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 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 "-",
then mhbuild will accept the composition draft on the
standard input. If the translation of this input is suc-
cessful, 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 "," 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 con-
tents 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 "compo-
sition 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 direc-
tives 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 informa-
tion in the user's profile to determine how the different
contents should be composed. This is accomplished by con-
sulting 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 com-
mands 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 ref-
erence to a content, rather than enclosing the contents
itself. Hence, instead of providing a filename as with
the type directives, external-parameters are supplied.
These look like regular parameters, so they must be sepa-
rated accordingly. For example,
#@application/octet-stream; \
type=tar; \
conversions=compress [] \
access-type=anon-ftp; \
name="nmh.tar.gz"; \
directory="/pub/nmh"; \
site="ftp.math.gatech.edu"
By specifying "[]", an empty description string is given,
and the start of the external-parameters is identified.
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 mes-
sage 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 mes-
sage 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 uti-
lize 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 con-
tent. When using the "begin" directive, you must specify
at least one content between the begin and end pairs.
#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 mul-
tipart 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-Desciption" header when the directive is pro-
cessed.
#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 start-
ing your text.
By default, plaintext is captured as a text/plain content.
You can override this by starting the plaintext with "#<"
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 identi-
fies the content type of the plaintext.
When composing a text content, you may indicate the rele-
vant 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 speci-
fied 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 charac-
ter 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
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 con-
tent 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 trans-
port.
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 charac-
ters 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 for-
matted as an mhbuild composition file. Once you have com-
posed 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
to your .mh_profile file.
Finally, you should consider adding this line to your pro-
file:
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 addi-
tional 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 defi-
nitions useful for that machine.
Finally, mhbuild will attempt to consult a global mhbuild
user profile, e.g.,
/etc/nmh/mhbuild.defaults
if it exists.
Syntax of Composition Files
The following is the formal syntax of a mhbuild "composi-
tion 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 ]
line ::= "##" text EOL
-- interpreted as "#"text EOL
| text EOL
FILES
$HOME/.mh_profile The user profile
$MHBUILD Additional profile entries
/etc/nmh/mhbuild.defaults System-default profile entries
PROFILE COMPONENTS
Path: To determine the user's nmh directory
Current-Folder: To find the default current folder
mhbuild-compose-<type>T*emplate for composing contents
SEE ALSO
mhn(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.