-.TH MHSHOW %manext1% "March 16, 2014" "%nmhversion%"
+.TH MHSHOW %manext1% "March 24, 2016" "%nmhversion%"
.\"
.\" %nmhwarning%
.\"
.HP 5
.na
.B mhshow
+.RB [ \-help ]
+.RB [ \-version ]
.RI [ +folder ]
.RI [ msgs ]
.RB [ \-file
.RB [ \-type
.IR content ]
\&...
+.RB [ \-prefer
+.IR content ]
+\&...
+.RB [ \-concat " | " \-noconcat ]
+.RB [ \-textonly " | " \-notextonly ]
+.RB [ \-inlineonly " | " \-noinlineonly ]
+.RB [ \-header " | " \-noheader ]
.RB [ \-form
.IR formfile ]
+.RB [ \-markform
+.IR formfile ]
.RB [ \-rcache
.IR policy ]
.RB [ \-wcache
.IR policy ]
.RB [ \-check " | " \-nocheck ]
-.RB [ \-version ]
-.RB [ \-help ]
.ad
.SH DESCRIPTION
The
.PP
By default
.B mhshow
-will display all parts of a multipart
-message. By using the
-.B \-part
+will display only text parts of a message that are not marked as attachments.
+This behavior can be changed by the
+.B \-notextonly
+and
+.B \-noinlineonly
+switches.
+In addition, by using the
+.BR \-part ,
+.BR \-type ,
and
+.B \-prefer
+switches, you may limit and reorder the set of parts to be displayed,
+based on part number and/or content type.
+The inclusion of any
+.B \-part
+or
.B \-type
-switches, you may
-limit the scope of
+switches will override the default settings of
+.B \-textonly
+and
+.BR \-inlineonly.
+.PP
+The
+.B \-header
+switch control whether
+.B mhshow
+will print a message separator header before each message that it
+displays. The header format can be controlled using
+.B \-headerform
+to specify a file containing
+.IR mh\-format (5)
+instructions. A copy of the built-in default
+headerform can be found in %nmhetcdir%/mhshow.header, for reference.
+In addition to the normal set of
+.IR mh\-format (5)
+instructions, a "%{folder}" escape provides a
+string representing the current folder.
+.PP
+By default
.B mhshow
-to particular subparts (of a
-multipart content) and/or particular content types.
+will concatenate all content under one pager. If you want each part to
+displayed separately, you can override the default behavior with
+.B \-noconcat.
.PP
The option
.B \-file
messages, see
.IR inc (1)).
.PP
+The
+.B \-part
+switch can be used (one or more times) to restrict the
+set of subparts that will be displayed. (Obviously with no
+.B \-part
+switches, all parts will be considered.) If a
+.B \-part
+switch specifies a specific subpart (i.e., a "leaf" in the tree of
+MIME parts), then that part will always be displayed. If a
+.B \-part
+switch references a multipart/alternative part, then (in
+the absence of a
+.B \-type
+switch) only the default subpart of that multipart will be displayed.
+.PP
A part specification consists of a series of numbers separated by dots.
For example, in a multipart content containing three parts, these
would be named as 1, 2, and 3, respectively. If part 2 was also a
multipart content containing two parts, these would be named as 2.1 and
2.2, respectively. Note that the
.B \-part
-switch is effective for only
+switch is effective only for
messages containing a multipart content. If a message has some other
kind of content, or if the part is itself another multipart content, the
.B \-part
switch will not prevent the content from being acted upon.
.PP
+The
+.B \-type
+switch can also be used to restrict (or, when used in conjunction with
+.BR \-part ,
+to further restrict) the display of parts according to content type.
+One or more
+.B \-type
+switches part will only select the first match
+from a multipart/alternative, even if there is more than one
+subpart that matches (one of) the given content type(s).
+.PP
+Using either
+.B \-part
+or
+.B -type
+switches alone will cause either to select
+the part(s) they match. Using them together will select only
+the part(s) matched by both (sets of) switches. In other
+words, the result is the intersection, and not the union, of their
+separate match results.
+.PP
A content specification consists of a content type and a subtype.
The initial list of \*(lqstandard\*(rq content types and subtypes can
be found in RFC 2046.
To specify a content, regardless of its subtype, just use the
name of the content, e.g., \*(lqaudio\*(rq. To specify a specific
subtype, separate the two with a slash, e.g., \*(lqaudio/basic\*(rq.
-Note that regardless of the values given to the `\-type' switch, a
+Note that regardless of the values given to the
+.B \-type
+switch, a
multipart content (of any subtype listed above) is always acted upon.
-Further note that if the `\-type' switch is used, and it is desirable to
-act on a message/external-body content, then the `\-type' switch must
+Further note that if the
+.B \-type
+switch is used, and it is desirable to
+act on a message/external-body content, then the
+.B \-type
+switch must
be used twice: once for message/external-body and once for the content
externally referenced.
+.PP
+In the absence of
+.BR \-prefer ,
+.B mhshow
+will select the "best" displayable subpart from
+multipart/alternative content. The
+.B \-prefer
+switch can be used (one or more times, in order of descending
+preference) to let MH know which content types from a
+multipart/alternative MIME part are preferred by the user, in order to
+override the default selection for display. For example, mail is
+often sent containing both plaintext and HTML-formatted versions of
+the same content, and the HTML version is usually indicated to be the
+"best" format for viewing. Using \*(lq-prefer text/plain\*(rq will
+cause the plaintext version to be displayed if possible, but still
+allow display of the HTML part if there is no plaintext subpart
+available. Using \*(lq-prefer text/plain -prefer image/png\*(rq
+would add a preference for PNG images, which might or might not
+ever appear in the same multipart/alternative section with text/plain.
+Implementation note: RFC 2046 requires that the subparts
+of a multipart/alternative be ordered according to "faithfulness to
+the original content", and MH by default selects the subpart ranked
+most "faithful" by that ordering. The
+.B \-prefer
+switch reorders the alternative parts (only internally, never changing
+the message file) to move the user's preferred part(s) to the "most
+faithful" position. Thus, when viewed by
+.BR mhlist ,
+the ordering of multipart/alternative parts will appear to change when
+invoked with or without various
+.B \-prefer
+switches.
.SS "Unseen Sequence"
If the profile entry \*(lqUnseen\-Sequence\*(rq is present and
non\-empty, then
command (part of the StarOffice package) can be used to display
Microsoft Word content, but it uses the suffix to determine how to display
the file. If no suffix is present, the file is not correctly loaded.
-Similarily, older versions of the
+Similarly, older versions of the
.B gs
command append a \*(lq.ps\*(rq suffix to
the filename if one was missing. As a result, these cannot be used to read
.IR iconv (3),
then all text/plain parts of the message(s) will be displayed using
the character set of the current locale. See the
-.BR mhparam (1)
+.IR mhparam (1)
man page for how determine whether your
.B nmh
installation includes
encounters a \*(lqcharset\*(rq parameter for
this content, it checks if your terminal can display this character
set natively.
-.B mhn
+.B mhshow
checks this by examining the current character set defined by the
.IR locale (1)
environment variables.
.fi
.RE
.PP
-need be present in this additional profile. Finally,
+need be present in this additional profile. Finally,
.B mhshow
-will attempt to consult one other additional user profile,
-e.g.,
+will attempt to consult
.PP
.RS 5
-%etcdir%/mhn.defaults
+%nmhetcdir%/mhn.defaults
.RE
.PP
which is created automatically during
.B nmh
installation.
+.PP
+See "Profile Lookup" in
+.IR mh-profile (5)
+for the profile search order, and for how duplicate entries are treated.
+.SS Content\-Type Marker
+.B mhshow
+will display a marker containing information about the part being displayed
+next. The default marker can be changed using the
+.B \-markform
+switch to specify a file containing
+.IR mh\-format (5)
+instructions to use when displaying the content marker. A copy of the
+default markform can be found in %nmhetcdir%/mhshow.marker, for
+reference. In addition to the normal set of
+.IR mh\-format (5)
+instructions, the following
+.I component
+escapes are supported:
+.PP
+.RS 5
+.nf
+.ta \w'cdispo-<PARAM> 'u +\w'Returns 'u
+.I "Escape Returns Description"
+part string MIME part number
+content\-type string MIME Content\-Type of part
+description string Content\-Description header
+disposition string Content disposition (attachment or inline)
+ctype-<PARAM> string Value of <PARAM> from Content\-Type header
+cdispo-<PARAM> string Value of <PARAM> from
+ Content\-Disposition header
+%(size) integer The size of the decoded part, in bytes
+%(unseen) boolean Returns true for suppressed parts
+.fi
+In this context, the %(unseen) function indicates whether
+.B mhshow
+has decided to not display a particular part due to the
+.B \-textonly
+or
+.B \-inlineonly
+switches.
+.RE
+All MIME parameters and the \*(lqContent-Description\*(rq header will have
+RFC 2231 decoding applied and be converted
+to the local character set.
+.PP
.SH FILES
.B mhshow
looks for all format files and mhn.defaults in multiple locations:
usernames, and files are searched for in the user's
.I Mail
directory as specified in their profile. If not found there, the directory
-.RI \*(lq %etcdir% \*(rq
+.RI \*(lq %nmhetcdir% \*(rq
is checked.
.PP
.fc ^ ~
.nf
-.ta \w'%etcdir%/ExtraBigFileName 'u
+.ta \w'%nmhetcdir%/ExtraBigFileName 'u
^$HOME/\&.mh\(ruprofile~^The user profile
^$MHSHOW~^Additional profile entries
-^%etcdir%/mhn.defaults~^System default MIME profile entries
-^%etcdir%/mhl.headers~^The headers template
+^%nmhetcdir%/mhn.defaults~^System default MIME profile entries
+^%nmhetcdir%/mhl.headers~^The headers template
+^%nmhetcdir%/mhshow.marker~^Example content marker
+^%nmhetcdir%/mhshow.header~^Example message separator header
.fi
.SH "PROFILE COMPONENTS"
.fc ^ ~
.RB ` +folder "' defaults to the current folder"
.RB ` msgs "' defaults to cur"
.RB ` \-nocheck '
+.RB ` \-concat '
+.RB ` \-textonly '
+.RB ` \-inlineonly '
.RB ` \-form\ mhl.headers '
.RB ` \-rcache\ ask '
.RB ` \-wcache\ ask '
projects / nmh / blobdiff