MHBUILD(1) [nmh-1.0.4] (MH.6.8) MHBUILD(1)
NAME
mhbuild - translate MIME composition draft
SYNOPSIS
mhbuild file
[-list] [-nolist] [-realsize] [-norealsize]
[-headers] [-noheaders] [-ebcdicsafe] [-noebcdicsafe]
[-rfc934mode] [-norfc934mode] [-verbose] [-noverbose]
[-check] [-nocheck] [-version] [-help]
DESCRIPTION
The mhbuild command will translate a MIME composition 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 -, 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 original file with the new MIME
message. It will rename the original file to start with the
, character and end with the string .orig, e.g., if you are
editing the file draft, it will be renamed to ,draft.orig.
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 native (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 extra
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 composition
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file into a valid MIME message. A mhbuild composition file
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 # as the first character of a line; or,
plaintext (one or more lines of text). The continuation
character, \, may be used to enter a single directive on
more than one line, e.g.,
#image/png \
/home/foobar/junk/picture.png
There are four kinds of directives: type directives, which
name the type and subtype of the content; external-type
directives, which also name the type and subtype of the
content; the message directive (#forw), which is used to
forward one or more messages; and, the begin directive
(#begin), which is used to create a multipart content.
The type 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 native (decoded)
format. If this filename starts with the | character, then
it represents a command to execute whose output is captured
accordingly. For example,
#audio/basic |raw2audio -F < /usr/lib/sound/giggle.au
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
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commands that are used to create contents in this way. The
composition string may contain the following escapes:
%a Insert parameters from directive
%f Insert filename containing content
%F %f, and stdout is not re-directed
%s Insert content subtype
%% Insert character %
First, mhbuild will look for an entry of the form:
mhbuild-compose-<type>/<subtype>
to determine the command to use to compose the content. If
this isn't found, mhbuild will look for an entry of the
form:
mhbuild-compose-<type>
to determine the composition command.
If this isn't found, mhbuild will complain.
An example entry might be:
mhbuild-compose-audio/basic: record | raw2audio -F
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 external-type 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,
#@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"
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You must give a description string to separate the content
parameters from the external-parameters (although this
string may be empty). This description string is specified
by enclosing it within []. These parameters are of the
form:
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
The message 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 (1) command, except that
the former uses the MIME rules for encapsulation rather than
those specified in RFC-934. For example,
#forw +inbox 42 43 99
If you include a single message, it will be included
directly as a content of type message/rfc822. If you
include more than one message, then mhbuild will add a
content of type multipart/digest and include each message as
a subpart of this content.
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
multipart/digest 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 -- providing 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 begin directive is used to create a multipart content.
When using the begin 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
If you use multiple directives in a composition draft,
mhbuild will automatically encapsulate them inside a
multipart content. Therefore the begin directive is only
necessary if you wish to use nested multiparts, or create a
multipart message containing only one part.
For all of these directives, the user may include a brief
description of the content between the [ character and the ]
character. This description will be copied into the
Content-Description header when the directive is processed.
#forw [important mail from Bob] +bob 1 2 3 4 5
By default, mhbuild will generate a unique Content-ID: for
each directive; however, the user may override this by
defining the ID using the < and > characters.
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 # at the beginning
of a line, simply double it, e.g.,
##when sent, this line will start with only one #
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 # character, e.g.,
this is the first content
#
and this is the second
Finally, if the plaintext starts with a line of the form:
Content-Description: text
then this will be used to describe the plaintext content.
You MUST follow this line with a blank line before starting
your text.
By default, plaintext is captured as a text/plain content.
You can override this by starting the plaintext with #<
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followed by a content-type specification. For example,
e.g.,
#<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
Note that if you use the #< plaintext-form, then the
content-description must be on the same line which
identifies the content type of the plaintext.
When composing a text content, you may indicate the relevant
character set by adding the charset parameter to the
directive.
#<text/plain; charset=iso-8859-5
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 x-unknown.
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 us-ascii
Putting this all together, here is an example of a more
complicated message draft. The following draft will expand
into a multipart/mixed message containing five parts:
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
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Integrity Check
If mhbuild is given the `-check' switch, then it will also
associate an integrity check with each leaf content. This
will add a Content-MD5 header field to the content, along
with the md5 sum of the unencoded contents. This may be
used by the receiver of the message to verify that the
contents of the message were not changed in transport.
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 quoted-printable
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 What now prompt with
What now? mime
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
automimeproc: 1
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to your .mh_profile file.
Finally, you should consider adding this line to your
profile:
lproc: show
This way, if you decide to list after invoking mime, the
command
What now? list
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, e.g.,
/usr/freeware/lib/nmh/etc/mhn.defaults
if it exists.
Syntax of Composition Files
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The following is the formal syntax of a mhbuild composition
file.
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 ]
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line ::= "##" text EOL
-- interpreted as "#"text EOL
| text EOL
FILES
$HOME/.mh_profile The user profile
$MHBUILD Additional profile entries
/usr/freeware/lib/nmh/etc/mhn.defaultSystem default MIME profile entries
PROFILE COMPONENTS
Path: To determine the user's nmh directory
Current-Folder: To find the default current folder
mhbuild-compose-<typeTemplate for composing contents
SEE ALSO
mhlist(1), mhshow(1), mhstore(1)
RFC-934:
Proposed Standard for Message Encapsulation,
RFC-2045:
Multipurpose Internet Mail Extensions (MIME) Part One:
Format of Internet Message Bodies,
RFC-2046:
Multipurpose Internet Mail Extensions (MIME) Part Two:
Media Types,
RFC-2047:
Multipurpose Internet Mail Extensions (MIME) Part Three:
Message Header Extensions for Non-ASCII Text,
RFC-2048:
Multipurpose Internet Mail Extensions (MIME) Part Four:
Registration Procedures,
RFC-2049:
Multipurpose Internet Mail Extensions (MIME) Part Five:
Conformance Criteria and Examples.
DEFAULTS
`-headers'
`-realsize'
`-norfc934mode'
`-nocheck'
`-noebcdicsafe'
`-noverbose'
CONTEXT
If a folder is given, it will become the current folder.
The last message selected will become the current message.
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