1MHL(1) [nmh-1.3] MHL(1)
2
6 mhl - produce formatted listings of nmh messages
7
9 /usr/libexec/nmh/mhl [-bell | -nobell] [-clear | -noclear] [-folder
10 +folder] [-form formfile] [-length lines] [-width columns] [-more‐
11 proc program] [-nomoreproc] [files ...] [-version] [-help]
12
14 Mhl is an nmh command for filtering and/or displaying text messages.
15 It is the default method of displaying text messages for nmh (it is the
16 default showproc).
17 As with more, each of the messages specified as arguments (or the stan‐
19 dard input) will be output. If more than one message file is speci‐
20 fied, the user will be prompted prior to each one, and a <RETURN> or
21 <EOT> will begin the output, with <RETURN> clearing the screen (if
22 appropriate), and <EOT> (usually CTRL-D) suppressing the screen clear.
23 An <INTERRUPT> (usually CTRL-C) will abort the current message output,
24 prompting for the next message (if there is one), and a <QUIT> (usually
25 CTRL-\) will terminate the program (without core dump).
26 The -bell option tells mhl to ring the terminal's bell at the end of
28 each page, while the -clear option tells mhl to clear the screen at the
29 end of each page (or output a formfeed after each message). Both of
30 these switches (and their inverse counterparts) take effect only if the
31 profile entry moreproc is defined but empty, and mhl is outputting to a
32 terminal. If the moreproc entry is defined and non-empty, and mhl is
33 outputting to a terminal, then mhl will cause the moreproc to be placed
34 between the terminal and mhl and the switches are ignored. Further‐
35 more, if the -clear switch is used and mhl's output is directed to a
36 terminal, then mhl will consult the $TERM and $TERMCAP environment
37 variables to determine the user's terminal type in order to find out
38 how to clear the screen. If the -clear switch is used and mhl's output
39 is not directed to a terminal (e.g., a pipe or a file), then mhl will
40 send a formfeed after each message.
41 To override the default moreproc and the profile entry, use the -more‐
43 proc program switch. Note that mhl will never start a moreproc if
44 invoked on a hardcopy terminal.
45 The -length length and -width width switches set the screen length and
47 width, respectively. These default to the values indicated by $TERM‐
48 CAP, if appropriate, otherwise they default to 40 and 80, respectively.
49 The default format file used by mhl is called “mhl.format”. mhl will
51 first search for this file in the user's nmh directory, and will then
52 search in the directory /etc/nmh. This default can be changed by using
53 the -form formatfile switch.
54 Finally, the -folder +folder switch sets the nmh folder name, which is
56 used for the “messagename:” field described below. The environment
57 variable $mhfolder is consulted for the default value, which show,
58 next, and prev initialize appropriately.
59 Mhl operates in two phases: 1) read and parse the format file, and 2)
61 process each message (file). During phase 1, an internal description
62 of the format is produced as a structured list. In phase 2, this list
63 is walked for each message, outputting message information under the
64 format constraints from the format file.
65 The format file can contain information controlling screen clearing,
67 screen size, wrap-around control, transparent text, component ordering,
68 and component formatting. Also, a list of components to ignore may be
69 specified, and a couple of “special” components are defined to provide
70 added functionality. Message output will be in the order specified by
71 the order in the format file.
72 Each line of a format file has one of the following forms:
74 ;comment
76 :cleartext
77 variable[,variable...]
78 component:[variable,...]
79 · A line beginning with a `;' is a comment, and is ignored.
81 · A line beginning with a `:' is clear text, and is output exactly as
83 is.
84 · A line containing only a `:' produces a blank line in the output.
86 · A line beginning with “component:” defines the format for the spec‐
88 ified component,
89 · Remaining lines define the global environment.
91 For example, the line:
93 width=80,length=40,clearscreen,overflowtext="***",overflowoffset=5
95 defines the screen size to be 80 columns by 40 rows, specifies that the
97 screen should be cleared prior to each page, that the overflow indenta‐
98 tion is 5, and that overflow text should be flagged with “***”.
99 Following are all of the current variables and their arguments. If
101 they follow a component, they apply only to that component, otherwise,
102 their affect is global. Since the whole format is parsed before any
103 output processing, the last global switch setting for a variable
104 applies to the whole message if that variable is used in a global con‐
105 text (i.e., bell, clearscreen, width, length).
106 variable type semantics
108 width integer screen width or component width
109 length integer screen length or component length
110 offset integer positions to indent “component: ”
111 overflowtext string text to use at the beginning of an
112 overflow line
113 overflowoffset integer positions to indent overflow lines
114 compwidth integer positions to indent component text
115 after the first line is output
116 uppercase flag output text of this component in all
117 upper case
118 nouppercase flag don't uppercase
119 clearscreen flag/G clear the screen prior to each page
120 noclearscreen flag/G don't clearscreen
121 bell flag/G ring the bell at the end of each page
122 nobell flag/G don't bell
123 component string/L name to use instead of “component” for
124 this component
125 nocomponent flag don't output “component: ” for this
126 component
127 center flag center component on line (works for
128 one-line components only)
129 nocenter flag don't center
130 leftadjust flag strip off leading whitespace on each
131 line of text
132 noleftadjust flag don't leftadjust
133 compress flag change newlines in text to spaces
134 nocompress flag don't compress
135 split flag don't combine multiple fields into
136 a single field
137 nosplit flag combine multiple fields into
138 a single field
139 newline flag print newline at end of components
140 (this is the default)
141 nonewline flag don't print newline at end of components
142 formatfield string format string for this component
143 (see below)
144 decode flag decode text as RFC-2047 encoded
145 header field
146 addrfield flag field contains addresses
147 datefield flag field contains dates
148 To specify the value of integer-valued and string-valued variables,
150 follow their name with an equals-sign and the value. Integer-valued
151 variables are given decimal values, while string-valued variables are
152 given arbitrary text bracketed by double-quotes. If a value is suf‐
153 fixed by “/G” or “/L”, then its value is useful in a global-only or
154 local-only context (respectively).
155 A line of the form:
157 ignores=component,...
159 specifies a list of components which are never output.
161 The component “MessageName” (case-insensitive) will output the actual
163 message name (file name) preceded by the folder name if one is speci‐
164 fied or found in the environment. The format is identical to that pro‐
165 duced by the -header option to show.
166 The component “Extras” will output all of the components of the message
168 which were not matched by explicit components, or included in the
169 ignore list. If this component is not specified, an ignore list is not
170 needed since all non-specified components will be ignored.
171 If “nocomponent” is NOT specified, then the component name will be out‐
173 put as it appears in the format file.
174 The default format file is:
176 ; mhl.format
178 ;
179 ; default message filter for `show'
180 ;
181 :
182 overflowtext="***",overflowoffset=5
183 leftadjust,compwidth=9
184 ignores=msgid,message-id,received,content-type,content-transfer-encoding,content-id
185 Date:formatfield="%<(nodate{text})%{text}%|%(pretty{text})%>"
186 To:
187 cc:
188 From:decode
189 Subject:decode
190 :
191 extras:nocomponent
192 :
193 body:nocomponent,overflowtext=,overflowoffset=0,noleftadjust
194 The variable “formatfield” specifies a format string (see mh-for‐
196 mat(5)). The flag variables “addrfield” and “datefield” (which are
197 mutually exclusive), tell mhl to interpret the escapes in the format
198 string as either addresses or dates, respectively.
199 By default, mhl does not apply any formatting string to fields contain‐
201 ing address or dates (see mh-mail(5) for a list of these fields). Note
202 that this results in faster operation since mhl must parse both
203 addresses and dates in order to apply a format string to them. If
204 desired, mhl can be given a default format string for either address or
205 date fields (but not both). To do this, on a global line specify:
206 either the flag addrfield or datefield, along with the appropriate for‐
207 matfield variable string.
208
211 /etc/nmh/mhl.format The message template
212 or <mh-dir>/mhl.format Rather than the standard template
213 $HOME/.mh_profile The user profile
214
217 moreproc: Program to use as interactive front-end
218
221 show(1), ap(8), dp(8)
222
225 `-bell'
226 `-noclear'
227 `-length40'
228 `-width80'
229
232 None
233
236 There should be some way to pass `bell' and `clear' information to the
237 front-end.
238 The “nonewline” option interacts badly with “compress” and “split”.
240MH.6.8 1 June 2008 MHL(1)