# mhl(1) - man - phpMan [MHL(1mh)](https://www.chedong.com/phpMan.php/man/MHL/1mh/markdown) [MHL(1mh)](https://www.chedong.com/phpMan.php/man/MHL/1mh/markdown) ## 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 or will begin the output, with clearing the screen (if ap‐ propriate), and (usually CTRL-D) suppressing the screen clear. An (usually CTRL-C) will abort the current message output, prompting for the next message (if there is one), and a (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 ter 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 ig‐ nored. 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 ter‐ minal 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 de‐ fault can be changed by using the **-form** _formatfile_ switch. Finally, the **-folder** _+folder_ switch sets the **nmh** folder name, which is used for the “message‐ name:” field described below. The environment variable **$mhfolder** is consulted for the de‐ fault 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 (respec‐ tively). 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 for‐ mat 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 Date:formatfield="%<(nodate{text})%{text}%|%(pretty{text})%>" To: cc: 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)](https://www.chedong.com/phpMan.php/man/mh-format/5/markdown)). 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)](https://www.chedong.com/phpMan.php/man/mh-mail/5/markdown) 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 speci‐ fied by the _formatproc_ profile entry. This filter program is expected to read data on stan‐ dard 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)](https://www.chedong.com/phpMan.php/man/repl/1/markdown)_ 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)](https://www.chedong.com/phpMan.php/man/mh-format/5/markdown) 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 /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)](https://www.chedong.com/phpMan.php/man/show/1/markdown), [_ap_(8)](https://www.chedong.com/phpMan.php/man/ap/8/markdown), [_dp_(8)](https://www.chedong.com/phpMan.php/man/dp/8/markdown) ## 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. nmh-1.7.1 2014-09-15 [MHL(1mh)](https://www.chedong.com/phpMan.php/man/MHL/1mh/markdown)