Provided by: nmh_1.3-1build1_amd64 bug


       mhl - produce formatted listings of nmh messages


       /usr/lib/mh/mhl [-bell | -nobell] [-clear | -noclear] [-folder +folder] [-form formfile]
            [-length lines] [-width columns] [-moreproc program] [-nomoreproc] [files ...]
            [-version] [-help]


       Mhl  is  an  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 output, 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

       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 screen 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
       terminal,  then  mhl will cause the moreproc to be placed between the terminal and mhl and
       the switches are ignored.  Furthermore, 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,
       otherwise they default to 40 and 80, respectively.

       The  default  format  file  used by mhl is called “mhl.format”.  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 initialize 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:


       ·   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:


       defines the screen size to be 80 columns by 40 rows, specifies that the screen  should  be
       cleared  prior  to  each  page, 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., 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
            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:


       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 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

       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'

       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.


       /etc/nmh/mhl.format        The message template
       or <mh-dir>/mhl.format     Rather than the standard template
       $HOME/.mh_profile          The user profile


       moreproc:            Program to use as interactive front-end


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






       There should be some way to pass `bell' and `clear' information to the front-end.

       The “nonewline” option interacts badly with “compress” and “split”.