MHL(1)
NAME
mhl - produce formatted listings of nmh messages
SYNOPSIS
/usr/lib/nmh/mhl [-bell] [-nobell] [-clear]
[-noclear] [-folder +folder] [-form formfile]
[-length lines] [-width columns] [-moreproc program]
[-nomoreproc] [files ...] [-version] [-help]
DESCRIPTION
Mhl is a nmh command for filtering and/or displaying text
messages. It is the default method of displaying text
messages for nmh (it is the default showproc).
As with more, each of the messages specified as arguments
(or the standard input) will be output. If more than one
message file is specified, the user will be prompted prior
to each one, and a <RETURN> or <EOT> will begin the out-
put, with <RETURN> clearing the screen (if appropriate),
and <EOT> (usually CTRL-D) suppressing the screen clear.
An <INTERRUPT> (usually CTRL-C) will abort the current
message output, prompting for the next message (if there
is one), and a <QUIT> (usually CTRL-\) will terminate the
program (without core dump).
The `-bell' option tells mhl to ring the terminal's bell
at the end of each page, while the `-clear' option tells
mhl to clear the scree at the end of each page (or output
a formfeed after each message). Both of these switches
(and their inverse counterparts) take effect only if the
profile entry moreproc is defined but empty, and mhl is
outputting to a terminal. If the moreproc entry is
defined and non-empty, and mhl is outputting to a termi-
nal, then mhl will cause the moreproc to be placed between
the terminal and mhl and the switches are ignored. Fur-
thermore, if the `-clear' switch is used and mhl's output
is directed to a terminal, then mhl will consult the $TERM
and $TERMCAP environment variables to determine the user's
terminal type in order to find out how to clear the
screen. If the `-clear' switch is used and mhl's output
is not directed to a terminal (e.g., a pipe or a file),
then mhl will send a formfeed after each message.
To override the default moreproc and the profile entry,
use the `-moreproc program' switch. Note that mhl will
never start a moreproc if invoked on a hardcopy terminal.
The `-length length' and `-width width' switches set the
screen length and width, respectively. These default to
the values indicated by $TERMCAP, if appropriate, other-
wise they default to 40 and 80, respectively.
The default format file used by mhl is called "mhl.for-
mat". mhl will first search for this file in the user's
nmh directory, and will then search in the directory
/etc/nmh. This default can be changed by using the
`-form formatfile' switch.
Finally, the `-folder +folder' switch sets the nmh folder
name, which is used for the "messagename:" field described
below. The environment variable $mhfolder is consulted
for the default value, which show, next, and prev initial-
ize appropriately.
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
clearing, 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 "compo-
nent:" defines the format for the specified component, and
finally, remaining lines define the global environment.
For example, the line:
width=80,length=40,clearscreen,overflow-
text="***",overflowoffset=5
defines the screen size to be 80 columns by 40 rows, spec-
ifies that the screen should be cleared prior to each
page, that the overflow indentation is 5, and that over-
flow text should be flagged with "***".
Following are all of the current variables and their argu-
ments. 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., bell, clearscreen, width, length).
variable type semantics
width integer screen width or component width
length integer screen length or 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
clearscreen flag/G clear the screen prior to each page
noclearscreen flag/G don't clearscreen
bell flag/G ring the bell at the end of each page
nobell flag/G don't bell
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
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.
The component "MessageName" (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 `-header'
option to show.
The component "Extras" will output all of the components
of the message which were not matched by explicit compo-
nents, 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})%>"
To:
cc:
From: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 "date-
field" (which are mutually exclusive), tell mhl to inter-
pret 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 apropriate formatfield variable string.
FILES
/etc/nmh/mhl.format The message template
or <mh-dir>/mhl.format Rather than the standard template
$HOME/.mh_profile The user profile
PROFILE COMPONENTS
moreproc: Program to use as interactive front-end
SEE ALSO
show(1) ap(8) dp(8)
DEFAULTS
`-bell'
`-noclear'
`-length 40'
`-width 80'
CONTEXT
None
BUGS
There should be some way to pass `bell' and `clear' infor-
mation to the front-end.
The "nonewline" option interacts badly with "compress" and
"split".