MHL(1mh)

NAME
mhl - produce formatted listings of mh messages

SYNOPSIS

mhl [-form formfile] [-width columns] [files ...] [-Version] [-help]

DESCRIPTION
Mhl is an mmh command for filtering and/or displaying text messages. It is the default method of displaying text messages for mmh (it is the default showproc).

The -width width switch sets the screen width. This defaults to the value indicated by $TERMCAP, if appropriate, otherwise it defaults to 80.

The default format file used by mhl is called `mhl.format'. mhl will first search for this file in the user's mmh directory, and will then search in the directory /etc/mmh. This default can be changed by using the -form formatfile switch. Note: In contrast to any other mmh tool, the -form switch does only take file names, but no format strings with a prepended equal sign `='.

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.

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 `special' components are defined to provide added functionality. Message output will be in the order specified by the order in the format file.

Each line of a format file has one of the following forms:

    ;comment
    :cleartext
    variable[,variable...]
    component:[variable,...]

•   A line beginning with a `;' is a comment, and is ignored.

•   A line beginning with a `:' is clear text, and is output exactly as is.

•   A line containing only a `:' produces a blank line in the output.

•   A line beginning with `component:' defines the format for the specified component,

•   Remaining lines define the global environment.

For example, the line:

    width=80,overflowtext="***",overflowoffset=5

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 `***'.

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).

    variable	type	semantics
    width	integer	screen width or component width
    length	integer	component length
    offset	integer	positions to indent `component: '
    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 `component' for
    		this component
    nocomponent	flag	don't output `component: ' 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
    rtrim	flag	trim whitespace at end of text lines
    nortrim	flag	retain whitespace at end of text lines (default)
    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

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 `/G' or `/L', then its value is useful in a global-only or local-only context (respectively).

A line of the form:

    ignores=component,...

specifies a list of components which are never output. This option supports some simple globbing, so a '*' at the end of a component will match for all components which start which the string. When you want to match a component which ends with a '*', you can escape the '*' with a '\'.

The component `MessageName' (case-insensitive) will output the message file name as a one-line header, similar to show. E.g. ``(Message 42)''

The component `Extras' 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.

If `nocomponent' is NOT specified, then the component name will be output as it appears in the format file.

The default format file is:

    ; mhl.format
    ;
    ; default message filter for `show'
    ;
    :
    overflowtext="***",overflowoffset=5
    leftadjust,compwidth=9
    ignores=msgid,message-id,received,content-type,content-transfer-encoding,content-id
    Date:formatfield="%<(nodate{text})%{text}%|%(pretty{text})%>"
    From:decode
    To:decode
    Cc:decode
    Subject:decode
    :
    extras:nocomponent
    :
    body:nocomponent,overflowtext=,overflowoffset=0,noleftadjust

The variable `formatfield' specifies a format string (see mh-format(5)). The flag variables `addrfield' and `datefield' (which are mutually exclusive), tell mhl to interpret the escapes in the format string as either addresses or dates, respectively.

By default, mhl does not apply any formatting string to fields containing address or dates (see mh-mail(5) for a list of these fields). Note that this results in faster operation since mhl must parse both addresses and dates in order to apply a format string to them. If desired, 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.

FILES
^/etc/mmh/mhl.format~^The message template
^or $HOME/.mmh/mhl.format~^Rather than the standard template
^$HOME/.mmh/profile~^The user profile

PROFILE COMPONENTS
none

SEE ALSO
show(1), ap(8), dp(8)

DEFAULTS
`-width 80'

CONTEXT
None

BUGS
In contrast to any other mmh tool, the -form switch does only take file names, but no format strings with a prepended equal sign `='.

The `nonewline' option interacts badly with `compress' and `split'.