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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 "Streamlining
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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20 I believe that the development of all-in-one mail systems is obsolete.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 streamline 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 streamlined
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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
|
|
meillo@87
|
308 .Ci eda72d6a7a7c20ff123043fb7f19c509ea01f932
|
|
meillo@87
|
309 when the new attachment system was activated, because
|
|
meillo@58
|
310 .Pn forw
|
|
meillo@76
|
311 could then cover the task itself.
|
|
meillo@62
|
312 The program
|
|
meillo@58
|
313 .Pn sendfiles
|
|
meillo@62
|
314 was rewritten as a shell script wrapper around
|
|
meillo@58
|
315 .Pn forw .
|
|
meillo@76
|
316 .Ci 0e82199cf3c991a173e0ac8aa776efdb3ded61e6
|
|
meillo@62
|
317 .BU
|
|
meillo@58
|
318 .Pn msgchk
|
|
meillo@87
|
319 was removed
|
|
meillo@87
|
320 .Ci bb9360ead7eb7a3fedcce2eeedfc660014e41dbe ,
|
|
meillo@87
|
321 because it lost its use case when POP support was removed.
|
|
meillo@76
|
322 A call to
|
|
meillo@58
|
323 .Pn msgchk
|
|
meillo@87
|
324 provided hardly more information than:
|
|
meillo@82
|
325 .VS
|
|
meillo@58
|
326 ls -l /var/mail/meillo
|
|
meillo@82
|
327 VE
|
|
meillo@100
|
328 It did distinguish between old and new mail, but
|
|
meillo@100
|
329 this detail information can be retrieved with
|
|
meillo@76
|
330 .Pn stat (1),
|
|
meillo@62
|
331 too.
|
|
meillo@100
|
332 A small shell script could be written to print the information
|
|
meillo@76
|
333 in a similar way, if truly necessary.
|
|
meillo@76
|
334 As mmh's
|
|
meillo@76
|
335 .Pn inc
|
|
meillo@87
|
336 only incorporates mail from the user's local maildrop,
|
|
meillo@62
|
337 and thus no data transfers over slow networks are involved,
|
|
meillo@76
|
338 there's hardly any need to check for new mail before incorporating it.
|
|
meillo@62
|
339 .BU
|
|
meillo@58
|
340 .Pn msh
|
|
meillo@87
|
341 was removed
|
|
meillo@76
|
342 .Ci 916690191222433a6923a4be54b0d8f6ac01bd02
|
|
meillo@87
|
343 because the tool was in conflict with the philosophy of MH.
|
|
meillo@76
|
344 It provided an interactive shell to access the features of MH,
|
|
meillo@76
|
345 but it wasn't just a shell, tailored to the needs of mail handling.
|
|
meillo@76
|
346 Instead it was one large program that had several MH tools built in.
|
|
meillo@76
|
347 This conflicts with the major feature of MH of being a tool chest.
|
|
meillo@76
|
348 .Pn msh 's
|
|
meillo@76
|
349 main use case had been accessing Bulletin Boards, which have seized to
|
|
meillo@62
|
350 be popular.
|
|
meillo@62
|
351 .P
|
|
meillo@62
|
352 Removing
|
|
meillo@58
|
353 .Pn msh ,
|
|
meillo@76
|
354 together with the truly archaic code relicts
|
|
meillo@58
|
355 .Pn vmh
|
|
meillo@58
|
356 and
|
|
meillo@58
|
357 .Pn wmh ,
|
|
meillo@62
|
358 saved more than 7\|000 lines of C code \(en
|
|
meillo@66
|
359 about 15\|% of the project's original source code amount.
|
|
meillo@100
|
360 Having less code \(en with equal readability, of course \(en
|
|
meillo@76
|
361 for the same functionality is an advantage.
|
|
meillo@63
|
362 Less code means less bugs and less maintenance work.
|
|
meillo@76
|
363 As
|
|
meillo@63
|
364 .Pn rcvtty
|
|
meillo@63
|
365 and
|
|
meillo@63
|
366 .Pn msgchk
|
|
meillo@87
|
367 are assumed to be rarely used and can be implemented in different ways,
|
|
meillo@87
|
368 why should one keep them?
|
|
meillo@125
|
369 Removing them streamlines 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@118
|
1641 In the over thirty years of MH's existence, its code base was
|
|
meillo@118
|
1642 extended more and more.
|
|
meillo@118
|
1643 New features entered the project and became alternatives to the
|
|
meillo@118
|
1644 existing behavior.
|
|
meillo@118
|
1645 Relicts from several decades have gathered in the code base,
|
|
meillo@118
|
1646 but seldom obsolete features were dropped.
|
|
meillo@118
|
1647 This section describes the removing of old code
|
|
meillo@118
|
1648 and the modernizing of the default setup.
|
|
meillo@118
|
1649 It focuses on the functional aspect only;
|
|
meillo@118
|
1650 the non-functional aspects of code style are discussed in
|
|
meillo@118
|
1651 .\" FIXME REF
|
|
meillo@118
|
1652 Sec. XXX.
|
|
meillo@58
|
1653
|
|
meillo@58
|
1654
|
|
meillo@100
|
1655 .H2 "Code Relicts
|
|
meillo@0
|
1656 .P
|
|
meillo@109
|
1657 My position to drop obsolete functions of mmh, in order to remove old code,
|
|
meillo@104
|
1658 is much more revolutional than the nmh community likes to have it.
|
|
meillo@104
|
1659 Working on an experimental version, I was able to quickly drop
|
|
meillo@104
|
1660 functionality I considered ancient.
|
|
meillo@104
|
1661 The need for consensus with peers would have slowed this process down.
|
|
meillo@104
|
1662 Without the need to justify my decisions, I was able to rush forward.
|
|
meillo@110
|
1663 In December 2011, Paul Vixie motivated the nmh developers to just
|
|
meillo@104
|
1664 do the work:
|
|
meillo@104
|
1665 .[
|
|
meillo@104
|
1666 paul vixie edginess nmh-workers
|
|
meillo@104
|
1667 .]
|
|
meillo@104
|
1668 .QS
|
|
meillo@104
|
1669 let's stop walking on egg shells with this code base. there's no need to
|
|
meillo@104
|
1670 discuss whether to keep using vfork, just note in [sic!] passing, [...]
|
|
meillo@104
|
1671 we don't need a separate branch for removing vmh
|
|
meillo@104
|
1672 or ridding ourselves of #ifdef's or removing posix replacement functions
|
|
meillo@104
|
1673 or depending on pure ansi/posix "libc".
|
|
meillo@104
|
1674 .QP
|
|
meillo@104
|
1675 these things should each be a day or two of work and the "main branch"
|
|
meillo@104
|
1676 should just be modern. [...]
|
|
meillo@104
|
1677 let's push forward, aggressively.
|
|
meillo@104
|
1678 .QE
|
|
meillo@104
|
1679 .LP
|
|
meillo@104
|
1680 I did so already in the months before.
|
|
meillo@104
|
1681 I pushed forward.
|
|
meillo@104
|
1682 I simply dropped the cruft.
|
|
meillo@104
|
1683 .P
|
|
meillo@104
|
1684 The decision to drop a feature was based on literature research and
|
|
meillo@104
|
1685 careful thinking, but whether having had contact to this particular
|
|
meillo@104
|
1686 feature within my own computer life served as a rule of thumb.
|
|
meillo@109
|
1687 Always, I explained my reasons in the commit messages
|
|
meillo@109
|
1688 in the version control system.
|
|
meillo@104
|
1689 Hence, others can comprehend my view and argue for undoing the change
|
|
meillo@104
|
1690 if I have missed an important aspect.
|
|
meillo@109
|
1691 I was quick in dropping parts.
|
|
meillo@109
|
1692 I rather re-included falsely dropped parts than going a slower pace.
|
|
meillo@109
|
1693 Mmh is experimental work; it required tough decisions.
|
|
meillo@12
|
1694
|
|
meillo@102
|
1695
|
|
meillo@104
|
1696 .U3 "Forking
|
|
meillo@12
|
1697 .P
|
|
meillo@109
|
1698 Being a tool chest, MH creates many processes.
|
|
meillo@104
|
1699 In earlier times
|
|
meillo@104
|
1700 .Fu fork()
|
|
meillo@104
|
1701 had been an expensive system call, because the process's image needed
|
|
meillo@104
|
1702 to be duplicated completely at once.
|
|
meillo@109
|
1703 This was especially painful in the common case when the image gets
|
|
meillo@104
|
1704 replaced by a call to
|
|
meillo@104
|
1705 .Fu exec()
|
|
meillo@104
|
1706 right after having forked the child process.
|
|
meillo@104
|
1707 The
|
|
meillo@104
|
1708 .Fu vfork()
|
|
meillo@104
|
1709 system call was invented to speed up this particular case.
|
|
meillo@104
|
1710 It completely omits the duplication of the image.
|
|
meillo@104
|
1711 On old systems this resulted in significant speed ups.
|
|
meillo@104
|
1712 Therefore MH used
|
|
meillo@104
|
1713 .Fu vfork()
|
|
meillo@104
|
1714 whenever possible.
|
|
meillo@12
|
1715 .P
|
|
meillo@104
|
1716 Modern memory management units support copy-on-write semantics, which make
|
|
meillo@104
|
1717 .Fu fork()
|
|
meillo@104
|
1718 almost as fast as
|
|
meillo@104
|
1719 .Fu vfork() .
|
|
meillo@104
|
1720 The man page of
|
|
meillo@104
|
1721 .Mp vfork (2)
|
|
meillo@104
|
1722 in FreeBSD 8.0 states:
|
|
meillo@104
|
1723 .QS
|
|
meillo@104
|
1724 This system call will be eliminated when proper system sharing mechanisms
|
|
meillo@104
|
1725 are implemented. Users should not depend on the memory sharing semantics
|
|
meillo@104
|
1726 of vfork() as it will, in that case, be made synonymous to fork(2).
|
|
meillo@104
|
1727 .QE
|
|
meillo@104
|
1728 .LP
|
|
meillo@104
|
1729 Vixie supports the removal with the note that ``the last
|
|
meillo@104
|
1730 system on which fork was so slow that an mh user would notice it, was
|
|
meillo@104
|
1731 Eunice. that was 1987''.
|
|
meillo@104
|
1732 .[
|
|
meillo@104
|
1733 nmh-workers vixie edginess
|
|
meillo@104
|
1734 .]
|
|
meillo@104
|
1735 I replaced all calls to
|
|
meillo@104
|
1736 .Fu vfork()
|
|
meillo@104
|
1737 with calls to
|
|
meillo@104
|
1738 .Fu fork() .
|
|
meillo@109
|
1739 .Ci 40821f5c1316e9205a08375e7075909cc9968e7d
|
|
meillo@104
|
1740 .P
|
|
meillo@104
|
1741 Related to the costs of
|
|
meillo@104
|
1742 .Fu fork()
|
|
meillo@104
|
1743 is the probability of its success.
|
|
meillo@109
|
1744 In the eighties, on heavy loaded systems, calls to
|
|
meillo@104
|
1745 .Fu fork()
|
|
meillo@104
|
1746 were prone to failure.
|
|
meillo@104
|
1747 Hence, many of the
|
|
meillo@104
|
1748 .Fu fork()
|
|
meillo@104
|
1749 calls in the code were wrapped into loops to retry the
|
|
meillo@104
|
1750 .Fu fork()
|
|
meillo@109
|
1751 several times, to increase the changes to succeed, eventually.
|
|
meillo@109
|
1752 On modern systems, a failing
|
|
meillo@104
|
1753 .Fu fork()
|
|
meillo@109
|
1754 call is unusual.
|
|
meillo@104
|
1755 Hence, in the rare case when
|
|
meillo@104
|
1756 .Fu fork()
|
|
meillo@104
|
1757 fails, mmh programs simply abort.
|
|
meillo@109
|
1758 .Ci 5fbf37ee68e018998ada61eeab73e035b26834b6
|
|
meillo@12
|
1759
|
|
meillo@12
|
1760
|
|
meillo@109
|
1761 .U3 "Header Fields
|
|
meillo@104
|
1762 .BU
|
|
meillo@84
|
1763 The
|
|
meillo@84
|
1764 .Hd Encrypted
|
|
meillo@104
|
1765 header field was introduced by RFC\|822,
|
|
meillo@109
|
1766 but already marked as legacy in RFC\|2822.
|
|
meillo@109
|
1767 Today, OpenPGP provides the basis for standardized exchange of encrypted
|
|
meillo@104
|
1768 messages [RFC\|4880, RFC\|3156].
|
|
meillo@109
|
1769 Hence, the support for
|
|
meillo@104
|
1770 .Hd Encrypted
|
|
meillo@104
|
1771 header fields is removed in mmh.
|
|
meillo@109
|
1772 .Ci 064527f7b57ab050e5af13e15ad99aeeab125857
|
|
meillo@104
|
1773 .BU
|
|
meillo@84
|
1774 Native support for
|
|
meillo@84
|
1775 .Hd Face
|
|
meillo@104
|
1776 header fields has been removed, as well.
|
|
meillo@109
|
1777 .Ci 8e5be81f784682822f5e868c1bf3c8624682bd23
|
|
meillo@104
|
1778 This feature is similar to the
|
|
meillo@84
|
1779 .Hd X-Face
|
|
meillo@84
|
1780 header field in its intent,
|
|
meillo@21
|
1781 but takes a different approach to store the image.
|
|
meillo@84
|
1782 Instead of encoding the image data directly into the header field,
|
|
meillo@109
|
1783 it contains the hostname and UDP port where the image
|
|
meillo@109
|
1784 date can be retrieved.
|
|
meillo@109
|
1785 There exists even a third Face system,
|
|
meillo@109
|
1786 which is the successor of
|
|
meillo@109
|
1787 .Hd X-Face ,
|
|
meillo@109
|
1788 although it re-uses the
|
|
meillo@104
|
1789 .Hd Face
|
|
meillo@109
|
1790 header field.
|
|
meillo@109
|
1791 It was invented in 2005 and supports colored PNG images.
|
|
meillo@104
|
1792 None of the Face systems described here is popular today.
|
|
meillo@104
|
1793 Hence, mmh has no direct support for them.
|
|
meillo@104
|
1794 .BU
|
|
meillo@104
|
1795 The
|
|
meillo@104
|
1796 .Hd Content-MD5
|
|
meillo@104
|
1797 header field was introduced by RFC\|1864.
|
|
meillo@104
|
1798 It provides detection of data corruption during the transfer.
|
|
meillo@104
|
1799 But it can not ensure verbatim end-to-end delivery of the contents
|
|
meillo@104
|
1800 [RFC\|1864].
|
|
meillo@104
|
1801 The proper approach to verify content integrity in an
|
|
meillo@104
|
1802 end-to-end relationship is the use of digital cryptography.
|
|
meillo@104
|
1803 .\" XXX (RFCs FIXME).
|
|
meillo@104
|
1804 On the other hand, transfer protocols should detect corruption during
|
|
meillo@109
|
1805 the transmission.
|
|
meillo@109
|
1806 The TCP includes a checksum field therefore.
|
|
meillo@104
|
1807 These two approaches in combinations render the
|
|
meillo@104
|
1808 .Hd Content-MD5
|
|
meillo@104
|
1809 header field superfluous.
|
|
meillo@109
|
1810 Not a single one out of 4\|200 messages from two decades
|
|
meillo@109
|
1811 in an nmh-workers mailing list archive contains a
|
|
meillo@104
|
1812 .Hd Content-MD5
|
|
meillo@104
|
1813 header field.
|
|
meillo@104
|
1814 Neither did any of the 60\|000 messages in my personal mail storage.
|
|
meillo@104
|
1815 Removing the support for this header field,
|
|
meillo@104
|
1816 removed the last place where MD5 computation was needed.
|
|
meillo@109
|
1817 .Ci 31dc797eb5178970d68962ca8939da3fd9a8efda
|
|
meillo@104
|
1818 Hence, the MD5 code could be removed as well.
|
|
meillo@104
|
1819 Over 500 lines of code vanished by this one change.
|
|
meillo@104
|
1820
|
|
meillo@104
|
1821
|
|
meillo@104
|
1822 .U3 "MMDF maildrop support
|
|
meillo@21
|
1823 .P
|
|
meillo@104
|
1824 This type of format is conceptionally similar to the mbox format,
|
|
meillo@104
|
1825 but uses a different message delimiter (`\fL^A^A^A^A\fP' instead of
|
|
meillo@104
|
1826 `\fLFrom\0\fP').
|
|
meillo@104
|
1827 Mbox is the de-facto standard maildrop format on Unix,
|
|
meillo@109
|
1828 whereas the MMDF maildrop format became forgotten.
|
|
meillo@104
|
1829 I did drop MMDF maildrop format support.
|
|
meillo@109
|
1830 Mbox is the only packed mailbox format supported in mmh.
|
|
meillo@104
|
1831 .P
|
|
meillo@109
|
1832 The simplifications within the code were moderate.
|
|
meillo@109
|
1833 Mainly, the reading and writing of MMDF mailbox files was removed.
|
|
meillo@109
|
1834 But also, switches of
|
|
meillo@109
|
1835 .Pn packf
|
|
meillo@104
|
1836 and
|
|
meillo@109
|
1837 .Pn rcvpack
|
|
meillo@109
|
1838 could be removed.
|
|
meillo@109
|
1839 .Ci 3916ab66ad5d183705ac12357621ea8661afd3c0
|
|
meillo@109
|
1840 In the message parsing function
|
|
meillo@109
|
1841 .Fn sbr/m_getfld.c ,
|
|
meillo@109
|
1842 knowledge of MMDF packed mail boxes was removed.
|
|
meillo@109
|
1843 .Ci 684ec30d81e1223a282764452f4902ed4ad1c754
|
|
meillo@109
|
1844 Further code structure simplifications may be possible there,
|
|
meillo@109
|
1845 because only one single packed mailbox format is left to be supported.
|
|
meillo@104
|
1846 I have not worked on them yet because
|
|
meillo@104
|
1847 .Fu m_getfld()
|
|
meillo@104
|
1848 is heavily optimized and thus dangerous to touch.
|
|
meillo@104
|
1849 The risk of damaging the intricate workings of the optimized code is
|
|
meillo@104
|
1850 too high.
|
|
meillo@104
|
1851 .\" XXX: move somewhere else
|
|
meillo@104
|
1852 This problem is know to the developers of nmh, too.
|
|
meillo@109
|
1853 They also avoid touching this minefield.
|
|
meillo@104
|
1854
|
|
meillo@12
|
1855
|
|
meillo@101
|
1856 .U3 "Prompter's Control Keys
|
|
meillo@20
|
1857 .P
|
|
meillo@20
|
1858 The program
|
|
meillo@20
|
1859 .Pn prompter
|
|
meillo@104
|
1860 queries the user to fill in a message form.
|
|
meillo@104
|
1861 When used by
|
|
meillo@20
|
1862 .Pn comp
|
|
meillo@104
|
1863 as
|
|
meillo@104
|
1864 .Cl "comp -editor prompter" ,
|
|
meillo@20
|
1865 the resulting behavior is similar to
|
|
meillo@20
|
1866 .Pn mailx .
|
|
meillo@51
|
1867 Apparently,
|
|
meillo@20
|
1868 .Pn prompter
|
|
meillo@104
|
1869 hadn't been touched lately.
|
|
meillo@104
|
1870 Otherwise it's hardly explainable why it
|
|
meillo@20
|
1871 still offered the switches
|
|
meillo@84
|
1872 .Sw -erase
|
|
meillo@84
|
1873 .Ar chr
|
|
meillo@20
|
1874 and
|
|
meillo@84
|
1875 .Sw -kill
|
|
meillo@84
|
1876 .Ar chr
|
|
meillo@20
|
1877 to name the characters for command line editing.
|
|
meillo@21
|
1878 The times when this had been necessary are long time gone.
|
|
meillo@20
|
1879 Today these things work out-of-the-box, and if not, are configured
|
|
meillo@20
|
1880 with the standard tool
|
|
meillo@20
|
1881 .Pn stty .
|
|
meillo@104
|
1882 The switches are removed now
|
|
meillo@104
|
1883 .Ci 0bd9750710cdbab80cfb4036dd87af20afe1552f .
|
|
meillo@20
|
1884
|
|
meillo@104
|
1885
|
|
meillo@109
|
1886 .U3 "Hardcopy Terminal Support
|
|
meillo@21
|
1887 .P
|
|
meillo@109
|
1888 More of a funny anecdote is a check for being connected to a
|
|
meillo@109
|
1889 hardcopy terminal.
|
|
meillo@109
|
1890 It remained in the code until Spring 2012, when I finally removed it
|
|
meillo@104
|
1891 .Ci b7764c4a6b71d37918a97594d866258f154017ca .
|
|
meillo@109
|
1892 I would be truly happy to see such a terminal in action today,
|
|
meillo@109
|
1893 maybe even being able to work on it.
|
|
meillo@109
|
1894 But I fear my chances are null.
|
|
meillo@21
|
1895 .P
|
|
meillo@109
|
1896 The check only prevented a pager to be placed between the printing
|
|
meillo@104
|
1897 program (\c
|
|
meillo@104
|
1898 .Pn mhl )
|
|
meillo@104
|
1899 and the terminal.
|
|
meillo@109
|
1900 In nmh, this could have been ensured statically with the
|
|
meillo@104
|
1901 .Sw -nomoreproc
|
|
meillo@109
|
1902 at the command line, too.
|
|
meillo@121
|
1903 In mmh, setting the profile entry
|
|
meillo@104
|
1904 .Pe Pager
|
|
meillo@104
|
1905 or the environment variable
|
|
meillo@104
|
1906 .Ev PAGER
|
|
meillo@104
|
1907 to
|
|
meillo@109
|
1908 .Pn cat
|
|
meillo@109
|
1909 does the job.
|
|
meillo@104
|
1910
|
|
meillo@104
|
1911
|
|
meillo@21
|
1912
|
|
meillo@12
|
1913
|
|
meillo@58
|
1914 .H2 "Attachments
|
|
meillo@22
|
1915 .P
|
|
meillo@101
|
1916 The mind model of email attachments is unrelated to MIME.
|
|
meillo@101
|
1917 Although the MIME RFCs (2045 through 2049) define the technical
|
|
meillo@109
|
1918 requirements for having attachments, they do not mention the word
|
|
meillo@101
|
1919 ``attachment''.
|
|
meillo@101
|
1920 Instead of attachments, MIME talks about ``multi-part message bodies''
|
|
meillo@101
|
1921 [RFC\|2045], a more general concept.
|
|
meillo@101
|
1922 Multi-part messages are messages
|
|
meillo@101
|
1923 ``in which one or more different
|
|
meillo@101
|
1924 sets of data are combined in a single body''
|
|
meillo@101
|
1925 [RFC\|2046].
|
|
meillo@101
|
1926 MIME keeps its descriptions generic;
|
|
meillo@101
|
1927 it does not imply specific usage models.
|
|
meillo@109
|
1928 One usage model became prevalent: attachments.
|
|
meillo@101
|
1929 The idea is having a main text document with files of arbitrary kind
|
|
meillo@101
|
1930 attached to it.
|
|
meillo@101
|
1931 In MIME terms, this is a multi-part message having a text part first
|
|
meillo@110
|
1932 and parts of arbitrary type following.
|
|
meillo@101
|
1933 .P
|
|
meillo@101
|
1934 MH's MIME support is a direct implementation of the RFCs.
|
|
meillo@101
|
1935 The perception of the topic described in the RFCs is clearly visible
|
|
meillo@101
|
1936 in MH's implementation.
|
|
meillo@109
|
1937 In result, MH had all the MIME features but no idea of attachments.
|
|
meillo@109
|
1938 But users don't need all the MIME features,
|
|
meillo@109
|
1939 they want convenient attachment handling.
|
|
meillo@109
|
1940
|
|
meillo@102
|
1941
|
|
meillo@102
|
1942 .U3 "Composing MIME Messages
|
|
meillo@102
|
1943 .P
|
|
meillo@102
|
1944 In order to improve the situation on the message composing side,
|
|
meillo@102
|
1945 Jon Steinhart had added an attachment system to nmh in 2002.
|
|
meillo@101
|
1946 .Ci 7480dbc14bc90f2d872d434205c0784704213252
|
|
meillo@102
|
1947 In the file
|
|
meillo@102
|
1948 .Fn docs/README-ATTACHMENTS ,
|
|
meillo@102
|
1949 he described his motivation to do so as such:
|
|
meillo@101
|
1950 .QS
|
|
meillo@101
|
1951 Although nmh contains the necessary functionality for MIME message handing,
|
|
meillo@101
|
1952 the interface to this functionality is pretty obtuse.
|
|
meillo@101
|
1953 There's no way that I'm ever going to convince my partner to write
|
|
meillo@101
|
1954 .Pn mhbuild
|
|
meillo@101
|
1955 composition files!
|
|
meillo@101
|
1956 .QE
|
|
meillo@102
|
1957 .LP
|
|
meillo@102
|
1958 With this change, the mind model of attachments entered nmh.
|
|
meillo@102
|
1959 In the same document:
|
|
meillo@101
|
1960 .QS
|
|
meillo@101
|
1961 These changes simplify the task of managing attachments on draft files.
|
|
meillo@101
|
1962 They allow attachments to be added, listed, and deleted.
|
|
meillo@101
|
1963 MIME messages are automatically created when drafts with attachments
|
|
meillo@101
|
1964 are sent.
|
|
meillo@101
|
1965 .QE
|
|
meillo@102
|
1966 .LP
|
|
meillo@102
|
1967 Unfortunately, the attachment system,
|
|
meillo@102
|
1968 like any new facilities in nmh,
|
|
meillo@110
|
1969 was inactive by default.
|
|
meillo@101
|
1970 .P
|
|
meillo@101
|
1971 During my work in Argentina, I tried to improve the attachment system.
|
|
meillo@102
|
1972 But, because of great opposition in the nmh community,
|
|
meillo@102
|
1973 my patch died as a proposal on the mailing list, after long discussions.
|
|
meillo@101
|
1974 .[
|
|
meillo@101
|
1975 nmh-workers attachment proposal
|
|
meillo@101
|
1976 .]
|
|
meillo@110
|
1977 In January 2012, I extended the patch and applied it to mmh.
|
|
meillo@101
|
1978 .Ci 8ff284ff9167eff8f5349481529332d59ed913b1
|
|
meillo@102
|
1979 In mmh, the attachment system is active by default.
|
|
meillo@102
|
1980 Instead of command line switches, the
|
|
meillo@102
|
1981 .Pe Attachment-Header
|
|
meillo@102
|
1982 profile entry is used to specify
|
|
meillo@102
|
1983 the name of the attachment header field.
|
|
meillo@102
|
1984 It is pre-defined to
|
|
meillo@102
|
1985 .Hd Attach .
|
|
meillo@101
|
1986 .P
|
|
meillo@101
|
1987 To add an attachment to a draft, simply add an attachment header:
|
|
meillo@101
|
1988 .VS
|
|
meillo@101
|
1989 To: bob
|
|
meillo@101
|
1990 Subject: The file you wanted
|
|
meillo@101
|
1991 Attach: /path/to/the/file-bob-wanted
|
|
meillo@101
|
1992 --------
|
|
meillo@101
|
1993 Here it is.
|
|
meillo@101
|
1994 VE
|
|
meillo@101
|
1995 The header field can be added to the draft manually in the editor,
|
|
meillo@102
|
1996 or by using the `attach' command at the WhatNow prompt, or
|
|
meillo@102
|
1997 non-interactively with
|
|
meillo@101
|
1998 .Pn anno :
|
|
meillo@101
|
1999 .VS
|
|
meillo@102
|
2000 anno -append -nodate -component Attach -text /path/to/attachment
|
|
meillo@101
|
2001 VE
|
|
meillo@102
|
2002 Drafts with attachment headers are converted to MIME automatically by
|
|
meillo@102
|
2003 .Pn send .
|
|
meillo@102
|
2004 The conversion to MIME is invisible to the user.
|
|
meillo@102
|
2005 The draft stored in the draft folder is always in source form, with
|
|
meillo@101
|
2006 attachment headers.
|
|
meillo@101
|
2007 If the MIMEification fails, for instance because the file to attach
|
|
meillo@101
|
2008 is not accessible, the original draft is not changed.
|
|
meillo@101
|
2009 .P
|
|
meillo@102
|
2010 The attachment system handles the forwarding of messages, too.
|
|
meillo@101
|
2011 If the attachment header value starts with a plus character (`+'),
|
|
meillo@101
|
2012 like in
|
|
meillo@101
|
2013 .Cl "Attach: +bob 30 42" ,
|
|
meillo@101
|
2014 The given messages in the specified folder will be attached.
|
|
meillo@101
|
2015 This allowed to simplify
|
|
meillo@101
|
2016 .Pn forw .
|
|
meillo@101
|
2017 .Ci f41f04cf4ceca7355232cf7413e59afafccc9550
|
|
meillo@101
|
2018 .P
|
|
meillo@101
|
2019 Closely related to attachments is non-ASCII text content,
|
|
meillo@101
|
2020 because it requires MIME too.
|
|
meillo@102
|
2021 In nmh, the user needed to call `mime' at the WhatNow prompt
|
|
meillo@101
|
2022 to have the draft converted to MIME.
|
|
meillo@102
|
2023 This was necessary whenever the draft contained non-ASCII characters.
|
|
meillo@101
|
2024 If the user did not call `mime', a broken message would be sent.
|
|
meillo@101
|
2025 Therefore, the
|
|
meillo@101
|
2026 .Pe automimeproc
|
|
meillo@101
|
2027 profile entry could be specified to have the `mime' command invoked
|
|
meillo@102
|
2028 automatically each time.
|
|
meillo@101
|
2029 Unfortunately, this approach conflicted with with attachment system
|
|
meillo@101
|
2030 because the draft would already be in MIME format at the time
|
|
meillo@101
|
2031 when the attachment system wanted to MIMEify it.
|
|
meillo@102
|
2032 To use nmh's attachment system, `mime' must not be called at the
|
|
meillo@102
|
2033 WhatNow prompt and
|
|
meillo@101
|
2034 .Pe automimeproc
|
|
meillo@102
|
2035 must not be set in the profile.
|
|
meillo@101
|
2036 But then the case of non-ASCII text without attachment headers was
|
|
meillo@101
|
2037 not caught.
|
|
meillo@102
|
2038 All in all, the solution was complex and irritating.
|
|
meillo@102
|
2039 My patch from December 2010 would have simplified the situation.
|
|
meillo@102
|
2040 .P
|
|
meillo@101
|
2041 Mmh's current solution is even more elaborate.
|
|
meillo@101
|
2042 Any necessary MIMEification is done automatically.
|
|
meillo@101
|
2043 There is no `mime' command at the WhatNow prompt anymore.
|
|
meillo@102
|
2044 The draft will be converted automatically to MIME when either an
|
|
meillo@102
|
2045 attachment header or non-ASCII text is present.
|
|
meillo@101
|
2046 Further more, the special meaning of the hash character (`#')
|
|
meillo@102
|
2047 at line beginnings in the draft message is removed.
|
|
meillo@102
|
2048 Users need not at all deal with the whole topic.
|
|
meillo@101
|
2049 .P
|
|
meillo@102
|
2050 Although the new approach does not anymore support arbitrary MIME
|
|
meillo@102
|
2051 compositions directly, the full power of
|
|
meillo@101
|
2052 .Pn mhbuild
|
|
meillo@101
|
2053 can still be accessed.
|
|
meillo@102
|
2054 Given no attachment headers are included, the user can create
|
|
meillo@101
|
2055 .Pn mhbuild
|
|
meillo@102
|
2056 composition drafts like in nmh.
|
|
meillo@101
|
2057 Then, at the WhatNow prompt, he needs to invoke
|
|
meillo@101
|
2058 .Cl "edit mhbuild
|
|
meillo@101
|
2059 to convert it to MIME.
|
|
meillo@110
|
2060 Because the resulting draft does neither contain non-ASCII characters
|
|
meillo@102
|
2061 nor has it attachment headers, the attachment system will not touch it.
|
|
meillo@101
|
2062 .P
|
|
meillo@121
|
2063 The approach taken in mmh is tailored towards todays most common case:
|
|
meillo@101
|
2064 a text part with possibly attachments.
|
|
meillo@102
|
2065 This case is simplified a lot for users.
|
|
meillo@102
|
2066
|
|
meillo@112
|
2067
|
|
meillo@102
|
2068 .U3 "MIME Type Guessing
|
|
meillo@102
|
2069 .P
|
|
meillo@102
|
2070 The use of
|
|
meillo@101
|
2071 .Pn mhbuild
|
|
meillo@102
|
2072 composition drafts had one notable advantage over attachment headers
|
|
meillo@102
|
2073 from the programmer's point of view: The user provides the appropriate
|
|
meillo@102
|
2074 MIME types for files to include.
|
|
meillo@102
|
2075 The attachment system needs to find out the correct MIME type itself.
|
|
meillo@102
|
2076 This is a difficult task, yet it spares the user irritating work.
|
|
meillo@102
|
2077 Determining the correct MIME type of content is partly mechanical,
|
|
meillo@102
|
2078 partly intelligent work.
|
|
meillo@102
|
2079 Forcing the user to find out the correct MIME type,
|
|
meillo@102
|
2080 forces him to do partly mechanical work.
|
|
meillo@102
|
2081 Letting the computer do the work, can lead to bad choices for difficult
|
|
meillo@102
|
2082 content.
|
|
meillo@102
|
2083 For mmh, the latter option was chosen.
|
|
meillo@102
|
2084 .P
|
|
meillo@102
|
2085 Determining the MIME type by the suffix of the file name is a dumb
|
|
meillo@102
|
2086 approach, yet it is simple to implement and provides good results
|
|
meillo@102
|
2087 for the common cases.
|
|
meillo@102
|
2088 Mmh implements this approach in the
|
|
meillo@102
|
2089 .Pn print-mimetype
|
|
meillo@102
|
2090 script.
|
|
meillo@112
|
2091 .Ci 4b5944268ea0da7bb30598a27857304758ea9b44
|
|
meillo@102
|
2092 Using it is the default choice.
|
|
meillo@102
|
2093 .P
|
|
meillo@112
|
2094 A far better, though less portable, approach is the use of
|
|
meillo@102
|
2095 .Pn file .
|
|
meillo@102
|
2096 This standard tool tries to determine the type of files.
|
|
meillo@102
|
2097 Unfortunately, its capabilities and accuracy varies from system to system.
|
|
meillo@102
|
2098 Additionally, its output was only intended for human beings,
|
|
meillo@102
|
2099 but not to be used by programs.
|
|
meillo@102
|
2100 It varies much.
|
|
meillo@102
|
2101 Nevertheless, modern versions of GNU
|
|
meillo@102
|
2102 .Pn file ,
|
|
meillo@102
|
2103 which is prevalent on the popular GNU/Linux systems,
|
|
meillo@102
|
2104 provides MIME type output in machine-readable form.
|
|
meillo@102
|
2105 Although this solution is highly system-dependent,
|
|
meillo@102
|
2106 it solves the difficult problem well.
|
|
meillo@102
|
2107 On systems where GNU
|
|
meillo@102
|
2108 .Pn file ,
|
|
meillo@102
|
2109 version 5.04 or higher, is available it should be used.
|
|
meillo@102
|
2110 One needs to specify the following profile entry to do so:
|
|
meillo@112
|
2111 .Ci 3baec236a39c5c89a9bda8dbd988d643a21decc6
|
|
meillo@102
|
2112 .VS
|
|
meillo@102
|
2113 Mime-Type-Query: file -b --mime
|
|
meillo@102
|
2114 VE
|
|
meillo@102
|
2115 .LP
|
|
meillo@102
|
2116 Other versions of
|
|
meillo@102
|
2117 .Pn file
|
|
meillo@102
|
2118 might possibly be usable with wrapper scripts to reformat the output.
|
|
meillo@102
|
2119 The diversity among
|
|
meillo@102
|
2120 .Pn file
|
|
meillo@102
|
2121 implementations is great; one needs to check the local variant.
|
|
meillo@102
|
2122 .P
|
|
meillo@102
|
2123 If no MIME type can be determined, text content gets sent as
|
|
meillo@102
|
2124 `text/plain' and anything else under the generic fall-back type
|
|
meillo@102
|
2125 `application/octet-stream'.
|
|
meillo@102
|
2126 It is not possible in mmh to override the automatic MIME type guessing
|
|
meillo@102
|
2127 for a specific file.
|
|
meillo@102
|
2128 To do so, the user would need to know in advance for which file
|
|
meillo@102
|
2129 the automatic guessing does fail, or the system would require interaction.
|
|
meillo@102
|
2130 I consider both cases impractical.
|
|
meillo@102
|
2131 The existing solution should be sufficient.
|
|
meillo@102
|
2132 If not, the user may always fall back to
|
|
meillo@102
|
2133 .Pn mhbuild
|
|
meillo@102
|
2134 composition drafts and ignore the attachment system.
|
|
meillo@101
|
2135
|
|
meillo@102
|
2136
|
|
meillo@102
|
2137 .U3 "Storing Attachments
|
|
meillo@102
|
2138 .P
|
|
meillo@108
|
2139 Extracting MIME parts of a message and storing them to disk is done by
|
|
meillo@108
|
2140 .Pn mhstore .
|
|
meillo@108
|
2141 The program has two operation modes,
|
|
meillo@108
|
2142 .Sw -auto
|
|
meillo@108
|
2143 and
|
|
meillo@108
|
2144 .Sw -noauto .
|
|
meillo@108
|
2145 With the former one, each part is stored under the filename given in the
|
|
meillo@108
|
2146 MIME part's meta information, if available.
|
|
meillo@108
|
2147 This naming information is usually available for modern attachments.
|
|
meillo@108
|
2148 If no filename is available, this MIME part is stored as if
|
|
meillo@108
|
2149 .Sw -noauto
|
|
meillo@108
|
2150 would have been specified.
|
|
meillo@108
|
2151 In the
|
|
meillo@108
|
2152 .Sw -noauto
|
|
meillo@108
|
2153 mode, the parts are processed according to rules, defined by
|
|
meillo@108
|
2154 .Pe mhstore-store-*
|
|
meillo@108
|
2155 profile entries.
|
|
meillo@108
|
2156 These rules define generic filename templates for storing
|
|
meillo@108
|
2157 or commands to post-process the contents in arbitrary ways.
|
|
meillo@108
|
2158 If no matching rule is available the part is stored under a generic
|
|
meillo@108
|
2159 filename, built from message number, MIME part number, and MIME type.
|
|
meillo@108
|
2160 .P
|
|
meillo@108
|
2161 The
|
|
meillo@108
|
2162 .Sw -noauto
|
|
meillo@108
|
2163 mode had been the default in nmh because it was considered safe,
|
|
meillo@108
|
2164 in contrast to the
|
|
meillo@108
|
2165 .Sw -auto
|
|
meillo@108
|
2166 mode.
|
|
meillo@108
|
2167 In mmh,
|
|
meillo@108
|
2168 .Sw -auto
|
|
meillo@108
|
2169 is not dangerous anymore.
|
|
meillo@108
|
2170 Two changes were necessary:
|
|
meillo@108
|
2171 .BU
|
|
meillo@108
|
2172 Any directory path is removed from the proposed filename.
|
|
meillo@108
|
2173 Thus, the files are always stored in the expected directory.
|
|
meillo@108
|
2174 .Ci 41b6eadbcecf63c9a66aa5e582011987494abefb
|
|
meillo@108
|
2175 .BU
|
|
meillo@108
|
2176 Tar files are not extracted automatically any more.
|
|
meillo@108
|
2177 Thus, the rest of the file system will not be touched.
|
|
meillo@108
|
2178 .Ci 94c80042eae3383c812d9552089953f9846b1bb6
|
|
meillo@108
|
2179 .LP
|
|
meillo@108
|
2180 Now, the outcome of mmh's
|
|
meillo@108
|
2181 .Cl "mhstore -auto
|
|
meillo@110
|
2182 can be foreseen from the output of
|
|
meillo@108
|
2183 .Cl "mhlist -verbose" .
|
|
meillo@108
|
2184 .P
|
|
meillo@108
|
2185 The
|
|
meillo@108
|
2186 .Sw -noauto
|
|
meillo@108
|
2187 mode is seen to be more powerful but less convenient.
|
|
meillo@108
|
2188 On the other hand,
|
|
meillo@108
|
2189 .Sw -auto
|
|
meillo@108
|
2190 is safe now and
|
|
meillo@108
|
2191 storing attachments under their original name is intuitive.
|
|
meillo@108
|
2192 Hence,
|
|
meillo@108
|
2193 .Sw -auto
|
|
meillo@108
|
2194 serves better as the default option.
|
|
meillo@108
|
2195 .Ci 3410b680416c49a7617491af38bc1929855a331d
|
|
meillo@108
|
2196 .P
|
|
meillo@108
|
2197 Files are stored into the directory given by the
|
|
meillo@108
|
2198 .Pe Nmh-Storage
|
|
meillo@108
|
2199 profile entry, if set, or
|
|
meillo@108
|
2200 into the current working directory, otherwise.
|
|
meillo@108
|
2201 Storing to different directories is only possible with
|
|
meillo@108
|
2202 .Pe mhstore-store-*
|
|
meillo@108
|
2203 profile entries.
|
|
meillo@108
|
2204 .P
|
|
meillo@108
|
2205 Still, in both modes, existing files get overwritten silently.
|
|
meillo@108
|
2206 This can be considered a bug.
|
|
meillo@108
|
2207 Yet, each other behavior has its draw-backs, too.
|
|
meillo@108
|
2208 Refusing to replace files requires adding a
|
|
meillo@108
|
2209 .Sw -force
|
|
meillo@108
|
2210 option.
|
|
meillo@108
|
2211 Users will likely need to invoke
|
|
meillo@108
|
2212 .Pn mhstore
|
|
meillo@108
|
2213 a second time with
|
|
meillo@108
|
2214 .Sw -force
|
|
meillo@108
|
2215 then.
|
|
meillo@108
|
2216 Eventually, only the user can decide in the concrete case.
|
|
meillo@108
|
2217 This requires interaction, which I like to avoid if possible.
|
|
meillo@108
|
2218 Appending a unique suffix to the filename is another bad option.
|
|
meillo@108
|
2219 For now, the behavior remains as it is.
|
|
meillo@108
|
2220 .P
|
|
meillo@108
|
2221 In mmh, only MIME parts of type message are special in
|
|
meillo@108
|
2222 .Pn mhstore 's
|
|
meillo@108
|
2223 .Sw -auto
|
|
meillo@108
|
2224 mode.
|
|
meillo@108
|
2225 Instead of storing message/rfc822 parts as files to disk,
|
|
meillo@108
|
2226 they are stored as messages into the current mail folder.
|
|
meillo@108
|
2227 The same applies to message/partial, only, the parts are reassembled
|
|
meillo@108
|
2228 automatically before.
|
|
meillo@108
|
2229 Parts of type message/external-body are not automatically retrieved
|
|
meillo@108
|
2230 anymore. Instead, Information on how to retrieve them is output.
|
|
meillo@108
|
2231 Not supporting this rare case saved nearly one thousand lines of code.
|
|
meillo@108
|
2232 .Ci 55e1d8c654ee0f7c45b9361ce34617983b454c32
|
|
meillo@108
|
2233 .\" XXX mention somewhere else too: (The profile entry `nmh-access-ftp'
|
|
meillo@108
|
2234 .\" and sbr/ruserpass.c for reading ~/.netrc are gone now.)
|
|
meillo@108
|
2235 Not special anymore is `application/octet-stream; type=tar'.
|
|
meillo@108
|
2236 Automatically extracting such MIME parts had been the dangerous part
|
|
meillo@108
|
2237 of the
|
|
meillo@108
|
2238 .Sw -auto
|
|
meillo@108
|
2239 mode.
|
|
meillo@108
|
2240 .Ci 94c80042eae3383c812d9552089953f9846b1bb6
|
|
meillo@108
|
2241
|
|
meillo@102
|
2242
|
|
meillo@102
|
2243
|
|
meillo@102
|
2244 .U3 "Showing MIME Messages
|
|
meillo@102
|
2245 .P
|
|
meillo@114
|
2246 The program
|
|
meillo@114
|
2247 .Pn mhshow
|
|
meillo@114
|
2248 had been written to display MIME messages.
|
|
meillo@114
|
2249 It implemented the conceptional view of the MIME RFCs.
|
|
meillo@114
|
2250 Nmh's
|
|
meillo@114
|
2251 .Pn mhshow
|
|
meillo@114
|
2252 handled each MIME part independently, presenting them separately
|
|
meillo@114
|
2253 to the user.
|
|
meillo@114
|
2254 This does not match today's understanding of email attachments,
|
|
meillo@114
|
2255 where displaying a message is seen to be a single, integrated operation.
|
|
meillo@114
|
2256 Today, email messages are expected to consist of a main text part
|
|
meillo@114
|
2257 plus possibly attachments.
|
|
meillo@114
|
2258 They are not any more seen to be arbitrary MIME hierarchies with
|
|
meillo@114
|
2259 information on how to display the individual parts.
|
|
meillo@114
|
2260 I adjusted
|
|
meillo@114
|
2261 .Pn mhshow 's
|
|
meillo@114
|
2262 behavior to the modern view on the topic.
|
|
meillo@114
|
2263 .P
|
|
meillo@114
|
2264 Note that this section completely ignores the original
|
|
meillo@114
|
2265 .Pn show
|
|
meillo@114
|
2266 program, because it was not capable to display MIME messages
|
|
meillo@114
|
2267 and is no longer part of mmh.
|
|
meillo@114
|
2268 Although
|
|
meillo@114
|
2269 .Pn mhshow
|
|
meillo@114
|
2270 was renamed to
|
|
meillo@114
|
2271 .Pn show
|
|
meillo@114
|
2272 in mmh, this section uses the name
|
|
meillo@114
|
2273 .Pn mhshow ,
|
|
meillo@114
|
2274 in order to avoid confusion.
|
|
meillo@114
|
2275 .P
|
|
meillo@114
|
2276 In mmh, the basic idea is that
|
|
meillo@114
|
2277 .Pn mhshow
|
|
meillo@114
|
2278 should display a message in one single pager session.
|
|
meillo@114
|
2279 Therefore,
|
|
meillo@114
|
2280 .Pn mhshow
|
|
meillo@114
|
2281 invokes a pager session for all its output,
|
|
meillo@114
|
2282 whenever it prints to a terminal.
|
|
meillo@114
|
2283 .Ci a4197ea6ffc5c1550e8b52d5a654bcaaaee04a4e
|
|
meillo@114
|
2284 In consequence,
|
|
meillo@114
|
2285 .Pn mhl
|
|
meillo@114
|
2286 does no more invoke a pager.
|
|
meillo@114
|
2287 .Ci 0e46503be3c855bddaeae3843e1b659279c35d70
|
|
meillo@114
|
2288 With
|
|
meillo@114
|
2289 .Pn mhshow
|
|
meillo@114
|
2290 replacing the original
|
|
meillo@114
|
2291 .Pn show ,
|
|
meillo@114
|
2292 output from
|
|
meillo@114
|
2293 .Pn mhl
|
|
meillo@114
|
2294 does not go to the terminal directly, but through
|
|
meillo@114
|
2295 .Pn mhshow .
|
|
meillo@114
|
2296 Hence,
|
|
meillo@114
|
2297 .Pn mhl
|
|
meillo@114
|
2298 does not need to invoke a pager.
|
|
meillo@114
|
2299 The one and only job of
|
|
meillo@114
|
2300 .Pn mhl
|
|
meillo@114
|
2301 is to format messages or parts of them.
|
|
meillo@114
|
2302 The only place in mmh, where a pager is invoked is
|
|
meillo@114
|
2303 .Pn mhshow .
|
|
meillo@114
|
2304 .P
|
|
meillo@114
|
2305 .Pe mhshow-show-*
|
|
meillo@114
|
2306 profile entries can be used to display MIME parts in a specific way.
|
|
meillo@114
|
2307 For instance, PDF and Postscript files could be converted to plain text
|
|
meillo@114
|
2308 to display them in the terminal.
|
|
meillo@114
|
2309 In mmh, the displaying of MIME parts will always be done serially.
|
|
meillo@114
|
2310 The request to display the MIME type `multipart/parallel' in parallel
|
|
meillo@114
|
2311 is ignored.
|
|
meillo@114
|
2312 It is simply treated as `multipart/mixed'.
|
|
meillo@114
|
2313 .Ci d0581ba306a7299113a346f9b4c46ce97bc4cef6
|
|
meillo@114
|
2314 This could already be requested with the, now removed,
|
|
meillo@114
|
2315 .Sw -serialonly
|
|
meillo@114
|
2316 switch of
|
|
meillo@114
|
2317 .Pn mhshow .
|
|
meillo@114
|
2318 As MIME parts are always processed exclusively , i.e. serially,
|
|
meillo@114
|
2319 the `%e' escape in
|
|
meillo@114
|
2320 .Pe mhshow-show-*
|
|
meillo@114
|
2321 profile entries became useless and was thus removed.
|
|
meillo@114
|
2322 .Ci a20d405db09b7ccca74d3e8c57550883da49e1ae
|
|
meillo@114
|
2323 .P
|
|
meillo@114
|
2324 In the intended setup, only text content would be displayed.
|
|
meillo@114
|
2325 Non-text content would be converted to text by appropriate
|
|
meillo@114
|
2326 .Pe mhshow-show-*
|
|
meillo@114
|
2327 profile entries before, if possible and wanted.
|
|
meillo@114
|
2328 All output would be displayed in a single pager session.
|
|
meillo@114
|
2329 Other kinds of attachments are ignored.
|
|
meillo@114
|
2330 With
|
|
meillo@114
|
2331 .Pe mhshow-show-*
|
|
meillo@114
|
2332 profile entries for them, they can be displayed serially along
|
|
meillo@114
|
2333 the message.
|
|
meillo@114
|
2334 For parallel display, the attachments need to be stored to disk first.
|
|
meillo@114
|
2335 .P
|
|
meillo@114
|
2336 To display text content in foreign charsets, they need to be converted
|
|
meillo@114
|
2337 to the native charset.
|
|
meillo@114
|
2338 Therefore,
|
|
meillo@114
|
2339 .Pe mhshow-charset-*
|
|
meillo@114
|
2340 profile entries used to be needed.
|
|
meillo@121
|
2341 In mmh, the conversion is done automatically by piping the text through
|
|
meillo@114
|
2342 the
|
|
meillo@114
|
2343 .Pn iconv
|
|
meillo@114
|
2344 command, if necessary.
|
|
meillo@114
|
2345 .Ci 2433122c20baccb10b70b49c04c6b0497b5b3b60
|
|
meillo@114
|
2346 Custom
|
|
meillo@114
|
2347 .Pe mhshow-show-*
|
|
meillo@114
|
2348 rules for textual content might need a
|
|
meillo@114
|
2349 .Cl "iconv -f %c %f |
|
|
meillo@114
|
2350 prefix to have the text converted to the native charset.
|
|
meillo@114
|
2351 .P
|
|
meillo@121
|
2352 Although the conversion of foreign charsets to the native one
|
|
meillo@114
|
2353 has improved, it is not consistent enough.
|
|
meillo@114
|
2354 Further work needs to be done and
|
|
meillo@114
|
2355 the basic concepts in this field need to be re-thought.
|
|
meillo@114
|
2356 Though, the default setup of mmh displays message in foreign charsets
|
|
meillo@114
|
2357 correctly without the need to configure anything.
|
|
meillo@114
|
2358
|
|
meillo@114
|
2359
|
|
meillo@114
|
2360 .ig
|
|
meillo@114
|
2361
|
|
meillo@114
|
2362 .P
|
|
meillo@114
|
2363 mhshow/mhstore: Removed support for retrieving message/external-body parts.
|
|
meillo@114
|
2364 These tools won't download the contents automatically anymore. Instead,
|
|
meillo@114
|
2365 they print the information needed to get the contents. If someone should
|
|
meillo@114
|
2366 really receive one of those rare message/external-body messages, he can
|
|
meillo@114
|
2367 do the job manually. We save nearly a thousand lines of code. That's worth
|
|
meillo@114
|
2368 it!
|
|
meillo@114
|
2369 (The profile entry `nmh-access-ftp' and sbr/ruserpass.c for reading
|
|
meillo@114
|
2370 ~/.netrc are gone now.)
|
|
meillo@114
|
2371 .Ci 55e1d8c654ee0f7c45b9361ce34617983b454c32
|
|
meillo@114
|
2372
|
|
meillo@114
|
2373 ..
|
|
meillo@102
|
2374
|
|
meillo@58
|
2375
|
|
meillo@58
|
2376
|
|
meillo@58
|
2377 .H2 "Digital Cryptography
|
|
meillo@22
|
2378 .P
|
|
meillo@58
|
2379 Signing and encryption.
|
|
meillo@112
|
2380 .P
|
|
meillo@112
|
2381 FIXME
|
|
meillo@58
|
2382
|
|
meillo@58
|
2383
|
|
meillo@102
|
2384
|
|
meillo@102
|
2385 .H2 "Modern Defaults
|
|
meillo@22
|
2386 .P
|
|
meillo@116
|
2387 Nmh has a bunch of convenience-improving features inactive by default,
|
|
meillo@116
|
2388 although one can expect every new user wanting to have them active.
|
|
meillo@112
|
2389 The reason they are inactive by default is the wish to stay compatible
|
|
meillo@112
|
2390 with old versions.
|
|
meillo@116
|
2391 But what is the definition for old versions.
|
|
meillo@116
|
2392 Still, the highly useful draft folder facility is not active by default
|
|
meillo@116
|
2393 although it had been introduced over twenty-five years ago
|
|
meillo@112
|
2394 .[
|
|
meillo@112
|
2395 rose romine real work
|
|
meillo@112
|
2396 .]
|
|
meillo@116
|
2397 \(en the community seems not to care.
|
|
meillo@116
|
2398 This is one of several examples that require new users to build up
|
|
meillo@116
|
2399 their profile before they can access the modern features of nmh.
|
|
meillo@116
|
2400 Without an extensively built-up profile, the setup is hardly usable
|
|
meillo@116
|
2401 for modern emailing.
|
|
meillo@116
|
2402 The point is not the customization of the setup,
|
|
meillo@116
|
2403 but the activating of generally useful facilities.
|
|
meillo@112
|
2404 .P
|
|
meillo@116
|
2405 Yet, the real problem lies less in enabling the features, as this is
|
|
meillo@116
|
2406 straight forward as soon as one knows what he wants.
|
|
meillo@116
|
2407 The real problem is that new users need deep insights into the project
|
|
meillo@116
|
2408 before they find out what they are missing and that nmh actually
|
|
meillo@116
|
2409 provides it already, it just was not activated.
|
|
meillo@116
|
2410 To give an example, I needed one year of using nmh
|
|
meillo@102
|
2411 before I became aware of the existence of the attachment system.
|
|
meillo@102
|
2412 One could argue that this fact disqualifies my reading of the
|
|
meillo@102
|
2413 documentation.
|
|
meillo@102
|
2414 If I would have installed nmh from source back then, I could agree.
|
|
meillo@116
|
2415 Yet, I had used a prepackaged version and had expected that it would
|
|
meillo@102
|
2416 just work.
|
|
meillo@121
|
2417 Nevertheless, I had been convinced by the concepts of MH already
|
|
meillo@116
|
2418 and I am a software developer,
|
|
meillo@116
|
2419 still I required a lot of time to discover the cool features.
|
|
meillo@116
|
2420 How can we expect users to be even more advanced than me,
|
|
meillo@116
|
2421 just to allow them use MH in a convenient and modern way?
|
|
meillo@116
|
2422 Unless they are strongly convinced of the concepts, they will fail.
|
|
meillo@116
|
2423 I have seen friends of me giving up disappointed
|
|
meillo@116
|
2424 before they truly used the system,
|
|
meillo@116
|
2425 although they had been motivated in the beginning.
|
|
meillo@116
|
2426 They suffer hard enough to get used to the toolchest approach,
|
|
meillo@116
|
2427 we should spare them further inconveniences.
|
|
meillo@116
|
2428 .P
|
|
meillo@116
|
2429 Maintaining compatibility for its own sake is for no good.
|
|
meillo@116
|
2430 If any MH implementation would be the back-end of widespread
|
|
meillo@116
|
2431 email clients with large user bases, compatibility would be more
|
|
meillo@116
|
2432 important.
|
|
meillo@116
|
2433 Yet, it appears as if this is not the case.
|
|
meillo@116
|
2434 Hence, compatibility is hardly important for technical reasons.
|
|
meillo@116
|
2435 Its importance originates rather from personal reasons.
|
|
meillo@116
|
2436 Nmh's user base is small and old.
|
|
meillo@116
|
2437 Changing the interfaces would cause inconvenience to long-term users of MH.
|
|
meillo@116
|
2438 It would force them to change their many years old MH configurations.
|
|
meillo@116
|
2439 I do understand this aspect, but it keeps new users from using MH.
|
|
meillo@116
|
2440 By sticking to the old users, new users are kept away.
|
|
meillo@116
|
2441 Yet, the future lies in new users.
|
|
meillo@116
|
2442 Hence, mmh invites new users by providing a convenient and modern setup,
|
|
meillo@116
|
2443 readily usable out-of-the-box.
|
|
meillo@116
|
2444 .P
|
|
meillo@116
|
2445 In mmh, all modern features are active by default.
|
|
meillo@116
|
2446 In consequence, a setup with a profile that defines only the path to the
|
|
meillo@116
|
2447 mail storage, is already convenient to use.
|
|
meillo@116
|
2448 Again, Paul Vixie's ``edginess'' appeal supports the direction I took:
|
|
meillo@116
|
2449 ``the `main branch' should just be modern''.
|
|
meillo@116
|
2450 .[
|
|
meillo@116
|
2451 paul vixie edginess nmh-workers
|
|
meillo@116
|
2452 .]
|
|
meillo@116
|
2453 .P
|
|
meillo@116
|
2454 Modern features that are active in mmh by default include:
|
|
meillo@116
|
2455 .BU
|
|
meillo@116
|
2456 The attachment system (\c
|
|
meillo@116
|
2457 .Hd Attach ).
|
|
meillo@116
|
2458 .Ci 8ff284ff9167eff8f5349481529332d59ed913b1
|
|
meillo@116
|
2459 .BU
|
|
meillo@116
|
2460 The draft folder facility (\c
|
|
meillo@116
|
2461 .Fn +drafts ).
|
|
meillo@116
|
2462 .Ci 337338b404931f06f0db2119c9e145e8ca5a9860
|
|
meillo@116
|
2463 .BU
|
|
meillo@116
|
2464 The unseen sequence (`u')
|
|
meillo@116
|
2465 .Ci c2360569e1d8d3678e294eb7c1354cb8bf7501c1
|
|
meillo@116
|
2466 and the sequence negation prefix (`!').
|
|
meillo@116
|
2467 .Ci db74c2bd004b2dc9bf8086a6d8bf773ac051f3cc
|
|
meillo@116
|
2468 .BU
|
|
meillo@116
|
2469 Quoting the original message in the reply.
|
|
meillo@116
|
2470 .Ci 67411b1f95d6ec987b4c732459e1ba8a8ac192c6
|
|
meillo@116
|
2471 .BU
|
|
meillo@116
|
2472 Forwarding messages using MIME.
|
|
meillo@116
|
2473 .Ci 6e271608b7b9c23771523f88d23a4d3593010cf1
|
|
meillo@116
|
2474
|
|
meillo@58
|
2475
|
|
meillo@58
|
2476
|
|
meillo@58
|
2477
|
|
meillo@100
|
2478 .H1 "Code Style
|
|
meillo@22
|
2479 .P
|
|
meillo@118
|
2480 Kernighan and Pike have emphasized the importance of style in the
|
|
meillo@118
|
2481 preface of their book:
|
|
meillo@118
|
2482 .[ [
|
|
meillo@118
|
2483 kernighan pike practice of programming
|
|
meillo@118
|
2484 .], p. x]
|
|
meillo@118
|
2485 .QS
|
|
meillo@118
|
2486 Chapter 1 discusses programming style.
|
|
meillo@118
|
2487 Good style is so important to good programming that we have chose
|
|
meillo@118
|
2488 to cover it first.
|
|
meillo@118
|
2489 .QE
|
|
meillo@118
|
2490 This section covers changes in mmh that were motivated by the desire
|
|
meillo@118
|
2491 to improve on style.
|
|
meillo@118
|
2492 Many of them follow the rules given in the quoted book.
|
|
meillo@118
|
2493 .[
|
|
meillo@118
|
2494 kernighan pike practice of programming
|
|
meillo@118
|
2495 .]
|
|
meillo@118
|
2496
|
|
meillo@118
|
2497
|
|
meillo@118
|
2498 .H2 "Style
|
|
meillo@118
|
2499 .P
|
|
meillo@118
|
2500 .U3 "Indentation Style
|
|
meillo@118
|
2501 .P
|
|
meillo@118
|
2502 Indentation styles are the holy cow of programmers.
|
|
meillo@118
|
2503 Again Kernighan and Pike:
|
|
meillo@118
|
2504 .[ [
|
|
meillo@118
|
2505 kernighan pike practice of programming
|
|
meillo@118
|
2506 .], p. 10]
|
|
meillo@118
|
2507 .QS
|
|
meillo@118
|
2508 Programmers have always argued about the layout of programs,
|
|
meillo@118
|
2509 but the specific style is much less important than its consistent
|
|
meillo@118
|
2510 application.
|
|
meillo@121
|
2511 Pick one style, preferably ours, use it consistently, and don't waste
|
|
meillo@118
|
2512 time arguing.
|
|
meillo@118
|
2513 .QE
|
|
meillo@118
|
2514 .P
|
|
meillo@118
|
2515 I agree that the constant application is most important,
|
|
meillo@118
|
2516 but I believe that some styles have advantages over others.
|
|
meillo@118
|
2517 For instance the indentation with tab characters only.
|
|
meillo@118
|
2518 Tab characters directly map to the nesting level \(en
|
|
meillo@118
|
2519 one tab, one level.
|
|
meillo@118
|
2520 Tab characters are flexible because developers can adjust them to
|
|
meillo@118
|
2521 whatever width they like to have.
|
|
meillo@118
|
2522 There is no more need to run
|
|
meillo@118
|
2523 .Pn unexpand
|
|
meillo@118
|
2524 or
|
|
meillo@118
|
2525 .Pn entab
|
|
meillo@118
|
2526 programs to ensure the correct mixture of leading tabs and spaces.
|
|
meillo@118
|
2527 The simple rules are: (1) Leading whitespace must consist of tabs only.
|
|
meillo@118
|
2528 (2) Any other whitespace should consist of spaces.
|
|
meillo@121
|
2529 These two rules ensure the integrity of the visual appearance.
|
|
meillo@121
|
2530 Although reformatting existing code should be avoided, I did it.
|
|
meillo@118
|
2531 I did not waste time arguing; I just did it.
|
|
meillo@118
|
2532 .Ci a485ed478abbd599d8c9aab48934e7a26733ecb1
|
|
meillo@118
|
2533
|
|
meillo@118
|
2534 .U3 "Comments
|
|
meillo@118
|
2535 .P
|
|
meillo@118
|
2536 Section 1.6 of
|
|
meillo@118
|
2537 .[ [
|
|
meillo@118
|
2538 kernighan pike practice of programming
|
|
meillo@118
|
2539 .], p. 23]
|
|
meillo@118
|
2540 demands: ``Don't belabor the obvious.''
|
|
meillo@122
|
2541 Hence, I simply removed all the comments in the following code excerpt:
|
|
meillo@118
|
2542 .VS
|
|
meillo@120
|
2543 context_replace(curfolder, folder); /* update current folder */
|
|
meillo@120
|
2544 seq_setcur(mp, mp->lowsel); /* update current message */
|
|
meillo@120
|
2545 seq_save(mp); /* synchronize message sequences */
|
|
meillo@120
|
2546 folder_free(mp); /* free folder/message structure */
|
|
meillo@120
|
2547 context_save(); /* save the context file */
|
|
meillo@120
|
2548
|
|
meillo@120
|
2549 [...]
|
|
meillo@120
|
2550
|
|
meillo@120
|
2551 int c; /* current character */
|
|
meillo@120
|
2552 char *cp; /* miscellaneous character pointer */
|
|
meillo@120
|
2553
|
|
meillo@120
|
2554 [...]
|
|
meillo@120
|
2555
|
|
meillo@120
|
2556 /* NUL-terminate the field */
|
|
meillo@120
|
2557 *cp = '\0';
|
|
meillo@118
|
2558 VE
|
|
meillo@120
|
2559 .Ci 426543622b377fc5d091455cba685e114b6df674
|
|
meillo@118
|
2560 .P
|
|
meillo@118
|
2561 The names of the functions explain enough already.
|
|
meillo@118
|
2562
|
|
meillo@118
|
2563 .U3 "Names
|
|
meillo@118
|
2564 .P
|
|
meillo@118
|
2565 Kernighan and Pike suggest:
|
|
meillo@118
|
2566 ``Use active names for functions''.
|
|
meillo@118
|
2567 .[ [
|
|
meillo@118
|
2568 kernighan pike practice of programming
|
|
meillo@118
|
2569 .], p. 4]
|
|
meillo@118
|
2570 One application of this rule was the rename of
|
|
meillo@118
|
2571 .Fu check_charset()
|
|
meillo@118
|
2572 to
|
|
meillo@118
|
2573 .Fu is_native_charset() .
|
|
meillo@118
|
2574 .Ci 8d77b48284c58c135a6b2787e721597346ab056d
|
|
meillo@118
|
2575 The same change fixed a violation of ``Be accurate'' as well.
|
|
meillo@118
|
2576 The code did not match the expectation the function suggested,
|
|
meillo@118
|
2577 as it, for whatever reason, only compared the first ten characters
|
|
meillo@118
|
2578 of the charset name.
|
|
meillo@118
|
2579 .P
|
|
meillo@118
|
2580 More important than using active names is using descriptive names.
|
|
meillo@118
|
2581 Renaming the obscure function
|
|
meillo@118
|
2582 .Fu m_unknown()
|
|
meillo@118
|
2583 was a delightful event.
|
|
meillo@118
|
2584 .Ci 611d68d19204d7cbf5bd585391249cb5bafca846
|
|
meillo@118
|
2585 .P
|
|
meillo@118
|
2586 Magic numbers are generally considered bad style.
|
|
meillo@118
|
2587 Obviously, Kernighan and Pike agree:
|
|
meillo@118
|
2588 ``Give names to magic numbers''.
|
|
meillo@118
|
2589 .[ [
|
|
meillo@118
|
2590 kernighan pike practice of programming
|
|
meillo@118
|
2591 .], p. 19]
|
|
meillo@118
|
2592 One such change was naming the type of input \(en mbox or mail folder \(en
|
|
meillo@118
|
2593 to be scanned:
|
|
meillo@118
|
2594 .VS
|
|
meillo@118
|
2595 #define SCN_MBOX (-1)
|
|
meillo@118
|
2596 #define SCN_FOLD 0
|
|
meillo@118
|
2597 VE
|
|
meillo@118
|
2598 .Ci 7ffb36d28e517a6f3a10272056fc127592ab1c19
|
|
meillo@118
|
2599 .P
|
|
meillo@118
|
2600 The argument
|
|
meillo@118
|
2601 .Ar outnum
|
|
meillo@118
|
2602 of the function
|
|
meillo@118
|
2603 .Fu scan()
|
|
meillo@118
|
2604 in
|
|
meillo@118
|
2605 .Fn uip/scansbr.c
|
|
meillo@118
|
2606 defines the number of the message to be created.
|
|
meillo@118
|
2607 If no message is to be created, the argument is misused to transport
|
|
meillo@118
|
2608 program logic.
|
|
meillo@118
|
2609 This lead to obscure code.
|
|
meillo@118
|
2610 I improved the clarity of the code by introducing two variables:
|
|
meillo@118
|
2611 .VS
|
|
meillo@118
|
2612 int incing = (outnum > 0);
|
|
meillo@118
|
2613 int ismbox = (outnum != 0);
|
|
meillo@118
|
2614 VE
|
|
meillo@118
|
2615 They cover the magic values and are used for conditions.
|
|
meillo@118
|
2616 The variable
|
|
meillo@118
|
2617 .Ar outnum
|
|
meillo@118
|
2618 is only used when it holds an ordinary message number.
|
|
meillo@118
|
2619 .Ci b8b075c77be7794f3ae9ff0e8cedb12b48fd139f
|
|
meillo@118
|
2620 The clarity improvement of the change showed detours in the program logic
|
|
meillo@118
|
2621 of related code parts.
|
|
meillo@118
|
2622 Having the new variables with descriptive names, a more
|
|
meillo@121
|
2623 straight forward implementation became apparent.
|
|
meillo@118
|
2624 Before the clarification was done,
|
|
meillo@118
|
2625 the possibility to improve had not be seen.
|
|
meillo@118
|
2626 .Ci aa60b0ab5e804f8befa890c0a6df0e3143ce0723
|
|
meillo@118
|
2627
|
|
meillo@118
|
2628 .U3 "Rework of \f(CWanno\fP
|
|
meillo@118
|
2629 .P
|
|
meillo@118
|
2630 At the end of their chapter on style,
|
|
meillo@118
|
2631 Kernighan and Pike ask: ``But why worry about style?''
|
|
meillo@121
|
2632 The following example of my rework of
|
|
meillo@118
|
2633 .Pn anno
|
|
meillo@121
|
2634 provides an answer why style is important in the first place.
|
|
meillo@118
|
2635 .P
|
|
meillo@120
|
2636 Until 2002,
|
|
meillo@120
|
2637 .Pn anno
|
|
meillo@120
|
2638 had six functional command line switches,
|
|
meillo@120
|
2639 .Sw -component
|
|
meillo@120
|
2640 and
|
|
meillo@120
|
2641 .Sw -text ,
|
|
meillo@120
|
2642 which took an argument each,
|
|
meillo@120
|
2643 and the two pairs of flags,
|
|
meillo@120
|
2644 .Sw -[no]date
|
|
meillo@120
|
2645 and
|
|
meillo@120
|
2646 .Sw -[no]inplace.,
|
|
meillo@120
|
2647 .Sw -component
|
|
meillo@120
|
2648 and
|
|
meillo@120
|
2649 .Sw -text ,
|
|
meillo@120
|
2650 which took an argument each,
|
|
meillo@120
|
2651 and the two pairs of flags,
|
|
meillo@120
|
2652 .Sw -[no]date
|
|
meillo@120
|
2653 and
|
|
meillo@120
|
2654 .Sw -[no]inplace .
|
|
meillo@120
|
2655 Then Jon Steinhart introduced his attachment system.
|
|
meillo@120
|
2656 In need for more advanced annotation handling, he extended
|
|
meillo@120
|
2657 .Pn anno .
|
|
meillo@120
|
2658 He added five more switches:
|
|
meillo@120
|
2659 .Sw -draft ,
|
|
meillo@120
|
2660 .Sw -list ,
|
|
meillo@120
|
2661 .Sw -delete ,
|
|
meillo@120
|
2662 .Sw -append ,
|
|
meillo@120
|
2663 and
|
|
meillo@120
|
2664 .Sw -number ,
|
|
meillo@120
|
2665 the last one taking an argument.
|
|
meillo@121
|
2666 .Ci 7480dbc14bc90f2d872d434205c0784704213252
|
|
meillo@120
|
2667 Later,
|
|
meillo@120
|
2668 .Sw -[no]preserve
|
|
meillo@120
|
2669 was added.
|
|
meillo@121
|
2670 .Ci d9b1d57351d104d7ec1a5621f090657dcce8cb7f
|
|
meillo@120
|
2671 Then, the Synopsis section of the man page
|
|
meillo@120
|
2672 .Mp anno (1)
|
|
meillo@120
|
2673 read:
|
|
meillo@120
|
2674 .VS
|
|
meillo@120
|
2675 anno [+folder] [msgs] [-component field] [-inplace | -noinplace]
|
|
meillo@120
|
2676 [-date | -nodate] [-draft] [-append] [-list] [-delete]
|
|
meillo@120
|
2677 [-number [num|all]] [-preserve | -nopreserve] [-version]
|
|
meillo@120
|
2678 [-help] [-text body]
|
|
meillo@120
|
2679 VE
|
|
meillo@120
|
2680 .LP
|
|
meillo@120
|
2681 The implementation followed the same structure.
|
|
meillo@120
|
2682 Problems became visible when
|
|
meillo@120
|
2683 .Cl "anno -list -number 42
|
|
meillo@120
|
2684 worked on the current message instead on message number 42,
|
|
meillo@120
|
2685 and
|
|
meillo@120
|
2686 .Cl "anno -list -number l:5
|
|
meillo@124
|
2687 did not work on the last five messages but failed with the mysterious
|
|
meillo@120
|
2688 error message: ``anno: missing argument to -list''.
|
|
meillo@121
|
2689 Yet, the invocation matched the specification in the man page.
|
|
meillo@120
|
2690 There, the correct use of
|
|
meillo@120
|
2691 .Sw -number
|
|
meillo@120
|
2692 was defined as being
|
|
meillo@120
|
2693 .Cl "[-number [num|all]]
|
|
meillo@120
|
2694 and the textual description for the combination with
|
|
meillo@120
|
2695 .Sw -list
|
|
meillo@120
|
2696 read:
|
|
meillo@120
|
2697 .QS
|
|
meillo@120
|
2698 The -list option produces a listing of the field bodies for
|
|
meillo@120
|
2699 header fields with names matching the specified component,
|
|
meillo@120
|
2700 one per line. The listing is numbered, starting at 1, if
|
|
meillo@120
|
2701 the -number option is also used.
|
|
meillo@120
|
2702 .QE
|
|
meillo@120
|
2703 .LP
|
|
meillo@120
|
2704 The problem was manifold.
|
|
meillo@120
|
2705 The code required a numeric argument to the
|
|
meillo@120
|
2706 .Sw -number
|
|
meillo@120
|
2707 switch.
|
|
meillo@120
|
2708 If it was missing or non-numeric,
|
|
meillo@120
|
2709 .Pn anno
|
|
meillo@120
|
2710 aborted with an error message that had an off-by-one error,
|
|
meillo@120
|
2711 printing the switch one before the failing one.
|
|
meillo@120
|
2712 Semantically, the argument to the
|
|
meillo@120
|
2713 .Sw -number
|
|
meillo@120
|
2714 switch is only necessary in combination with
|
|
meillo@120
|
2715 .Sw -delete ,
|
|
meillo@120
|
2716 but not with
|
|
meillo@120
|
2717 .Sw -list .
|
|
meillo@120
|
2718 In the former case it is even necessary.
|
|
meillo@120
|
2719 .P
|
|
meillo@120
|
2720 Trying to fix these problems on the surface would not have solved it truly.
|
|
meillo@120
|
2721 The problems discovered originate from a discrepance between the semantic
|
|
meillo@120
|
2722 structure of the problem and the structure implemented in the program.
|
|
meillo@120
|
2723 Such structural differences can not be cured on the surface.
|
|
meillo@120
|
2724 They need to be solved by adjusting the structure of the implementation
|
|
meillo@120
|
2725 to the structure of the problem.
|
|
meillo@120
|
2726 .P
|
|
meillo@120
|
2727 In 2002, the new switches
|
|
meillo@120
|
2728 .Sw -list
|
|
meillo@120
|
2729 and
|
|
meillo@120
|
2730 .Sw -delete
|
|
meillo@120
|
2731 were added in the same way, the
|
|
meillo@120
|
2732 .Sw -number
|
|
meillo@120
|
2733 switch for instance had been added.
|
|
meillo@120
|
2734 Yet, they are of structural different type.
|
|
meillo@120
|
2735 Semantically,
|
|
meillo@120
|
2736 .Sw -list
|
|
meillo@120
|
2737 and
|
|
meillo@120
|
2738 .Sw -delete
|
|
meillo@120
|
2739 introduce modes of operation.
|
|
meillo@120
|
2740 Historically,
|
|
meillo@120
|
2741 .Pn anno
|
|
meillo@120
|
2742 had only one operation mode: adding header fields.
|
|
meillo@120
|
2743 With the extension, it got two moder modes:
|
|
meillo@120
|
2744 listing and deleting header fields.
|
|
meillo@120
|
2745 The structure of the code changes did not pay respect to this
|
|
meillo@120
|
2746 fundamental change to
|
|
meillo@120
|
2747 .Pn anno 's
|
|
meillo@120
|
2748 behavior.
|
|
meillo@120
|
2749 Neither the implementation nor the documentation did clearly
|
|
meillo@120
|
2750 define them as being exclusive modes of operation.
|
|
meillo@120
|
2751 Having identified the problem, I solved it by putting structure into
|
|
meillo@120
|
2752 .Pn anno
|
|
meillo@120
|
2753 and its documentation.
|
|
meillo@120
|
2754 .Ci d54c8db8bdf01e8381890f7729bc0ef4a055ea11
|
|
meillo@120
|
2755 .P
|
|
meillo@120
|
2756 The difference is visible in both, the code and the documentation.
|
|
meillo@121
|
2757 The following code excerpt:
|
|
meillo@120
|
2758 .VS
|
|
meillo@120
|
2759 int delete = -2; /* delete header element if set */
|
|
meillo@120
|
2760 int list = 0; /* list header elements if set */
|
|
meillo@120
|
2761 [...]
|
|
meillo@121
|
2762 case DELETESW: /* delete annotations */
|
|
meillo@121
|
2763 delete = 0;
|
|
meillo@121
|
2764 continue;
|
|
meillo@121
|
2765 case LISTSW: /* produce a listing */
|
|
meillo@121
|
2766 list = 1;
|
|
meillo@121
|
2767 continue;
|
|
meillo@120
|
2768 VE
|
|
meillo@121
|
2769 .LP
|
|
meillo@121
|
2770 was replaced by:
|
|
meillo@120
|
2771 .VS
|
|
meillo@120
|
2772 static enum { MODE_ADD, MODE_DEL, MODE_LIST } mode = MODE_ADD;
|
|
meillo@120
|
2773 [...]
|
|
meillo@121
|
2774 case DELETESW: /* delete annotations */
|
|
meillo@121
|
2775 mode = MODE_DEL;
|
|
meillo@121
|
2776 continue;
|
|
meillo@121
|
2777 case LISTSW: /* produce a listing */
|
|
meillo@121
|
2778 mode = MODE_LIST;
|
|
meillo@121
|
2779 continue;
|
|
meillo@120
|
2780 VE
|
|
meillo@120
|
2781 .LP
|
|
meillo@121
|
2782 The replacement code does not only reflect the problem's structure better,
|
|
meillo@121
|
2783 it is easier to understand as well.
|
|
meillo@121
|
2784 The same applies to the documentation.
|
|
meillo@120
|
2785 The man page was completely reorganized to propagate the same structure.
|
|
meillo@121
|
2786 This is visible in the Synopsis section:
|
|
meillo@120
|
2787 .VS
|
|
meillo@120
|
2788 anno [+folder] [msgs] [-component field] [-text body]
|
|
meillo@120
|
2789 [-append] [-date | -nodate] [-preserve | -nopreserve]
|
|
meillo@120
|
2790 [-Version] [-help]
|
|
meillo@120
|
2791
|
|
meillo@120
|
2792 anno -delete [+folder] [msgs] [-component field] [-text
|
|
meillo@120
|
2793 body] [-number num | all ] [-preserve | -nopreserve]
|
|
meillo@120
|
2794 [-Version] [-help]
|
|
meillo@120
|
2795
|
|
meillo@120
|
2796 anno -list [+folder] [msgs] [-component field] [-number]
|
|
meillo@120
|
2797 [-Version] [-help]
|
|
meillo@120
|
2798 VE
|
|
meillo@121
|
2799 .\" XXX think about explaining the -preserve rework?
|
|
meillo@118
|
2800
|
|
meillo@58
|
2801
|
|
meillo@58
|
2802
|
|
meillo@121
|
2803 .H2 "Standard Libraries
|
|
meillo@22
|
2804 .P
|
|
meillo@121
|
2805 MH is one decade older than the POSIX and ANSI C standards.
|
|
meillo@121
|
2806 Hence, MH included own implementations of functions
|
|
meillo@121
|
2807 that are standardized and thus widely available today,
|
|
meillo@121
|
2808 but were not back then.
|
|
meillo@121
|
2809 Today, twenty years after the POSIX and ANSI C were published,
|
|
meillo@121
|
2810 developers can expect system to comply with these standards.
|
|
meillo@121
|
2811 In consequence, MH-specific replacements for standard functions
|
|
meillo@121
|
2812 can and should be dropped.
|
|
meillo@121
|
2813 Kernighan and Pike advise: ``Use standard libraries.''
|
|
meillo@121
|
2814 .[ [
|
|
meillo@121
|
2815 kernighan pike practice of programming
|
|
meillo@121
|
2816 .], p. 196]
|
|
meillo@121
|
2817 Actually, MH had followed this advice in history,
|
|
meillo@121
|
2818 but it had not adjusted to the changes in this field.
|
|
meillo@121
|
2819 The
|
|
meillo@121
|
2820 .Fu snprintf()
|
|
meillo@121
|
2821 function, for instance, was standardized with C99 and is available
|
|
meillo@121
|
2822 almost everywhere because of its high usefulness.
|
|
meillo@123
|
2823 In project's own implementation of
|
|
meillo@121
|
2824 .Fu snprintf()
|
|
meillo@123
|
2825 was dropped in March 2012 in favor for using the one of the
|
|
meillo@123
|
2826 standard library.
|
|
meillo@123
|
2827 .Ci 0052f1024deb0a0a2fc2e5bacf93d45a5a9c9b32
|
|
meillo@123
|
2828 Such decisions limit the portability of mmh
|
|
meillo@121
|
2829 if systems don't support these standardized and widespread functions.
|
|
meillo@123
|
2830 This compromise is made because mmh focuses on the future.
|
|
meillo@121
|
2831 .P
|
|
meillo@123
|
2832 I am not yet thirty years old and my C and Unix experience comprises
|
|
meillo@123
|
2833 only half a dozen years.
|
|
meillo@121
|
2834 Hence, I need to learn about the history in retrospective.
|
|
meillo@121
|
2835 I have not used those ancient constructs myself.
|
|
meillo@121
|
2836 I have not suffered from their incompatibilities.
|
|
meillo@121
|
2837 I have not longed for standardization.
|
|
meillo@121
|
2838 All my programming experience is from a time when ANSI C and POSIX
|
|
meillo@121
|
2839 were well established already.
|
|
meillo@121
|
2840 I have only read a lot of books about the (good) old times.
|
|
meillo@121
|
2841 This puts me in a difficult positions when working with old code.
|
|
meillo@123
|
2842 I need to freshly acquire knowledge about old code constructs and ancient
|
|
meillo@123
|
2843 programming styles, whereas older programmers know these things by
|
|
meillo@123
|
2844 heart from their own experience.
|
|
meillo@121
|
2845 .P
|
|
meillo@123
|
2846 Being aware of the situation, I rather let people with more historic
|
|
meillo@123
|
2847 experience replace ancient code constructs with standardized ones.
|
|
meillo@121
|
2848 Lyndon Nerenberg covered large parts of this task for the nmh project.
|
|
meillo@121
|
2849 He converted project-specific functions to POSIX replacements,
|
|
meillo@121
|
2850 also removing the conditionals compilation of now standardized features.
|
|
meillo@123
|
2851 Ken Hornstein and David Levine had their part in the work, too.
|
|
meillo@121
|
2852 Often, I only needed to pull over changes from nmh into mmh.
|
|
meillo@121
|
2853 These changes include many commits; these are among them:
|
|
meillo@121
|
2854 .Ci 768b5edd9623b7238e12ec8dfc409b82a1ed9e2d
|
|
meillo@121
|
2855 .Ci 0052f1024deb0a0a2fc2e5bacf93d45a5a9c9b32 .
|
|
meillo@102
|
2856 .P
|
|
meillo@123
|
2857 During my own work, I tidied up the \fIMH standard library\fP,
|
|
meillo@123
|
2858 .Fn libmh.a ,
|
|
meillo@123
|
2859 which is located in the
|
|
meillo@123
|
2860 .Fn sbr
|
|
meillo@123
|
2861 (``subroutines'') directory in the source tree.
|
|
meillo@123
|
2862 The MH library includes functions that mmh tools usually need.
|
|
meillo@123
|
2863 Among them are MH-specific functions for profile, context, sequence,
|
|
meillo@123
|
2864 and folder handling, but as well
|
|
meillo@123
|
2865 MH-independent functions, such as auxiliary string functions,
|
|
meillo@123
|
2866 portability interfaces and error-checking wrappers for critical
|
|
meillo@123
|
2867 functions of the standard library.
|
|
meillo@123
|
2868 .P
|
|
meillo@123
|
2869 I have replaced the
|
|
meillo@121
|
2870 .Fu atooi()
|
|
meillo@121
|
2871 function with calls to
|
|
meillo@123
|
2872 .Fu strtoul()
|
|
meillo@121
|
2873 with the third parameter \(en the base \(en set to eight.
|
|
meillo@121
|
2874 .Fu strtoul()
|
|
meillo@123
|
2875 is part of C89 and thus considered safe to use.
|
|
meillo@121
|
2876 .Ci c490c51b3c0f8871b6953bd0c74551404f840a74
|
|
meillo@102
|
2877 .P
|
|
meillo@121
|
2878 I did remove project-included fallback implementations of
|
|
meillo@121
|
2879 .Fu memmove()
|
|
meillo@121
|
2880 and
|
|
meillo@121
|
2881 .Fu strerror() ,
|
|
meillo@121
|
2882 although Peter Maydell had re-included them into nmh in 2008
|
|
meillo@121
|
2883 to support SunOS 4.
|
|
meillo@121
|
2884 Nevertheless, these functions are part of ANSI C.
|
|
meillo@121
|
2885 Systems that do not even provide full ANSI C support should not
|
|
meillo@121
|
2886 put a load on mmh.
|
|
meillo@121
|
2887 .Ci b067ff5c465a5d243ce5a19e562085a9a1a97215
|
|
meillo@121
|
2888 .P
|
|
meillo@121
|
2889 The
|
|
meillo@121
|
2890 .Fu copy()
|
|
meillo@121
|
2891 function copies the string in argument one to the location in two.
|
|
meillo@121
|
2892 In contrast to
|
|
meillo@121
|
2893 .Fu strcpy() ,
|
|
meillo@121
|
2894 it returns a pointer to the terminating null-byte in the destination area.
|
|
meillo@123
|
2895 The code was adjusted to replace
|
|
meillo@121
|
2896 .Fu copy()
|
|
meillo@123
|
2897 with
|
|
meillo@121
|
2898 .Fu strcpy() ,
|
|
meillo@121
|
2899 except within
|
|
meillo@121
|
2900 .Fu concat() ,
|
|
meillo@121
|
2901 where
|
|
meillo@121
|
2902 .Fu copy()
|
|
meillo@123
|
2903 was more convenient.
|
|
meillo@123
|
2904 Therefore, the definition of
|
|
meillo@121
|
2905 .Fu copy()
|
|
meillo@123
|
2906 was moved into the source file of
|
|
meillo@121
|
2907 .Fu concat()
|
|
meillo@123
|
2908 and its visibility is now limited to it.
|
|
meillo@121
|
2909 .Ci 552fd7253e5ee9e554c5c7a8248a6322aa4363bb
|
|
meillo@121
|
2910 .P
|
|
meillo@121
|
2911 The function
|
|
meillo@121
|
2912 .Fu r1bindex()
|
|
meillo@121
|
2913 had been a generalized version of
|
|
meillo@121
|
2914 .Fu basename()
|
|
meillo@121
|
2915 with minor differences.
|
|
meillo@121
|
2916 As all calls to
|
|
meillo@121
|
2917 .Fu r1bindex()
|
|
meillo@121
|
2918 had the slash (`/') as delimiter anyway,
|
|
meillo@121
|
2919 replacing
|
|
meillo@121
|
2920 .Fu r1bindex()
|
|
meillo@121
|
2921 with the more specific and better-named function
|
|
meillo@121
|
2922 .Fu basename()
|
|
meillo@121
|
2923 became desirable.
|
|
meillo@121
|
2924 Unfortunately, many of the 54 calls to
|
|
meillo@121
|
2925 .Fu r1bindex()
|
|
meillo@123
|
2926 depended on a special behavior,
|
|
meillo@121
|
2927 which differed from the POSIX specification for
|
|
meillo@121
|
2928 .Fu basename() .
|
|
meillo@121
|
2929 Hence,
|
|
meillo@121
|
2930 .Fu r1bindex()
|
|
meillo@121
|
2931 was kept but renamed to
|
|
meillo@123
|
2932 .Fu mhbasename() ,
|
|
meillo@123
|
2933 fixing the delimiter to the slash.
|
|
meillo@121
|
2934 .Ci 240013872c392fe644bd4f79382d9f5314b4ea60
|
|
meillo@121
|
2935 For possible uses of
|
|
meillo@121
|
2936 .Fu r1bindex()
|
|
meillo@121
|
2937 with a different delimiter,
|
|
meillo@121
|
2938 the ANSI C function
|
|
meillo@121
|
2939 .Fu strrchr()
|
|
meillo@121
|
2940 provides the core functionality.
|
|
meillo@121
|
2941 .P
|
|
meillo@121
|
2942 The
|
|
meillo@121
|
2943 .Fu ssequal()
|
|
meillo@121
|
2944 function \(en apparently for ``substring equal'' \(en
|
|
meillo@121
|
2945 was renamed to
|
|
meillo@121
|
2946 .Fu isprefix() ,
|
|
meillo@121
|
2947 because this is what it actually checks.
|
|
meillo@121
|
2948 .Ci c20b4fa14515c7ab388ce35411d89a7a92300711
|
|
meillo@121
|
2949 Its source file had included the following comments, no joke.
|
|
meillo@121
|
2950 .VS
|
|
meillo@121
|
2951 /*
|
|
meillo@121
|
2952 * THIS CODE DOES NOT WORK AS ADVERTISED.
|
|
meillo@121
|
2953 * It is actually checking if s1 is a PREFIX of s2.
|
|
meillo@121
|
2954 * All calls to this function need to be checked to see
|
|
meillo@121
|
2955 * if that needs to be changed. Prefix checking is cheaper, so
|
|
meillo@121
|
2956 * should be kept if it's sufficient.
|
|
meillo@121
|
2957 */
|
|
meillo@121
|
2958
|
|
meillo@121
|
2959 /*
|
|
meillo@121
|
2960 * Check if s1 is a substring of s2.
|
|
meillo@121
|
2961 * If yes, then return 1, else return 0.
|
|
meillo@121
|
2962 */
|
|
meillo@121
|
2963 VE
|
|
meillo@123
|
2964 Two months later, it was completely removed by replacing it with
|
|
meillo@123
|
2965 .Fu strncmp() .
|
|
meillo@123
|
2966 .Ci b0b1dd37ff515578cf7cba51625189eb34a196cb
|
|
meillo@121
|
2967
|
|
meillo@102
|
2968
|
|
meillo@102
|
2969
|
|
meillo@102
|
2970
|
|
meillo@22
|
2971
|
|
meillo@118
|
2972 .H2 "Modularization
|
|
meillo@118
|
2973 .P
|
|
meillo@123
|
2974 The source code of the mmh tools is located in the
|
|
meillo@122
|
2975 .Fn uip
|
|
meillo@123
|
2976 (``user interface programs'') directory.
|
|
meillo@123
|
2977 Each tools has a source file with the same name.
|
|
meillo@122
|
2978 For example,
|
|
meillo@122
|
2979 .Pn rmm
|
|
meillo@122
|
2980 is built from
|
|
meillo@122
|
2981 .Fn uip/rmm.c .
|
|
meillo@123
|
2982 Some source files are used for multiple programs.
|
|
meillo@122
|
2983 For example
|
|
meillo@122
|
2984 .Fn uip/scansbr.c
|
|
meillo@123
|
2985 is used for both,
|
|
meillo@122
|
2986 .Pn scan
|
|
meillo@122
|
2987 and
|
|
meillo@122
|
2988 .Pn inc .
|
|
meillo@122
|
2989 In nmh, 49 tools were built from 76 source files.
|
|
meillo@123
|
2990 This is a ratio of 1.6 source files per program.
|
|
meillo@123
|
2991 32 programs depended on multiple source files;
|
|
meillo@123
|
2992 17 programs depended on one source file only.
|
|
meillo@122
|
2993 In mmh, 39 tools are built from 51 source files.
|
|
meillo@123
|
2994 This is a ratio of 1.3 source files per program.
|
|
meillo@123
|
2995 18 programs depend on multiple source files;
|
|
meillo@123
|
2996 21 programs depend on one source file only.
|
|
meillo@123
|
2997 (These numbers and the ones in the following text ignore the MH library
|
|
meillo@123
|
2998 as well as shell scripts and multiple names for the same program.)
|
|
meillo@122
|
2999 .P
|
|
meillo@123
|
3000 Splitting the source code of a large program into multiple files can
|
|
meillo@122
|
3001 increase the readability of its source code.
|
|
meillo@124
|
3002 Most of the mmh tools, however, are simple and straight-forward programs.
|
|
meillo@122
|
3003 With the exception of the MIME handling tools,
|
|
meillo@122
|
3004 .Pn pick
|
|
meillo@122
|
3005 is the largest tools.
|
|
meillo@122
|
3006 It contains 1\|037 lines of source code (measured with
|
|
meillo@122
|
3007 .Pn sloccount ), excluding the MH library.
|
|
meillo@122
|
3008 Only the MIME handling tools (\c
|
|
meillo@122
|
3009 .Pn mhbuild ,
|
|
meillo@122
|
3010 .Pn mhstore ,
|
|
meillo@122
|
3011 .Pn show ,
|
|
meillo@122
|
3012 etc.)
|
|
meillo@122
|
3013 are larger.
|
|
meillo@122
|
3014 Splitting programs with less than 1\|000 lines of code into multiple
|
|
meillo@123
|
3015 source files seldom leads to better readability.
|
|
meillo@123
|
3016 For such tools, splitting makes sense
|
|
meillo@122
|
3017 when parts of the code are reused in other programs,
|
|
meillo@122
|
3018 and the reused code fragment is not general enough
|
|
meillo@122
|
3019 for including it in the MH library,
|
|
meillo@124
|
3020 or, if the code has dependencies on a library that only few programs need.
|
|
meillo@122
|
3021 .Fn uip/packsbr.c ,
|
|
meillo@122
|
3022 for instance, provides the core program logic for the
|
|
meillo@122
|
3023 .Pn packf
|
|
meillo@122
|
3024 and
|
|
meillo@122
|
3025 .Pn rcvpack
|
|
meillo@122
|
3026 programs.
|
|
meillo@122
|
3027 .Fn uip/packf.c
|
|
meillo@122
|
3028 and
|
|
meillo@122
|
3029 .Fn uip/rcvpack.c
|
|
meillo@122
|
3030 mainly wrap the core function appropriately.
|
|
meillo@122
|
3031 No other tools use the folder packing functions.
|
|
meillo@123
|
3032 As another example,
|
|
meillo@123
|
3033 .Fn uip/termsbr.c
|
|
meillo@123
|
3034 provides termcap support, which requires linking with a termcap or
|
|
meillo@123
|
3035 curses library.
|
|
meillo@123
|
3036 Including
|
|
meillo@123
|
3037 .Fn uip/termsbr.c
|
|
meillo@123
|
3038 into the MH library would require every program to be linked with
|
|
meillo@123
|
3039 termcap or curses, although only few of the programs require it.
|
|
meillo@122
|
3040 .P
|
|
meillo@122
|
3041 The task of MIME handling is complex enough that splitting its code
|
|
meillo@122
|
3042 into multiple source files improves the readability.
|
|
meillo@122
|
3043 The program
|
|
meillo@122
|
3044 .Pn mhstore ,
|
|
meillo@122
|
3045 for instance, is compiled out of seven source files with 2\|500
|
|
meillo@122
|
3046 lines of code in summary.
|
|
meillo@122
|
3047 The main code file
|
|
meillo@122
|
3048 .Fn uip/mhstore.c
|
|
meillo@123
|
3049 consists of 800 lines; the other 1\|700 lines of code are reused in
|
|
meillo@123
|
3050 other MIME handling tools.
|
|
meillo@123
|
3051 It seems to be worthwhile to bundle the generic MIME handling code into
|
|
meillo@123
|
3052 a MH-MIME library, as a companion to the MH standard library.
|
|
meillo@122
|
3053 This is left open for the future.
|
|
meillo@122
|
3054 .P
|
|
meillo@123
|
3055 The work already done, focussed on the non-MIME tools.
|
|
meillo@122
|
3056 The amount of code compiled into each program was reduced.
|
|
meillo@123
|
3057 This eases the understanding of the code base.
|
|
meillo@122
|
3058 In nmh,
|
|
meillo@122
|
3059 .Pn comp
|
|
meillo@122
|
3060 was built from six source files:
|
|
meillo@122
|
3061 .Fn comp.c ,
|
|
meillo@122
|
3062 .Fn whatnowproc.c ,
|
|
meillo@122
|
3063 .Fn whatnowsbr.c ,
|
|
meillo@122
|
3064 .Fn sendsbr.c ,
|
|
meillo@122
|
3065 .Fn annosbr.c ,
|
|
meillo@122
|
3066 and
|
|
meillo@122
|
3067 .Fn distsbr.c .
|
|
meillo@122
|
3068 In mmh, it builds from only two:
|
|
meillo@122
|
3069 .Fn comp.c
|
|
meillo@122
|
3070 and
|
|
meillo@122
|
3071 .Fn whatnowproc.c .
|
|
meillo@123
|
3072 In nmh's
|
|
meillo@123
|
3073 .Pn comp ,
|
|
meillo@123
|
3074 the core function of
|
|
meillo@122
|
3075 .Pn whatnow ,
|
|
meillo@122
|
3076 .Pn send ,
|
|
meillo@122
|
3077 and
|
|
meillo@122
|
3078 .Pn anno
|
|
meillo@123
|
3079 were compiled into
|
|
meillo@122
|
3080 .Pn comp .
|
|
meillo@123
|
3081 This saved the need to execute these programs with
|
|
meillo@122
|
3082 .Fu fork()
|
|
meillo@122
|
3083 and
|
|
meillo@122
|
3084 .Fu exec() ,
|
|
meillo@122
|
3085 two expensive system calls.
|
|
meillo@122
|
3086 Whereis this approach improved the time performance,
|
|
meillo@122
|
3087 it interweaved the source code.
|
|
meillo@122
|
3088 Core functionalities were not encapsulated into programs but into
|
|
meillo@122
|
3089 function, which were then wrapped by programs.
|
|
meillo@122
|
3090 For example,
|
|
meillo@122
|
3091 .Fn uip/annosbr.c
|
|
meillo@122
|
3092 included the function
|
|
meillo@122
|
3093 .Fu annotate() .
|
|
meillo@122
|
3094 Each program that wanted to annotate messages, included the source file
|
|
meillo@123
|
3095 .Fn uip/annosbr.c
|
|
meillo@123
|
3096 and called
|
|
meillo@123
|
3097 .Fu annotate() .
|
|
meillo@123
|
3098 Because the function
|
|
meillo@123
|
3099 .Fu annotate()
|
|
meillo@123
|
3100 was used like the tool
|
|
meillo@123
|
3101 .Pn anno ,
|
|
meillo@123
|
3102 it had seven parameters, reflecting the command line switches of the tool.
|
|
meillo@122
|
3103 When another pair of command line switches was added to
|
|
meillo@122
|
3104 .Pn anno ,
|
|
meillo@122
|
3105 a rather ugly hack was implemented to avoid adding another parameter
|
|
meillo@122
|
3106 to the function.
|
|
meillo@122
|
3107 .Ci d9b1d57351d104d7ec1a5621f090657dcce8cb7f
|
|
meillo@122
|
3108 .P
|
|
meillo@122
|
3109 Separation simplifies the understanding of program code
|
|
meillo@122
|
3110 because the area influenced by any particular statement is smaller.
|
|
meillo@122
|
3111 The separating on the program-level is more strict than the separation
|
|
meillo@122
|
3112 on the function level.
|
|
meillo@122
|
3113 In mmh, the relevant code of
|
|
meillo@122
|
3114 .Pn comp
|
|
meillo@122
|
3115 comprises the two files
|
|
meillo@122
|
3116 .Fn uip/comp.c
|
|
meillo@122
|
3117 and
|
|
meillo@122
|
3118 .Fn uip/whatnowproc.c ,
|
|
meillo@123
|
3119 together 210 lines of code.
|
|
meillo@122
|
3120 In nmh,
|
|
meillo@122
|
3121 .Pn comp
|
|
meillo@122
|
3122 comprises six files with 2\|450 lines.
|
|
meillo@123
|
3123 Not all of the code in these six files was actually used by
|
|
meillo@122
|
3124 .Pn comp ,
|
|
meillo@123
|
3125 but the code reader needed to read all of the code first to know which
|
|
meillo@123
|
3126 parts were used.
|
|
meillo@122
|
3127 .P
|
|
meillo@123
|
3128 As I have read a lot in the code base during the last two years,
|
|
meillo@123
|
3129 I learned about the easy and the difficult parts.
|
|
meillo@123
|
3130 Code is easy to understand if:
|
|
meillo@123
|
3131 .BU
|
|
meillo@123
|
3132 The influenced code area is small
|
|
meillo@123
|
3133 .BU
|
|
meillo@124
|
3134 The boundaries are strictly defined
|
|
meillo@123
|
3135 .BU
|
|
meillo@123
|
3136 The code is written straight-forward
|
|
meillo@123
|
3137 .P
|
|
meillo@123
|
3138 .\" XXX move this paragraph somewhere else?
|
|
meillo@123
|
3139 Reading
|
|
meillo@122
|
3140 .Pn rmm 's
|
|
meillo@122
|
3141 source code in
|
|
meillo@122
|
3142 .Fn uip/rmm.c
|
|
meillo@122
|
3143 is my recommendation for a beginner's entry point into the code base of nmh.
|
|
meillo@122
|
3144 The reasons are that the task of
|
|
meillo@122
|
3145 .Pn rmm
|
|
meillo@122
|
3146 is straight forward and it consists of one small source code file only,
|
|
meillo@122
|
3147 yet its source includes code constructs typical for MH tools.
|
|
meillo@122
|
3148 With the introduction of the trash folder in mmh,
|
|
meillo@122
|
3149 .Pn rmm
|
|
meillo@122
|
3150 became a bit more complex, because it invokes
|
|
meillo@122
|
3151 .Pn refile .
|
|
meillo@122
|
3152 Still, it is a good example for a simple tool with clear sources.
|
|
meillo@122
|
3153 .P
|
|
meillo@122
|
3154 Understanding
|
|
meillo@122
|
3155 .Pn comp
|
|
meillo@122
|
3156 requires to read 210 lines of code in mmh, but ten times as much in nmh.
|
|
meillo@123
|
3157 Due to the aforementioned hack in
|
|
meillo@122
|
3158 .Pn anno
|
|
meillo@122
|
3159 to save the additional parameter, information passed through the program's
|
|
meillo@122
|
3160 source base in obscure ways.
|
|
meillo@123
|
3161 Thus, understanding
|
|
meillo@122
|
3162 .Pn comp ,
|
|
meillo@123
|
3163 required understanding the inner workings of
|
|
meillo@122
|
3164 .Fn uip/annosbr.c
|
|
meillo@122
|
3165 first.
|
|
meillo@123
|
3166 To be sure to fully understand a program, its whole source code needs
|
|
meillo@122
|
3167 to be examined.
|
|
meillo@123
|
3168 Not doing so is a leap of faith, assuming that the developers
|
|
meillo@122
|
3169 have avoided obscure programming techniques.
|
|
meillo@122
|
3170 By separating the tools on the program-level, the boundaries are
|
|
meillo@122
|
3171 clearly visible and technically enforced.
|
|
meillo@122
|
3172 The interfaces are calls to
|
|
meillo@122
|
3173 .Fu exec()
|
|
meillo@122
|
3174 rather than arbitrary function calls.
|
|
meillo@123
|
3175 .P
|
|
meillo@123
|
3176 But the real problem is another:
|
|
meillo@123
|
3177 Nmh violates the golden ``one tool, one job'' rule of the Unix philosophy.
|
|
meillo@123
|
3178 Understanding
|
|
meillo@122
|
3179 .Pn comp
|
|
meillo@123
|
3180 requires understanding
|
|
meillo@123
|
3181 .Fn uip/annosbr.c
|
|
meillo@123
|
3182 and
|
|
meillo@123
|
3183 .Fn uip/sendsbr.c
|
|
meillo@123
|
3184 because
|
|
meillo@123
|
3185 .Pn comp
|
|
meillo@123
|
3186 does annotate and send messages.
|
|
meillo@123
|
3187 In nmh, there surely exists the tool
|
|
meillo@122
|
3188 .Pn send ,
|
|
meillo@123
|
3189 which does (almost) only send messages.
|
|
meillo@123
|
3190 But
|
|
meillo@122
|
3191 .Pn comp
|
|
meillo@123
|
3192 and
|
|
meillo@122
|
3193 .Pn repl
|
|
meillo@122
|
3194 and
|
|
meillo@122
|
3195 .Pn forw
|
|
meillo@122
|
3196 and
|
|
meillo@122
|
3197 .Pn dist
|
|
meillo@122
|
3198 and
|
|
meillo@122
|
3199 .Pn whatnow
|
|
meillo@122
|
3200 and
|
|
meillo@123
|
3201 .Pn viamail ,
|
|
meillo@123
|
3202 they all (!) have the same message sending function included, too.
|
|
meillo@123
|
3203 In result,
|
|
meillo@123
|
3204 .Pn comp
|
|
meillo@123
|
3205 sends messages without using
|
|
meillo@123
|
3206 .Pn send .
|
|
meillo@123
|
3207 The situation is the same as if
|
|
meillo@123
|
3208 .Pn grep
|
|
meillo@123
|
3209 would page without
|
|
meillo@123
|
3210 .Pn more
|
|
meillo@123
|
3211 just because both programs are part of the same code base.
|
|
meillo@123
|
3212 .P
|
|
meillo@122
|
3213 The clear separation on the surface \(en the toolchest approach \(en
|
|
meillo@123
|
3214 is violated on the level below.
|
|
meillo@122
|
3215 This violation is for the sake of time performance.
|
|
meillo@122
|
3216 On systems where
|
|
meillo@122
|
3217 .Fu fork()
|
|
meillo@122
|
3218 and
|
|
meillo@122
|
3219 .Fu exec()
|
|
meillo@122
|
3220 are expensive, the quicker response might be noticable.
|
|
meillo@124
|
3221 In the old times, sacrificing readability and conceptional beauty for
|
|
meillo@124
|
3222 speed might even have been a must to prevent MH from being unusably slow.
|
|
meillo@122
|
3223 Whatever the reasons had been, today they are gone.
|
|
meillo@123
|
3224 No longer should we sacrifice readability or conceptional beauty.
|
|
meillo@122
|
3225 No longer should we violate the Unix philosophy's ``one tool, one job''
|
|
meillo@122
|
3226 guideline.
|
|
meillo@123
|
3227 No longer should we keep speed improvements that became unnecessary.
|
|
meillo@122
|
3228 .P
|
|
meillo@123
|
3229 Therefore, mmh's
|
|
meillo@123
|
3230 .Pn comp
|
|
meillo@123
|
3231 does no longer send messages.
|
|
meillo@123
|
3232 In mmh, different jobs are divided among separate programs that
|
|
meillo@122
|
3233 invoke each other as needed.
|
|
meillo@123
|
3234 In consequence,
|
|
meillo@123
|
3235 .Pn comp
|
|
meillo@123
|
3236 invokes
|
|
meillo@123
|
3237 .Pn whatnow
|
|
meillo@123
|
3238 which thereafter invokes
|
|
meillo@123
|
3239 .Pn send .
|
|
meillo@123
|
3240 The clear separation on the surface is maintained on the level below.
|
|
meillo@123
|
3241 Human users and the tools use the same interface \(en
|
|
meillo@123
|
3242 annotations, for example, are made by invoking
|
|
meillo@123
|
3243 .Pn anno ,
|
|
meillo@123
|
3244 no matter if requested by programs or by human beings.
|
|
meillo@123
|
3245 The decrease of tools built from multiple source files and thus
|
|
meillo@123
|
3246 the decrease of
|
|
meillo@123
|
3247 .Fn uip/*sbr.c
|
|
meillo@123
|
3248 files confirm the improvement.
|
|
meillo@123
|
3249 .P
|
|
meillo@123
|
3250 One disadvantage needs to be taken with this change:
|
|
meillo@123
|
3251 The compiler can no longer check the integrity of the interfaces.
|
|
meillo@123
|
3252 By changing the command line interfaces of tools, it is
|
|
meillo@123
|
3253 the developer's job to adjust the invocations of these tools as well.
|
|
meillo@123
|
3254 As this is a manual task and regression tests, which could detect such
|
|
meillo@124
|
3255 problems, are not available yet, it is prone to errors.
|
|
meillo@123
|
3256 These errors will not be detected at compile time but at run time.
|
|
meillo@123
|
3257 Installing regression tests is a task left to do.
|
|
meillo@123
|
3258 In the best case, a uniform way of invoking tools from other tools
|
|
meillo@123
|
3259 can be developed to allow automated testing at compile time.
|
|
meillo@122
|
3260
|
|
meillo@118
|
3261
|
|
meillo@118
|
3262
|
|
meillo@118
|
3263
|
|
meillo@126
|
3264 .H2 "User Data Locations
|
|
meillo@0
|
3265 .P
|
|
meillo@126
|
3266 In nmh, a personal setup consists of the MH profile and the MH directory.
|
|
meillo@126
|
3267 The profile is a file named
|
|
meillo@19
|
3268 .Fn \&.mh_profile
|
|
meillo@126
|
3269 in the user's home directory.
|
|
meillo@126
|
3270 It contains the static configuration.
|
|
meillo@126
|
3271 It also contains the location of the MH directory in the profile entry
|
|
meillo@126
|
3272 .Pe Path .
|
|
meillo@126
|
3273 The MH directory contains the mail storage and is the first
|
|
meillo@126
|
3274 place to search for personal forms, scan formats, and similar
|
|
meillo@126
|
3275 configuration files.
|
|
meillo@126
|
3276 The location of the MH directory can be chosen freely by the user.
|
|
meillo@126
|
3277 The default and usual name is a directory named
|
|
meillo@19
|
3278 .Fn Mail
|
|
meillo@126
|
3279 in the home directory.
|
|
meillo@19
|
3280 .P
|
|
meillo@126
|
3281 The way MH data is splitted between profile and MH directory is a legacy.
|
|
meillo@126
|
3282 It is only sensible in a situation where the profile is the only
|
|
meillo@126
|
3283 configuration file.
|
|
meillo@126
|
3284 Why else should the mail storage and the configuration files be intermixed?
|
|
meillo@126
|
3285 They are different kinds of data:
|
|
meillo@126
|
3286 The data to be operated on and the configuration to change how
|
|
meillo@126
|
3287 tools operate.
|
|
meillo@126
|
3288 Splitting the configuration between the profile and the MH directory
|
|
meillo@126
|
3289 is bad.
|
|
meillo@126
|
3290 Merging the mail storage and the configuration in one directory is bad
|
|
meillo@126
|
3291 as well.
|
|
meillo@126
|
3292 As the mail storage and the configuration were not separated sensibly
|
|
meillo@126
|
3293 in the first place, I did it now.
|
|
meillo@19
|
3294 .P
|
|
meillo@126
|
3295 Personal mmh data is grouped by type, resulting in two distinct parts:
|
|
meillo@126
|
3296 The mail storage and the configuration.
|
|
meillo@126
|
3297 In mmh, the mail storage directory still contains all the messages,
|
|
meillo@126
|
3298 but, in exception of public sequences files, nothing else.
|
|
meillo@126
|
3299 In difference to nmh, the auxiliary configuration files are no longer
|
|
meillo@126
|
3300 located there.
|
|
meillo@126
|
3301 Therefore, the directory is no longer called the user's \fIMH directory\fP
|
|
meillo@126
|
3302 but his \fImail storage\fP.
|
|
meillo@126
|
3303 Its location is still user-chosen, with the default name
|
|
meillo@19
|
3304 .Fn Mail ,
|
|
meillo@104
|
3305 in the user's home directory.
|
|
meillo@126
|
3306 In mmh, the configuration is grouped together in
|
|
meillo@126
|
3307 the hidden directory
|
|
meillo@19
|
3308 .Fn \&.mmh
|
|
meillo@19
|
3309 in the user's home directory.
|
|
meillo@126
|
3310 This \fImmh directory\fP contains the context file, personal forms,
|
|
meillo@126
|
3311 scan formats, and the like, but also the user's profile, now named
|
|
meillo@126
|
3312 .Fn profile .
|
|
meillo@126
|
3313 The location of the profile is no longer fixed to
|
|
meillo@126
|
3314 .Fn $HOME/.mh_profile
|
|
meillo@126
|
3315 but to
|
|
meillo@126
|
3316 .Fn $HOME/.mmh/profile .
|
|
meillo@126
|
3317 Having both, the file
|
|
meillo@126
|
3318 .Fn $HOME/.mh_profile
|
|
meillo@126
|
3319 and the configuration directory
|
|
meillo@126
|
3320 .Fn $HOME/.mmh
|
|
meillo@126
|
3321 appeared to be inconsistent.
|
|
meillo@126
|
3322 The approach chosen for mmh is consistent, simple, and familiar to
|
|
meillo@126
|
3323 Unix users.
|
|
meillo@19
|
3324 .P
|
|
meillo@126
|
3325 MH allows users to have multiiple MH setups.
|
|
meillo@126
|
3326 Therefore, it is necessary to select a different profile.
|
|
meillo@126
|
3327 The profile is the single entry point to access the rest of a
|
|
meillo@126
|
3328 personal MH setup.
|
|
meillo@126
|
3329 In nmh, the environment variable
|
|
meillo@19
|
3330 .Ev MH
|
|
meillo@126
|
3331 could be used to specifiy a different profile.
|
|
meillo@126
|
3332 To operate in the same MH setup with a separate context,
|
|
meillo@126
|
3333 the
|
|
meillo@19
|
3334 .Ev MHCONTEXT
|
|
meillo@126
|
3335 environment variable could be used.
|
|
meillo@126
|
3336 This allows having own current folders and current messages in
|
|
meillo@126
|
3337 each terminal, for instance.
|
|
meillo@126
|
3338 In mmh, three environment variables are used.
|
|
meillo@19
|
3339 .Ev MMH
|
|
meillo@126
|
3340 overrides the default location of the mmh directory (\c
|
|
meillo@126
|
3341 .Fn .mmh ).
|
|
meillo@19
|
3342 .Ev MMHP
|
|
meillo@19
|
3343 and
|
|
meillo@19
|
3344 .Ev MMHC
|
|
meillo@126
|
3345 override the paths to the profile and context files, respectively.
|
|
meillo@126
|
3346 This approach allows the set of personal configuration files to be chosen
|
|
meillo@126
|
3347 independently from the profile, context, and mail storage.
|
|
meillo@126
|
3348 .P
|
|
meillo@126
|
3349 The separation of the files by type is sensible and convenient.
|
|
meillo@126
|
3350 The new approach has no functional disadvantages,
|
|
meillo@126
|
3351 as every setup I can imagine can be implemented with both approaches,
|
|
meillo@126
|
3352 possibly even easier with the new approach.
|
|
meillo@126
|
3353 The main achievement of the change is the clear and sensible split
|
|
meillo@126
|
3354 between mail storage and configuration.
|
|
meillo@0
|
3355
|
|
meillo@49
|
3356
|
|
meillo@58
|
3357
|
|
meillo@58
|
3358
|
|
meillo@58
|
3359
|
|
meillo@58
|
3360
|
|
meillo@89
|
3361 .H1 "Concept Exploitation/Homogeneity
|
|
meillo@58
|
3362
|
|
meillo@58
|
3363
|
|
meillo@58
|
3364 .H2 "Draft Folder
|
|
meillo@58
|
3365 .P
|
|
meillo@58
|
3366 Historically, MH provided exactly one draft message, named
|
|
meillo@58
|
3367 .Fn draft
|
|
meillo@58
|
3368 and
|
|
meillo@104
|
3369 being located in the MH directory.
|
|
meillo@104
|
3370 When starting to compose another message
|
|
meillo@58
|
3371 before the former one was sent, the user had been questioned whether to use,
|
|
meillo@104
|
3372 refile or replace the old draft.
|
|
meillo@104
|
3373 Working on multiple drafts at the same time
|
|
meillo@104
|
3374 was impossible.
|
|
meillo@104
|
3375 One could only work on them in alteration by refiling the
|
|
meillo@104
|
3376 previous one to some directory and fetching some other one for reediting.
|
|
meillo@58
|
3377 This manual draft management needed to be done each time the user wanted
|
|
meillo@58
|
3378 to switch between editing one draft to editing another.
|
|
meillo@58
|
3379 .P
|
|
meillo@58
|
3380 To allow true parallel editing of drafts, in a straight forward way, the
|
|
meillo@104
|
3381 draft folder facility exists.
|
|
meillo@104
|
3382 It had been introduced already in July 1984
|
|
meillo@104
|
3383 by Marshall T. Rose.
|
|
meillo@110
|
3384 The facility was inactive by default.
|
|
meillo@110
|
3385 Even in nmh, the draft folder facility remained inactive by default.
|
|
meillo@58
|
3386 At least, Richard Coleman added the man page
|
|
meillo@58
|
3387 .Mp mh-draft(5)
|
|
meillo@58
|
3388 to document
|
|
meillo@58
|
3389 the feature well.
|
|
meillo@58
|
3390 .P
|
|
meillo@58
|
3391 The only advantage of not using the draft folder facility is the static
|
|
meillo@104
|
3392 name of the draft file.
|
|
meillo@104
|
3393 This could be an issue for MH front-ends like mh-e.
|
|
meillo@58
|
3394 But as they likely want to provide working on multiple drafts in parallel,
|
|
meillo@104
|
3395 the issue is only concerning compatibility.
|
|
meillo@104
|
3396 The aim of nmh to stay compatible
|
|
meillo@58
|
3397 prevented the default activation of the draft folder facility.
|
|
meillo@58
|
3398 .P
|
|
meillo@58
|
3399 On the other hand, a draft folder is the much more natural concept than
|
|
meillo@104
|
3400 a draft message.
|
|
meillo@104
|
3401 MH's mail storage consists of folders and messages,
|
|
meillo@104
|
3402 the messages named with ascending numbers.
|
|
meillo@104
|
3403 A draft message breaks with this
|
|
meillo@58
|
3404 concept by introducing a message in a file named
|
|
meillo@58
|
3405 .Fn draft .
|
|
meillo@58
|
3406 This draft
|
|
meillo@104
|
3407 message is special.
|
|
meillo@104
|
3408 It can not be simply listed with the available tools,
|
|
meillo@104
|
3409 but instead requires special switches.
|
|
meillo@104
|
3410 I.e. corner-cases were
|
|
meillo@104
|
3411 introduced.
|
|
meillo@104
|
3412 A draft folder, in contrast, does not introduce such
|
|
meillo@104
|
3413 corner-cases.
|
|
meillo@104
|
3414 The available tools can operate on the messages within that
|
|
meillo@104
|
3415 folder like on any messages within any mail folders.
|
|
meillo@104
|
3416 The only difference
|
|
meillo@58
|
3417 is the fact that the default folder for
|
|
meillo@58
|
3418 .Pn send
|
|
meillo@58
|
3419 is the draft folder,
|
|
meillo@58
|
3420 instead of the current folder, like for all other tools.
|
|
meillo@58
|
3421 .P
|
|
meillo@58
|
3422 The trivial part of the change was activating the draft folder facility
|
|
meillo@104
|
3423 by default and setting a default name for this folder.
|
|
meillo@104
|
3424 Obviously, I chose
|
|
meillo@58
|
3425 the name
|
|
meillo@58
|
3426 .Fn +drafts .
|
|
meillo@58
|
3427 This made the
|
|
meillo@82
|
3428 .Sw -draftfolder
|
|
meillo@58
|
3429 and
|
|
meillo@82
|
3430 .Sw -draftmessage
|
|
meillo@58
|
3431 switches useless, and I could remove them.
|
|
meillo@58
|
3432 The more difficult but also the part that showed the real improvement,
|
|
meillo@58
|
3433 was updating the tools to the new concept.
|
|
meillo@82
|
3434 .Sw -draft
|
|
meillo@58
|
3435 switches could
|
|
meillo@58
|
3436 be dropped, as operating on a draft message became indistinguishable to
|
|
meillo@58
|
3437 operating on any other message for the tools.
|
|
meillo@58
|
3438 .Pn comp
|
|
meillo@58
|
3439 still has its
|
|
meillo@82
|
3440 .Sw -use
|
|
meillo@58
|
3441 switch for switching between its two modes: (1) Compose a new
|
|
meillo@104
|
3442 draft, possibly by taking some existing message as a form.
|
|
meillo@104
|
3443 (2) Modify
|
|
meillo@104
|
3444 an existing draft.
|
|
meillo@104
|
3445 In either case, the behavior of
|
|
meillo@58
|
3446 .Pn comp is
|
|
meillo@104
|
3447 deterministic.
|
|
meillo@104
|
3448 There is no more need to query the user.
|
|
meillo@104
|
3449 I consider this
|
|
meillo@104
|
3450 a major improvement.
|
|
meillo@104
|
3451 By making
|
|
meillo@58
|
3452 .Pn send
|
|
meillo@58
|
3453 simply operate on the current
|
|
meillo@58
|
3454 message in the draft folder by default, with message and folder both
|
|
meillo@58
|
3455 overridable by specifying them on the command line, it is now possible
|
|
meillo@58
|
3456 to send a draft anywhere within the storage by simply specifying its folder
|
|
meillo@58
|
3457 and name.
|
|
meillo@58
|
3458 .P
|
|
meillo@58
|
3459 All theses changes converted special cases to regular cases, thus
|
|
meillo@58
|
3460 simplifying the tools and increasing the flexibility.
|
|
meillo@58
|
3461
|
|
meillo@58
|
3462
|
|
meillo@58
|
3463 .H2 "Trash Folder
|
|
meillo@58
|
3464 .P
|
|
meillo@58
|
3465 Similar to the situation for drafts is the situation for removed messages.
|
|
meillo@104
|
3466 Historically, a message was deleted by renaming.
|
|
meillo@104
|
3467 A specific
|
|
meillo@58
|
3468 \fIbackup prefix\fP, often comma (\c
|
|
meillo@58
|
3469 .Fn , )
|
|
meillo@58
|
3470 or hash (\c
|
|
meillo@58
|
3471 .Fn # ),
|
|
meillo@104
|
3472 being prepended to the file name.
|
|
meillo@104
|
3473 Thus, MH wouldn't recognize the file
|
|
meillo@58
|
3474 as a message anymore, as only files whose name consists of digits only
|
|
meillo@104
|
3475 are treated as messages.
|
|
meillo@104
|
3476 The removed messages remained as files in the
|
|
meillo@58
|
3477 same directory and needed some maintenance job to truly delete them after
|
|
meillo@104
|
3478 some grace time.
|
|
meillo@104
|
3479 Usually, by running a command similar to
|
|
meillo@82
|
3480 .VS
|
|
meillo@82
|
3481 find /home/user/Mail -ctime +7 -name ',*' | xargs rm
|
|
meillo@82
|
3482 VE
|
|
meillo@104
|
3483 in a cron job.
|
|
meillo@104
|
3484 Within the grace time interval
|
|
meillo@58
|
3485 the original message could be restored by stripping the
|
|
meillo@104
|
3486 the backup prefix from the file name.
|
|
meillo@104
|
3487 If however, the last message of
|
|
meillo@58
|
3488 a folder is been removed \(en say message
|
|
meillo@58
|
3489 .Fn 6
|
|
meillo@58
|
3490 becomes file
|
|
meillo@58
|
3491 .Fn ,6
|
|
meillo@58
|
3492 \(en and a new message enters the same folder, thus the same
|
|
meillo@58
|
3493 numbered being given again \(en in our case
|
|
meillo@58
|
3494 .Fn 6
|
|
meillo@58
|
3495 \(en, if that one
|
|
meillo@58
|
3496 is removed too, then the backup of the former message gets overwritten.
|
|
meillo@58
|
3497 Thus, the ability to restore removed messages does not only depend on
|
|
meillo@58
|
3498 the ``sweeping cron job'' but also on the removing of further messages.
|
|
meillo@58
|
3499 This is undesirable, because the real mechanism is hidden from the user
|
|
meillo@58
|
3500 and the consequences of further removals are not always obvious.
|
|
meillo@58
|
3501 Further more, the backup files are scattered within the whole mail
|
|
meillo@58
|
3502 storage, instead of being collected at one place.
|
|
meillo@58
|
3503 .P
|
|
meillo@58
|
3504 To improve the situation, the profile entry
|
|
meillo@58
|
3505 .Pe rmmproc
|
|
meillo@58
|
3506 (previously named
|
|
meillo@58
|
3507 .Pe Delete-Prog )
|
|
meillo@58
|
3508 was introduced, very early.
|
|
meillo@58
|
3509 It could be set to any command, which would care for the mail removal
|
|
meillo@58
|
3510 instead of taking the default action, described above.
|
|
meillo@58
|
3511 Refiling the to-be-removed files to some garbage folder was a common
|
|
meillo@104
|
3512 example.
|
|
meillo@104
|
3513 Nmh's man page
|
|
meillo@58
|
3514 .Mp rmm(1)
|
|
meillo@58
|
3515 proposes
|
|
meillo@58
|
3516 .Cl "refile +d
|
|
meillo@58
|
3517 to move messages to the garbage folder and
|
|
meillo@58
|
3518 .Cl "rm `mhpath +d all`
|
|
meillo@58
|
3519 the empty the garbage folder.
|
|
meillo@104
|
3520 Managing the message removal this way is a sane approach.
|
|
meillo@104
|
3521 It keeps
|
|
meillo@58
|
3522 the removed messages in one place, makes it easy to remove the backup
|
|
meillo@58
|
3523 files, and, most important, enables the user to use the tools of MH
|
|
meillo@104
|
3524 itself to operate on the removed messages.
|
|
meillo@104
|
3525 One can
|
|
meillo@58
|
3526 .Pn scan
|
|
meillo@58
|
3527 them,
|
|
meillo@58
|
3528 .Pn show
|
|
meillo@58
|
3529 them, and restore them with
|
|
meillo@58
|
3530 .Pn refile .
|
|
meillo@58
|
3531 There's no more
|
|
meillo@58
|
3532 need to use
|
|
meillo@58
|
3533 .Pn mhpath
|
|
meillo@58
|
3534 to switch over from MH tools to Unix tools \(en MH can do it all itself.
|
|
meillo@58
|
3535 .P
|
|
meillo@58
|
3536 This approach matches perfect with the concepts of MH, thus making
|
|
meillo@104
|
3537 it powerful.
|
|
meillo@104
|
3538 Hence, I made it the default.
|
|
meillo@104
|
3539 And even more, I also
|
|
meillo@58
|
3540 removed the old backup prefix approach, as it is clearly less powerful.
|
|
meillo@58
|
3541 Keeping unused alternative in the code is a bad choice as they likely
|
|
meillo@104
|
3542 gather bugs, by not being constantly tested.
|
|
meillo@104
|
3543 Also, the increased code
|
|
meillo@104
|
3544 size and more conditions crease the maintenance costs.
|
|
meillo@104
|
3545 By strictly
|
|
meillo@58
|
3546 converting to the trash folder approach, I simplified the code base.
|
|
meillo@58
|
3547 .Pn rmm
|
|
meillo@58
|
3548 calls
|
|
meillo@58
|
3549 .Pn refile
|
|
meillo@58
|
3550 internally to move the to-be-removed
|
|
meillo@58
|
3551 message to the trash folder (\c
|
|
meillo@58
|
3552 .Fn +trash
|
|
meillo@104
|
3553 by default).
|
|
meillo@104
|
3554 Messages
|
|
meillo@58
|
3555 there can be operated on like on any other message in the storage.
|
|
meillo@58
|
3556 The sweep clean, one can use
|
|
meillo@82
|
3557 .Cl "rmm -unlink +trash a" ,
|
|
meillo@58
|
3558 where the
|
|
meillo@82
|
3559 .Sw -unlink
|
|
meillo@58
|
3560 switch causes the files to be truly unliked instead
|
|
meillo@58
|
3561 of moved to the trash folder.
|
|
meillo@58
|
3562
|
|
meillo@58
|
3563
|
|
meillo@58
|
3564 .H2 "Path Notations
|
|
meillo@58
|
3565 .P
|
|
meillo@58
|
3566 foo
|
|
meillo@58
|
3567
|
|
meillo@58
|
3568
|
|
meillo@58
|
3569 .H2 "MIME Integration
|
|
meillo@58
|
3570 .P
|
|
meillo@58
|
3571 user-visible access to whole messages and MIME parts are inherently
|
|
meillo@58
|
3572 different
|
|
meillo@58
|
3573
|
|
meillo@58
|
3574
|
|
meillo@58
|
3575 .H2 "Of One Cast
|
|
meillo@58
|
3576 .P
|
