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NAME

       mhbuild - translate MIME composition draft

SYNOPSIS

       mhbuild file [-auto | -noauto] [-list | -nolist] [-realsize | -norealsize] [-headers | -noheaders]
            [-directives | -nodirectives] [-rfc934mode | -norfc934mode] [-contentid | -nocontentid] [-verbose |
            -noverbose] [-disposition | -nodisposition] [-check | -nocheck] [-headerencoding encoding-algorithm
            | -autoheaderencoding] [-maxunencoded line-length] [-dist] [-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 to RFC 2049.  This includes the encoding of
       message headers as specified by RFC 2047, and the encoding of MIME parameters as specified in RFC 2231.

       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.

       If the -disposition switch is present, then the listing will  show  any  relevant  information  from  the
       “Content-Disposition” header.

   Simplified Attachment Interface
       For  users  who  wish  to simply attach files to text content, mhbuild will scan the composition file for
       “Attach” headers.  An “Attach” header contains a filename that will be  appended  to  the  message  using
       normal  MIME  encapsulation  rules.   One  filename is allowed per “Attach” header, but multiple “Attach”
       headers are allowed ber composition file.

       These files will be appended after any other MIME content, including any  content  specified  by  mhbuild
       directives (see below).  See send(1) for more details.

   Translating the Composition File
       mhbuild  is  essentially  a  filter  to aid in the composition of MIME messages.  mhbuild will convert an
       mhbuild “composition 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  five  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; the “begin” directive (#begin), which is used to
       create a multipart content; and the “on/off/pop” directives (#on, #off, #pop) which control  whether  any
       other directives are honored at all.

       The  -directives  switch  allows control over whether mhbuild will honor any of the “#”-directives.  This
       can also be affected with the #on or #off directives, and #pop, which restores the state of processing to
       that  preceding  the most recent #on or #off.  (The #on, #off, and #pop directives are always honored, of
       course.) This allows inclusion of plain text which looks like mhbuild directives, without causing errors:

            #off
            #include <stdio.h>
            printf("Hello, World!);
            #pop

       Currently the stack depth for the #on/off/pop directives is 32.

       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 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] \
                {attachment; filename="nmh.tar.gz"} \
                name="nmh.tar.gz"; \
                directory="/pub/nmh"; \
                site="ftp.math.gatech.edu"; \
                access-type=anon-ftp; \
                mode="image"

       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  “[]”.
       A disposition string, to appear in a “Content-Disposition” header, may appear in the optional “{}”.

       These parameters are of the form:

            access-type=  usually anon-ftp, mail-server, or url
            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
            url=          URL of content

       A mimimum “external-type” directive for the url access-type would be as follows:

          #@application/octet-stream [] access-type=url; \
            url="http://download.savannah.gnu.org/releases/nmh/nmh-1.5.tar.gz"

       Any long URLs will be wrapped according to RFC 2231 rules.

       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 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.

            #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

       Similarly, a disposition string may optionally be provided between “{” and “}”  characters;  it  will  be
       copied into the “Content-Disposition” header when the directive is processed.  If a disposition string is
       provided that does not contain a filename parameter, and a filename is provided in the directive, it will
       be added to the “Content-Disposition” header.  For example, the following directive:

            #text/plain; charset=iso-8859-1 <>{attachment} /tmp/summary.txt

       creates these message part headers:

            Content-Type: text/plain; charset="iso-8859-1"
            Content-Disposition: attachment; filename="summary.txt"

       By  default,  mhbuild  will  generate  a  unique  “Content-ID:” for each directive, corresponding to each
       message part; however, the user may override this by defining the ID using the “<”  and  “>”  characters.
       The  -nocontentid  switch  suppresses creation of all “Content-ID:” headers, even in the top level of the
       message.

       Normally mhbuild will choose an appropriate Content-Transfer-Encoding based on the content and  the  MIME
       Content-Type.  However, you can override that in an mhbuild directive by specifying “*” and the encoding.
       Acceptable encoding values are “8bit”, “qpρq (for quoted-printable), and “b64” (for base64 encoding).  It
       should  be  noted  that  undesired  results  may occur if 8bit or quoted-printable is selected for binary
       content, due to the translation between Unix line endings and the line endings use by the mail  transport
       system.

       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 “#<” 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 8-bit 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
       standard locale(1) environment variables.  If these environment variables are not set, then the character
       set will be labeled as “x-unknown”.

       If  a  text  content contains only 7-bit characters and the character set is not specified as above, then
       the character set will be labeled as “us-ascii”.

       By default text content with the high bit set is encoded with a 8bit Content-Transfer-Encoding.   If  the
       text  has  lines  longer  than the value of -maxunencoded (which defaults to 78) then the text is encoded
       using the quoted-printable encoding.

       The -headerencoding switch will indicate which algorithm to use when encoding any  message  headers  that
       contain  8-bit  characters.   The  valid  arguments  are  base64  for  based-64  encoding  and quoted for
       quoted-printable encoding.  The -autoheaderencoding switch will instruct mhbuild  to  automatically  pick
       the algorithm that results in a shorter encoded string.

       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, per RFC 1864.  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 7-bit data.  This is to
       increase the likelihood that the content is not changed while in transport.

   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.

       Normally  it  is  an  error to invoke mhbuild on file that already in MIME format.  The -auto switch will
       cause mhbuild to exit without error if the input file already has valid MIME headers.  The use  of  -auto
       also enables the -nodirectives switch.

       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.

       The  -dist switch is intended to be used by dist.  It will cause mhbuild to not generate any MIME headers
       in the composition file (such as “MIME-Version” or “Content-Type”), but  it  will  still  encode  message
       headers according to RFC 2047.

   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

            /etc/nmh/mhn.defaults

       if it exists.

       See "Profile Lookup" in mh-profile(5) for the profile search order, and for  how  duplicate  entries  are
       treated.

   Syntax of Composition Files
       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 "]" ]
                                     [ "{" disposition "}" ]
                           [ "*8bit" | "*qp" | "*b64" ]
                                     [ filename ]
                                     EOL

                               | "#@" type "/" subtype
                                     0*(";" attribute "=" value)
                                     [ "(" comment ")" ]
                                     [ "<" id ">" ]
                                     [ "[" description "]" ]
                                     [ "{" disposition "}" ]
                           [ "*8bit" | "*qp" | "*b64" ]
                                     external-parameters
                                     EOL

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

                               | "#begin"
                                       [ "<" id ">" ]
                                       [ "[" description "]" ]
                                       [ "{" disposition "}" ]
                                       [   "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 "]" ]
                                     [ "{" disposition "}" ]
                           [ "*8bit" | "*qp" | "*b64" ]
                                     EOL
                                     1*line
                                 [ "#" EOL ]

            line         ::=     "##" text EOL
                                 -- interpreted as "#"text EOL
                               | text EOL

FILES

       mhbuild  looks  for  additional  user  profile  files  and  mhn.defaults  in multiple locations: absolute
       pathnames are accessed directly, tilde expansion is done on usernames, and files are searched for in  the
       user's  Mail  directory  as  specified in their profile.  If not found there, the directory “/etc/nmh” is
       checked.

       $HOME/.mh_profile          The user profile
       $MHBUILD                   Additional profile entries
       /etc/nmh/mhn.defaults      System default MIME profile entries

PROFILE COMPONENTS

       Path:                To determine the user's nmh directory
       Current-Folder:      To find the default current folder
       mhbuild-compose-<type>Template for composing contents

SEE ALSO

       mhlist(1), mhshow(1), mhstore(1)

       Proposed Standard for Message Encapsulation (RFC 934),

       The Content-MD5 Header Field (RFC 1864),

       Multipurpose Internet Mail Extensions (MIME) Part One: Format of Internet Message Bodies (RFC 2045),

       Multipurpose Internet Mail Extensions (MIME) Part Two: Media Types (RFC 2046),

       Multipurpose Internet Mail Extensions (MIME) Part Three: Message Header  Extensions  for  Non-ASCII  Text
       (RFC 2047),

       Multipurpose Internet Mail Extensions (MIME) Part Four: Registration Procedures (RFC 2048),

       Multipurpose Internet Mail Extensions (MIME) Part Five: Conformance Criteria and Examples (RFC 2049),

       Definition of the URL MIME External-Body Access-Type (RFC 2017),

       MIME Parameter Value and Encoded Word Extensions: Character Sets, Languages, and Continuations (RFC 2231)

DEFAULTS

       `-headers'
       `-realsize'
       `-norfc934mode'
       `-contentid'
       `-nocheck'
       `-noverbose'
       `-nodisposition'
       `-autoheaderencoding'
       `-maxunencoded 78'