1MH-MIME(7) Miscellaneous Information Manual MH-MIME(7)
2
6 mh-mime - overview of nmh MIME message composition and display
7
9 The acronym MIME stands for Multipurpose Internet Mail Extensions, the
10 format of Internet messages used to send multi-media content. The nmh
11 command suite has support for the display and composition of MIME mes‐
12 sages, but currently MIME support is not completely integrated into all
13 tools. This document provides an overview as to which tools support
14 MIME message display, storage, and composition.
15 Local Character Set Conversion
17 All of the nmh commands convert non-native character sets to the local
18 character set, as specified by the operating system locale settings.
19 See locale(1) for more details on the environment variables used to set
20 the local character set. Character set conversion will only take place
21 if nmh was built with iconv(3) support. See mhparam(1) for how to de‐
22 termine whether your nmh installation includes iconv(3) support.
23 Depending on the source and target character set, it may not be possi‐
25 ble to convert all characters to the local character set. In this case
26 a substitution character will be used for the characters that cannot be
27 converted.
28 Message Display
30 The default format used by scan(1) will automatically decode MIME-en‐
31 coded headers. If you have a custom scan format, see the examples pro‐
32 vided with the nmh distribution (found in the “/etc/nmh” directory) and
33 mh-format(5) for details on how to make sure your MIME headers are
34 properly decoded.
35 By default, if show detects that it is reading a MIME message it will
37 invoke mhshow(1). The default behavior of mhshow is to only display
38 text parts that are not marked as attachments. See mhshow(1) for de‐
39 tails on how to control what mhshow will display.
40 Message Interrogation and Storage
42 The mhlist(1) command will display a listing of the MIME parts con‐
43 tained within a message. That information can be used in conjunction
44 with the mhstore command to save individual parts or content types of a
45 message. See mhlist(1) and mhstore(1) for more details on how these
46 commands work.
47 Message Composition and Reply
49 All messages sent by send(1) will automatically be processed by mh‐
50 build(1) before being passed to post(1) for message submission. mh‐
51 build will use the locale settings to mark text content with the appro‐
52 priate character set and apply any necessary encoding. If you wish to
53 include text in your message using a character set that does not match
54 your locale, you will need to specify the character set using an mh‐
55 build directive; see mhbuild(1) for more information.
56 For attaching files or composing other non-text content, there are two
58 options: the attach system and mhbuild directives.
59 The attach system is best suited for content where one or more files
61 are being attached to a message. You can use the attach system by ei‐
62 ther using the attach command at the “What now?” prompt, or by insert‐
63 ing an “Attach:” header in the message draft containing the name of the
64 file you wish to attach to the message (note that all the attach com‐
65 mand does is place an “Attach:” header in the message draft). mhbuild
66 will then automatically include the specified file(s) in the outgoing
67 message. See send(1) for details on how mhbuild determines the proper
68 content type of attached files.
69 The other method of composing MIME messages is to use mhbuild direc‐
71 tives. This allows exact control over the contents and format of the
72 MIME message, but has a more complicated syntax. mhbuild(1) contains
73 details on the directive syntax and examples of directives for differ‐
74 ent media types. It is important to note that when using mhbuild di‐
75 rectives the user must run mhbuild outside of send to have it process
76 directives; when being run by send, mhbuild is configured to not
77 process directives so normal user text is not mistaken for a directive.
78 When using directives a user typically uses the mime command at the
79 “What now?” prompt to process them.
80 When replying to messages using repl(1) the traditional MH method of
82 including the original text in the reply does not interoperate with
83 MIME messages. The -convertargs switch to repl(1) provides one solu‐
84 tion. Another solution: the contrib directory
85 (/usr/share/doc/nmh/contrib) contains a Perl program called replyfilter
86 which will decode text parts and present them in an appropriate manner
87 to be included in a message reply. See the comments at the top of re‐
88 plyfilter for instructions on how to configure nmh to work with it.
89 Message Rewrite
91 The mhfixmsg(1) command can apply various transformations to MIME mes‐
92 sages, including decoding of text parts, converting the character set
93 of text parts, and insertion of text/plain parts to correspond to text
94 parts of other subtypes. mhfixmsg can also repair defects in MIME mes‐
95 sages, such as mismatched top-level boundary indicators and invalid
96 Content-Transfer-Encoding values.
97
99 comp(1), iconv(3), mh-format(5), mhbuild(1), mhfixmsg(1), mhparam(1),
100 nmh(7), repl(1), whatnow(1),
101 /usr/share/doc/nmh/contrib/replyfilter,
102 /usr/share/doc/nmh/contrib/replaliases
103
105 MIME support should be more integrated into all of the nmh tools than
106 it currently is.
107nmh-1.8 2014-12-15 MH-MIME(7)