
|
1357 .P
|
meillo@95
|
1358 With the removal of MMDF maildrop format support,
|
meillo@95
|
1359 .Pn packf
|
meillo@95
|
1360 and
|
meillo@95
|
1361 .Pn rcvpack
|
meillo@95
|
1362 no longer needed their
|
meillo@95
|
1363 .Sw -mbox
|
meillo@95
|
1364 and
|
meillo@95
|
1365 .Sw -mmdf
|
meillo@95
|
1366 switches.
|
meillo@95
|
1367 .Sw -mbox
|
meillo@95
|
1368 is the sole behavior now.
|
meillo@97
|
1369 .Ci 3916ab66ad5d183705ac12357621ea8661afd3c0
|
meillo@95
|
1370 In the same go,
|
meillo@95
|
1371 .Pn packf
|
meillo@97
|
1372 and
|
meillo@97
|
1373 .Pn rcvpack
|
meillo@97
|
1374 were reworked (see Sec. XXX) and their
|
meillo@95
|
1375 .Sw -file
|
meillo@95
|
1376 switch became unnecessary.
|
meillo@97
|
1377 .Ci ca1023716d4c2ab890696f3e41fa0d94267a940e
|
meillo@95
|
1378
|
meillo@95
|
1379
|
meillo@95
|
1380 .U3 "Terminal Magic
|
meillo@95
|
1381 .P
|
meillo@95
|
1382 Mmh's tools will no longer clear the screen (\c
|
meillo@95
|
1383 .Pn scan 's
|
meillo@95
|
1384 and
|
meillo@95
|
1385 .Pn mhl 's
|
meillo@95
|
1386 .Sw -[no]clear
|
meillo@97
|
1387 switches
|
meillo@97
|
1388 .Ci e57b17343dcb3ff373ef4dd089fbe778f0c7c270
|
meillo@97
|
1389 .Ci 943765e7ac5693ae177fd8d2b5a2440e53ce816e ).
|
meillo@95
|
1390 Neither will
|
meillo@95
|
1391 .Pn mhl
|
meillo@95
|
1392 ring the bell (\c
|
meillo@97
|
1393 .Sw -[no]bell
|
meillo@97
|
1394 .Ci e11983f44e59d8de236affa5b0d0d3067c192e24 )
|
meillo@95
|
1395 nor page the output itself (\c
|
meillo@97
|
1396 .Sw -length
|
meillo@97
|
1397 .Ci 5b9d883db0318ed2b84bb82dee880d7381f99188 ).
|
meillo@95
|
1398 .P
|
meillo@95
|
1399 Generally, the pager to use is no longer specified with the
|
meillo@95
|
1400 .Sw -[no]moreproc
|
meillo@95
|
1401 command line switches for
|
meillo@95
|
1402 .Pn mhl
|
meillo@95
|
1403 and
|
meillo@95
|
1404 .Pn show /\c
|
meillo@95
|
1405 .Pn mhshow .
|
meillo@97
|
1406 .Ci 39e87a75b5c2d3572ec72e717720b44af291e88a
|
meillo@95
|
1407 .P
|
meillo@95
|
1408 .Pn prompter
|
meillo@95
|
1409 lost its
|
meillo@95
|
1410 .Sw -erase
|
meillo@95
|
1411 and
|
meillo@95
|
1412 .Sw -kill
|
meillo@95
|
1413 switches because today the terminal cares for the line editing keys.
|
meillo@95
|
1414
|
meillo@95
|
1415
|
meillo@95
|
1416 .U3 "Header Printing
|
meillo@95
|
1417 .P
|
meillo@95
|
1418 .Pn folder 's
|
meillo@95
|
1419 data output is self-explaining enough that
|
meillo@95
|
1420 displaying the header line makes few sense.
|
meillo@95
|
1421 Hence, the
|
meillo@95
|
1422 .Sw -[no]header
|
meillo@95
|
1423 switch was removed and headers are never printed.
|
meillo@97
|
1424 .Ci 601cc73d1fa05ce96faa728f036d6c51b91701c7
|
meillo@95
|
1425 .P
|
meillo@95
|
1426 In
|
meillo@95
|
1427 .Pn mhlist ,
|
meillo@95
|
1428 the
|
meillo@95
|
1429 .Sw -[no]header
|
meillo@95
|
1430 switches were removed, too.
|
meillo@97
|
1431 .Ci b24f96523aaf60e44e04a3ffb1d22e69a13a602f
|
meillo@95
|
1432 But in this case headers are always printed,
|
meillo@95
|
1433 because the output is not self-explaining.
|
meillo@95
|
1434 .P
|
meillo@95
|
1435 .Pn scan
|
meillo@95
|
1436 also had
|
meillo@95
|
1437 .Sw -[no]header
|
meillo@95
|
1438 switches.
|
meillo@95
|
1439 Printing the header had been sensible until the introduction of
|
meillo@95
|
1440 format strings made it impossible to display the column headings.
|
meillo@95
|
1441 Only the folder name and the current date remained to be printed.
|
meillo@95
|
1442 As this information can be perfectly retrieved by
|
meillo@95
|
1443 .Pn folder
|
meillo@95
|
1444 and
|
meillo@95
|
1445 .Pn date ,
|
meillo@95
|
1446 consequently, the switches were removed.
|
meillo@97
|
1447 .Ci c477dc5d1d03fa6d9a8ab3dd3508c63cbddc044e
|
meillo@95
|
1448 .P
|
meillo@95
|
1449 By removing all
|
meillo@95
|
1450 .Sw -header
|
meillo@95
|
1451 switches, the collision with
|
meillo@95
|
1452 .Sw -help
|
meillo@95
|
1453 on the first two letters was resolved.
|
meillo@95
|
1454 Currently,
|
meillo@95
|
1455 .Sw -h
|
meillo@95
|
1456 evaluates to
|
meillo@95
|
1457 .Sw -help
|
meillo@95
|
1458 for all tools of mmh.
|
meillo@95
|
1459
|
meillo@95
|
1460
|
meillo@95
|
1461 .U3 "Suppressing Edits or the WhatNow Shell
|
meillo@95
|
1462 .P
|
meillo@95
|
1463 The
|
meillo@95
|
1464 .Sw -noedit
|
meillo@100
|
1465 switch of
|
meillo@95
|
1466 .Pn comp ,
|
meillo@95
|
1467 .Pn repl ,
|
meillo@95
|
1468 .Pn forw ,
|
meillo@95
|
1469 .Pn dist ,
|
meillo@95
|
1470 and
|
meillo@95
|
1471 .Pn whatnow
|
meillo@95
|
1472 was removed, but it can now be replaced by specifying
|
meillo@95
|
1473 .Sw -editor
|
meillo@95
|
1474 with an empty argument.
|
meillo@97
|
1475 .Ci 75fca31a5b9d5c1a99c74ab14c94438d8852fba9
|
meillo@95
|
1476 (Specifying
|
meillo@95
|
1477 .Cl "-editor true
|
meillo@95
|
1478 is nearly the same, only differing by the previous editor being set.)
|
meillo@95
|
1479 .P
|
meillo@95
|
1480 The more important change is the removal of the
|
meillo@95
|
1481 .Sw -nowhatnowproc
|
meillo@95
|
1482 switch.
|
meillo@97
|
1483 .Ci ee4f43cf2ef0084ec698e4e87159a94c01940622
|
meillo@95
|
1484 This switch had introduced an awkward behavior, as explained in nmh's
|
meillo@95
|
1485 man page for
|
meillo@95
|
1486 .Mp comp (1):
|
meillo@98
|
1487 .QS
|
meillo@98
|
1488 The \-editor editor switch indicates the editor to use for
|
meillo@98
|
1489 the initial edit. Upon exiting from the editor, comp will
|
meillo@98
|
1490 invoke the whatnow program. See whatnow(1) for a discussion
|
meillo@98
|
1491 of available options. The invocation of this program can be
|
meillo@98
|
1492 inhibited by using the \-nowhatnowproc switch. (In truth of
|
meillo@98
|
1493 fact, it is the whatnow program which starts the initial
|
meillo@98
|
1494 edit. Hence, \-nowhatnowproc will prevent any edit from
|
meillo@95
|
1495 occurring.)
|
meillo@98
|
1496 .QE
|
meillo@95
|
1497 .P
|
meillo@95
|
1498 Effectively, the
|
meillo@95
|
1499 .Sw -nowhatnowproc
|
meillo@100
|
1500 switch creates only a draft message.
|
meillo@95
|
1501 As
|
meillo@95
|
1502 .Cl "-whatnowproc true
|
meillo@95
|
1503 causes the same behavior, the
|
meillo@95
|
1504 .Sw -nowhatnowproc
|
meillo@95
|
1505 switch was removed for being redundant.
|
meillo@100
|
1506 Likely, the
|
meillo@95
|
1507 .Sw -nowhatnowproc
|
meillo@100
|
1508 switch was intended to be used by front-ends.
|
meillo@95
|
1509
|
meillo@95
|
1510
|
meillo@95
|
1511 .U3 "Compatibility Switches
|
meillo@95
|
1512 .BU
|
meillo@95
|
1513 The hidden
|
meillo@95
|
1514 .Sw -[no]total
|
meillo@95
|
1515 switches of
|
meillo@95
|
1516 .Pn flist .
|
meillo@95
|
1517 They were simply the inverse of the visible
|
meillo@95
|
1518 .Sw -[no]fast
|
meillo@95
|
1519 switches:
|
meillo@95
|
1520 .Sw -total
|
meillo@95
|
1521 was
|
meillo@95
|
1522 .Sw -nofast
|
meillo@95
|
1523 and
|
meillo@95
|
1524 .Sw -nototal
|
meillo@95
|
1525 was
|
meillo@95
|
1526 .Sw -fast .
|
meillo@95
|
1527 I removed the
|
meillo@95
|
1528 .Sw -[no]total
|
meillo@95
|
1529 legacy.
|
meillo@97
|
1530 .Ci ea21fe2c4bd23c639bef251398fae809875732ec
|
meillo@95
|
1531 .BU
|
meillo@95
|
1532 The
|
meillo@95
|
1533 .Sw -subject
|
meillo@95
|
1534 switch of
|
meillo@95
|
1535 .Pn sortm
|
meillo@95
|
1536 existed for compatibility only.
|
meillo@95
|
1537 It can be fully replaced by
|
meillo@95
|
1538 .Cl "-textfield subject
|
meillo@95
|
1539 thus it was removed.
|
meillo@97
|
1540 .Ci 00140a3c86e9def69d98ba2ffd4d6e50ef6326ea
|
meillo@95
|
1541
|
meillo@95
|
1542
|
meillo@95
|
1543 .U3 "Various
|
meillo@95
|
1544 .BU
|
meillo@96
|
1545 In order to avoid prefix collisions among switch names, the
|
meillo@95
|
1546 .Sw -version
|
meillo@95
|
1547 switch was renamed to
|
meillo@95
|
1548 .Sw -Version
|
meillo@95
|
1549 (with capital `V').
|
meillo@97
|
1550 .Ci 32b2354dbaf4bf934936eb5b102a4a3d2fdd209a
|
meillo@95
|
1551 Every program has the
|
meillo@95
|
1552 .Sw -version
|
meillo@95
|
1553 switch but its first three letters collided with the
|
meillo@95
|
1554 .Sw -verbose
|
meillo@95
|
1555 switch, present in many programs.
|
meillo@95
|
1556 The rename solved this problem once for all.
|
meillo@95
|
1557 Although this rename breaks a basic interface, having the
|
meillo@95
|
1558 .Sw -V
|
meillo@95
|
1559 abbreviation to display the version information, isn't all too bad.
|
meillo@95
|
1560 .BU
|
meillo@95
|
1561 .Sw -[no]preserve
|
meillo@95
|
1562 of
|
meillo@95
|
1563 .Pn refile
|
meillo@95
|
1564 was removed because what use was it anyway?
|
meillo@98
|
1565 .QS
|
meillo@95
|
1566 Normally when a message is refiled, for each destination
|
meillo@95
|
1567 folder it is assigned the number which is one above the current
|
meillo@95
|
1568 highest message number in that folder. Use of the
|
meillo@95
|
1569 \-preserv [sic!] switch will override this message renaming, and try
|
meillo@95
|
1570 to preserve the number of the message. If a conflict for a
|
meillo@95
|
1571 particular folder occurs when using the \-preserve switch,
|
meillo@95
|
1572 then refile will use the next available message number which
|
meillo@95
|
1573 is above the message number you wish to preserve.
|
meillo@98
|
1574 .QE
|
meillo@95
|
1575 .BU
|
meillo@95
|
1576 The removal of the
|
meillo@95
|
1577 .Sw -[no]reverse
|
meillo@95
|
1578 switches of
|
meillo@95
|
1579 .Pn scan
|
meillo@97
|
1580 .Ci 8edc5aaf86f9f77124664f6801bc6c6cdf258173
|
meillo@95
|
1581 is a bug fix, supported by the comments
|
meillo@95
|
1582 ``\-[no]reverse under #ifdef BERK (I really HATE this)''
|
meillo@95
|
1583 by Rose and
|
meillo@95
|
1584 ``Lists messages in reverse order with the `\-reverse' switch.
|
meillo@95
|
1585 This should be considered a bug.'' by Romine in the documentation.
|
meillo@97
|
1586 The question remains why neither Rose and Romine had fixed this
|
meillo@109
|
1587 bug in the eighties when they wrote these comments nor has anyone
|
meillo@95
|
1588 thereafter.
|
meillo@93
|
1589
|
meillo@93
|
1590
|
meillo@93
|
1591 .ig
|
meillo@93
|
1592
|
meillo@95
|
1593 forw: [no]dashstuffing(mhl)
|
meillo@93
|
1594
|
meillo@95
|
1595 mhshow: [no]pause [no]serialonly
|
meillo@93
|
1596
|
meillo@93
|
1597 mhmail: resent queued
|
meillo@93
|
1598 inc: snoop, (pop)
|
meillo@93
|
1599
|
meillo@95
|
1600 mhl: [no]faceproc folder sleep
|
meillo@95
|
1601 [no]dashstuffing(forw) digest list volume number issue number
|
meillo@93
|
1602
|
meillo@95
|
1603 prompter: [no]doteof
|
meillo@93
|
1604
|
meillo@93
|
1605 refile: [no]preserve [no]unlink [no]rmmproc
|
meillo@93
|
1606
|
meillo@95
|
1607 send: [no]forward [no]mime [no]msgid
|
meillo@93
|
1608 [no]push split [no]unique (sasl) width snoop [no]dashstuffing
|
meillo@93
|
1609 attach attachformat
|
meillo@93
|
1610 whatnow: (noedit) attach
|
meillo@93
|
1611
|
meillo@93
|
1612 slocal: [no]suppressdups
|
meillo@93
|
1613
|
meillo@95
|
1614 spost: [no]filter [no]backup width [no]push idanno
|
meillo@93
|
1615 [no]check(whom) whom(whom)
|
meillo@93
|
1616
|
meillo@93
|
1617 whom: ???
|
meillo@93
|
1618
|
meillo@95
|
1619 ..
|
meillo@93
|
1620
|
meillo@93
|
1621
|
meillo@93
|
1622 .ig
|
meillo@93
|
1623
|
meillo@93
|
1624 .P
|
meillo@93
|
1625 In the best case, all switches are unambiguous on the first character,
|
meillo@93
|
1626 or on the three-letter prefix for the `no' variants.
|
meillo@96
|
1627 Reducing switch prefix collisions, shortens the necessary prefix length
|
meillo@93
|
1628 the user must type.
|
meillo@93
|
1629 Having less switches helps best.
|
meillo@93
|
1630
|
meillo@93
|
1631 ..
|
meillo@58
|
1632
|
meillo@95
|
1633
|
meillo@102
|
1634 .\" XXX: whatnow prompt commands
|
meillo@102
|
1635
|
meillo@102
|
1636
|
meillo@95
|
1637
|
meillo@95
|
1638
|
meillo@74
|
1639 .H1 "Modernizing
|
meillo@102
|
1640 .P
|
meillo@109
|
1641 The code base of mmh originates from the late seventies.
|
meillo@109
|
1642 Through the eighties, extensive work had been done on it.
|
meillo@109
|
1643 In the nineties, it was partly reorganized and extended.
|
meillo@102
|
1644 Relicts from each decade have gathered in the code base.
|
meillo@102
|
1645 My goal was to modernize the code base.
|
meillo@102
|
1646
|
meillo@102
|
1647 .P
|
meillo@102
|
1648 FIXME functional aspect only here
|
meillo@102
|
1649 .P
|
meillo@102
|
1650 FIXME ref to `code style' for non-functional aspects.
|
meillo@58
|
1651
|
meillo@58
|
1652
|
meillo@100
|
1653 .H2 "Code Relicts
|
meillo@0
|
1654 .P
|
meillo@109
|
1655 My position to drop obsolete functions of mmh, in order to remove old code,
|
meillo@104
|
1656 is much more revolutional than the nmh community likes to have it.
|
meillo@104
|
1657 Working on an experimental version, I was able to quickly drop
|
meillo@104
|
1658 functionality I considered ancient.
|
meillo@104
|
1659 The need for consensus with peers would have slowed this process down.
|
meillo@104
|
1660 Without the need to justify my decisions, I was able to rush forward.
|
meillo@110
|
1661 In December 2011, Paul Vixie motivated the nmh developers to just
|
meillo@104
|
1662 do the work:
|
meillo@104
|
1663 .[
|
meillo@104
|
1664 paul vixie edginess nmh-workers
|
meillo@104
|
1665 .]
|
meillo@104
|
1666 .QS
|
meillo@104
|
1667 let's stop walking on egg shells with this code base. there's no need to
|
meillo@104
|
1668 discuss whether to keep using vfork, just note in [sic!] passing, [...]
|
meillo@104
|
1669 we don't need a separate branch for removing vmh
|
meillo@104
|
1670 or ridding ourselves of #ifdef's or removing posix replacement functions
|
meillo@104
|
1671 or depending on pure ansi/posix "libc".
|
meillo@104
|
1672 .QP
|
meillo@104
|
1673 these things should each be a day or two of work and the "main branch"
|
meillo@104
|
1674 should just be modern. [...]
|
meillo@104
|
1675 let's push forward, aggressively.
|
meillo@104
|
1676 .QE
|
meillo@104
|
1677 .LP
|
meillo@104
|
1678 I did so already in the months before.
|
meillo@104
|
1679 I pushed forward.
|
meillo@104
|
1680 I simply dropped the cruft.
|
meillo@104
|
1681 .P
|
meillo@104
|
1682 The decision to drop a feature was based on literature research and
|
meillo@104
|
1683 careful thinking, but whether having had contact to this particular
|
meillo@104
|
1684 feature within my own computer life served as a rule of thumb.
|
meillo@109
|
1685 Always, I explained my reasons in the commit messages
|
meillo@109
|
1686 in the version control system.
|
meillo@104
|
1687 Hence, others can comprehend my view and argue for undoing the change
|
meillo@104
|
1688 if I have missed an important aspect.
|
meillo@109
|
1689 I was quick in dropping parts.
|
meillo@109
|
1690 I rather re-included falsely dropped parts than going a slower pace.
|
meillo@109
|
1691 Mmh is experimental work; it required tough decisions.
|
meillo@12
|
1692
|
meillo@102
|
1693
|
meillo@104
|
1694 .U3 "Forking
|
meillo@12
|
1695 .P
|
meillo@109
|
1696 Being a tool chest, MH creates many processes.
|
meillo@104
|
1697 In earlier times
|
meillo@104
|
1698 .Fu fork()
|
meillo@104
|
1699 had been an expensive system call, because the process's image needed
|
meillo@104
|
1700 to be duplicated completely at once.
|
meillo@109
|
1701 This was especially painful in the common case when the image gets
|
meillo@104
|
1702 replaced by a call to
|
meillo@104
|
1703 .Fu exec()
|
meillo@104
|
1704 right after having forked the child process.
|
meillo@104
|
1705 The
|
meillo@104
|
1706 .Fu vfork()
|
meillo@104
|
1707 system call was invented to speed up this particular case.
|
meillo@104
|
1708 It completely omits the duplication of the image.
|
meillo@104
|
1709 On old systems this resulted in significant speed ups.
|
meillo@104
|
1710 Therefore MH used
|
meillo@104
|
1711 .Fu vfork()
|
meillo@104
|
1712 whenever possible.
|
meillo@12
|
1713 .P
|
meillo@104
|
1714 Modern memory management units support copy-on-write semantics, which make
|
meillo@104
|
1715 .Fu fork()
|
meillo@104
|
1716 almost as fast as
|
meillo@104
|
1717 .Fu vfork() .
|
meillo@104
|
1718 The man page of
|
meillo@104
|
1719 .Mp vfork (2)
|
meillo@104
|
1720 in FreeBSD 8.0 states:
|
meillo@104
|
1721 .QS
|
meillo@104
|
1722 This system call will be eliminated when proper system sharing mechanisms
|
meillo@104
|
1723 are implemented. Users should not depend on the memory sharing semantics
|
meillo@104
|
1724 of vfork() as it will, in that case, be made synonymous to fork(2).
|
meillo@104
|
1725 .QE
|
meillo@104
|
1726 .LP
|
meillo@104
|
1727 Vixie supports the removal with the note that ``the last
|
meillo@104
|
1728 system on which fork was so slow that an mh user would notice it, was
|
meillo@104
|
1729 Eunice. that was 1987''.
|
meillo@104
|
1730 .[
|
meillo@104
|
1731 nmh-workers vixie edginess
|
meillo@104
|
1732 .]
|
meillo@104
|
1733 I replaced all calls to
|
meillo@104
|
1734 .Fu vfork()
|
meillo@104
|
1735 with calls to
|
meillo@104
|
1736 .Fu fork() .
|
meillo@109
|
1737 .Ci 40821f5c1316e9205a08375e7075909cc9968e7d
|
meillo@104
|
1738 .P
|
meillo@104
|
1739 Related to the costs of
|
meillo@104
|
1740 .Fu fork()
|
meillo@104
|
1741 is the probability of its success.
|
meillo@109
|
1742 In the eighties, on heavy loaded systems, calls to
|
meillo@104
|
1743 .Fu fork()
|
meillo@104
|
1744 were prone to failure.
|
meillo@104
|
1745 Hence, many of the
|
meillo@104
|
1746 .Fu fork()
|
meillo@104
|
1747 calls in the code were wrapped into loops to retry the
|
meillo@104
|
1748 .Fu fork()
|
meillo@109
|
1749 several times, to increase the changes to succeed, eventually.
|
meillo@109
|
1750 On modern systems, a failing
|
meillo@104
|
1751 .Fu fork()
|
meillo@109
|
1752 call is unusual.
|
meillo@104
|
1753 Hence, in the rare case when
|
meillo@104
|
1754 .Fu fork()
|
meillo@104
|
1755 fails, mmh programs simply abort.
|
meillo@109
|
1756 .Ci 5fbf37ee68e018998ada61eeab73e035b26834b6
|
meillo@12
|
1757
|
meillo@12
|
1758
|
meillo@109
|
1759 .U3 "Header Fields
|
meillo@104
|
1760 .BU
|
meillo@84
|
1761 The
|
meillo@84
|
1762 .Hd Encrypted
|
meillo@104
|
1763 header field was introduced by RFC\|822,
|
meillo@109
|
1764 but already marked as legacy in RFC\|2822.
|
meillo@109
|
1765 Today, OpenPGP provides the basis for standardized exchange of encrypted
|
meillo@104
|
1766 messages [RFC\|4880, RFC\|3156].
|
meillo@109
|
1767 Hence, the support for
|
meillo@104
|
1768 .Hd Encrypted
|
meillo@104
|
1769 header fields is removed in mmh.
|
meillo@109
|
1770 .Ci 064527f7b57ab050e5af13e15ad99aeeab125857
|
meillo@104
|
1771 .BU
|
meillo@84
|
1772 Native support for
|
meillo@84
|
1773 .Hd Face
|
meillo@104
|
1774 header fields has been removed, as well.
|
meillo@109
|
1775 .Ci 8e5be81f784682822f5e868c1bf3c8624682bd23
|
meillo@104
|
1776 This feature is similar to the
|
meillo@84
|
1777 .Hd X-Face
|
meillo@84
|
1778 header field in its intent,
|
meillo@21
|
1779 but takes a different approach to store the image.
|
meillo@84
|
1780 Instead of encoding the image data directly into the header field,
|
meillo@109
|
1781 it contains the hostname and UDP port where the image
|
meillo@109
|
1782 date can be retrieved.
|
meillo@109
|
1783 There exists even a third Face system,
|
meillo@109
|
1784 which is the successor of
|
meillo@109
|
1785 .Hd X-Face ,
|
meillo@109
|
1786 although it re-uses the
|
meillo@104
|
1787 .Hd Face
|
meillo@109
|
1788 header field.
|
meillo@109
|
1789 It was invented in 2005 and supports colored PNG images.
|
meillo@104
|
1790 None of the Face systems described here is popular today.
|
meillo@104
|
1791 Hence, mmh has no direct support for them.
|
meillo@104
|
1792 .BU
|
meillo@104
|
1793 The
|
meillo@104
|
1794 .Hd Content-MD5
|
meillo@104
|
1795 header field was introduced by RFC\|1864.
|
meillo@104
|
1796 It provides detection of data corruption during the transfer.
|
meillo@104
|
1797 But it can not ensure verbatim end-to-end delivery of the contents
|
meillo@104
|
1798 [RFC\|1864].
|
meillo@104
|
1799 The proper approach to verify content integrity in an
|
meillo@104
|
1800 end-to-end relationship is the use of digital cryptography.
|
meillo@104
|
1801 .\" XXX (RFCs FIXME).
|
meillo@104
|
1802 On the other hand, transfer protocols should detect corruption during
|
meillo@109
|
1803 the transmission.
|
meillo@109
|
1804 The TCP includes a checksum field therefore.
|
meillo@104
|
1805 These two approaches in combinations render the
|
meillo@104
|
1806 .Hd Content-MD5
|
meillo@104
|
1807 header field superfluous.
|
meillo@109
|
1808 Not a single one out of 4\|200 messages from two decades
|
meillo@109
|
1809 in an nmh-workers mailing list archive contains a
|
meillo@104
|
1810 .Hd Content-MD5
|
meillo@104
|
1811 header field.
|
meillo@104
|
1812 Neither did any of the 60\|000 messages in my personal mail storage.
|
meillo@104
|
1813 Removing the support for this header field,
|
meillo@104
|
1814 removed the last place where MD5 computation was needed.
|
meillo@109
|
1815 .Ci 31dc797eb5178970d68962ca8939da3fd9a8efda
|
meillo@104
|
1816 Hence, the MD5 code could be removed as well.
|
meillo@104
|
1817 Over 500 lines of code vanished by this one change.
|
meillo@104
|
1818
|
meillo@104
|
1819
|
meillo@104
|
1820 .U3 "MMDF maildrop support
|
meillo@21
|
1821 .P
|
meillo@104
|
1822 This type of format is conceptionally similar to the mbox format,
|
meillo@104
|
1823 but uses a different message delimiter (`\fL^A^A^A^A\fP' instead of
|
meillo@104
|
1824 `\fLFrom\0\fP').
|
meillo@104
|
1825 Mbox is the de-facto standard maildrop format on Unix,
|
meillo@109
|
1826 whereas the MMDF maildrop format became forgotten.
|
meillo@104
|
1827 I did drop MMDF maildrop format support.
|
meillo@109
|
1828 Mbox is the only packed mailbox format supported in mmh.
|
meillo@104
|
1829 .P
|
meillo@109
|
1830 The simplifications within the code were moderate.
|
meillo@109
|
1831 Mainly, the reading and writing of MMDF mailbox files was removed.
|
meillo@109
|
1832 But also, switches of
|
meillo@109
|
1833 .Pn packf
|
meillo@104
|
1834 and
|
meillo@109
|
1835 .Pn rcvpack
|
meillo@109
|
1836 could be removed.
|
meillo@109
|
1837 .Ci 3916ab66ad5d183705ac12357621ea8661afd3c0
|
meillo@109
|
1838 In the message parsing function
|
meillo@109
|
1839 .Fn sbr/m_getfld.c ,
|
meillo@109
|
1840 knowledge of MMDF packed mail boxes was removed.
|
meillo@109
|
1841 .Ci 684ec30d81e1223a282764452f4902ed4ad1c754
|
meillo@109
|
1842 Further code structure simplifications may be possible there,
|
meillo@109
|
1843 because only one single packed mailbox format is left to be supported.
|
meillo@104
|
1844 I have not worked on them yet because
|
meillo@104
|
1845 .Fu m_getfld()
|
meillo@104
|
1846 is heavily optimized and thus dangerous to touch.
|
meillo@104
|
1847 The risk of damaging the intricate workings of the optimized code is
|
meillo@104
|
1848 too high.
|
meillo@104
|
1849 .\" XXX: move somewhere else
|
meillo@104
|
1850 This problem is know to the developers of nmh, too.
|
meillo@109
|
1851 They also avoid touching this minefield.
|
meillo@104
|
1852
|
meillo@12
|
1853
|
meillo@101
|
1854 .U3 "Prompter's Control Keys
|
meillo@20
|
1855 .P
|
meillo@20
|
1856 The program
|
meillo@20
|
1857 .Pn prompter
|
meillo@104
|
1858 queries the user to fill in a message form.
|
meillo@104
|
1859 When used by
|
meillo@20
|
1860 .Pn comp
|
meillo@104
|
1861 as
|
meillo@104
|
1862 .Cl "comp -editor prompter" ,
|
meillo@20
|
1863 the resulting behavior is similar to
|
meillo@20
|
1864 .Pn mailx .
|
meillo@51
|
1865 Apparently,
|
meillo@20
|
1866 .Pn prompter
|
meillo@104
|
1867 hadn't been touched lately.
|
meillo@104
|
1868 Otherwise it's hardly explainable why it
|
meillo@20
|
1869 still offered the switches
|
meillo@84
|
1870 .Sw -erase
|
meillo@84
|
1871 .Ar chr
|
meillo@20
|
1872 and
|
meillo@84
|
1873 .Sw -kill
|
meillo@84
|
1874 .Ar chr
|
meillo@20
|
1875 to name the characters for command line editing.
|
meillo@21
|
1876 The times when this had been necessary are long time gone.
|
meillo@20
|
1877 Today these things work out-of-the-box, and if not, are configured
|
meillo@20
|
1878 with the standard tool
|
meillo@20
|
1879 .Pn stty .
|
meillo@104
|
1880 The switches are removed now
|
meillo@104
|
1881 .Ci 0bd9750710cdbab80cfb4036dd87af20afe1552f .
|
meillo@20
|
1882
|
meillo@104
|
1883
|
meillo@109
|
1884 .U3 "Hardcopy Terminal Support
|
meillo@21
|
1885 .P
|
meillo@109
|
1886 More of a funny anecdote is a check for being connected to a
|
meillo@109
|
1887 hardcopy terminal.
|
meillo@109
|
1888 It remained in the code until Spring 2012, when I finally removed it
|
meillo@104
|
1889 .Ci b7764c4a6b71d37918a97594d866258f154017ca .
|
meillo@109
|
1890 I would be truly happy to see such a terminal in action today,
|
meillo@109
|
1891 maybe even being able to work on it.
|
meillo@109
|
1892 But I fear my chances are null.
|
meillo@21
|
1893 .P
|
meillo@109
|
1894 The check only prevented a pager to be placed between the printing
|
meillo@104
|
1895 program (\c
|
meillo@104
|
1896 .Pn mhl )
|
meillo@104
|
1897 and the terminal.
|
meillo@109
|
1898 In nmh, this could have been ensured statically with the
|
meillo@104
|
1899 .Sw -nomoreproc
|
meillo@109
|
1900 at the command line, too.
|
meillo@109
|
1901 In mmh, seting the profile entry
|
meillo@104
|
1902 .Pe Pager
|
meillo@104
|
1903 or the environment variable
|
meillo@104
|
1904 .Ev PAGER
|
meillo@104
|
1905 to
|
meillo@109
|
1906 .Pn cat
|
meillo@109
|
1907 does the job.
|
meillo@104
|
1908
|
meillo@104
|
1909
|
meillo@21
|
1910
|
meillo@12
|
1911
|
meillo@58
|
1912 .H2 "Attachments
|
meillo@22
|
1913 .P
|
meillo@101
|
1914 The mind model of email attachments is unrelated to MIME.
|
meillo@101
|
1915 Although the MIME RFCs (2045 through 2049) define the technical
|
meillo@109
|
1916 requirements for having attachments, they do not mention the word
|
meillo@101
|
1917 ``attachment''.
|
meillo@101
|
1918 Instead of attachments, MIME talks about ``multi-part message bodies''
|
meillo@101
|
1919 [RFC\|2045], a more general concept.
|
meillo@101
|
1920 Multi-part messages are messages
|
meillo@101
|
1921 ``in which one or more different
|
meillo@101
|
1922 sets of data are combined in a single body''
|
meillo@101
|
1923 [RFC\|2046].
|
meillo@101
|
1924 MIME keeps its descriptions generic;
|
meillo@101
|
1925 it does not imply specific usage models.
|
meillo@109
|
1926 One usage model became prevalent: attachments.
|
meillo@101
|
1927 The idea is having a main text document with files of arbitrary kind
|
meillo@101
|
1928 attached to it.
|
meillo@101
|
1929 In MIME terms, this is a multi-part message having a text part first
|
meillo@110
|
1930 and parts of arbitrary type following.
|
meillo@101
|
1931 .P
|
meillo@101
|
1932 MH's MIME support is a direct implementation of the RFCs.
|
meillo@101
|
1933 The perception of the topic described in the RFCs is clearly visible
|
meillo@101
|
1934 in MH's implementation.
|
meillo@109
|
1935 In result, MH had all the MIME features but no idea of attachments.
|
meillo@109
|
1936 But users don't need all the MIME features,
|
meillo@109
|
1937 they want convenient attachment handling.
|
meillo@109
|
1938
|
meillo@102
|
1939
|
meillo@102
|
1940 .U3 "Composing MIME Messages
|
meillo@102
|
1941 .P
|
meillo@102
|
1942 In order to improve the situation on the message composing side,
|
meillo@102
|
1943 Jon Steinhart had added an attachment system to nmh in 2002.
|
meillo@101
|
1944 .Ci 7480dbc14bc90f2d872d434205c0784704213252
|
meillo@102
|
1945 In the file
|
meillo@102
|
1946 .Fn docs/README-ATTACHMENTS ,
|
meillo@102
|
1947 he described his motivation to do so as such:
|
meillo@101
|
1948 .QS
|
meillo@101
|
1949 Although nmh contains the necessary functionality for MIME message handing,
|
meillo@101
|
1950 the interface to this functionality is pretty obtuse.
|
meillo@101
|
1951 There's no way that I'm ever going to convince my partner to write
|
meillo@101
|
1952 .Pn mhbuild
|
meillo@101
|
1953 composition files!
|
meillo@101
|
1954 .QE
|
meillo@102
|
1955 .LP
|
meillo@102
|
1956 With this change, the mind model of attachments entered nmh.
|
meillo@102
|
1957 In the same document:
|
meillo@101
|
1958 .QS
|
meillo@101
|
1959 These changes simplify the task of managing attachments on draft files.
|
meillo@101
|
1960 They allow attachments to be added, listed, and deleted.
|
meillo@101
|
1961 MIME messages are automatically created when drafts with attachments
|
meillo@101
|
1962 are sent.
|
meillo@101
|
1963 .QE
|
meillo@102
|
1964 .LP
|
meillo@102
|
1965 Unfortunately, the attachment system,
|
meillo@102
|
1966 like any new facilities in nmh,
|
meillo@110
|
1967 was inactive by default.
|
meillo@101
|
1968 .P
|
meillo@101
|
1969 During my work in Argentina, I tried to improve the attachment system.
|
meillo@102
|
1970 But, because of great opposition in the nmh community,
|
meillo@102
|
1971 my patch died as a proposal on the mailing list, after long discussions.
|
meillo@101
|
1972 .[
|
meillo@101
|
1973 nmh-workers attachment proposal
|
meillo@101
|
1974 .]
|
meillo@110
|
1975 In January 2012, I extended the patch and applied it to mmh.
|
meillo@101
|
1976 .Ci 8ff284ff9167eff8f5349481529332d59ed913b1
|
meillo@102
|
1977 In mmh, the attachment system is active by default.
|
meillo@102
|
1978 Instead of command line switches, the
|
meillo@102
|
1979 .Pe Attachment-Header
|
meillo@102
|
1980 profile entry is used to specify
|
meillo@102
|
1981 the name of the attachment header field.
|
meillo@102
|
1982 It is pre-defined to
|
meillo@102
|
1983 .Hd Attach .
|
meillo@101
|
1984 .P
|
meillo@101
|
1985 To add an attachment to a draft, simply add an attachment header:
|
meillo@101
|
1986 .VS
|
meillo@101
|
1987 To: bob
|
meillo@101
|
1988 Subject: The file you wanted
|
meillo@101
|
1989 Attach: /path/to/the/file-bob-wanted
|
meillo@101
|
1990 --------
|
meillo@101
|
1991 Here it is.
|
meillo@101
|
1992 VE
|
meillo@101
|
1993 The header field can be added to the draft manually in the editor,
|
meillo@102
|
1994 or by using the `attach' command at the WhatNow prompt, or
|
meillo@102
|
1995 non-interactively with
|
meillo@101
|
1996 .Pn anno :
|
meillo@101
|
1997 .VS
|
meillo@102
|
1998 anno -append -nodate -component Attach -text /path/to/attachment
|
meillo@101
|
1999 VE
|
meillo@102
|
2000 Drafts with attachment headers are converted to MIME automatically by
|
meillo@102
|
2001 .Pn send .
|
meillo@102
|
2002 The conversion to MIME is invisible to the user.
|
meillo@102
|
2003 The draft stored in the draft folder is always in source form, with
|
meillo@101
|
2004 attachment headers.
|
meillo@101
|
2005 If the MIMEification fails, for instance because the file to attach
|
meillo@101
|
2006 is not accessible, the original draft is not changed.
|
meillo@101
|
2007 .P
|
meillo@102
|
2008 The attachment system handles the forwarding of messages, too.
|
meillo@101
|
2009 If the attachment header value starts with a plus character (`+'),
|
meillo@101
|
2010 like in
|
meillo@101
|
2011 .Cl "Attach: +bob 30 42" ,
|
meillo@101
|
2012 The given messages in the specified folder will be attached.
|
meillo@101
|
2013 This allowed to simplify
|
meillo@101
|
2014 .Pn forw .
|
meillo@101
|
2015 .Ci f41f04cf4ceca7355232cf7413e59afafccc9550
|
meillo@101
|
2016 .P
|
meillo@101
|
2017 Closely related to attachments is non-ASCII text content,
|
meillo@101
|
2018 because it requires MIME too.
|
meillo@102
|
2019 In nmh, the user needed to call `mime' at the WhatNow prompt
|
meillo@101
|
2020 to have the draft converted to MIME.
|
meillo@102
|
2021 This was necessary whenever the draft contained non-ASCII characters.
|
meillo@101
|
2022 If the user did not call `mime', a broken message would be sent.
|
meillo@101
|
2023 Therefore, the
|
meillo@101
|
2024 .Pe automimeproc
|
meillo@101
|
2025 profile entry could be specified to have the `mime' command invoked
|
meillo@102
|
2026 automatically each time.
|
meillo@101
|
2027 Unfortunately, this approach conflicted with with attachment system
|
meillo@101
|
2028 because the draft would already be in MIME format at the time
|
meillo@101
|
2029 when the attachment system wanted to MIMEify it.
|
meillo@102
|
2030 To use nmh's attachment system, `mime' must not be called at the
|
meillo@102
|
2031 WhatNow prompt and
|
meillo@101
|
2032 .Pe automimeproc
|
meillo@102
|
2033 must not be set in the profile.
|
meillo@101
|
2034 But then the case of non-ASCII text without attachment headers was
|
meillo@101
|
2035 not caught.
|
meillo@102
|
2036 All in all, the solution was complex and irritating.
|
meillo@102
|
2037 My patch from December 2010 would have simplified the situation.
|
meillo@102
|
2038 .P
|
meillo@101
|
2039 Mmh's current solution is even more elaborate.
|
meillo@101
|
2040 Any necessary MIMEification is done automatically.
|
meillo@101
|
2041 There is no `mime' command at the WhatNow prompt anymore.
|
meillo@102
|
2042 The draft will be converted automatically to MIME when either an
|
meillo@102
|
2043 attachment header or non-ASCII text is present.
|
meillo@101
|
2044 Further more, the special meaning of the hash character (`#')
|
meillo@102
|
2045 at line beginnings in the draft message is removed.
|
meillo@102
|
2046 Users need not at all deal with the whole topic.
|
meillo@101
|
2047 .P
|
meillo@102
|
2048 Although the new approach does not anymore support arbitrary MIME
|
meillo@102
|
2049 compositions directly, the full power of
|
meillo@101
|
2050 .Pn mhbuild
|
meillo@101
|
2051 can still be accessed.
|
meillo@102
|
2052 Given no attachment headers are included, the user can create
|
meillo@101
|
2053 .Pn mhbuild
|
meillo@102
|
2054 composition drafts like in nmh.
|
meillo@101
|
2055 Then, at the WhatNow prompt, he needs to invoke
|
meillo@101
|
2056 .Cl "edit mhbuild
|
meillo@101
|
2057 to convert it to MIME.
|
meillo@110
|
2058 Because the resulting draft does neither contain non-ASCII characters
|
meillo@102
|
2059 nor has it attachment headers, the attachment system will not touch it.
|
meillo@101
|
2060 .P
|
meillo@101
|
2061 The approach taken in mmh is taylored towards todays most common case:
|
meillo@101
|
2062 a text part with possibly attachments.
|
meillo@102
|
2063 This case is simplified a lot for users.
|
meillo@102
|
2064
|
meillo@112
|
2065
|
meillo@102
|
2066 .U3 "MIME Type Guessing
|
meillo@102
|
2067 .P
|
meillo@102
|
2068 The use of
|
meillo@101
|
2069 .Pn mhbuild
|
meillo@102
|
2070 composition drafts had one notable advantage over attachment headers
|
meillo@102
|
2071 from the programmer's point of view: The user provides the appropriate
|
meillo@102
|
2072 MIME types for files to include.
|
meillo@102
|
2073 The attachment system needs to find out the correct MIME type itself.
|
meillo@102
|
2074 This is a difficult task, yet it spares the user irritating work.
|
meillo@102
|
2075 Determining the correct MIME type of content is partly mechanical,
|
meillo@102
|
2076 partly intelligent work.
|
meillo@102
|
2077 Forcing the user to find out the correct MIME type,
|
meillo@102
|
2078 forces him to do partly mechanical work.
|
meillo@102
|
2079 Letting the computer do the work, can lead to bad choices for difficult
|
meillo@102
|
2080 content.
|
meillo@102
|
2081 For mmh, the latter option was chosen.
|
meillo@102
|
2082 .P
|
meillo@102
|
2083 Determining the MIME type by the suffix of the file name is a dumb
|
meillo@102
|
2084 approach, yet it is simple to implement and provides good results
|
meillo@102
|
2085 for the common cases.
|
meillo@102
|
2086 Mmh implements this approach in the
|
meillo@102
|
2087 .Pn print-mimetype
|
meillo@102
|
2088 script.
|
meillo@112
|
2089 .Ci 4b5944268ea0da7bb30598a27857304758ea9b44
|
meillo@102
|
2090 Using it is the default choice.
|
meillo@102
|
2091 .P
|
meillo@112
|
2092 A far better, though less portable, approach is the use of
|
meillo@102
|
2093 .Pn file .
|
meillo@102
|
2094 This standard tool tries to determine the type of files.
|
meillo@102
|
2095 Unfortunately, its capabilities and accuracy varies from system to system.
|
meillo@102
|
2096 Additionally, its output was only intended for human beings,
|
meillo@102
|
2097 but not to be used by programs.
|
meillo@102
|
2098 It varies much.
|
meillo@102
|
2099 Nevertheless, modern versions of GNU
|
meillo@102
|
2100 .Pn file ,
|
meillo@102
|
2101 which is prevalent on the popular GNU/Linux systems,
|
meillo@102
|
2102 provides MIME type output in machine-readable form.
|
meillo@102
|
2103 Although this solution is highly system-dependent,
|
meillo@102
|
2104 it solves the difficult problem well.
|
meillo@102
|
2105 On systems where GNU
|
meillo@102
|
2106 .Pn file ,
|
meillo@102
|
2107 version 5.04 or higher, is available it should be used.
|
meillo@102
|
2108 One needs to specify the following profile entry to do so:
|
meillo@112
|
2109 .Ci 3baec236a39c5c89a9bda8dbd988d643a21decc6
|
meillo@102
|
2110 .VS
|
meillo@102
|
2111 Mime-Type-Query: file -b --mime
|
meillo@102
|
2112 VE
|
meillo@102
|
2113 .LP
|
meillo@102
|
2114 Other versions of
|
meillo@102
|
2115 .Pn file
|
meillo@102
|
2116 might possibly be usable with wrapper scripts to reformat the output.
|
meillo@102
|
2117 The diversity among
|
meillo@102
|
2118 .Pn file
|
meillo@102
|
2119 implementations is great; one needs to check the local variant.
|
meillo@102
|
2120 .P
|
meillo@102
|
2121 If no MIME type can be determined, text content gets sent as
|
meillo@102
|
2122 `text/plain' and anything else under the generic fall-back type
|
meillo@102
|
2123 `application/octet-stream'.
|
meillo@102
|
2124 It is not possible in mmh to override the automatic MIME type guessing
|
meillo@102
|
2125 for a specific file.
|
meillo@102
|
2126 To do so, the user would need to know in advance for which file
|
meillo@102
|
2127 the automatic guessing does fail, or the system would require interaction.
|
meillo@102
|
2128 I consider both cases impractical.
|
meillo@102
|
2129 The existing solution should be sufficient.
|
meillo@102
|
2130 If not, the user may always fall back to
|
meillo@102
|
2131 .Pn mhbuild
|
meillo@102
|
2132 composition drafts and ignore the attachment system.
|
meillo@101
|
2133
|
meillo@102
|
2134
|
meillo@102
|
2135 .U3 "Storing Attachments
|
meillo@102
|
2136 .P
|
meillo@108
|
2137 Extracting MIME parts of a message and storing them to disk is done by
|
meillo@108
|
2138 .Pn mhstore .
|
meillo@108
|
2139 The program has two operation modes,
|
meillo@108
|
2140 .Sw -auto
|
meillo@108
|
2141 and
|
meillo@108
|
2142 .Sw -noauto .
|
meillo@108
|
2143 With the former one, each part is stored under the filename given in the
|
meillo@108
|
2144 MIME part's meta information, if available.
|
meillo@108
|
2145 This naming information is usually available for modern attachments.
|
meillo@108
|
2146 If no filename is available, this MIME part is stored as if
|
meillo@108
|
2147 .Sw -noauto
|
meillo@108
|
2148 would have been specified.
|
meillo@108
|
2149 In the
|
meillo@108
|
2150 .Sw -noauto
|
meillo@108
|
2151 mode, the parts are processed according to rules, defined by
|
meillo@108
|
2152 .Pe mhstore-store-*
|
meillo@108
|
2153 profile entries.
|
meillo@108
|
2154 These rules define generic filename templates for storing
|
meillo@108
|
2155 or commands to post-process the contents in arbitrary ways.
|
meillo@108
|
2156 If no matching rule is available the part is stored under a generic
|
meillo@108
|
2157 filename, built from message number, MIME part number, and MIME type.
|
meillo@108
|
2158 .P
|
meillo@108
|
2159 The
|
meillo@108
|
2160 .Sw -noauto
|
meillo@108
|
2161 mode had been the default in nmh because it was considered safe,
|
meillo@108
|
2162 in contrast to the
|
meillo@108
|
2163 .Sw -auto
|
meillo@108
|
2164 mode.
|
meillo@108
|
2165 In mmh,
|
meillo@108
|
2166 .Sw -auto
|
meillo@108
|
2167 is not dangerous anymore.
|
meillo@108
|
2168 Two changes were necessary:
|
meillo@108
|
2169 .BU
|
meillo@108
|
2170 Any directory path is removed from the proposed filename.
|
meillo@108
|
2171 Thus, the files are always stored in the expected directory.
|
meillo@108
|
2172 .Ci 41b6eadbcecf63c9a66aa5e582011987494abefb
|
meillo@108
|
2173 .BU
|
meillo@108
|
2174 Tar files are not extracted automatically any more.
|
meillo@108
|
2175 Thus, the rest of the file system will not be touched.
|
meillo@108
|
2176 .Ci 94c80042eae3383c812d9552089953f9846b1bb6
|
meillo@108
|
2177 .LP
|
meillo@108
|
2178 Now, the outcome of mmh's
|
meillo@108
|
2179 .Cl "mhstore -auto
|
meillo@110
|
2180 can be foreseen from the output of
|
meillo@108
|
2181 .Cl "mhlist -verbose" .
|
meillo@108
|
2182 .P
|
meillo@108
|
2183 The
|
meillo@108
|
2184 .Sw -noauto
|
meillo@108
|
2185 mode is seen to be more powerful but less convenient.
|
meillo@108
|
2186 On the other hand,
|
meillo@108
|
2187 .Sw -auto
|
meillo@108
|
2188 is safe now and
|
meillo@108
|
2189 storing attachments under their original name is intuitive.
|
meillo@108
|
2190 Hence,
|
meillo@108
|
2191 .Sw -auto
|
meillo@108
|
2192 serves better as the default option.
|
meillo@108
|
2193 .Ci 3410b680416c49a7617491af38bc1929855a331d
|
meillo@108
|
2194 .P
|
meillo@108
|
2195 Files are stored into the directory given by the
|
meillo@108
|
2196 .Pe Nmh-Storage
|
meillo@108
|
2197 profile entry, if set, or
|
meillo@108
|
2198 into the current working directory, otherwise.
|
meillo@108
|
2199 Storing to different directories is only possible with
|
meillo@108
|
2200 .Pe mhstore-store-*
|
meillo@108
|
2201 profile entries.
|
meillo@108
|
2202 .P
|
meillo@108
|
2203 Still, in both modes, existing files get overwritten silently.
|
meillo@108
|
2204 This can be considered a bug.
|
meillo@108
|
2205 Yet, each other behavior has its draw-backs, too.
|
meillo@108
|
2206 Refusing to replace files requires adding a
|
meillo@108
|
2207 .Sw -force
|
meillo@108
|
2208 option.
|
meillo@108
|
2209 Users will likely need to invoke
|
meillo@108
|
2210 .Pn mhstore
|
meillo@108
|
2211 a second time with
|
meillo@108
|
2212 .Sw -force
|
meillo@108
|
2213 then.
|
meillo@108
|
2214 Eventually, only the user can decide in the concrete case.
|
meillo@108
|
2215 This requires interaction, which I like to avoid if possible.
|
meillo@108
|
2216 Appending a unique suffix to the filename is another bad option.
|
meillo@108
|
2217 For now, the behavior remains as it is.
|
meillo@108
|
2218 .P
|
meillo@108
|
2219 In mmh, only MIME parts of type message are special in
|
meillo@108
|
2220 .Pn mhstore 's
|
meillo@108
|
2221 .Sw -auto
|
meillo@108
|
2222 mode.
|
meillo@108
|
2223 Instead of storing message/rfc822 parts as files to disk,
|
meillo@108
|
2224 they are stored as messages into the current mail folder.
|
meillo@108
|
2225 The same applies to message/partial, only, the parts are reassembled
|
meillo@108
|
2226 automatically before.
|
meillo@108
|
2227 Parts of type message/external-body are not automatically retrieved
|
meillo@108
|
2228 anymore. Instead, Information on how to retrieve them is output.
|
meillo@108
|
2229 Not supporting this rare case saved nearly one thousand lines of code.
|
meillo@108
|
2230 .Ci 55e1d8c654ee0f7c45b9361ce34617983b454c32
|
meillo@108
|
2231 .\" XXX mention somewhere else too: (The profile entry `nmh-access-ftp'
|
meillo@108
|
2232 .\" and sbr/ruserpass.c for reading ~/.netrc are gone now.)
|
meillo@108
|
2233 Not special anymore is `application/octet-stream; type=tar'.
|
meillo@108
|
2234 Automatically extracting such MIME parts had been the dangerous part
|
meillo@108
|
2235 of the
|
meillo@108
|
2236 .Sw -auto
|
meillo@108
|
2237 mode.
|
meillo@108
|
2238 .Ci 94c80042eae3383c812d9552089953f9846b1bb6
|
meillo@108
|
2239
|
meillo@102
|
2240
|
meillo@102
|
2241
|
meillo@102
|
2242 .U3 "Showing MIME Messages
|
meillo@102
|
2243 .P
|
meillo@102
|
2244 FIXME
|
meillo@102
|
2245
|
meillo@58
|
2246
|
meillo@58
|
2247
|
meillo@58
|
2248 .H2 "Digital Cryptography
|
meillo@22
|
2249 .P
|
meillo@58
|
2250 Signing and encryption.
|
meillo@112
|
2251 .P
|
meillo@112
|
2252 FIXME
|
meillo@58
|
2253
|
meillo@58
|
2254
|
meillo@102
|
2255
|
meillo@102
|
2256 .H2 "Modern Defaults
|
meillo@22
|
2257 .P
|
meillo@112
|
2258 Nmh has a bunch of convenience-improving features available,
|
meillo@112
|
2259 but they are inactive by default.
|
meillo@112
|
2260 The user needs to activate them.
|
meillo@112
|
2261 Today one can expect every new user to want to have them available.
|
meillo@112
|
2262 The reason they are inactive by default is the wish to stay compatible
|
meillo@112
|
2263 with old versions.
|
meillo@112
|
2264 Surprisingly, the community seems not to care that the highly useful
|
meillo@112
|
2265 draft folder still is not available by default although it had been
|
meillo@112
|
2266 introduced over twenty-five years ago.
|
meillo@112
|
2267 .[
|
meillo@112
|
2268 rose romine real work
|
meillo@112
|
2269 .]
|
meillo@112
|
2270 This is one of several examples that require new users to first
|
meillo@112
|
2271 build up an extensive profile in order to convert the default
|
meillo@112
|
2272 nmh installation into a convenient state.
|
meillo@112
|
2273 .P
|
meillo@112
|
2274 To give an example, it took one year of using nmh
|
meillo@102
|
2275 before I became aware of the existence of the attachment system.
|
meillo@102
|
2276 One could argue that this fact disqualifies my reading of the
|
meillo@102
|
2277 documentation.
|
meillo@102
|
2278 If I would have installed nmh from source back then, I could agree.
|
meillo@102
|
2279 Yet I had used a prepackaged version and had expected that it would
|
meillo@102
|
2280 just work.
|
meillo@58
|
2281
|
meillo@58
|
2282
|
meillo@58
|
2283
|
meillo@100
|
2284 .H1 "Code Style
|
meillo@22
|
2285 .P
|
meillo@58
|
2286 foo
|
meillo@58
|
2287
|
meillo@58
|
2288
|
meillo@58
|
2289 .H2 "Standard Code
|
meillo@22
|
2290 .P
|
meillo@58
|
2291 POSIX
|
meillo@22
|
2292
|
meillo@102
|
2293 .U3 "Converting to Standard Code
|
meillo@102
|
2294 .P
|
meillo@102
|
2295 One part of this task was converting obsolete code constructs
|
meillo@102
|
2296 to standard constructs.
|
meillo@102
|
2297 As I'm not even thirty years old and have no more than seven years of
|
meillo@102
|
2298 Unix experience, I needed to learn about the history in retrospective.
|
meillo@102
|
2299 Older people likely have used those ancient constructs themselves
|
meillo@102
|
2300 and have suffered from their incompatibilities and have longed for
|
meillo@102
|
2301 standardization.
|
meillo@102
|
2302 Unfortunately, I have only read that others had done so.
|
meillo@102
|
2303 This put me in a much more difficult positions when working on the old
|
meillo@102
|
2304 code.
|
meillo@102
|
2305 I needed to recherche what other would have known by heart from
|
meillo@102
|
2306 experience.
|
meillo@102
|
2307 All my programming experience comes from a time past ANSI C
|
meillo@102
|
2308 and past POSIX.
|
meillo@102
|
2309 Although I knew about the times before, I took the
|
meillo@102
|
2310 current state implicitly for granted most of the time.
|
meillo@102
|
2311 .P
|
meillo@102
|
2312 Being aware of
|
meillo@102
|
2313 these facts, I rather let people with more historic experience solve the
|
meillo@102
|
2314 task of converting the ancient code constructs to standardized ones.
|
meillo@102
|
2315 Luckily, Lyndon Nerenberg focused on this task at the nmh project.
|
meillo@102
|
2316 He converted large parts of the code to POSIX constructs, removing
|
meillo@102
|
2317 the conditionals compilation for now standardized features.
|
meillo@104
|
2318 I'm thankful for this task being solved.
|
meillo@104
|
2319 I only pulled the changes into
|
meillo@102
|
2320 mmh.
|
meillo@102
|
2321
|
meillo@102
|
2322
|
meillo@102
|
2323
|
meillo@22
|
2324
|
meillo@58
|
2325 .H2 "Separation
|
meillo@14
|
2326
|
meillo@58
|
2327 .U2 "MH Directory Split
|
meillo@0
|
2328 .P
|
meillo@19
|
2329 In MH and nmh, a personal setup had consisted of two parts:
|
meillo@19
|
2330 The MH profile, named
|
meillo@19
|
2331 .Fn \&.mh_profile
|
meillo@19
|
2332 and being located directly in the user's home directory.
|
meillo@19
|
2333 And the MH directory, where all his mail messages and also his personal
|
meillo@104
|
2334 forms, scan formats, other configuration files are stored.
|
meillo@104
|
2335 The location
|
meillo@104
|
2336 of this directory could be user-chosen.
|
meillo@104
|
2337 The default was to name it
|
meillo@19
|
2338 .Fn Mail
|
meillo@19
|
2339 and have it directly in the home directory.
|
meillo@19
|
2340 .P
|
meillo@19
|
2341 I've never liked the data storage and the configuration to be intermixed.
|
meillo@104
|
2342 They are different kinds of data.
|
meillo@104
|
2343 One part, are the messages,
|
meillo@104
|
2344 which are the data to operate on.
|
meillo@104
|
2345 The other part, are the personal
|
meillo@19
|
2346 configuration files, which are able to change the behavior of the operations.
|
meillo@19
|
2347 The actual operations are defined in the profile, however.
|
meillo@19
|
2348 .P
|
meillo@19
|
2349 When storing data, one should try to group data by its type.
|
meillo@19
|
2350 There's sense in the Unix file system hierarchy, where configuration
|
meillo@19
|
2351 file are stored separate (\c
|
meillo@19
|
2352 .Fn /etc )
|
meillo@19
|
2353 to the programs (\c
|
meillo@19
|
2354 .Fn /bin
|
meillo@19
|
2355 and
|
meillo@19
|
2356 .Fn /usr/bin )
|
meillo@19
|
2357 to their sources (\c
|
meillo@19
|
2358 .Fn /usr/src ).
|
meillo@19
|
2359 Such separation eases the backup management, for instance.
|
meillo@19
|
2360 .P
|
meillo@19
|
2361 In mmh, I've reorganized the file locations.
|
meillo@19
|
2362 Still there are two places:
|
meillo@19
|
2363 There's the mail storage directory, which, like in MH, contains all the
|
meillo@19
|
2364 messages, but, unlike in MH, nothing else.
|
meillo@19
|
2365 Its location still is user-chosen, with the default name
|
meillo@19
|
2366 .Fn Mail ,
|
meillo@104
|
2367 in the user's home directory.
|
meillo@104
|
2368 This is much similar to the case in nmh.
|
meillo@19
|
2369 The configuration files, however, are grouped together in the new directory
|
meillo@19
|
2370 .Fn \&.mmh
|
meillo@19
|
2371 in the user's home directory.
|
meillo@19
|
2372 The user's profile now is a file, named
|
meillo@19
|
2373 .Fn profile ,
|
meillo@19
|
2374 in this mmh directory.
|
meillo@19
|
2375 Consistently, the context file and all the personal forms, scan formats,
|
meillo@19
|
2376 and the like, are also there.
|
meillo@19
|
2377 .P
|
meillo@19
|
2378 The naming changed with the relocation.
|
meillo@19
|
2379 The directory where everything, except the profile, had been stored (\c
|
meillo@19
|
2380 .Fn $HOME/Mail ),
|
meillo@104
|
2381 used to be called \fIMH directory\fP.
|
meillo@104
|
2382 Now, this directory is called the
|
meillo@104
|
2383 user's \fImail storage\fP.
|
meillo@104
|
2384 The name \fImmh directory\fP is now given to
|
meillo@19
|
2385 the new directory
|
meillo@19
|
2386 (\c
|
meillo@19
|
2387 .Fn $HOME/.mmh ),
|
meillo@19
|
2388 containing all the personal configuration files.
|
meillo@19
|
2389 .P
|
meillo@19
|
2390 The separation of the files by type of content is logical and convenient.
|
meillo@19
|
2391 There are no functional differences as any possible setup known to me
|
meillo@19
|
2392 can be implemented with both approaches, although likely a bit easier
|
meillo@104
|
2393 with the new approach.
|
meillo@104
|
2394 The main goal of the change had been to provide
|
meillo@19
|
2395 sensible storage locations for any type of personal mmh file.
|
meillo@19
|
2396 .P
|
meillo@19
|
2397 In order for one user to have multiple MH setups, he can use the
|
meillo@19
|
2398 environment variable
|
meillo@19
|
2399 .Ev MH
|
meillo@19
|
2400 the point to a different profile file.
|
meillo@19
|
2401 The MH directory (mail storage plus personal configuration files) is
|
meillo@19
|
2402 defined by the
|
meillo@19
|
2403 .Pe Path
|
meillo@19
|
2404 profile entry.
|
meillo@19
|
2405 The context file could be defined by the
|
meillo@19
|
2406 .Pe context
|
meillo@19
|
2407 profile entry or by the
|
meillo@19
|
2408 .Ev MHCONTEXT
|
meillo@19
|
2409 environment variable.
|
meillo@19
|
2410 The latter is useful to have a distinct context (e.g. current folders)
|
meillo@19
|
2411 in each terminal window, for instance.
|
meillo@19
|
2412 In mmh, there are three environment variables now.
|
meillo@19
|
2413 .Ev MMH
|
meillo@19
|
2414 may be used to change the location of the mmh directory.
|
meillo@19
|
2415 .Ev MMHP
|
meillo@19
|
2416 and
|
meillo@19
|
2417 .Ev MMHC
|
meillo@19
|
2418 change the profile and context files, respectively.
|
meillo@19
|
2419 Besides providing a more consistent feel (which simply is the result
|
meillo@19
|
2420 of being designed anew), the set of personal configuration files can
|
meillo@19
|
2421 be chosen independently from the profile (including mail storage location)
|
meillo@104
|
2422 and context, now.
|
meillo@104
|
2423 Being it relevant for practical use or not, it
|
meillo@104
|
2424 de-facto is an improvement.
|
meillo@104
|
2425 However, the main achievement is the
|
meillo@19
|
2426 split between mail storage and personal configuration files.
|
meillo@17
|
2427
|
meillo@0
|
2428
|
meillo@58
|
2429 .H2 "Modularization
|
meillo@0
|
2430 .P
|
meillo@58
|
2431 whatnowproc
|
meillo@0
|
2432 .P
|
meillo@49
|
2433 The \fIMH library\fP
|
meillo@49
|
2434 .Fn libmh.a
|
meillo@49
|
2435 collects a bunch of standard functions that many of the MH tools need,
|
meillo@49
|
2436 like reading the profile or context files.
|
meillo@49
|
2437 This doesn't hurt the separation.
|
meillo@49
|
2438
|
meillo@58
|
2439
|
meillo@58
|
2440 .H2 "Style
|
meillo@58
|
2441 .P
|
meillo@58
|
2442 Code layout, goto, ...
|
meillo@58
|
2443
|
meillo@102
|
2444 .P
|
meillo@102
|
2445 anno rework
|
meillo@102
|
2446
|
meillo@58
|
2447
|
meillo@58
|
2448
|
meillo@58
|
2449
|
meillo@89
|
2450 .H1 "Concept Exploitation/Homogeneity
|
meillo@58
|
2451
|
meillo@58
|
2452
|
meillo@58
|
2453 .H2 "Draft Folder
|
meillo@58
|
2454 .P
|
meillo@58
|
2455 Historically, MH provided exactly one draft message, named
|
meillo@58
|
2456 .Fn draft
|
meillo@58
|
2457 and
|
meillo@104
|
2458 being located in the MH directory.
|
meillo@104
|
2459 When starting to compose another message
|
meillo@58
|
2460 before the former one was sent, the user had been questioned whether to use,
|
meillo@104
|
2461 refile or replace the old draft.
|
meillo@104
|
2462 Working on multiple drafts at the same time
|
meillo@104
|
2463 was impossible.
|
meillo@104
|
2464 One could only work on them in alteration by refiling the
|
meillo@104
|
2465 previous one to some directory and fetching some other one for reediting.
|
meillo@58
|
2466 This manual draft management needed to be done each time the user wanted
|
meillo@58
|
2467 to switch between editing one draft to editing another.
|
meillo@58
|
2468 .P
|
meillo@58
|
2469 To allow true parallel editing of drafts, in a straight forward way, the
|
meillo@104
|
2470 draft folder facility exists.
|
meillo@104
|
2471 It had been introduced already in July 1984
|
meillo@104
|
2472 by Marshall T. Rose.
|
meillo@110
|
2473 The facility was inactive by default.
|
meillo@110
|
2474 Even in nmh, the draft folder facility remained inactive by default.
|
meillo@58
|
2475 At least, Richard Coleman added the man page
|
meillo@58
|
2476 .Mp mh-draft(5)
|
meillo@58
|
2477 to document
|
meillo@58
|
2478 the feature well.
|
meillo@58
|
2479 .P
|
meillo@58
|
2480 The only advantage of not using the draft folder facility is the static
|
meillo@104
|
2481 name of the draft file.
|
meillo@104
|
2482 This could be an issue for MH front-ends like mh-e.
|
meillo@58
|
2483 But as they likely want to provide working on multiple drafts in parallel,
|
meillo@104
|
2484 the issue is only concerning compatibility.
|
meillo@104
|
2485 The aim of nmh to stay compatible
|
meillo@58
|
2486 prevented the default activation of the draft folder facility.
|
meillo@58
|
2487 .P
|
meillo@58
|
2488 On the other hand, a draft folder is the much more natural concept than
|
meillo@104
|
2489 a draft message.
|
meillo@104
|
2490 MH's mail storage consists of folders and messages,
|
meillo@104
|
2491 the messages named with ascending numbers.
|
meillo@104
|
2492 A draft message breaks with this
|
meillo@58
|
2493 concept by introducing a message in a file named
|
meillo@58
|
2494 .Fn draft .
|
meillo@58
|
2495 This draft
|
meillo@104
|
2496 message is special.
|
meillo@104
|
2497 It can not be simply listed with the available tools,
|
meillo@104
|
2498 but instead requires special switches.
|
meillo@104
|
2499 I.e. corner-cases were
|
meillo@104
|
2500 introduced.
|
meillo@104
|
2501 A draft folder, in contrast, does not introduce such
|
meillo@104
|
2502 corner-cases.
|
meillo@104
|
2503 The available tools can operate on the messages within that
|
meillo@104
|
2504 folder like on any messages within any mail folders.
|
meillo@104
|
2505 The only difference
|
meillo@58
|
2506 is the fact that the default folder for
|
meillo@58
|
2507 .Pn send
|
meillo@58
|
2508 is the draft folder,
|
meillo@58
|
2509 instead of the current folder, like for all other tools.
|
meillo@58
|
2510 .P
|
meillo@58
|
2511 The trivial part of the change was activating the draft folder facility
|
meillo@104
|
2512 by default and setting a default name for this folder.
|
meillo@104
|
2513 Obviously, I chose
|
meillo@58
|
2514 the name
|
meillo@58
|
2515 .Fn +drafts .
|
meillo@58
|
2516 This made the
|
meillo@82
|
2517 .Sw -draftfolder
|
meillo@58
|
2518 and
|
meillo@82
|
2519 .Sw -draftmessage
|
meillo@58
|
2520 switches useless, and I could remove them.
|
meillo@58
|
2521 The more difficult but also the part that showed the real improvement,
|
meillo@58
|
2522 was updating the tools to the new concept.
|
meillo@82
|
2523 .Sw -draft
|
meillo@58
|
2524 switches could
|
meillo@58
|
2525 be dropped, as operating on a draft message became indistinguishable to
|
meillo@58
|
2526 operating on any other message for the tools.
|
meillo@58
|
2527 .Pn comp
|
meillo@58
|
2528 still has its
|
meillo@82
|
2529 .Sw -use
|
meillo@58
|
2530 switch for switching between its two modes: (1) Compose a new
|
meillo@104
|
2531 draft, possibly by taking some existing message as a form.
|
meillo@104
|
2532 (2) Modify
|
meillo@104
|
2533 an existing draft.
|
meillo@104
|
2534 In either case, the behavior of
|
meillo@58
|
2535 .Pn comp is
|
meillo@104
|
2536 deterministic.
|
meillo@104
|
2537 There is no more need to query the user.
|
meillo@104
|
2538 I consider this
|
meillo@104
|
2539 a major improvement.
|
meillo@104
|
2540 By making
|
meillo@58
|
2541 .Pn send
|
meillo@58
|
2542 simply operate on the current
|
meillo@58
|
2543 message in the draft folder by default, with message and folder both
|
meillo@58
|
2544 overridable by specifying them on the command line, it is now possible
|
meillo@58
|
2545 to send a draft anywhere within the storage by simply specifying its folder
|
meillo@58
|
2546 and name.
|
meillo@58
|
2547 .P
|
meillo@58
|
2548 All theses changes converted special cases to regular cases, thus
|
meillo@58
|
2549 simplifying the tools and increasing the flexibility.
|
meillo@58
|
2550
|
meillo@58
|
2551
|
meillo@58
|
2552 .H2 "Trash Folder
|
meillo@58
|
2553 .P
|
meillo@58
|
2554 Similar to the situation for drafts is the situation for removed messages.
|
meillo@104
|
2555 Historically, a message was deleted by renaming.
|
meillo@104
|
2556 A specific
|
meillo@58
|
2557 \fIbackup prefix\fP, often comma (\c
|
meillo@58
|
2558 .Fn , )
|
meillo@58
|
2559 or hash (\c
|
meillo@58
|
2560 .Fn # ),
|
meillo@104
|
2561 being prepended to the file name.
|
meillo@104
|
2562 Thus, MH wouldn't recognize the file
|
meillo@58
|
2563 as a message anymore, as only files whose name consists of digits only
|
meillo@104
|
2564 are treated as messages.
|
meillo@104
|
2565 The removed messages remained as files in the
|
meillo@58
|
2566 same directory and needed some maintenance job to truly delete them after
|
meillo@104
|
2567 some grace time.
|
meillo@104
|
2568 Usually, by running a command similar to
|
meillo@82
|
2569 .VS
|
meillo@82
|
2570 find /home/user/Mail -ctime +7 -name ',*' | xargs rm
|
meillo@82
|
2571 VE
|
meillo@104
|
2572 in a cron job.
|
meillo@104
|
2573 Within the grace time interval
|
meillo@58
|
2574 the original message could be restored by stripping the
|
meillo@104
|
2575 the backup prefix from the file name.
|
meillo@104
|
2576 If however, the last message of
|
meillo@58
|
2577 a folder is been removed \(en say message
|
meillo@58
|
2578 .Fn 6
|
meillo@58
|
2579 becomes file
|
meillo@58
|
2580 .Fn ,6
|
meillo@58
|
2581 \(en and a new message enters the same folder, thus the same
|
meillo@58
|
2582 numbered being given again \(en in our case
|
meillo@58
|
2583 .Fn 6
|
meillo@58
|
2584 \(en, if that one
|
meillo@58
|
2585 is removed too, then the backup of the former message gets overwritten.
|
meillo@58
|
2586 Thus, the ability to restore removed messages does not only depend on
|
meillo@58
|
2587 the ``sweeping cron job'' but also on the removing of further messages.
|
meillo@58
|
2588 This is undesirable, because the real mechanism is hidden from the user
|
meillo@58
|
2589 and the consequences of further removals are not always obvious.
|
meillo@58
|
2590 Further more, the backup files are scattered within the whole mail
|
meillo@58
|
2591 storage, instead of being collected at one place.
|
meillo@58
|
2592 .P
|
meillo@58
|
2593 To improve the situation, the profile entry
|
meillo@58
|
2594 .Pe rmmproc
|
meillo@58
|
2595 (previously named
|
meillo@58
|
2596 .Pe Delete-Prog )
|
meillo@58
|
2597 was introduced, very early.
|
meillo@58
|
2598 It could be set to any command, which would care for the mail removal
|
meillo@58
|
2599 instead of taking the default action, described above.
|
meillo@58
|
2600 Refiling the to-be-removed files to some garbage folder was a common
|
meillo@104
|
2601 example.
|
meillo@104
|
2602 Nmh's man page
|
meillo@58
|
2603 .Mp rmm(1)
|
meillo@58
|
2604 proposes
|
meillo@58
|
2605 .Cl "refile +d
|
meillo@58
|
2606 to move messages to the garbage folder and
|
meillo@58
|
2607 .Cl "rm `mhpath +d all`
|
meillo@58
|
2608 the empty the garbage folder.
|
meillo@104
|
2609 Managing the message removal this way is a sane approach.
|
meillo@104
|
2610 It keeps
|
meillo@58
|
2611 the removed messages in one place, makes it easy to remove the backup
|
meillo@58
|
2612 files, and, most important, enables the user to use the tools of MH
|
meillo@104
|
2613 itself to operate on the removed messages.
|
meillo@104
|
2614 One can
|
meillo@58
|
2615 .Pn scan
|
meillo@58
|
2616 them,
|
meillo@58
|
2617 .Pn show
|
meillo@58
|
2618 them, and restore them with
|
meillo@58
|
2619 .Pn refile .
|
meillo@58
|
2620 There's no more
|
meillo@58
|
2621 need to use
|
meillo@58
|
2622 .Pn mhpath
|
meillo@58
|
2623 to switch over from MH tools to Unix tools \(en MH can do it all itself.
|
meillo@58
|
2624 .P
|
meillo@58
|
2625 This approach matches perfect with the concepts of MH, thus making
|
meillo@104
|
2626 it powerful.
|
meillo@104
|
2627 Hence, I made it the default.
|
meillo@104
|
2628 And even more, I also
|
meillo@58
|
2629 removed the old backup prefix approach, as it is clearly less powerful.
|
meillo@58
|
2630 Keeping unused alternative in the code is a bad choice as they likely
|
meillo@104
|
2631 gather bugs, by not being constantly tested.
|
meillo@104
|
2632 Also, the increased code
|
meillo@104
|
2633 size and more conditions crease the maintenance costs.
|
meillo@104
|
2634 By strictly
|
meillo@58
|
2635 converting to the trash folder approach, I simplified the code base.
|
meillo@58
|
2636 .Pn rmm
|
meillo@58
|
2637 calls
|
meillo@58
|
2638 .Pn refile
|
meillo@58
|
2639 internally to move the to-be-removed
|
meillo@58
|
2640 message to the trash folder (\c
|
meillo@58
|
2641 .Fn +trash
|
meillo@104
|
2642 by default).
|
meillo@104
|
2643 Messages
|
meillo@58
|
2644 there can be operated on like on any other message in the storage.
|
meillo@58
|
2645 The sweep clean, one can use
|
meillo@82
|
2646 .Cl "rmm -unlink +trash a" ,
|
meillo@58
|
2647 where the
|
meillo@82
|
2648 .Sw -unlink
|
meillo@58
|
2649 switch causes the files to be truly unliked instead
|
meillo@58
|
2650 of moved to the trash folder.
|
meillo@58
|
2651
|
meillo@58
|
2652
|
meillo@58
|
2653 .H2 "Path Notations
|
meillo@58
|
2654 .P
|
meillo@58
|
2655 foo
|
meillo@58
|
2656
|
meillo@58
|
2657
|
meillo@58
|
2658 .H2 "MIME Integration
|
meillo@58
|
2659 .P
|
meillo@58
|
2660 user-visible access to whole messages and MIME parts are inherently
|
meillo@58
|
2661 different
|
meillo@58
|
2662
|
meillo@58
|
2663
|
meillo@58
|
2664 .H2 "Of One Cast
|
meillo@58
|
2665 .P
|