MHBUILD (1)

SYNOPSIS

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mhbuild file \%[-list] \%[-nolist] \%[-realsize] \%[-norealsize] \%[-headers] \%[-noheaders] \%[-ebcdicsafe] \%[-noebcdicsafe] \%[-rfc934mode] \%[-norfc934mode] \%[-verbose] \%[-noverbose] \%[-check] \%[-nocheck] \%[-version] \%[-help] -.5i

DESCRIPTION

The mhbuild command will translate a MIME compostion draft into a valid MIME message.

mhbuild creates multi-media messages as specified in RFC-2045 thru RFC-2049. Currently mhbuild only supports encodings in message bodies, and does not support the encoding of message headers as specified in RFC-2047.

If you specify the name of the composition file as \*(lq-\*(rq, then mhbuild will accept the composition draft on the standard input. If the translation of this input is successful, mhbuild will output the new MIME message to the standard output. This argument must be the last argument on the command line.

Otherwise if the file argument to mhbuild is the name of a valid composition file, and the translation is successful, mhbuild will replace the orginal file with the new MIME message. It will rename the original file to start with the \*(lq,\*(rq character and end with the string \*(lq.orig\*(rq, e.g., if you are editing the file \*(lqdraft\*(rq, it will be renamed to \*(lq,draft.orig\*(rq. This allows you to easily recover the mhbuild input file.

"Listing the Contents" The `-list' switch tells mhbuild to list the table of contents associated with the MIME message that is created.

The `-headers' switch indicates that a one-line banner should be displayed above the listing. The `-realsize' switch tells mhbuild to evaluate the \*(lqnative\*(rq (decoded) format of each content prior to listing. This provides an accurate count at the expense of a small delay. If the `-verbose' switch is present, then the listing will show any \*(lqextra\*(rq information that is present in the message, such as comments in the Content-Type header.

"Translating the Composition File" mhbuild is essentially a filter to aid in the composition of MIME messages. mhbuild will convert an mhbuild \*(lqcomposition file\*(rq into a valid MIME message. A mhbuild \*(lqcomposition file\*(rq is just a file containing plain text that is interspersed with various mhbuild directives. When this file is processed by mhbuild, the various directives will be expanded to the appropriate content, and will be encoded according to the MIME standards. The resulting MIME message can then be sent by electronic mail.

The formal syntax for a mhbuild composition file is defined at the end of this document, but the ideas behind this format are not complex. Basically, the body contains one or more contents. A content consists of either a directive, indicated with a \*(lq#\*(rq as the first character of a line; or, plaintext (one or more lines of text). The continuation character, \*(lq\\\*(lq, may be used to enter a single directive on more than one line, e.g.,

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#image/png \\
    /home/foobar/junk/picture.png
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There are four kinds of directives: \*(lqtype\*(rq directives, which name the type and subtype of the content; \*(lqexternal-type\*(rq directives, which also name the type and subtype of the content; the \*(lqmessage\*(rq directive (#forw), which is used to forward one or more messages; and, the \*(lqbegin\*(rq directive (#begin), which is used to create a multipart content.

The \*(lqtype\*(rq directive is used to directly specify the type and subtype of a content. You may only specify discrete types in this manner (can't specify the types multipart or message with this directive). You may optionally specify the name of a file containing the contents in \*(lqnative\*(rq (decoded) format. If this filename starts with the \*(lq|\*(rq character, then it represents a command to execute whose output is captured accordingly. For example,

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#audio/basic |raw2audio -F < /usr/lib/sound/giggle.au
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If a filename is not given, mhbuild will look for information in the user's profile to determine how the different contents should be composed. This is accomplished by consulting a composition string, and executing it under /bin/sh, with the standard output set to the content. If the `-verbose' switch is given, mhbuild will echo any commands that are used to create contents in this way. 13 The composition string may contain the following escapes:

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\w'%P  'u
%a      Insert parameters from directive
%f      Insert filename containing content
%F      %f, and stdout is not re-directed
%s      Insert content subtype
%%      Insert character %

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First, mhbuild will look for an entry of the form: +.5i mhbuild-compose-<type>/<subtype> -.5i to determine the command to use to compose the content. If this isn't found, mhbuild will look for an entry of the form: +.5i mhbuild-compose-<type> -.5i to determine the composition command.

If this isn't found, mhbuild will complain.

An example entry might be: +.5i mhbuild-compose-audio/basic: record | raw2audio -F -.5i Because commands like these will vary, depending on the display environment used for login, composition strings for different contents should probably be put in the file specified by the $MHBUILD environment variable, instead of directly in your user profile.

The \*(lqexternal-type\*(rq directives are used to provide a MIME reference to a content, rather than enclosing the contents itself (for instance, by specifying an ftp site). Hence, instead of providing a filename as with the type directives, external-parameters are supplied. These look like regular parameters, so they must be separated accordingly. For example,

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#@application/octet-stream; \\
    type=tar; \\
    conversions=compress \\
    [this is the nmh distribution] \\
    name="nmh.tar.gz"; \\
    directory="/pub/nmh"; \\
    site="ftp.math.gatech.edu"; \\
    access-type=anon-ftp; \\
    mode="image"
-.5i

+.5i
\w'access-type=  'u
access-type=    usually anon-ftp or mail-server
name=   filename
permission=     read-only or read-write
site=   hostname
directory=      directoryname (optional)
mode=   usually ascii or image (optional)
size=   number of octets
server= mailbox
subject=        subject to send
body=   command to send for retrieval
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The \*(lqmessage\*(rq directive (#forw) is used to specify a message or group of messages to include. You may optionally specify the name of the folder and which messages are to be forwarded. If a folder is not given, it defaults to the current folder. Similarly, if a message is not given, it defaults to the current message. Hence, the message directive is similar to the forw\0(1) command, except that the former uses the MIME rules for encapsulation rather than those specified in RFC-934. For example,

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#forw +inbox 42 43 99
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If you are using this directive to include more than one message, you may use the `-rfc934mode' switch. This switch will indicate that mhbuild should attempt to utilize the MIME encapsulation rules in such a way that the \*(lqmultipart/digest\*(rq that is created is (mostly) compatible with the encapsulation specified in RFC-934. If given, then RFC-934 compliant user-agents should be able to burst the message on reception\0--\0providing that the messages being encapsulated do not contain encapsulated messages themselves. The drawback of this approach is that the encapsulations are generated by placing an extra newline at the end of the body of each message.

The \*(lqbegin\*(rq directive is used to create a multipart content. When using the \*(lqbegin\*(rq directive, you must specify at least one content between the begin and end pairs.

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#begin
This will be a multipart with only one part.
#end
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For all of these directives, the user may include a brief description of the content between the \*(lq[\*(rq character and the \*(lq]\*(rq character. This description will be copied into the \*(lqContent-Desciption\*(rq header when the directive is processed.

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#forw [important mail from Bob] +bob 1 2 3 4 5
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In addition to the various directives, plaintext can be present. Plaintext is gathered, until a directive is found or the draft is exhausted, and this is made to form a text content. If the plaintext must contain a \*(lq#\*(rq at the beginning of a line, simply double it, 6 e.g., +.5i ##when sent, this line will start with only one # -.5i If you want to end the plaintext prior to a directive, e.g., to have two plaintext contents adjacent, simply insert a line containing a single \*(lq#\*(rq character, 10 e.g.,

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this is the first content
#
and this is the second
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By default, plaintext is captured as a text/plain content. You can override this by starting the plaintext with \*(lq#<\*(rq followed by a content-type specification. For example, 11 e.g.,

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#<text/enriched
this content will be tagged as text/enriched
#
and this content will be tagged as text/plain
#
#<application/x-patch [this is a patch]
and this content will be tagged as application/x-patch
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When composing a text content, you may indicate the relevant character set by adding the \*(lqcharset\*(rq parameter to the directive. +.5i #<text/plain; charset=iso-8859-5 -.5i If a text content contains any 8bit characters (characters with the high bit set) and the character set is not specified as above, then mhbuild will assume the character set is of the type given by the environment variable MM_CHARSET. If this environment variable is not set, then the character set will be labeled as \*(lqx-unknown\*(rq.

If a text content contains only 7bit characters and the character set is not specified as above, then the character set will be labeled as \*(lqus-ascii\*(rq

Putting this all together, 15 here is an example of a more complicated message draft. The following draft will expand into a multipart/mixed message containing five parts:

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To: nobody@nowhere.org
cc:
Subject: Look and listen to me!
--------
The first part will be text/plain
#<text/enriched
The second part will be text/enriched
#
This third part will be text/plain
#audio/basic [silly giggle]  \\
    |raw2audio -F < /usr/lib/sounds/giggle.au
#image/gif   [photo of foobar] \\
                    /home/foobar/lib/picture.gif
-.5i

"Transfer Encodings" After mhbuild constructs the new MIME message by parsing directives, including files, etc., it scans the contents of the message to determine which transfer encoding to use. It will check for 8bit data, long lines, spaces at the end of lines, and clashes with multipart boundaries. It will then choose a transfer encoding appropriate for each content type.

If an integrity check is being associated with each content by using the `-check' switch, then mhbuild will encode each content with a transfer encoding, even it the content contains only 7bit data. This is to increase the likelihood that the content is not changed while in transport.

The switch `-ebcdicsafe' will cause mhbuild to slightly change the way in which it performs the \*(lqquoted-printable\*(rq transfer encoding. Along with encoding 8bit characters, it will now also encode certain common punctuation characters as well. This slightly reduces the readability of the message, but allows the message to pass more reliably through mail gateways which involve the EBCDIC character encoding.

"Invoking mhbuild" Typically, mhbuild is invoked by the whatnow program. This command will expect the body of the draft to be formatted as an mhbuild composition file. Once you have composed this input file using a command such as comp, repl, or forw, you invoke mhbuild at the \*(lqWhat now\*(rq prompt with +.5i What now? mime -.5i prior to sending the draft. This will cause whatnow to execute mhbuild to translate the composition file into MIME format.

It is also possible to have the whatnow program invoke mhbuild automatically when a message is sent. To do this, you must add the line +.5i automimeproc: 1 -.5i to your .mh\(ruprofile file.

Finally, you should consider adding this line to your profile: +.5i lproc: show -.5i This way, if you decide to list after invoking mime, the command +.5i What now? list -.5i will work as you expect.

"User Environment" Because the environment in which mhbuild operates may vary for a user, mhbuild will look for the environment variable $MHBUILD. If present, this specifies the name of an additional user profile which should be read. Hence, when a user logs in on a particular machine, this environment variable should be set to refer to a file containing definitions useful for that machine.

Finally, mhbuild will attempt to consult a global mhbuild user profile, 6 e.g., +.5i /etc/nmh/mhbuild.defaults -.5i if it exists.

"Syntax of Composition Files" 59 The following is the formal syntax of a mhbuild \*(lqcomposition file\*(rq.

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   body         ::=     1*(content | EOL)

   content      ::=     directive | plaintext

   directive    ::=     "#" type "/" subtype
                            0*(";" attribute "=" value)
                            [ "(" comment ")" ]
                            [ "<" id ">" ]
                            [ "[" description "]" ]
                            [ filename ]
                            EOL

                      | "#@" type "/" subtype
                            0*(";" attribute "=" value)
                            [ "(" comment ")" ]
                            [ "<" id ">" ]
                            [ "[" description "]" ]
                            external-parameters
                            EOL

                      | "#forw"
                            [ "<" id ">" ]
                            [ "[" description "]" ]
                            [ "+"folder ] [ 0*msg ]
                            EOL

                      | "#begin"
                              [ "<" id ">" ]
                              [ "[" description "]" ]
                              [   "alternative"
                                | "parallel"
                                | something-else    ]
                              EOL
                            1*body
                        "#end" EOL

   plaintext    ::=     [ "Content-Description:"
                              description EOL EOL ]
                            1*line
                        [ "#" EOL ]

                      | "#<" type "/" subtype
                            0*(";" attribute "=" value)
                            [ "(" comment ")" ]
                            [ "[" description "]" ]
                            EOL
                            1*line
                        [ "#" EOL ]

   line         ::=     "##" text EOL
                        -- interpreted as "#"text EOL
                      | text EOL
-.5i

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