+.TH MH-FORMAT %manext5% "November 4, 2012" "%nmhversion%"
.\"
.\" %nmhwarning%
-.\" $Id$
.\"
-.TH MH-FORMAT %manext5% "%nmhdate%" MH.6.8 [%nmhversion%]
.SH NAME
mh-format \- format file for nmh message system
-.SH SYNOPSIS
-some
-.B nmh
-commands
.SH DESCRIPTION
Several
.B nmh
uses a format file which directs it
how to generate the reply to a message, and so on.
.PP
-Format strings are designed to be efficiently parsed by
-.B nmh
-which means they are not necessarily simple to write and understand.
-This means that novice, casual, or even advanced users of
-.B nmh
-should not have to deal with them.
-.PP
There are a few alternate scan listing formats available
in
-.IR %etcdir%/scan.time ,
-.IR %etcdir%/scan.size ,
+.IR nmh/etc/scan.time ,
+.IR nmh/etc/scan.size ,
and
-.IR %etcdir%/scan.timely .
+.IR nmh/etc/scan.timely .
Look in
-.I %etcdir%
+.I nmh/etc
for other
.B scan
and
routine is assumed.
.PP
A format string consists of ordinary text, and special multi-character
-escapesequences which begin with `%'. When specifying a format
+escape sequences which begin with `%'. When specifying a format
string, the usual C backslash characters are honored: `\\b', `\\f',
`\\n', `\\r', and `\\t'. Continuation lines in format files end with
`\\' followed by the newline character.
-
.\" TALK ABOUT SYNTAX FIRST, THEN SEMANTICS
.SS SYNTAX
+Format strings are built around
+.IR "escape sequences" .
There are three types of escape sequences: header
.IR components ,
built-in
.IR functions ,
and flow
.IR control .
+Comments may be inserted in most places where a function argument is
+not expected. A comment begins with `%;' and ends with a (non-escaped)
+newline.
.PP
A
.I component
compressed by converting any control characters (tab and newline included)
to spaces, then eliding any leading or multiple spaces. However, commands
may give different interpretations to some component escapes; be sure
-to refer to each command's manual entry for complete details.
+to refer to each command's manual entry for complete details. Some commands
+(such as
+.B ap
+and
+.BR mhl )
+use a special component
+.RI `%{ text }'
+to refer to the text being processed; see their respective man pages for
+details and examples.
.PP
A
.I function
escape is specified as
.RI `%( function )'.
All functions are built-in, and most have a string or numeric value.
-
-.SS "Control-flow escapes"
+A function escape may have an
+.IR argument .
+The argument follows the function escape: separating
+whitespace is discarded:
+.RI `%( function " " argument )'.
+.PP
+In addition to literal numbers or strings,
+the argument to a function escape can be another function, a component,
+or a control escape. When the argument is a function or a
+component, they are listed without a leading `%'. When control escapes
+are used as function arguments, they written as normally, with
+a leading `%';
+.SS "Control escapes"
+.PP
A
.I control
escape is one of: `%<', `%?', `%|', or `%>'.
.PP
.RS 5
.nf
-%<condition
-.RI " " "format text 1"
-%?condition2
-.RI " " "format text 2"
-%?condition3
-.RI " " "format text 3"
-\&...
-%|
-.RI " " "format text N"
+.RI "%< " condition " " "format-text"
+.RI "%? " condition " " "format-text"
+ \&...
+.RI "%| " "format-text"
%>
.fi
.RE
constructs may be nested without ambiguity. They form a general
.B if\-elseif\-else\-endif
block where only one of the
-.I format text
-segments is interpreted.
+format-texts
+is interpreted. In other
+words, `%<' is like the "if", `%?' is like the "elseif", `%|' is like
+"else", and `%>' is like "endif".
.PP
-The `%<' and `%?' control escapes causes a condition to be evaluated.
-This condition may be either a
+A `%<' or `%?' control escape causes its condition to be evaluated.
+This condition is a
.I component
-or a
+or
.IR function .
-The four constructs have the following syntax:
-.PP
-.RS 5
-.nf
-%<{component}
-%<(function)
-%?{component}
-%?(function)
-.fi
-.RE
-.PP
-These control escapes test whether the function or component value is
-non-zero (for integer-valued escapes), or non-empty (for string-valued
-escapes).
-.PP
-If this test evaulates true, then the format text up to the next
-corresponding control escape (one of `%|', `%?', or `%>') is interpreted
-normally. Next, all format text (if any) up to the corresponding `%>'
-control escape is skipped. The `%>' control escape is not interpreted;
-normal interpretation resumes after the `%>' escape.
-.PP
-If the test evaluates false, however, then the format text up to
-the next corresponding control escape (again, one of `%|', `%?', or
-`%>') is skipped, instead of being interpreted. If the control escape
-encountered was `%?', then the condition associated with that control
-escape is evaluated, and interpretation proceeds after that test as
-described in the previous paragraph. If the control escape encountered
-was `%|', then the format text up to the corresponding `%>' escape is
-interpreted normally. As above, the `%>' escape is not interpreted and
-normal interpretation resumes after the `%>' escape.
-.PP
-The `%?' control escape and its following format text is optional, and may
-be included zero or more times. The `%|' control escape and its following
-format text is also optional, and may be included zero or one times.
-
+For integer valued functions or components, the condition is true
+if the function return or component value is non-zero, and false if zero.
+For string valued functions or components, the condition is true
+if the function return or component value is
+a non-empty string, and false for an empty string.
+.PP
+The `%?' control escape is optional, and may there may be more
+than one `%?' control escape in a conditional block.
+The `%|' control escape
+is also optional, but may be included at most once.
.SS "Function escapes"
-Most functions expect an argument of a particular type:
+Functions expecting an argument generally
+require an argument of a particular type.
+In addition to the number and string types,
+these include:
.PP
.RS 5
.nf
.ta +\w'Argument 'u +\w'An optional component, 'u
-.I Argument Description Example Syntax
-literal A literal number, %(\fIfunc\fR 1234)
+.I "Argument Description Example Syntax"
+literal A literal number %(\fIfunc\fR 1234)
or string %(\fIfunc\fR text string)
-comp Any header component %(\fIfunc\fR\^{\fIin-reply-to\fR\^})
+comp Any component %(\fIfunc\fR\^{\fIin-reply-to\fR\^})
date A date component %(\fIfunc\fR\^{\fIdate\fR\^})
addr An address component %(\fIfunc\fR\^{\fIfrom\fR\^})
-expr An optional component, %(\fIfunc\fR\^(\fIfunc2\fR\^))
- function or control, %(\fIfunc\fR %<{\fIreply-to\fR\^}%|%{\fIfrom\fR\^}%>)
- perhaps nested %(\fIfunc\fR\^(\fIfunc2\fR\^{\fIcomp\fR\^}))
+expr Nothing %(\fIfunc\fR)
+ or a subexpression %(\fIfunc\fR\^(\fIfunc2\fR\^))
+ or control escape %(\fIfunc\fR %<{\fIreply-to\fR\^}%|%{\fIfrom\fR\^}%>)
.fi
.RE
.PP
but require that the header component be a date string, or address
string, respectively.
.PP
-All arguments except those of type
+Most arguments not of type
.IR expr
-are required. For the
-.I expr
-argument type, the leading `%' must be omitted for component
-and function escape arguments, and must be present (with a leading space)
-for control escape arguments.
-.PP
-The evaluation of format strings is based on a simple virtual machine
-with an integer register
+are required.
+When escapes are nested (via expr arguments), evaluation is done from inner-most to outer-most.
+As noted above, for the
+expr
+argument type,
+functions and components are written without a
+leading `%'.
+Control escape arguments must use a leading `%', preceded by a space.
+.PP
+For example,
+.PP
+.RS 5
+.nf
+%<(mymbox{from}) To: %{to}%>
+.fi
+.RE
+.PP
+writes the value of the header component \*(lqFrom:\*(rq to the
+internal register named str; then (\fImymbox\fR\^) reads str and
+writes its result to the internal register named
+.IR num ;
+then the control escape evaluates
+.IR num .
+If
.IR num
-, and a text string register
+is non-zero, the
+string \*(lqTo:\*(rq is printed followed by the value of the
+header component \*(lqTo:\*(rq.
+.SS Evaluation
+The evaluation of format strings is performed
+by a small virtual machine.
+The machine is capable of evaluating nested expressions
+as described above, and in addition
+has an integer register
+.IR num ,
+and a text string register
.IR str .
-When a function escape is processed, if it accepts an optional
-.I expr
-argument which is not present, it reads the current value of either
+When a function escape that
+accepts an optional argument is processed,
+and the argument is not present, the current value of either
.I num
or
.I str
-as appropriate.
-
-.SS "Return values"
+is used as the argument: which register is
+used depends on the function, as listed below.
+.PP
Component escapes write the value of their message header in
.IR str .
Function escapes write their return value in
.I str
for functions returning string values. (The boolean type is a subset
of integers with usual values 0=false and 1=true.) Control escapes
-return a boolean value, and set
-.IR num .
+return a boolean value, setting
+.I num
+to 1 if the last explicit condition
+evaluated by a `%<' or `%?' control
+succeeded, and 0 otherwise.
.PP
All component escapes, and those function escapes which return an
-integer or string value, pass this value back to their caller
-in addition to setting
-I str
+integer or string value, evaluate to their value as well as setting
+.I str
or
.IR num .
-These escapes will print
-out this value unless called as part of an argument to another escape
-sequence. Escapes which return a boolean value do pass this value
-back to their caller in
-.IR num ,
-but will never print out the value.
+Outermost escape expressions in
+these forms will print
+their value, but outermost escapes which return a boolean value
+do not result in printed output.
+.SS Functions
+The function escapes may be roughly grouped into a few categories.
.PP
.RS 5
.nf
-.ta \w'Formataddr 'u +\w'Argument 'u +\w'Rboolean 'u
-.I Function Argument Return Description
+.ta \w'Fformataddr 'u +\w'Aboolean 'u +\w'Rboolean 'u
+.I "Function Argument Result Description"
msg integer message number
-cur integer message is current
-unseen integer message is unseen
+cur integer message is current (0 or 1)
+unseen integer message is unseen (0 or 1)
size integer size of message
strlen integer length of \fIstr\fR
width integer output buffer size in bytes
charleft integer bytes left in output buffer
timenow integer seconds since the UNIX epoch
-me string the user's mailbox
+me string the user's mailbox (username)
+myhost string the user's local hostname
+myname string the user's name
+localmbox string the complete local mailbox
eq literal boolean \fInum\fR == \fIarg\fR
ne literal boolean \fInum\fR != \fIarg\fR
gt literal boolean \fInum\fR > \fIarg\fR
minus literal integer \fIarg\fR minus \fInum\fR
divide literal integer \fInum\fR divided by \fIarg\fR
modulo literal integer \fInum\fR modulo \fIarg\fR
-num literal integer Set \fInum\fR to \fIarg\fR
-lit literal string Set \fIstr\fR to \fIarg\fR
+num literal integer Set \fInum\fR to \fIarg\fR.
+num integer Set \fInum\fR to zero.
+lit literal string Set \fIstr\fR to \fIarg\fR.
+lit string Clear \fIstr\fR.
getenv literal string Set \fIstr\fR to environment value of \fIarg\fR
-profile literal string Set \fIstr\fR to profile component \fIarg\fR value
+profile literal string Set \fIstr\fR to profile component \fIarg\fR
+ value
.\" dat literal int return value of dat[arg]
nonzero expr boolean \fInum\fR is non-zero
zero expr boolean \fInum\fR is zero
compval comp integer Set \fInum\fR to \*(lq\fBatoi\fR(\fIcomp\fR\^)\*(rq
.\" compflag comp integer Set \fInum\fR to component flags bits (internal)
.\" decodecomp comp string Set \fIstr\fR to RFC-2047 decoded component text
-decode expr string decode \fIstr\fR as RFC-2047 component
+decode expr string decode \fIstr\fR as RFC-2047 (MIME-encoded)
+ component
+unquote expr string remove RFC-2822 quotes from \fIstr\fR
trim expr trim trailing white-space from \fIstr\fR
putstr expr print \fIstr\fR
putstrf expr print \fIstr\fR in a fixed width
putnum expr print \fInum\fR
putnumf expr print \fInum\fR in a fixed width
.\" addtoseq literal add msg to sequence (LBL option)
+putlit expr print \fIstr\fR without space compression
+zputlit expr print \fIstr\fR without space compression;
+ \fIstr\fR must occupy no width on display
+formataddr expr append \fIarg\fR to \fIstr\fR as a
+ (comma separated) address list
+concataddr expr append \fIarg\fR to \fIstr\fR as a
+ (comma separated) address list,
+ including duplicates,
+ see Special Handling
+putaddr literal print \fIstr\fR address list with
+ \fIarg\fR as optional label;
+ get line width from \fInum\fR
.fi
.RE
.PP
-These functions require a date component as an argument:
+The (\fIme\fR\^) function returns the username of the current user. The
+(\fImyhost\fR\^) function returns the
+.B localname
+entry in
+.IR mts.conf ,
+or the local hostname if
+.B localname
+is not configured. The (\fImyname\fR\^) function will return the value of
+the
+.B SIGNATURE
+environment variable if set, otherwise will return the passwd GECOS field
+(truncated at the first comma if it contains one) for
+the current user. The (\fIlocalmbox\fR\^) function will return the complete
+form of the local mailbox, suitable for use in a \*(lqFrom\*(rq header.
+It will return the
+.RI \*(lq Local-Mailbox \*(rq
+profile entry if it is set; if it is not, it will be equivalent to:
.PP
.RS 5
.nf
-.ta \w'Formataddr 'u +\w'Argument 'u +\w'Rboolean 'u
-.I Function Argument Return Description
+%(myname) <%(me)@%(myhost)>
+.fi
+.RE
+.PP
+The following functions require a date component as an argument:
+.PP
+.RS 5
+.nf
+.ta \w'Fformataddr 'u +\w'Aboolean 'u +\w'Rboolean 'u
+.I "Function Argument Return Description"
sec date integer seconds of the minute
min date integer minutes of the hour
hour date integer hours of the day (0-23)
day date string day of the week (abbrev.)
weekday date string day of the week
sday date integer day of the week known?
- (0=implicit,\-1=unknown)
+ (1=explicit,0=implicit,\-1=unknown)
mday date integer day of the month
yday date integer day of the year
mon date integer month of the year
zone date integer timezone in hours
tzone date string timezone string
szone date integer timezone explicit?
- (0=implicit,\-1=unknown)
+ (1=explicit,0=implicit,\-1=unknown)
date2local date coerce date to local timezone
date2gmt date coerce date to GMT
-dst date integer daylight savings in effect?
+dst date integer daylight savings in effect? (0 or 1)
clock date integer seconds since the UNIX epoch
rclock date integer seconds prior to current time
tws date string official 822 rendering
pretty date string user-friendly rendering
-nodate date integer \fIstr\fR not a date string
.fi
.RE
.PP
These functions require an address component as an argument.
-The return value of functions noted with `*' pertain only to
+The return value of functions noted with `*' is computed from
the first address present in the header component.
.PP
.RS 5
.nf
-.ta \w'Formataddr 'u +\w'Argument 'u +\w'Rboolean 'u
-.I Function Argument Return Description
+.ta \w'Fformataddr 'u +\w'Aboolean 'u +\w'Rboolean 'u
+.I "Function Argument Return Description"
proper addr string official 822 rendering
friendly addr string user-friendly rendering
addr addr string mbox@host or host!mbox rendering*
pers addr string the personal name*
note addr string commentary text*
mbox addr string the local mailbox*
-mymbox addr integer the user's addresses? (0=no,1=yes)
+mymbox addr integer List has the user's address? (0 or 1)
host addr string the host domain*
-nohost addr integer no host was present*
+nohost addr integer no host was present (0 or 1)*
type addr integer host type* (0=local,1=network,
\-1=uucp,2=unknown)
path addr string any leading host route*
-ingrp addr integer address was inside a group*
+ingrp addr integer address was inside a group (0 or 1)*
gname addr string name of group*
-formataddr expr append \fIarg\fR to \fIstr\fR as a
- (comma separated) address list
-putaddr literal print \fIstr\fR address list with
- \fIarg\fR as optional label;
- get line width from \fInum\fR
-.fi
-.RE
-.PP
-When escapes are nested, evaluation is done from inner-most to outer-most.
-The outer-most escape must begin with `%'; the inner escapes must not.
-For example,
-.PP
-.RS 5
-.nf
-%<(mymbox{from}) To: %{to}%>
.fi
.RE
.PP
-writes the value of the header component \*(lqFrom:\*(rq to
-.IR str ;
-then (\fImymbox\fR\^) reads
-.I str
-and writes its result to
-.IR num ;
-then the control escape evaluates
-.IR num .
-If
-.I num
-is non-zero, the string \*(lqTo:\*(rq is printed followed by the value of the header
-component \*(lqTo:\*(rq.
-.PP
-A minor explanation of (\fImymbox\fR\^{\fIcomp\fR\^}) is in order.
-In general, it checks each of the addresses in the header component
+(A clarification on (\fImymbox\fR\^{\fIcomp\fR\^}) is in order.
+This function checks each of the addresses in the header component
\*(lq\fIcomp\fR\*(rq against the user's mailbox name and any
.RI \*(lq Alternate-Mailboxes \*(rq.
It returns true if any address matches,
however, it also returns true if the \*(lq\fIcomp\fR\*(rq header is not
present in the message. If needed, the (\fInull\fR\^) function can be
-used to explicitly test for this condition.
-.PP
+used to explicitly test for this case.)
+.SS Formatting
When a function or component escape is interpreted and the result will
be immediately printed, an optional field width can be specified to
print the field in exactly a given number of characters. For example, a
with the fill character (normally, a blank). If the field width argument
begins with a leading zero, then the fill character is set to a zero.
.PP
-As above, the functions (\fIputnumf\fR\^) and (\fIputstrf\fR\^)
+The functions (\fIputnumf\fR\^) and (\fIputstrf\fR\^)
print their result in exactly the number of characters
specified by their leading field width argument. For example,
%06(\fIputnumf\fR\^(\fIsize\fR\^)) will print the message
component in fourteen characters with trailing spaces added as needed.
For \fIputstrf\fR, using a negative value for the field width causes
right-justification of the string within the field, with padding on
-the left up to the field width. The functions (\fIputnum\fR\^) and
-(\fIputstr\fR\^) print their result in the minimum number of characters
-required, and ignore any leading field width argument.
+the left up to the field width.
+The functions (\fIputnum\fR\^) and
+(\fIputstr\fR\^) are somewhat special: they print their result in the minimum number of characters
+required, and ignore any leading field width argument. The (\fIputlit\fR\^)
+function outputs the exact contents of the str register without any changes
+such as duplicate space removal or control character conversion.
+The (\fIzputlit\fR\^) function similarly outputs the exact contents of
+the str register, but requires that those contents not occupy any
+output width. It can therefore be used for outputting terminal escape
+sequences.
.PP
The available output width is kept in an internal register; any output
past this width will be truncated.
+.SS Special Handling
+A few functions have different behavior depending on what command they are
+being invoked from.
+.PP
+In
+.BR repl
+the (\fIformataddr\fR\^) function stores all email addresses encountered into
+an internal cache and will use this cache to suppress duplicate addresses.
+If you need to create an address list that includes previously-seen
+addresses you may use the (\fIconcataddr\fR\^) function, which is identical
+to (\fIformataddr\fR\^) in all other respects. Note that (\fIconcataddr\fR\^)
+will NOT add addresses to the duplicate-suppression cache.
+.SS Other Hints and Tips
+Sometimes to format function writers it is confusing as to why output is
+duplicated. The general rule to remember is simple: If a function or
+component escape is used where it starts with a %, then it will generate
+text in the output file. Otherwise, it will not.
+.PP
+A good example is a simple attempt to generate a To: header based on
+the From: and Reply-To: headers:
.PP
-Comments may be inserted in most places where a function argument is
-not expected. A comment begins with `%;' and ends with a (non-escaped)
-newline.
+.RS 5
+.nf
+%(formataddr %<{reply-to}%|%{from})%(putaddr To: )
+.fi
+.RE
+.PP
+Unfortuantely if the Reply-to: header is NOT present, the output line that is
+generated will be something like:
+.PP
+.RS 5
+.nf
+My From User <from@example.com>To: My From User <from@example.com>
+.fi
+.RE
.PP
+What went wrong? When performing the test for the
+.B if
+clause (%<), the component is not output because it is considered an
+argument to the
+.B if
+statement (hence the rule about the lack of % applies). But the component
+escape in our
+.B else
+statement (everything after the `%|') is NOT an argument to anything; the
+syntax is that it is written with a %, and thus the value of that component
+is output. This also has the side effect of setting the
+.I str
+register, which is later picked up by the (\fIformataddr\fR\^) function
+and then output by (\fIputaddr\fR\^). This format string has another bug
+as well; there should always be a valid width value in the
+.I num
+register when (\fIputaddr\fR\^) is called, otherwise bad formatting can take
+place.
+.PP
+The solution is to use the (\fIvoid\fR\^) function; this will prevent the
+function or component from outputting any text. With this in place (and
+using (\fIwidth\fR\^) to set the
+.I num
+register for the width, a better implementation would look like:
+.PP
+.RS 3
+.nf
+%(formataddr %<{reply-to}%|%(void{from})%(void(width))%(putaddr To: )
+.fi
+.RE
+.PP
+It should be noted here that the side-effects of functions and component
+escapes still are in force: as a result each component
+test in the
+.B if\-elseif\-else\-endif
+clause sets the
+.I str
+register.
+.PP
+As an additional note, the (\fIformataddr\fR\^) and (\fIconcataddr\fR\^)
+functions have some behavior when it comes to the
+.I str
+register. The starting point of the register is saved and is used to
+build up entries in the address list.
+.PP
+You will find the
+.B ap
+and
+.B fmtdump
+utilities invaluable in debugging problems with format strings.
+.SS Examples
With all this in mind,
here's the default format string for
.BR scan .
.fi
.RE
.PP
-which says that the message number should be printed in four digits,
-if the message is the current message then a `+' else a space should
-be printed, and if a \*(lqReplied:\*(rq field is present then a `\-'
+which says that the message number should be printed in four digits.
+If the message is the current message then a `+' else a space should
+be printed; if a \*(lqReplied:\*(rq field is present then a `\-'
else if an \*(lqEncrypted:\*(rq field is present then an `E' otherwise
a space should be printed. Next:
.PP
.PP
.RS 5
.nf
-%<{date} %|*>
+%<{date} %|*%>
.fi
.RE
.PP
.PP
.RS 5
.nf
-%<(mymbox{from})%<{to}To:%14(friendly{to})%>%>
+%<(mymbox{from})%<{to}To:%14(decode(friendly{to}))%>%>
.fi
.RE
.PP
-if the message is from me,
-and there is a \*(lqTo:\*(rq header,
-print `To:' followed by a \*(lquser-friendly\*(rq rendering of the
-first address in the \*(lqTo:\*(rq field.
+if the message is from me, and there is a \*(lqTo:\*(rq header,
+print \*(lqTo:\*(rq followed by a \*(lquser-friendly\*(rq rendering of the
+first address in the \*(lqTo:\*(rq field; any MIME-encoded
+characters are decoded into the actual characters.
Continuing,
.PP
.RS 5
.nf
-%<(zero)%17(friendly{from})%>
+%<(zero)%17(decode(friendly{from}))%>
.fi
.RE
.PP
if either of the above two tests failed,
then the \*(lqFrom:\*(rq address is printed
-in a \*(lquser-friendly\*(rq format.
+in a mime-decoded, \*(lquser-friendly\*(rq format.
And finally,
.PP
.RS 5
.nf
-%{subject}%<{body}<<%{body}%>
+%(decode{subject})%<{body}<<%{body}>>%>
.fi
.RE
.PP
-the subject and initial body (if any) are printed.
+the mime-decoded subject and initial body (if any) are printed.
.PP
For a more complicated example, next consider
-the default
+a possible
.I replcomps
format file.
.PP
switch was given to
.B repl
(see
-.BR repl (1)
+.IR repl (1)
for more details about %{\fIfcc\fR\^}),
an \*(lqFcc:\*(rq header is output.
.PP
.PP
.RS 5
.nf
-%<{date}In-reply-to: Your message of "\\
-%<(nodate{date})%{date}%|%(pretty{date})%>."%<{message-id}
- %{message-id}%>\\n%>\\
+%<{message-id}In-Reply-To: %{message-id}\\n%>\\
+%<{message-id}References: %<{references} %{references}%>\\
+%{message-id}\\n%>
\-\-\-\-\-\-\-\-
.fi
.RE
.PP
-If a date component was present, an \*(lqIn-Reply-To:\*(rq header is
-output with the preface \*(lqYour message of \*(rq. If the date was
-parseable, it is output in a user-friendly format, otherwise it is
-output as-is. The message-id is included if present. As with all
+If a message-id component was present, an \*(lqIn-Reply-To:\*(rq header is
+output including the message-id, followed by a \*(lqReferences:\*(rq
+header with references, if present, and the message-id.
+As with all
plain-text, the row of dashes are output as-is.
.PP
This last part is a good example for a little more elaboration.
.RS 5
.nf
.ta .5i 1i 1.5i 2i
-if (comp_exists(date)) then
- print (\*(lqIn-reply-to: Your message of \\\*(lq\*(rq)
- if (not_date_string(date.value) then
- print (date.value)
- else
- print (pretty(date.value))
- endif
- print (\*(lq\\\*(rq\*(rq)
- if (comp_exists(message-id)) then
- print (\*(lq\\n\\t\*(rq)
- print (message-id.value)
+if (comp_exists(message-id)) then
+ print (\*(lqIn-reply-to: \*(rq)
+ print (message-id.value)
+ print (\*(lq\\n\*(rq)
+endif
+if (comp_exists(message-id)) then
+ print (\*(lqReferences: \*(rq)
+ if (comp_exists(references)) then
+ print(references.value);
endif
+ print (message-id.value)
print (\*(lq\\n\*(rq)
endif
.fi
.RE
.PP
-Although this seems complicated,
-in point of fact,
-this method is flexible enough to extract individual fields and print them in
-any format the user desires.
-
+.\" (Note that this pseudocode begs the question ``why not just
+.\" support this syntax?'' MH has been hacked on for a long time...)
+.\".PP
+One more example: Currently,
+.B nmh
+supports very
+large message numbers, and it is not uncommon for a folder
+to have far more than 10000 messages.
+.\" (Indeed, the original MH
+.\" tutorial document by Rose and Romine is entitled "How to
+.\" process 200 messages a day and still get some real work
+.\" done." The authors apparently only planned to get
+.\" real work done for about 50 days per folder.)
+Nontheless (as noted above)
+the various scan format strings are inherited
+from older MH versions, and are generally hard-coded to 4
+digits of message number before formatting problems
+start to occur.
+The nmh format strings can be modified to behave more sensibly with larger
+message numbers:
+.PP
+.RS
+.nf
+%(void(msg))%<(gt 9999)%(msg)%|%4(msg)%>
+.fi
+.RE
+.PP
+The current message number is placed in \fInum\fP.
+(Note that
+.RI ( msg )
+is an int function, not a component.)
+The
+.RI ( gt )
+conditional
+is used to test whether the message number
+has 5
+or more digits.
+If so, it is printed at full width, otherwise
+at 4 digits.
.SH "SEE ALSO"
-scan(1), repl(1), ap(8), dp(8)
-
+.IR scan (1),
+.IR repl (1),
+.IR ap (8),
+.IR dp (8)
.SH CONTEXT
None
projects / mmh / blobdiff