mhl.1mh

<B>Digital的Unix操作系统VAX 4.2源码</B>

.TH mhl 1mh
.SH Name
mhl \- produce formatted listings of MH messages
.SH Syntax
.B mhl
[
.I options
] [
.I "files..."
]
.\"
.\"
.\"
.\"
.SH Description
.NXR "mhl command"
.NXR "Listing formatted messages"
The 
.PN mhl
command is a program for listing formatted messages,
which can be used as a replacement for 
.PN more ,
the default 
.PN showproc 
program.
.PP
As with 
.PN more ,
each of the messages specified as arguments 
(or the standard input) are output.
If more than one message file is specified,
you are prompted prior to each one,
and a <RETURN> or <EOT> begins the output.
<RETURN> clears the screen (if appropriate),
and <EOT>, usually <CTRL/D>, suppresses the screen clear.
An <INTERRUPT>, usually <CTRL/C>, aborts the current message output,
prompting for the next message, if there is one.
A <QUIT>, usually <CTRL/E>, terminates the program 
without generating a core dump.
.PP
The
.PN mhl
command
operates in two phases:
it reads and parses the format file; 
then it processes each message (file).
During the first phase, an internal description 
of the format is produced as a structured list.
In the second phase, this list is traversed for each message,
and message information is output according to the instructions
contained in the format file.
.\"
.\"
.SS The Form File mhl.format
The 
.PN mhl.format
form file contains information controlling
screen clearing, screen size, wrap-around control, transparent text,
component ordering, and component formatting.
A list of components that should be ignored may also be specified,
and some special components are defined to provide added
functionality.
Message output is in the order specified by the order in the format file.
.PP
Each line of the 
.PN mhl.format 
file has one of the following formats:
.EX
     ;comment
     :cleartext
     variable[\fIvariable...\fP]
     component:[\fIvariable...\fP]
.EE
A line beginning with a semi colon (;) is a comment, and is ignored.
A line beginning with a colon (:) is clear text, 
and is output exactly as it is.
A line containing only a colon (:)
produces a blank line in the output.
A line beginning with \f(CWcomponent:\fR 
defines the format for the specified component.
Remaining lines define the global environment.
Examples of these are given below,
together with the system default form file.
.PP
If variables or arguments follow a component,
they apply only to that component; otherwise, 
their effect 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,
provided that the variable is used in a global context
(bell, clearscreen, width, length).
All of the current variables and their arguments
are shown in the following table:
.PP
.TS
tab(+);
l l l.
_
.sp 6p
Variable+Type+Semantics
.sp 6p
_
.sp 6p
width+integer+screen width or component width
length+integer+screen length or component length
offset+integer+positions to indent the 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+do not use uppercase
clearscreen+flag/G+clear the screen prior to each page
noclearscreen+flag/G+do not clear the screen
bell+flag/G+ring the bell at the end of each page
nobell+flag/G+disable bell
component+string/L+name to use instead of \f(CWcomponent\fR for
++this component
nocomponent+flag+do not output \f(CWcomponent: \fRfor this
++component
center+flag+center component on line (works for
++one-line components only)
nocenter+flag+do not center
leftadjust+flag+strip off leading white-space on each
++line of text
noleftadjust+flag+do not leftadjust
compress+flag+change newlines in text to spaces
nocompress+flag+do not compress
formatfield+string+format string for this component
addrfield+flag+field contains addresses
datefield+flag+field contains dates
.sp 6p
_
.TE
.PP
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 \f(CW/G\fR or \f(CW/L\fR,
then its value is useful in a global-only or local-only context
(respectively).
A line of the form:
.EX
    ignores=component,...
.EE
specifies a list of components which are never output.
.PP
The component \f(CWMessageName\fR
outputs 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 
.B \-header
option to
.PN show .
.PP
The component \f(CWExtras\fR outputs 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 are ignored.
.PP
If 
.B \-nocomponent
is not specified, then the component name is 
output as it appears in the format file.
.PP
The variable \f(CWformatfield\fR
specifies a format string; see 
.MS mh-format 5mh .
The variables \f(CWaddrfield\fR and \f(CWdatefield\fR,
which are mutually exclusive,
control the interpretation of the escapes.
.PP
By default,
.PN mhl
does not apply any formatting string to fields
containing address or dates; see 
.MS mh-mail 5mh
for a list of these fields.
This results in faster operation since 
.PN mhl
must parse both addresses and dates in order to apply a
format string to them.
If desired,
.PN 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 variable 
\f(CWaddrfield\fR or the variable \f(CWdatefield\fR,
along with the variable \f(CWformatfield\fR.
.\"
.\"
.\"
.\"
.SH Options
.IP \-bell 10
.PD 0
.IP \-nobell 10
.PD
Tells 
.PN mhl
to ring the terminal bell at the end of each page.
This is the default behavior.
You can suppress this by using the 
.B \-nobell
option.
.IP
This option takes effect only if the profile entry 
.PN moreproc
is defined but empty,
and if
.PN mhl
is outputting to a terminal.
If the 
.PN moreproc
entry is defined and non-empty,
and 
.PN mhl
is outputting to a terminal,
then 
.PN mhl
causes the 
.PN moreproc
to be placed between the
terminal and 
.PN mhl ,
and the switches are ignored.
.\"
.IP \-clear 10
.PD 0
.IP \-noclear 10
.PD 
Tells 
.PN mhl
to clear the screen at the end of
each page, or output a formfeed after each message.
You can suppress this by using the
.B \-noclear
option.
The default behavior is 
.BR \-noclear .
.IP
This option takes effect only if the profile entry 
.PN moreproc
is defined but empty,
and if
.PN mhl
is outputting to a terminal.
If the 
.PN moreproc
entry in the user's 
.PN \&.mh_profile 
is defined and non-empty, and 
.PN mhl
is outputting to a terminal,
then 
.PN mhl
causes the 
.PN moreproc
program to be placed between the terminal and 
.PN mhl ,
and the options are ignored.
.IP
If the 
.B \-clear
option is used and the output of
.PN mhl
is directed to a terminal,
then 
.PN mhl
consults the \f(CW$TERM\fR and \f(CW$TERMCAP\fR
environment variables to determine your terminal type 
in order to find out how to clear the screen.
If the 
.B \-clear
switch is used and the output of
.PN mhl
is not directed to a terminal 
(if, for example, it is directed to a pipe or a file),
then 
.PN mhl
sends a formfeed after each message.
.\"
.IP "\-folder \fI+foldername\fB" 10
Sets the folder name.
This is used by components in the 
.PN mhl.format 
form file to output the message name.
If you do not use this option,
.PN mhl 
consults the environmental variable \f(CW$mhfolder\fR.
.\"
.IP "\-form \fIformfile\fB" 10
Specifies the format file used.
If this option is not given, 
.PN mhl
searches in your Mail directory for a file called
.PN mhl.format ;
or, if this file does not exist,
it uses the system default file
.PN /usr/lib/mh/mhl.format .
.\"
.IP \-help 10
Prints a list of the valid options to this command.
.\"
.IP "\-length \fIlines\fB" 10
Sets the screen length.
This defaults to the value indicated by
.PN $TERMINFO , 
if appropriate; otherwise, it defaults to 40.
.\"
.IP "\-width \fIcolumns\fB" 10
Sets the screen width.
This defaults to the value indicated by
.PN $TERMINFO ,
if appropriate; otherwise, it defaults to 80.
.\"
.IP "\-moreproc \fIprogram\fB" 10
.PD 0
.IP "\-nomoreproc" 10
.PD
Overrides the default 
.PN moreproc
program.
Note that 
.PN mhl
never starts a 
.PN moreproc
if invoked on a
hardcopy terminal.
.\"
.\"
.PP
The defaults for this command are:
.IP
.B "\-bell"
.br
.B "\-noclear"
.br
.B "\-length 40"
.br
.B "\-width 80"
.\"
.\"
.\"
.\"
.\"
.SH Examples
The first example gives a typical line of a form file:
.EX
width=80,length=40,clearscreen,overflowtext="***",overflowoffset=5
.EE
The first two elements define the screen width to be 80 characters,
and the screen length to be 40 lines.
The next element, \f(CWclearscreen\fR, specifies that
the screen should be cleared prior to each page.
The next element, \f(CWoverflowoffset=5\fR, states that 
that the overflow indentation is 5.
The final element, \f(CWoverflowtext="***"\fR, specifies
that overflow text should be flagged with three asterisks.
.PP
The system default form file,
.PN /usr/lib/mh/mhl.format ,
is:
.EX
: \-\- using template mhl.format \- \-
overflowtext="***",overflowoffset=5
leftadjust,compwidth=9
ignores=msid,msgid,message-id,received
Date:formatfield="%<(nodate{text})%{text}%|%(pretty{text})%>"
To:
cc:
:
From:
Subject:
:
extras:nocomponent
:
body:nocomponent,overflowtext=,overflowoffset=0,noleftadjust
.EE
.\"
.\"
.\"
.\"
.SH Profile Components
.TS
tab(+);
l l.
Path:+To determine your Mail directory
moreproc:+Program to use as interactive front-end
.TE
.\"
.\"
.\"
.\"
.SH Files
.TP 10
.PN /usr/lib/mh/mhl.format
The system default form file, used to format message.
.TP 10
.PN <mh-dir>/mhl.format
The user-supplied alternate to the system default form file.
.TP 10
.PN $HOME/.mh_profile
The user profile.
.\"
.\"
.\"
.\"
.SH See Also
more(1), show(1mh), mh_profile(5mh), ap(8mh), dp(8mh)