xenial (1) mhfixmsg.1mh.gz

Provided by: nmh_1.6-8build1_amd64 bug

NAME

       mhfixmsg - rewrite MIME messages with various transformations

SYNOPSIS

       mhfixmsg [+folder] [msgs | absolute pathname | -file file] [-decodetext 8bit/7bit | -nodecodetext]
            [-textcharset charset | -notextcharset] [-reformat | -noreformat] [-replacetextplain |
            -noreplacetextplain] [-fixboundary | -nofixboundary] [-fixcte | -nofixcte] [-outfile outfile]
            [-rmmproc program] [-normmproc] [-verbose | -noverbose] [-version] [-help]

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.

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

       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  -textcharset  switch  specifies  that  all text/plain parts of the message(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,
       mhfixmsg 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/alternative part, if present.   If  not,  it
       creates a multipart/alternative part.

       The  -replacetextplain switch broadens the applicability of -reformat by always replacing a corresponding
       text/plain part, if one exists.  If -verbose if enabled, the replacement will be shown as two  steps:   a
       removal 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 reformatted.  The mhfixmsg-format-
       text/subtype profile entries are based on external conversion programs, and are used the  same  way  that
       mhshow  uses  its  mhshow-show-text/subtype entries.  When nmh is installed, 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  message”  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 8bit in message parts with a Content-Type of multipart, 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 -verbose switch directs mhfixmsg to output informational message for each transformation applied.

       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 argument may be provided.  The -file switch is implied if file is
       an absolute 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 applying them, e.g.,

            mhfixmsg -outfile /dev/null -verbose

       As always, this usage obeys any mhfixmsg switches in the user's profile.

       -outfile can be combined with rcvstore to add a single transformed message 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 content type and/or encoding as follows:

            -decodetext   base64 and quoted-printable encoded text parts
            -textcharset  text/plain parts
            -reformat     text parts that are not text/plain
            -fixboundary  outermost multipart part
            -fixcte       multipart part

   Backup of Original Message/File
       If  it  applies  any  transformations to a message or file, and the -outfile 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.   Alternatively,  a
       simple  shell alias or function can be used to call mhfixmsg immediately after a successful invocation of
       inc.  For example, with bash:

            alias inc='inc && mhfixmsg'

   Integration with procmail
       By way of example, here is an excerpt from a procmailrc  file  that  filters  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 mktemp, which is a non-POSIX utility to generate a temporary file.   If
       you  do  not  have that utility, then the mkstemp(3) function could form the basis for a substitute.  Or,
       mhfixmsg could be called on the message after it is stored.

            PATH = /usr/bin/mh:$PATH
            MAILDIR = `mhparam path`
            MKTEMP = 'mktemp Backups/mhfixmsg.XXXXXXXX'
            MHFIXMSG = 'mhfixmsg -noverbose -file - -outfile -'
            STORE = /usr/lib/mh/rcvstore

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

FILES

       mhfixmsg looks for 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
       /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

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

DEFAULTS

       `+folder' defaults to the current folder
       `msgs' defaults to cur
       `-decodetext 8bit'
       `-notextcharset'
       `-reformat'
       `-noreplacetextplain'
       `-fixboundary'
       `-fixcte'
       `-noverbose'

CONTEXT

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