[mmh] / man / mhl.man1

.\"
.\" %nmhwarning%
.\"
.TH MHL %manext1% "%nmhdate%" MH.6.8 [%nmhversion%]
.SH NAME
mhl \- produce formatted listings of nmh messages
.SH SYNOPSIS
.HP 5
.na
.B mhl
.RB [ \-folder
.IR +folder ]
.RB [ \-form
.IR formfile ]
.RB [ \-width
.IR columns ]
.RB [ \-moreproc
.IR program ]
.RI [ files
.IR \&... ]
.RB [ \-version ]
.RB [ \-help ]
.ad
.SH DESCRIPTION
.B Mhl
is an
.B nmh
command for filtering and/or displaying text
messages.  It is the default method of displaying text messages for
.B nmh
(it is the default
.IR showproc ).
.PP
If
.B mhl
is outputting to a terminal, then
.B mhl
will
cause the
.I moreproc
to be placed between the terminal and
.BR mhl .
.PP
To override the default
.I moreproc
and the profile entry, use the
.B \-moreproc
.I program
switch.
.PP
The
.B \-width
.I width
switch sets the screen width.  This defaults to the value indicated by
.BR $TERMCAP ,
if appropriate, otherwise it defaults to 80.
.PP
The default format file used by
.B mhl
is called
.RI \*(lq mhl.format \*(rq.
.B mhl
will first search for this file in the user's
.B mmh
directory, and will then search in the directory
.IR %etcdir% .
This default
can be changed by using the
.B \-form
.I formatfile
switch.
Note: In contrast to any other
.B mmh
tool, the
.B \-form
switch does only take file names, but no format strings with a prepended
equal sign `='.
.PP
Finally, the
.B \-folder
.I +folder
switch sets the
.B nmh
folder name,
which is used for the \*(lqmessagename:\*(rq field described below.  The
environment variable
.B $mhfolder
is consulted for the default value,
which
.BR show ,
.BR next ,
and
.B prev
initialize appropriately.
.PP
.B Mhl
operates in two phases: 1) read and parse the format file, and
2) process each message (file).  During phase 1, an internal description
of the format is produced as a structured list.  In phase 2, this list
is walked for each message, outputting message information under the
format constraints from the format file.
.PP
The format file can contain information controlling
screen size, wrap\-around control, transparent text, component ordering,
and component formatting.  Also, a list of components to ignore may be
specified, and a couple of \*(lqspecial\*(rq components are defined
to provide added functionality.  Message output will be in the order
specified by the order in the format file.
.PP
Each line of a format file has one of the following forms:
.PP
.RS 5
.nf
;comment
:cleartext
variable[,variable...]
component:[variable,...]
.fi
.RE
.PP
.IP \(bu 4
A line beginning with a `;' is a comment, and is ignored.
.IP \(bu 4
A line beginning with a `:' is clear text, and is output exactly as is.
.IP \(bu 4
A line containing only a `:' produces a blank line in the output.
.IP \(bu 4
A line beginning with \*(lqcomponent:\*(rq defines the format for the specified
component,
.IP \(bu 4
Remaining lines define the global environment.
.PP
For example, the line:
.PP
.RS 5
width=80,overflowtext="***",overflowoffset=5
.RE
.PP
defines the screen size to be 80 columns by 40 rows, specifies that the
overflow indentation
is 5, and that overflow text should be flagged with \*(lq***\*(rq.
.PP
Following are all of the current variables and their arguments.  If they
follow a component, they apply only to that component, otherwise, their
affect is global.  Since the whole format is parsed before any output
processing, the last global switch setting for a variable applies to
the whole message if that variable is used in a global context (i.e.,
width).
.PP
.RS 5
.nf
.ta \w'xxxxxxxxxxxxx  'u +\w'integer/G  'u
.I variable     type    semantics
width   integer screen width or component width
length  integer component length
offset  integer positions to indent \*(lqcomponent: \*(rq
overflowtext    string  text to use at the beginning of an
                overflow line
overflowoffset  integer positions to indent overflow lines
compwidth       integer positions to indent component text
                after the first line is output
uppercase       flag    output text of this component in all
                upper case
nouppercase     flag    don't uppercase
component       string/L        name to use instead of \*(lqcomponent\*(rq for
                this component
nocomponent     flag    don't output \*(lqcomponent: \*(rq for this
                component
center  flag    center component on line (works for
                one\-line components only)
nocenter        flag    don't center
leftadjust      flag    strip off leading whitespace on each
                line of text
noleftadjust    flag    don't leftadjust
compress        flag    change newlines in text to spaces
nocompress      flag    don't compress
split   flag    don't combine multiple fields into
                a single field
nosplit flag    combine multiple fields into
                a single field
newline flag    print newline at end of components
                (this is the default)
nonewline       flag    don't print newline at end of components
formatfield     string  format string for this component
                (see below)
decode  flag    decode text as RFC-2047 encoded
                header field
addrfield       flag    field contains addresses
datefield       flag    field contains dates
.fi
.RE
.PP
To specify the value of integer\-valued and string\-valued variables,
follow their name with an equals\-sign and the value.  Integer\-valued
variables are given decimal values, while string\-valued variables
are given arbitrary text bracketed by double\-quotes.  If a value is
suffixed by \*(lq/G\*(rq or \*(lq/L\*(rq, then its value is useful in
a global\-only or local\-only context (respectively).
.PP
A line of the form:
.PP
.RS 5
ignores=component,...
.RE
.PP
specifies a list of components which are never output.
.PP
The component \*(lqMessageName\*(rq (case\-insensitive) will output the
actual message name (file name) preceded by the folder name if one is
specified or found in the environment.  The format is identical to that
produced by the
.B \-header
option to
.BR show .
.PP
The component \*(lqExtras\*(rq will output all of the components of the
message which were not matched by explicit components, or included in
the ignore list.  If this component is not specified, an ignore list is
not needed since all non\-specified components will be ignored.
.PP
If \*(lqnocomponent\*(rq is NOT specified, then the component name will
be output as it appears in the format file.
.PP
The default format file is:
.PP
.RS 5
.nf
%mhl_format%
.fi
.RE
.PP
The variable \*(lqformatfield\*(rq specifies a format string (see
.BR mh\-format (5)).
The flag variables \*(lqaddrfield\*(rq and
\*(lqdatefield\*(rq (which are mutually exclusive), tell
.B mhl
to interpret the escapes in the format string as either addresses or
dates, respectively.
.PP
By default,
.B mhl
does not apply any formatting string to fields
containing address or dates (see
.BR mh\-mail (5)
for a list of these
fields).  Note that this results in faster operation since
.B mhl
must parse both addresses and dates in order to apply a format string
to them.  If desired,
.B mhl
can be given a default format string for
either address or date fields (but not both).  To do this, on a global
line specify: either the flag addrfield or datefield, along with the
appropriate formatfield variable string.

.SH FILES
.fc ^ ~
.nf
.ta \w'%etcdir%/ExtraBigFileName  'u
^%etcdir%/mhl.format~^The message template
^or $HOME/.mmh/mhl.format~^Rather than the standard template
^$HOME/.mh/profile~^The user profile
.fi

.SH "PROFILE COMPONENTS"
.fc ^ ~
.nf
.ta 2.4i
.ta \w'ExtraBigProfileName  'u
^moreproc:~^Program to use as interactive front\-end
.fi

.SH "SEE ALSO"
show(1), ap(8), dp(8)

.SH DEFAULTS
.nf
.RB ` \-width 80 '
.fi

.SH CONTEXT
None

.SH BUGS
In contrast to any other
.B mmh
tool, the
.B \-form
switch does only take file names, but no format strings with a prepended
equal sign `='.
.PP
The \*(lqnonewline\*(rq option interacts badly with \*(lqcompress\*(rq
and \*(lqsplit\*(rq.