Provided by: nmh_1.8-1_amd64 bug

NAME

       mhl - produce formatted listings of nmh messages

SYNOPSIS

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

DESCRIPTION

       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 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 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 given 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 next, show, 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:

            ;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,length=40,clearscreen,overflowtext="***",overflowoffset=5

       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
                                      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
            rtrim          flag       trim whitespace at end of text lines
            nortrim        flag       retain whitespace at end of text
                                      lines (default)
            compress       flag       change newlines in text to spaces
            nocompress     flag       don't compress
            wrap           flag       Wrap lines that exceed width (default)
            nowrap         flag       Do not perform line wrapping
            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
            format         flag       Run component through formatproc filter
                                      (body only)
            noformat       flag       Do not run component through
                                      formatproc filter (default)
            formatarg      string     Argument to format filter

       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 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
            Resent-To:formatfield="%(unquote(decode{text}))"
            Resent-cc:formatfield="%(unquote(decode{text}))"
            Resent-From:formatfield="%(unquote(decode{text}))"
            Date:formatfield="%<(nodate{text})%{text}%|%(pretty{text})%>"
            To:formatfield="%(unquote(decode{text}))"
            cc:formatfield="%(unquote(decode{text}))"
            From:formatfield="%(unquote(decode{text}))"
            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.

       The “format” flag specifies that this component will be run  through  the  filter  program
       specified  by  the formatproc profile entry.  This filter program is expected to read data
       on standard input and output data on standard output.  Currently the “format” flag is only
       supported  for  the  “body”  component.  The component name will be prefixed to the output
       after the filter has been run.  The expected use of this is to filter a  message  body  to
       create  more  pleasing  text  to  use  in  a reply message.  A suggested filter to use for
       repl(1) is as follows:

            body:component=">",overflowtext=">",overflowoffset=0,format,nowrap

       The -fmtproc and -nofmtproc switches can be used to override the formatproc profile entry.

       The formatarg option specifies a string that is used as an argument to the format  filter.
       This  string  is processed by mh-format(5) and all of the message components are available
       for use.  Multiple formatarg options can be used to build up  multiple  arguments  to  the
       format filter.

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
       formatproc:          Program to use as a filter for components that
                            have the “format” flag set.

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' information to the front-end.

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

       The “format” option really should work on something other than the body component.