2 .\" THIS FILE HAS BEEN AUTOMATICALLY GENERATED. DO NOT EDIT.
5 .TH MH-FORMAT %manext5% "%nmhdate%" MH.6.8 [%nmhversion%]
7 mh-format \- format file for nmh message system
11 commands utilize either a
15 file during their execution. For example,
17 uses a format string which directs it how to generate the scan listing
20 uses a format file which directs it
21 how to generate the reply to a message, and so on.
23 There are a few alternate scan listing formats available
25 .IR nmh/etc/scan.time ,
26 .IR nmh/etc/scan.size ,
28 .IR nmh/etc/scan.timely .
35 format files which may have been written at your site.
37 It suffices to have your local
39 expert actually write new format
40 commands or modify existing ones. This manual section explains how to
41 do that. Note: familiarity with the C
45 A format string consists of ordinary text, and special multi-character
46 escape sequences which begin with `%'. When specifying a format
47 string, the usual C backslash characters are honored: `\\b', `\\f',
48 `\\n', `\\r', and `\\t'. Continuation lines in format files end with
49 `\\' followed by the newline character.
51 .\" TALK ABOUT SYNTAX FIRST, THEN SEMANTICS
53 Format strings are built around
54 .IR "escape sequences" .
55 There are three types of escape sequences: header
61 Comments may be inserted in most places where a function argument is
62 not expected. A comment begins with `%;' and ends with a (non-escaped)
67 escape is specified as
70 exists for each header found in the message being processed. For example
72 refers to the \*(lqDate:\*(rq field of the appropriate message.
73 All component escapes have a string value. Normally, component values are
74 compressed by converting any control characters (tab and newline included)
75 to spaces, then eliding any leading or multiple spaces. However, commands
76 may give different interpretations to some component escapes; be sure
77 to refer to each command's manual entry for complete details.
81 escape is specified as
83 All functions are built-in, and most have a string or numeric value.
84 A function escape may have an
86 The argument follows the function escape: separating
87 whitespace is discarded:
88 .RI `%( function " " argument )'.
90 In addition to literal numbers or strings,
91 the argument to a function escape can be another function, a component,
92 or a control escape. When the argument is a function or a
93 component, they are listed without a leading `%'. When control escapes
94 are used as function arguments, they written as normally, with
101 escape is one of: `%<', `%?', `%|', or `%>'.
102 These are combined into the conditional execution construct:
106 .RI "%< " condition " " "format-text"
107 .RI "%? " condition " " "format-text"
109 .RI "%| " "format-text"
114 Extra white space is shown here only for clarity. These
115 constructs may be nested without ambiguity. They form a general
116 .B if\-elseif\-else\-endif
117 block where only one of the
119 is interpreted. In other
120 words, `%<' is like the "if", `%?' is like the "elseif", `%|' is like
121 "else", and `%>' is like "endif".
123 A `%<' or `%?' control escape causes its condition to be evaluated.
128 For integer valued functions or components, the condition is true
129 if the function return or component value is non-zero, and false if zero.
130 For string valued functions or components, the condition is true
131 if the function return or component value is
132 a non-empty string, and false for an empty string.
135 The `%?' control escape is optional, and may there may be more
136 than one `%?' control escape in a conditional block.
137 The `%|' control escape
138 is also optional, but may be included at most once.
140 .SS "Function escapes"
141 Functions expecting an argument generally
142 require an argument of a particular type.
143 In addition to the number and string types,
148 .ta +\w'Argument 'u +\w'An optional component, 'u
149 .I Argument Description Example Syntax
150 literal A literal number %(\fIfunc\fR 1234)
151 or string %(\fIfunc\fR text string)
152 comp Any component %(\fIfunc\fR\^{\fIin-reply-to\fR\^})
153 date A date component %(\fIfunc\fR\^{\fIdate\fR\^})
154 addr An address component %(\fIfunc\fR\^{\fIfrom\fR\^})
155 expr Nothing %(\fIfunc\fR)
156 or a subexpression %(\fIfunc\fR\^(\fIfunc2\fR\^))
157 or control escape %(\fIfunc\fR %<{\fIreply-to\fR\^}%|%{\fIfrom\fR\^}%>)
165 have the same syntax as
167 but require that the header component be a date string, or address
168 string, respectively.
170 Most arguments not of type
173 When escapes are nested (via expr arguments), evaluation is done from inner-most to outer-most.
174 As noted above, for the
177 functions and components are written without a
179 Control escape arguments must use a leading `%', preceded by a space.
185 %<(mymbox{from}) To: %{to}%>
189 writes the value of the header component \*(lqFrom:\*(rq to the
190 internal register named str; then (\fImymbox\fR\^) reads str and
191 writes its result to the internal register named
193 then the control escape evaluates
198 string \*(lqTo:\*(rq is printed followed by the value of the
199 header component \*(lqTo:\*(rq.
201 The evaluation of format strings is performed
202 by a small virtual machine.
203 The machine is capable of evaluating nested expressions
204 as described above, and in addition
205 has an integer register
207 and a text string register
209 When a function escape that
210 accepts an optional argument is processed,
211 and the argument is not present, the current value of either
215 is used as the argument: which register is
216 used depends on the function, as listed below.
218 Component escapes write the value of their message header in
220 Function escapes write their return value in
222 for functions returning integer or boolean values, and in
224 for functions returning string values. (The boolean type is a subset
225 of integers with usual values 0=false and 1=true.) Control escapes
226 return a boolean value, setting
228 to 1 if the last explicit condition
229 evaluated by a `%<' or `%?' control
230 succeeded, and 0 otherwise.
232 All component escapes, and those function escapes which return an
233 integer or string value, evaluate to their value as well as setting
237 Outermost escape expressions in
238 these forms will print
239 their value, but outermost escapes which return a boolean value
240 do not result in printed output.
242 The function escapes may be roughly grouped into a few categories.
246 .ta \w'Fformataddr 'u +\w'Aboolean 'u +\w'Rboolean 'u
247 .I Function Argument Result Description
248 msg integer message number
249 cur integer message is current (0 or 1)
250 unseen integer message is unseen (0 or 1)
251 size integer size of message
252 strlen integer length of \fIstr\fR
253 width integer output buffer size in bytes
254 charleft integer bytes left in output buffer
255 timenow integer seconds since the UNIX epoch
256 me string the user's mailbox
257 eq literal boolean \fInum\fR == \fIarg\fR
258 ne literal boolean \fInum\fR != \fIarg\fR
259 gt literal boolean \fInum\fR > \fIarg\fR
260 match literal boolean \fIstr\fR contains \fIarg\fR
261 amatch literal boolean \fIstr\fR starts with \fIarg\fR
262 plus literal integer \fIarg\fR plus \fInum\fR
263 minus literal integer \fIarg\fR minus \fInum\fR
264 divide literal integer \fInum\fR divided by \fIarg\fR
265 modulo literal integer \fInum\fR modulo \fIarg\fR
266 num literal integer Set \fInum\fR to \fIarg\fR.
267 num integer Set \fInum\fR to zero.
268 lit literal string Set \fIstr\fR to \fIarg\fR.
269 lit string Clear \fIstr\fR.
270 getenv literal string Set \fIstr\fR to environment value of \fIarg\fR
271 profile literal string Set \fIstr\fR to profile component \fIarg\fR
273 .\" dat literal int return value of dat[arg]
274 nonzero expr boolean \fInum\fR is non-zero
275 zero expr boolean \fInum\fR is zero
276 null expr boolean \fIstr\fR is empty
277 nonnull expr boolean \fIstr\fR is non-empty
278 void expr Set \fIstr\fR or \fInum\fR
279 comp comp string Set \fIstr\fR to component text
280 compval comp integer Set \fInum\fR to \*(lq\fBatoi\fR(\fIcomp\fR\^)\*(rq
281 .\" compflag comp integer Set \fInum\fR to component flags bits (internal)
282 .\" decodecomp comp string Set \fIstr\fR to RFC-2047 decoded component text
283 decode expr string decode \fIstr\fR as RFC-2047 (MIME-encoded)
285 trim expr trim trailing white-space from \fIstr\fR
286 putstr expr print \fIstr\fR
287 putstrf expr print \fIstr\fR in a fixed width
288 putnum expr print \fInum\fR
289 putnumf expr print \fInum\fR in a fixed width
290 .\" addtoseq literal add msg to sequence (LBL option)
291 nodate string integer Argument not a date string (0 or 1)
292 formataddr expr append \fIarg\fR to \fIstr\fR as a
293 (comma separated) address list
294 putaddr literal print \fIstr\fR address list with
295 \fIarg\fR as optional label;
296 get line width from \fInum\fR
300 The following functions require a date component as an argument:
304 .ta \w'Fformataddr 'u +\w'Aboolean 'u +\w'Rboolean 'u
305 .I Function Argument Return Description
306 sec date integer seconds of the minute
307 min date integer minutes of the hour
308 hour date integer hours of the day (0-23)
309 wday date integer day of the week (Sun=0)
310 day date string day of the week (abbrev.)
311 weekday date string day of the week
312 sday date integer day of the week known?
313 (1=explicit,0=implicit,\-1=unknown)
314 mday date integer day of the month
315 yday date integer day of the year
316 mon date integer month of the year
317 month date string month of the year (abbrev.)
318 lmonth date string month of the year
319 year date integer year (may be > 100)
320 zone date integer timezone in hours
321 tzone date string timezone string
322 szone date integer timezone explicit?
323 (1=explicit,0=implicit,\-1=unknown)
324 date2local date coerce date to local timezone
325 date2gmt date coerce date to GMT
326 dst date integer daylight savings in effect? (0 or 1)
327 clock date integer seconds since the UNIX epoch
328 rclock date integer seconds prior to current time
329 tws date string official 822 rendering
330 pretty date string user-friendly rendering
334 These functions require an address component as an argument.
335 The return value of functions noted with `*' is computed from
336 the first address present in the header component.
340 .ta \w'Fformataddr 'u +\w'Aboolean 'u +\w'Rboolean 'u
341 .I Function Argument Return Description
342 proper addr string official 822 rendering
343 friendly addr string user-friendly rendering
344 addr addr string mbox@host or host!mbox rendering*
345 pers addr string the personal name*
346 note addr string commentary text*
347 mbox addr string the local mailbox*
348 mymbox addr integer List has the user's address? (0 or 1)
349 host addr string the host domain*
350 nohost addr integer no host was present (0 or 1)*
351 type addr integer host type* (0=local,1=network,
353 path addr string any leading host route*
354 ingrp addr integer address was inside a group (0 or 1)*
355 gname addr string name of group*
359 (A clarification on (\fImymbox\fR\^{\fIcomp\fR\^}) is in order.
360 This function checks each of the addresses in the header component
361 \*(lq\fIcomp\fR\*(rq against the user's mailbox name and any
362 .RI \*(lq Alternate-Mailboxes \*(rq.
363 It returns true if any address matches,
364 however, it also returns true if the \*(lq\fIcomp\fR\*(rq header is not
365 present in the message. If needed, the (\fInull\fR\^) function can be
366 used to explicitly test for this case.)
368 When a function or component escape is interpreted and the result will
369 be immediately printed, an optional field width can be specified to
370 print the field in exactly a given number of characters. For example, a
371 numeric escape like %4(\fIsize\fR\^) will print at most 4 digits of the
372 message size; overflow will be indicated by a `?' in the first position
373 (like `?234'). A string escape like %4(\fIme\fR\^) will print the first 4
374 characters and truncate at the end. Short fields are padded at the right
375 with the fill character (normally, a blank). If the field width argument
376 begins with a leading zero, then the fill character is set to a zero.
378 The functions (\fIputnumf\fR\^) and (\fIputstrf\fR\^)
379 print their result in exactly the number of characters
380 specified by their leading field width argument. For example,
381 %06(\fIputnumf\fR\^(\fIsize\fR\^)) will print the message
382 size in a field six characters wide filled with leading zeros;
383 %14(\fIputstrf\^\fR{\fIfrom\^\fR}) will print the \*(lqFrom:\*(rq header
384 component in fourteen characters with trailing spaces added as needed.
385 For \fIputstrf\fR, using a negative value for the field width causes
386 right-justification of the string within the field, with padding on
387 the left up to the field width.
388 The functions (\fIputnum\fR\^) and
389 (\fIputstr\fR\^) are somewhat special: they print their result in the minimum number of characters
390 required, and ignore any leading field width argument.
392 The available output width is kept in an internal register; any output
393 past this width will be truncated.
395 With all this in mind,
396 here's the default format string for
398 It's been divided into several pieces for readability.
403 %4(msg)%<(cur)+%| %>%<{replied}\-%?{encrypted}E%| %>
407 which says that the message number should be printed in four digits.
408 If the message is the current message then a `+' else a space should
409 be printed; if a \*(lqReplied:\*(rq field is present then a `\-'
410 else if an \*(lqEncrypted:\*(rq field is present then an `E' otherwise
411 a space should be printed. Next:
415 %02(mon{date})/%02(mday{date})
419 the month and date are printed in two digits (zero filled) separated by
428 If a \*(lqDate:\*(rq field was present,
429 then a space is printed, otherwise a `*'.
434 %<(mymbox{from})%<{to}To:%14(decode(friendly{to}))%>%>
438 if the message is from me, and there is a \*(lqTo:\*(rq header,
439 print \*(lqTo:\*(rq followed by a \*(lquser-friendly\*(rq rendering of the
440 first address in the \*(lqTo:\*(rq field; any MIME-encoded
441 characters are decoded into the actual characters.
446 %<(zero)%17(decode(friendly{from}))%>
450 if either of the above two tests failed,
451 then the \*(lqFrom:\*(rq address is printed
452 in a mime-decoded, \*(lquser-friendly\*(rq format.
457 %(decode{subject})%<{body}<<%{body}>>%>
461 the mime-decoded subject and initial body (if any) are printed.
463 For a more complicated example, next consider
470 %(lit)%(formataddr %<{reply-to}
476 and formats the \*(lqReply-To:\*(rq header
477 if present. If not present, the else-if clause is executed.
481 %?{from}%?{sender}%?{return-path}%>)\\
486 \*(lqFrom:\*(rq, \*(lqSender:\*(rq and \*(lqReturn-Path:\*(rq
487 headers, stopping as soon as one of them is present. Next:
491 %<(nonnull)%(void(width))%(putaddr To: )\\n%>\\
495 If the \fIformataddr\fR result is non-null, it is printed as
496 an address (with line folding if needed) in a field \fIwidth\fR
497 wide with a leading label of \*(lqTo:\*(rq.
501 %(lit)%(formataddr{to})%(formataddr{cc})%(formataddr(me))\\
506 is cleared, and the \*(lqTo:\*(rq and \*(lqCc:\*(rq headers, along with the user's
507 address (depending on what was specified with
508 the \*(lq\-cc\*(rq switch to \fIrepl\fR\^) are formatted.
512 %<(nonnull)%(void(width))%(putaddr cc: )\\n%>\\
516 If the result is non-null, it is printed as above with a
517 leading label of \*(lqcc:\*(rq.
521 %<{fcc}Fcc: %{fcc}\\n%>\\
532 for more details about %{\fIfcc\fR\^}),
533 an \*(lqFcc:\*(rq header is output.
537 %<{subject}Subject: Re: %{subject}\\n%>\\
541 If a subject component was present,
542 a suitable reply subject is output.
546 %<{message-id}In-Reply-To: %{message-id}\\n%>\\
547 %<{message-id}References: %<{references} %{references}%>\\
553 If a message-id component was present, an \*(lqIn-Reply-To:\*(rq header is
554 output including the message-id, followed by a \*(lqReferences:\*(rq
555 header with references, if present, and the message-id.
557 plain-text, the row of dashes are output as-is.
559 This last part is a good example for a little more elaboration.
560 Here's that part again in pseudo-code:
565 if (comp_exists(message-id)) then
566 print (\*(lqIn-reply-to: \*(rq)
567 print (message-id.value)
568 print (\*(lq\\n\*(rq)
570 if (comp_exists(message-id)) then
571 print (\*(lqReferences: \*(rq)
572 if (comp_exists(references)) then
573 print(references.value);
575 print (message-id.value)
576 print (\*(lq\\n\*(rq)
581 .\" (Note that this pseudocode begs the question ``why not just
582 .\" support this syntax?'' MH has been hacked on for a long time...)
584 One more example: Currently,
587 large message numbers, and it is not uncommon for a folder
588 to have far more than 10000 messages.
589 .\" (Indeed, the original MH
590 .\" tutorial document by Rose and Romine is entitled "How to
591 .\" process 200 messages a day and still get some real work
592 .\" done." The authors apparently only planned to get
593 .\" real work done for about 50 days per folder.)
594 Nontheless (as noted above)
595 the various scan format strings are inherited
596 from older MH versions, and are generally hard-coded to 4
597 digits of message number before formatting problems
599 The nmh format strings can be modified to behave more sensibly with larger
604 %(void(msg))%<(gt 9999)%(msg)%|%4(msg)%>
608 The current message number is placed in \fInum\fP.
611 is an int function, not a component.)
615 is used to test whether the message number
618 If so, it is printed at full width: otherwise
621 scan(1), repl(1), ap(8), dp(8)