phpMan > info > mhfixmsg(1)

MHFIXMSG(1mh)                                                    MHFIXMSG(1mh)

NAME
       mhfixmsg - nmh's MIME-email rewriter with various transformations

SYNOPSIS
       mhfixmsg [-help] [-version] [+folder] [msgs | absolute pathname | -file
            file] [-decodetext 8bit|7bit|binary | -nodecodetext] [-decodetypes
            type/[subtype][,...]]  [-crlflinebreaks | -nocrlflinebreaks]
            [-textcharset charset | -notextcharset] [-reformat | -noreformat]
            [-replacetextplain | -noreplacetextplain] [-fixboundary |
            -nofixboundary] [-fixcte | -nofixcte] [-fixtype mimetype] [-out-
            file outfile] [-rmmproc program] [-normmproc] [-changecur |
            -nochangecur] [-verbose | -noverbose]

DESCRIPTION
       mhfixmsg rewrites MIME messages, applying specific transformations such
       as  decoding  of  MIME-encoded message parts and repairing invalid MIME
       headers.

       MIME messages are specified in RFC 2045 to RFC 2049  (see  mhbuild(1)).
       The  mhlist  command is invaluable for viewing the content structure of
       MIME messages.  mhfixmsg passes non-MIME messages through  without  any
       transformations.   If  no  transformations apply to a MIME message, the
       original message or file is not modified or  removed.   Thus,  mhfixmsg
       can safely be run multiple times on a message.

       The  -decodetext  switch enables a transformation to decode each base64
       and quoted-printable text message part to the selected 8-bit, 7-bit, or
       binary  encoding.   If  7-bit is selected for a base64 part but it will
       only fit 8-bit, as defined by RFC 2045, then  it  will  be  decoded  to
       8-bit  quoted-printable.   Similarly,  with  8-bit, if the decoded text
       would be binary, then the part is not decoded (and a  message  will  be
       displayed  if  -verbose  is enabled).  Note that -decodetext binary can
       produce messages that are not RFC 2045 compliant.

       When the -decodetext switch is enabled, each carriage return  character
       that  precedes  a linefeed character is removed from text parts encoded
       in ASCII, ISO-8859-x, UTF-8, or Windows-12xx.

       The -decodetypes switch specifies the message parts, by  type  and  op-
       tionally  subtype,  to  which  -decodetext  applies.  Its argument is a
       comma-separated list of type/subtype elements.  If an element does  not
       contain  a  subtype,  then  -decodetext  applies to all subtypes of the
       type.  The default is -decodetypes text; it can  be  overridden,  e.g.,
       with -decodetypes text/plain to restrict -decodetext to just text/plain
       parts.

       By default, carriage return characters are preserved or inserted at the
       end  of  each line of text content.  The -crlflinebreaks switch selects
       this behavior and is enabled by default.  The -nocrlflinebreaks  switch
       causes carriage return characters to be stripped from, and not inserted
       in, text content when it is decoded and encoded.  Note that its use can
       cause  the generation of MIME messages that do not conform to RFC 2046,
       <section>4.1.1, paragraph 1.

       The -textcharset switch specifies that all text/plain parts of the mes-
       sage(s)  should  be  converted to charset.  Charset conversions require
       that nmh be built with iconv(3); see the mhparam(1) man  page  for  how
       determine whether your nmh installation includes that.  To convert text
       parts other than text/plain, an external program can be used,  via  the
       -reformat switch.

       The  -reformat  switch  enables  a transformation for text parts in the
       message.  For each text part that is not text/plain and that  does  not
       have  a  corresponding  text/plain in a multipart/alternative part, mh-
       fixmsg looks for  a  mhfixmsg-format-text/subtype  profile  entry  that
       matches  the  subtype  of the part.  If one is found and can be used to
       successfully convert the part  to  text/plain,  mhfixmsg  inserts  that
       text/plain  part  at the beginning of the containing multipart/alterna-
       tive part, if present.  If  not,  it  creates  a  multipart/alternative
       part.

       With  the -reformat switch, multipart/related parts are handled differ-
       ently than multipart/alternative.  If the multipart/related has only  a
       single  part that is not text/plain and can be converted to text/plain,
       a text/plain part is added and the type of the part is changed to  mul-
       tipart/alternative.   If  the  multipart/related has more than one part
       but does not have a text/plain part, mhfixmsg tries to add one.

       The -replacetextplain switch broadens the applicability  of  -reformat,
       by always replacing a corresponding text/plain part, if one exists.  If
       -verbose is enabled, the replacement will be shown as two steps:  a re-
       moval  of the text/plain part, followed by the usual insertion of a new
       part.

       -reformat requires a profile entry for each text part subtype to be re-
       formatted.   The mhfixmsg-format-text/subtype profile entries are based
       on external conversion programs, and are used  in  the  same  way  that
       mhshow  uses  its  mhshow-show-text/subtype  entries.   When nmh is in-
       stalled, it searches for a conversion program  for  text/html  content,
       and  if  one  is  found,  inserts  a mhfixmsg-format-text/html entry in
       /etc/nmh/mhn.defaults.  An entry of the same name in the user's profile
       takes  precedence.  The user can add entries for other text subtypes to
       their profile.

       The -fixboundary switch enables a transformation to repair the boundary
       portion  of  the  Content-Type header field of the message to match the
       boundaries of the outermost multipart part of the message, if  it  does
       not.  That condition is indicated by a "bogus multipart content in mes-
       sage" error message from mhlist and other nmh programs that parse  MIME
       messages.

       The  -fixcte  switch  enables  a  transformation to change the Content-
       Transfer-Encoding from an invalid value to 8-bit in message parts  with
       a  Content-Type  of  multipart  and  message,  as required by RFC 2045,
       <section>6.4.  That condition is indicated by a  "must  be  encoded  in
       7bit, 8bit, or binary" error message from mhlist and other nmh programs
       that parse MIME messages.

       The -fixtype switch ensures that each part of the message has the  cor-
       rect  MIME  type shown in its Content-Type header.  It may be repeated.
       It is typically used to replace "application/octet-stream" with a  more
       descriptive  MIME  type.   It may not be used for multipart and message
       types.

       mhfixmsg applies two transformations unconditionally.   The  first  re-
       moves an extraneous trailing semicolon from the parameter lists of MIME
       header field values.  The second replaces RFC 2047  encoding  with  RFC
       2231  encoding of name and filename parameters in Content-Type and Con-
       tent-Disposition header field values, respectively.

       The -verbose switch directs mhfixmsg to  output  informational  message
       for each transformation applied.

       The  return status of mhfixmsg is 0 if all of the requested transforma-
       tions are performed, or non-zero otherwise.  (mhfixmsg will not  decode
       to  binary  content with the default -decodetext setting, but a request
       to do so is not considered a failure, and is noted with -verbose.)   If
       a  problem  is detected with any one of multiple messages such that the
       return status is non-zero, then none of the messages will be modified.

       The -file file switch directs mhfixmsg to use the specified file as the
       source message, rather than a message from a folder.  Only one file ar-
       gument may be provided.  The -file switch is implied if file is an  ab-
       solute  pathname.  If the file is "-", then mhfixmsg accepts the source
       message on the standard input stream.  If the -outfile  switch  is  not
       enabled when using the standard input stream, mhfixmsg will not produce
       a transformed output message.

       mhfixmsg, by default, transforms the message in place.  If the -outfile
       switch  is  enabled, then mhfixmsg does not modify the input message or
       file, but instead places its output in the specified file.  An  outfile
       name of "-" specifies the standard output stream.

       Combined  with  the -verbose switch, the -outfile switch can be used to
       show what transformations mhfixmsg would apply without actually  apply-
       ing them, e.g.,

            mhfixmsg -outfile /dev/null -verbose

       As  always,  this  usage obeys any mhfixmsg switches in the user's pro-
       file.

       -outfile can be combined with rcvstore to add a single transformed mes-
       sage to a different folder, e.g.,

            mhfixmsg -outfile - | \
            /usr/lib/mh/rcvstore +folder

   Summary of Applicability
       The  transformations  apply to the parts of a message depending on con-
       tent type and/or encoding as follows:

            -decodetext         base64 and quoted-printable encoded text parts
            -decodetypes        limits parts to which -decodetext applies
            -crlflinebreaks     text parts
            -textcharset        text/plain parts
            -reformat           text parts that are not text/plain
            -fixboundary        outermost multipart part
            -fixcte             multipart or message part
            -fixtype            all except multipart and message parts

   Backup of Original Message/File
       If it applies any transformations to a message or file, and  the  -out-
       file switch is not used, mhfixmsg backs up the original the same way as
       rmm.  That is, it uses the rmmproc profile component, if  present.   If
       not present, mhfixmsg moves the original message to a backup file.  The
       -rmmproc switch may be used to override this  profile  component.   The
       -normmproc switch disables the use of any rmmproc profile component and
       negates all prior -rmmproc switches.

   Integration with inc
       mhfixmsg   can   be   used   as   an   add-hook,   as   described    in
       /usr/share/doc/nmh/README-HOOKS.   Note  that add-hooks are called from
       all nmh programs that add a message to a folder, not just inc.   Alter-
       natively, a simple shell alias or function can be used to call mhfixmsg
       immediately after a successful invocation of inc.  One  approach  could
       be based on:

            msgs=`inc  -format  '%(msg)'`   &&  [ -n "$msgs" ]  &&  scan $msgs
            &&  mhfixmsg -nochangecur $msgs

       Another approach would rely on adding a  sequence  to  Unseen-Sequence,
       which  inc sets with the newly incorporated messages.  Those could then
       be supplied to mhfixmsg.  An example is shown below.

   Integration with procmail
       By way of example, here is an excerpt from a procmailrc file that  fil-
       ters  messages  through mhfixmsg before storing them in the user's nmh-
       workers folder.  It also stores the incoming  message  in  the  Backups
       folder in a filename generated by mkstemp, which is a non-POSIX utility
       to generate a temporary file.  Alternatively, mhfixmsg could be  called
       on the message after it is stored.

            PATH = /usr/bin/mh:$PATH
            LANG = en_US.utf8
            MAILDIR = `mhparam path`
            #### The Backups directory is relative to MAILDIR.
            MKSTEMP = 'mkstemp -directory Backups -prefix mhfixmsg'
            MHFIXMSG = 'mhfixmsg -noverbose -file - -outfile -'
            STORE = /usr/lib/mh/rcvstore

            :0 w: nmh-workers/procmail.$LOCKEXT
            * ^TOnmh-workers AT nongnu.org
            | tee `$MKSTEMP` | $MHFIXMSG | $STORE +nmh-workers

EXAMPLES
   Basic usage
       To  run mhfixmsg on the current message in the current folder, with de-
       fault transformations to fix MIME boundaries  and  Content-Transfer-En-
       coding,  to decode text and application/ics content parts to 8 bit, and
       to add a corresponding text/plain part where lacking:

              mhfixmsg -verbose

   Specified folder and messages
       To run mhfixmsg on specified messages, without its  informational  out-
       put:

              mhfixmsg +inbox last:4

   View without modification
       By default, mhfixmsg transforms the message in place.  To view the MIME
       structure that would result from running mhfixmsg on the  current  mes-
       sage, without modifying the message:

              mhfixmsg -outfile - | mhlist -file -

   Search message without modification
       To search the current message, which possibly contains base64 or quoted
       printable encoded text parts, without modifying it,  use  the  -outfile
       switch:

              mhfixmsg -outfile - | grep pattern

       -outfile  can  be  abbreviated  in  usual MH fashion, e.g., to -o.  The
       search will be on the entire message, not just text parts.

   Translate text/plain parts to UTF-8
       To translate all text/plain parts in the current message to  UTF-8,  in
       addition to all of the default transformations:

              mhfixmsg -textcharset utf-8

   Fix all messages in a folder
       To run mhfixmsg on all of the messages in a folder:

              mhfixmsg +folder all

       Alternatively,  mhfixmsg  can  be run on each message separately, e.g.,
       using a Bourne shell loop:

              for msg in `pick +folder`; do mhfixmsg +folder $msg; done

       The two appearances of the  +folder  switch  in  that  command  protect
       against concurrent context changes by other nmh command invocations.

   Run on newly incorporated messages
       To run mhfixmsg on messages as they are incorporated:

              inc  &&  mhfixmsg -nochangecur unseen

       This  assumes  that the Unseen-Sequence profile entry is set to unseen,
       as shown in mh-profile(5).

FILES
       mhfixmsg looks for mhn.defaults in multiple locations:  absolute  path-
       names  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
       /etc/nmh/mhn.defaults  Default mhfixmsg conversion entries

PROFILE COMPONENTS
       Path:                To determine the user's nmh directory
       Current-Folder:      To find the default current folder
       rmmproc:             Program to delete original messages or files

SEE ALSO
       iconv(3), inc(1), mh-mkstemp(1), mh-profile(5), mhbuild(1),  mhlist(1),
       mhparam(1), mhshow(1), procmail(1), procmailrc(5), rcvstore(1), rmm(1)

DEFAULTS
       `+folder' defaults to the current folder
       `msgs' defaults to cur
       `-decodetext 8bit'
       `-decodetypes text,application/ics'
       `-crlflinebreaks'
       `-notextcharset'
       `-reformat'
       `-noreplacetextplain'
       `-fixboundary'
       `-fixcte'
       `-changecur'
       `-noverbose'

CONTEXT
       If a folder is given, it will become the current folder.  The last mes-
       sage selected from a folder will become the current message, unless the
       -nochangecur  switch  is  enabled.   If the -file switch or an absolute
       pathname is used, the context will not be modified.

nmh-1.7.1                         2016-11-08                     MHFIXMSG(1mh)