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MHFIXMSG(1)		    General Commands Manual		   MHFIXMSG(1)

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,
       A<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
       /usr/local/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,
       A<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/local/libexec/nmh/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/lo-
       cal/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/local/bin:$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/local/libexec/nmh/rcvstore

	    :0 w: nmh-workers/procmail.$LOCKEXT
	    * ^TOnmh-workers@nongnu.org
	    | tee `$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 "/usr/local/etc/nmh"
       is checked.

       $HOME/.mh_profile		The user profile
       /usr/local/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(1)

NAME | SYNOPSIS | DESCRIPTION | EXAMPLES | FILES | PROFILE COMPONENTS | SEE ALSO | DEFAULTS | CONTEXT

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