5 .\" include the -mh macro file
8 .TH MHL %manext1% "%nmhdate%" MH.6.8 [%nmhversion%]
10 mhl \- produce formatted listings of nmh messages
15 \%[\-bell] \%[\-nobell]
22 \%[\-length\ lines] \%[\-width\ columns]
23 \%[\-moreproc\ program]
31 \fIMhl\fR is a \fInmh\fR command for filtering and/or displaying text
32 messages. It is the default method of displaying text messages for
33 \fInmh\fR (it is the default \fIshowproc\fR).
35 As with \fImore\fR, each of the messages specified as arguments (or
36 the standard input) will be output. If more than one message file is
37 specified, the user will be prompted prior to each one, and a <RETURN>
38 or <EOT> will begin the output, with <RETURN> clearing the screen (if
39 appropriate), and <EOT> (usually CTRL\-D) suppressing the screen clear.
40 An <INTERRUPT> (usually CTRL\-C) will abort the current message output,
41 prompting for the next message (if there is one), and a <QUIT> (usually
42 CTRL-\\) will terminate the program (without core dump).
44 The `\-bell' option tells \fImhl\fR to ring the terminal's bell at the
45 end of each page, while the `\-clear' option tells \fImhl\fR to clear the
46 scree at the end of each page (or output a formfeed after each message).
47 Both of these switches (and their inverse counterparts) take effect only
48 if the profile entry \fImoreproc\fR is defined but empty, and \fImhl\fR
49 is outputting to a terminal. If the \fImoreproc\fR entry is defined and
50 non-empty, and \fImhl\fR is outputting to a terminal, then \fImhl\fR will
51 cause the \fImoreproc\fR to be placed between the terminal and \fImhl\fR
52 and the switches are ignored. Furthermore, if the `\-clear' switch is
53 used and \fImhl's\fR output is directed to a terminal, then \fImhl\fR
54 will consult the \fB$TERM\fR and \fB$TERMCAP\fR environment variables
55 to determine the user's terminal type in order to find out how to clear
56 the screen. If the `\-clear' switch is used and \fImhl's\fR output is
57 not directed to a terminal (e.g., a pipe or a file), then \fImhl\fR will
58 send a formfeed after each message.
60 To override the default \fImoreproc\fR and the profile entry, use the
61 `\-moreproc\ program' switch. Note that \fImhl\fR will never start a
62 \fImoreproc\fR if invoked on a hardcopy terminal.
64 The `\-length\ length' and `\-width\ width' switches set the screen
65 length and width, respectively. These default to the values indicated
66 by \fB$TERMCAP\fR, if appropriate, otherwise they default to 40 and
69 The default format file used by \fImhl\fR is called \*(lqmhl.format\*(rq.
70 \fImhl\fR will first search for this file in the user's \fInmh\fR
71 directory, and will then search in the directory %etcdir%. This default
72 can be changed by using the `\-form\ formatfile' switch.
74 Finally, the `\-folder\ +folder' switch sets the \fInmh\fR folder name,
75 which is used for the \*(lqmessagename:\*(rq field described below. The
76 environment variable \fB$mhfolder\fR is consulted for the default value,
77 which \fIshow\fR, \fInext\fR, and \fIprev\fR initialize appropriately.
79 \fIMhl\fR operates in two phases: 1) read and parse the format file, and
80 2) process each message (file). During phase 1, an internal description
81 of the format is produced as a structured list. In phase 2, this list
82 is walked for each message, outputting message information under the
83 format constraints from the format file.
85 The format file can contain information controlling screen clearing,
86 screen size, wrap\-around control, transparent text, component ordering,
87 and component formatting. Also, a list of components to ignore may be
88 specified, and a couple of \*(lqspecial\*(rq components are defined
89 to provide added functionality. Message output will be in the order
90 specified by the order in the format file.
92 Each line of a format file has one of the following forms:
96 variable[,variable...]
97 component:[variable,...]
99 A line beginning with a `;' is a comment, and is ignored.
100 A line beginning with a `:' is clear text,
101 and is output exactly as is.
102 A line containing only a `:' produces a blank line in the output.
103 A line beginning with \*(lqcomponent:\*(rq defines the format for the specified
105 and finally, remaining lines define the global environment.
107 For example, the line:
110 width=80,length=40,clearscreen,overflowtext="***",overflowoffset=5
112 defines the screen size to be 80 columns by 40 rows, specifies that the
113 screen should be cleared prior to each page, that the overflow indentation
114 is 5, and that overflow text should be flagged with \*(lq***\*(rq.
116 Following are all of the current variables and their arguments. If they
117 follow a component, they apply only to that component, otherwise, their
118 affect is global. Since the whole format is parsed before any output
119 processing, the last global switch setting for a variable applies to
120 the whole message if that variable is used in a global context (i.e.,
121 bell, clearscreen, width, length).
125 .ta \w'noclearscreen 'u +\w'integer/G 'u
126 \fIvariable\fR \fItype\fR \fIsemantics\fR
127 width integer screen width or component width
128 length integer screen length or component length
129 offset integer positions to indent \*(lqcomponent: \*(rq
130 overflowtext string text to use at the beginning of an
132 overflowoffset integer positions to indent overflow lines
133 compwidth integer positions to indent component text
134 after the first line is output
135 uppercase flag output text of this component in all
137 nouppercase flag don't uppercase
138 clearscreen flag/G clear the screen prior to each page
139 noclearscreen flag/G don't clearscreen
140 bell flag/G ring the bell at the end of each page
141 nobell flag/G don't bell
142 component string/L name to use instead of \*(lqcomponent\*(rq for
144 nocomponent flag don't output \*(lqcomponent: \*(rq for this
146 center flag center component on line (works for
147 one\-line components only)
148 nocenter flag don't center
149 leftadjust flag strip off leading whitespace on each
151 noleftadjust flag don't leftadjust
152 compress flag change newlines in text to spaces
153 nocompress flag don't compress
154 split flag don't combine multiple fields into
156 nosplit flag combine multiple fields into
158 newline flag print newline at end of components
159 (this is the default)
160 nonewline flag don't print newline at end of components
161 formatfield string format string for this component
163 decode flag decode text as RFC-2047 encoded
165 addrfield flag field contains addresses
166 datefield flag field contains dates
171 To specify the value of integer\-valued and string\-valued variables,
172 follow their name with an equals\-sign and the value. Integer\-valued
173 variables are given decimal values, while string\-valued variables
174 are given arbitrary text bracketed by double\-quotes. If a value is
175 suffixed by \*(lq/G\*(rq or \*(lq/L\*(rq, then its value is useful in
176 a global\-only or local\-only context (respectively).
180 ignores=component,...
182 specifies a list of components which are never output.
184 The component \*(lqMessageName\*(rq (case\-insensitive) will output the
185 actual message name (file name) preceded by the folder name if one is
186 specified or found in the environment. The format is identical to that
187 produced by the `\-header' option to \fIshow\fR.
189 The component \*(lqExtras\*(rq will output all of the components of the
190 message which were not matched by explicit components, or included in
191 the ignore list. If this component is not specified, an ignore list is
192 not needed since all non\-specified components will be ignored.
194 If \*(lqnocomponent\*(rq is NOT specified, then the component name will
195 be output as it appears in the format file.
197 The default format file is:
203 .so %etcdir%/mhl.format
208 The variable \*(lqformatfield\*(rq specifies a format string (see
209 \fImh\-format\fR\0(5)). The flag variables \*(lqaddrfield\*(rq and
210 \*(lqdatefield\*(rq (which are mutually exclusive), tell \fImhl\fR
211 to interpret the escapes in the format string as either addresses or
214 By default, \fImhl\fR does not apply any formatting string to fields
215 containing address or dates (see \fImh\-mail\fR\0(5) for a list of these
216 fields). Note that this results in faster operation since \fImhl\fR
217 must parse both addresses and dates in order to apply a format string
218 to them. If desired, \fImhl\fR can be given a default format string for
219 either address or date fields (but not both). To do this, on a global
220 line specify: either the flag addrfield or datefield, along with the
221 appropriate formatfield variable string.
223 ^%etcdir%/mhl.format~^The message template
224 ^or <mh\-dir>/mhl.format~^Rather than the standard template
225 ^$HOME/\&.mh\(ruprofile~^The user profile
227 ^moreproc:~^Program to use as interactive front\-end
229 show(1), ap(8), dp(8)
241 There should be some way to pass `bell' and `clear' information to the
244 The \*(lqnonewline\*(rq option interacts badly with \*(lqcompress\*(rq