MHFIXMSG(1)                 General Commands Manual                MHFIXMSG(1)



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
       /usr/local/lib/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/local/libexec/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/local/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/local/bin:$PATH
            MAILDIR = `mhparam path`
            MKTEMP = 'mktemp Backups/mhfixmsg.XXXXXXXX'
            MHFIXMSG = 'mhfixmsg -noverbose -file - -outfile -'
            STORE = /usr/local/libexec/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 "/usr/local/lib/nmh"
       is checked.

       $HOME/.mh_profile                The user profile
       /usr/local/lib/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.



nmh-1.6                         March 16, 2014                     MHFIXMSG(1)
