.Dd January 17, 2021
.Dt MSHOW 1
.Os
.Sh NAME
.Nm mshow
.Nd render messages and extract MIME parts
.Sh SYNOPSIS
.Nm
.Op Fl h Ar headers
.Op Fl A Ar mimetypes
.Op Fl nqrBFHLN
.Op Ar msgs\ ...
.Nm
.Fl x Ar msg
.Ar parts\ ...
.Nm
.Fl O Ar msg
.Ar parts\ ...
.Nm
.Fl t
.Ar msgs\ ...
.Nm
.Fl R
.Ar msg
.Sh DESCRIPTION
.Nm
renders the specified
.Ar msgs
to the standard output, by default.
.Po
See
.Xr mmsg 7
for the message argument syntax.
.Pc
If used interactively and no
.Ar msgs
are specified,
.Nm
displays the current message using colorization and a pager.
.Pp
The options are as follows:
.Bl -tag -width Ds
.It Fl h Ar headers
Display the headers in the colon-separated list
.Ar headers ,
instead of the default headers
.Sq Li from\&:subject\&:to\&:cc\&:date\&:reply\&-to\&: .
.It Fl A Ar mimetypes
Define
.Sq Li "multipart/alternative"
preference.
.Ar mimetypes
is a colon-separated list of
MIME types which will be preferred,
in the order given,
when rendering
.Sq Li "multipart/alternative"
parts.
If no MIME type matches, the last MIME part will be rendered.
.Pp
When
.Ar mimetypes
is
.Sq Li all ,
.Nm
will render all parts of a
.Sq Li "multipart/alternative"
part.
.Pp
Defaults to
.Sq Li "text/plain:text/html" .
.It Fl n
Don't update the current message link.
.It Fl q
Don't render the body, stop after header output.
.It Fl r
Don't render the body, print raw body.
This may be dangerous to use on a tty.
.It Fl B
Decode encoded-words also in MIME parameters in direct violation
of RFC 2047.
This is useful if the attachment names look like
.Sq Li =?UTF-8?Q?stuff?= .
.It Fl F
Don't apply filters to MIME parts.
.It Fl H
Don't decode the headers, print all raw headers.
This may be dangerous to use on a tty.
.It Fl L
Don't filter the headers, print all decoded headers.
.It Fl N
Don't show MIME structure markers.
.It Fl x Ar msg
Switch to extraction mode: extract
.Ar parts
from the message
.Ar msg
into files.
.Ar parts
can be specified by number, filename or
.Xr fnmatch 3
pattern.
If no
.Ar parts
are specified, extracts all attachments with a filename.
.It Fl O Ar msg
Like
.Fl x
but write to standard output.
This may be dangerous to use on a tty.
When used together with
.Fl r ,
the whole part is raw,
that is,
un-decoded and including MIME part headers.
.It Fl t
Switch to list mode: list all MIME parts
of each
.Ar msg .
.It Fl R Ar msg
Render the text parts from
.Ar msg ,
suitable for use in a reply.
.El
.Sh FILTERS
.Nm ,
by default, decodes all
.Sq Li text/* ,
.Sq Li message/rfc822
and
.Sq Li multipart/*
parts,
and re-encodes them into UTF-8 if necessary.
.Pp
Other filters can be specified in the file
.Pa ${MBLAZE:-$HOME/.mblaze}/filter
.Po
or via
.Ev MAILFILTER
.Pc ,
in the format:
.Pp
.D1 Ar type/subtype Ns Li \&: Ar command
or
.D1 Ar type Ns Li \&: Ar command
.Pp
.Nm
will then spawn a pipe to
.Ar command ,
write the MIME part
to standard input
and display the output.
The environment variable
.Ev PIPE_CHARSET
will be set to the charset declared in the MIME part,
if known.
.Pp
Filters can communicate with
.Nm
using their exit status:
.Bl -tag -compact -width 8n
.It 0
The output is printed as plain text.
.It 62
The output is printed raw, without escaping.
.It 63
Behave as if the filter never ran.
.It 64
The output is an RFC 5322 message that should be rendered again.
.It 65 to 80
Render the
.Va n Ns \&- Ns 64th
part of this text/multipart part.
.El
All other exit statuses are regarded as errors.
.Sh ENVIRONMENT
.Bl -tag -width MBLAZE_NOCOLOR
.It Ev MAILFILTER
Path to an alternative
.Pa filter
file.
.It Ev MBLAZE_NOCOLOR
If non-empty,
.Nm
will not spawn a colorization filter.
.It Ev MBLAZE_PAGER
Any non-empty value of the environment variable
.Ev MBLAZE_PAGER
is used instead of the standard pagination program, specified in
.Ev PAGER .
When empty or set to
.Sq Ic cat ,
no pager is spawned.
.El
.Sh EXIT STATUS
.Ex -std
.Sh SEE ALSO
.Xr mmsg 7
.Sh AUTHORS
.An Leah Neukirchen Aq Mt leah@vuxu.org
.Sh LICENSE
.Nm
is in the public domain.
.Pp
To the extent possible under law,
the creator of this work
has waived all copyright and related or
neighboring rights to this work.
.Pp
.Lk http://creativecommons.org/publicdomain/zero/1.0/