4 .TH MH-FORMAT %manext5% "%nmhdate%" MH.6.8 [%nmhversion%]
6 mh-format \- format file for nmh message system
10 commands utilize either a
14 file during their execution. For example,
16 uses a format string which directs it how to generate the scan listing
19 uses a format file which directs it
20 how to generate the reply to a message, and so on.
22 There are a few alternate scan listing formats available
24 .IR nmh/etc/scan.time ,
25 .IR nmh/etc/scan.size ,
27 .IR nmh/etc/scan.timely .
34 format files which may have been written at your site.
36 It suffices to have your local
38 expert actually write new format
39 commands or modify existing ones. This manual section explains how to
40 do that. Note: familiarity with the C
44 A format string consists of ordinary text, and special multi-character
45 escape sequences which begin with `%'. When specifying a format
46 string, the usual C backslash characters are honored: `\\b', `\\f',
47 `\\n', `\\r', and `\\t'. Continuation lines in format files end with
48 `\\' followed by the newline character.
50 .\" TALK ABOUT SYNTAX FIRST, THEN SEMANTICS
52 Format strings are built around
53 .IR "escape sequences" .
54 There are three types of escape sequences: header
60 Comments may be inserted in most places where a function argument is
61 not expected. A comment begins with `%;' and ends with a (non-escaped)
66 escape is specified as
69 exists for each header found in the message being processed. For example
71 refers to the \*(lqDate:\*(rq field of the appropriate message.
72 All component escapes have a string value. Normally, component values are
73 compressed by converting any control characters (tab and newline included)
74 to spaces, then eliding any leading or multiple spaces. However, commands
75 may give different interpretations to some component escapes; be sure
76 to refer to each command's manual entry for complete details.
80 escape is specified as
82 All functions are built-in, and most have a string or numeric value.
83 A function escape may have an
85 The argument follows the function escape: separating
86 whitespace is discarded:
87 .RI `%( function " " argument )'.
89 In addition to literal numbers or strings,
90 the argument to a function escape can be another function, a component,
91 or a control escape. When the argument is a function or a
92 component, they are listed without a leading `%'. When control escapes
93 are used as function arguments, they written as normally, with
100 escape is one of: `%<', `%?', `%|', or `%>'.
101 These are combined into the conditional execution construct:
105 .RI "%< " condition " " "format-text"
106 .RI "%? " condition " " "format-text"
108 .RI "%| " "format-text"
113 Extra white space is shown here only for clarity. These
114 constructs may be nested without ambiguity. They form a general
115 .B if\-elseif\-else\-endif
116 block where only one of the
118 is interpreted. In other
119 words, `%<' is like the "if", `%?' is like the "elseif", `%|' is like
120 "else", and `%>' is like "endif".
122 A `%<' or `%?' control escape causes its condition to be evaluated.
127 For integer valued functions or components, the condition is true
128 if the function return or component value is non-zero, and false if zero.
129 For string valued functions or components, the condition is true
130 if the function return or component value is
131 a non-empty string, and false for an empty string.
134 The `%?' control escape is optional, and may there may be more
135 than one `%?' control escape in a conditional block.
136 The `%|' control escape
137 is also optional, but may be included at most once.
139 .SS "Function escapes"
140 Functions expecting an argument generally
141 require an argument of a particular type.
142 In addition to the number and string types,
147 .ta +\w'Argument 'u +\w'An optional component, 'u
148 .I Argument Description Example Syntax
149 literal A literal number %(\fIfunc\fR 1234)
150 or string %(\fIfunc\fR text string)
151 comp Any component %(\fIfunc\fR\^{\fIin-reply-to\fR\^})
152 date A date component %(\fIfunc\fR\^{\fIdate\fR\^})
153 addr An address component %(\fIfunc\fR\^{\fIfrom\fR\^})
154 expr Nothing %(\fIfunc\fR)
155 or a subexpression %(\fIfunc\fR\^(\fIfunc2\fR\^))
156 or control escape %(\fIfunc\fR %<{\fIreply-to\fR\^}%|%{\fIfrom\fR\^}%>)
164 have the same syntax as
166 but require that the header component be a date string, or address
167 string, respectively.
169 Most arguments not of type
172 When escapes are nested (via expr arguments), evaluation is done from inner-most to outer-most.
173 As noted above, for the
176 functions and components are written without a
178 Control escape arguments must use a leading `%', preceded by a space.
184 %<(mymbox{from}) To: %{to}%>
188 writes the value of the header component \*(lqFrom:\*(rq to the
189 internal register named str; then (\fImymbox\fR\^) reads str and
190 writes its result to the internal register named
192 then the control escape evaluates
197 string \*(lqTo:\*(rq is printed followed by the value of the
198 header component \*(lqTo:\*(rq.
200 The evaluation of format strings is performed
201 by a small virtual machine.
202 The machine is capable of evaluating nested expressions
203 as described above, and in addition
204 has an integer register
206 and a text string register
208 When a function escape that
209 accepts an optional argument is processed,
210 and the argument is not present, the current value of either
214 is used as the argument: which register is
215 used depends on the function, as listed below.
217 Component escapes write the value of their message header in
219 Function escapes write their return value in
221 for functions returning integer or boolean values, and in
223 for functions returning string values. (The boolean type is a subset
224 of integers with usual values 0=false and 1=true.) Control escapes
225 return a boolean value, setting
227 to 1 if the last explicit condition
228 evaluated by a `%<' or `%?' control
229 succeeded, and 0 otherwise.
231 All component escapes, and those function escapes which return an
232 integer or string value, evaluate to their value as well as setting
236 Outermost escape expressions in
237 these forms will print
238 their value, but outermost escapes which return a boolean value
239 do not result in printed output.
241 The function escapes may be roughly grouped into a few categories.
245 .ta \w'Fformataddr 'u +\w'Aboolean 'u +\w'Rboolean 'u
246 .I Function Argument Result Description
247 msg integer message number
248 cur integer message is current (0 or 1)
249 unseen integer message is unseen (0 or 1)
250 size integer size of message
251 strlen integer length of \fIstr\fR
252 width integer output buffer size in bytes
253 charleft integer bytes left in output buffer
254 timenow integer seconds since the UNIX epoch
255 me string the user's mailbox
256 eq literal boolean \fInum\fR == \fIarg\fR
257 ne literal boolean \fInum\fR != \fIarg\fR
258 gt literal boolean \fInum\fR > \fIarg\fR
259 match literal boolean \fIstr\fR contains \fIarg\fR
260 amatch literal boolean \fIstr\fR starts with \fIarg\fR
261 plus literal integer \fIarg\fR plus \fInum\fR
262 minus literal integer \fIarg\fR minus \fInum\fR
263 divide literal integer \fInum\fR divided by \fIarg\fR
264 modulo literal integer \fInum\fR modulo \fIarg\fR
265 num literal integer Set \fInum\fR to \fIarg\fR.
266 num integer Set \fInum\fR to zero.
267 lit literal string Set \fIstr\fR to \fIarg\fR.
268 lit string Clear \fIstr\fR.
269 getenv literal string Set \fIstr\fR to environment value of \fIarg\fR
270 profile literal string Set \fIstr\fR to profile component \fIarg\fR
272 .\" dat literal int return value of dat[arg]
273 nonzero expr boolean \fInum\fR is non-zero
274 zero expr boolean \fInum\fR is zero
275 null expr boolean \fIstr\fR is empty
276 nonnull expr boolean \fIstr\fR is non-empty
277 void expr Set \fIstr\fR or \fInum\fR
278 comp comp string Set \fIstr\fR to component text
279 compval comp integer Set \fInum\fR to \*(lq\fBatoi\fR(\fIcomp\fR\^)\*(rq
280 .\" compflag comp integer Set \fInum\fR to component flags bits (internal)
281 .\" decodecomp comp string Set \fIstr\fR to RFC-2047 decoded component text
282 decode expr string decode \fIstr\fR as RFC-2047 (MIME-encoded)
284 unquote expr string remove RFC-2822 quotes from \fIstr\fR
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 putlit expr print \fIstr\fR without space compression
292 nodate string integer Argument not a date string (0 or 1)
293 formataddr expr append \fIarg\fR to \fIstr\fR as a
294 (comma separated) address list
295 concataddr expr append \fIarg\fR to \fIstr\fR as a
296 (comma separated) address list,
297 including duplicates,
299 putaddr literal print \fIstr\fR address list with
300 \fIarg\fR as optional label;
301 get line width from \fInum\fR
305 The following functions require a date component as an argument:
309 .ta \w'Fformataddr 'u +\w'Aboolean 'u +\w'Rboolean 'u
310 .I Function Argument Return Description
311 sec date integer seconds of the minute
312 min date integer minutes of the hour
313 hour date integer hours of the day (0-23)
314 wday date integer day of the week (Sun=0)
315 day date string day of the week (abbrev.)
316 weekday date string day of the week
317 sday date integer day of the week known?
318 (1=explicit,0=implicit,\-1=unknown)
319 mday date integer day of the month
320 yday date integer day of the year
321 mon date integer month of the year
322 month date string month of the year (abbrev.)
323 lmonth date string month of the year
324 year date integer year (may be > 100)
325 zone date integer timezone in hours
326 tzone date string timezone string
327 szone date integer timezone explicit?
328 (1=explicit,0=implicit,\-1=unknown)
329 date2local date coerce date to local timezone
330 date2gmt date coerce date to GMT
331 dst date integer daylight savings in effect? (0 or 1)
332 clock date integer seconds since the UNIX epoch
333 rclock date integer seconds prior to current time
334 tws date string official 822 rendering
335 pretty date string user-friendly rendering
339 These functions require an address component as an argument.
340 The return value of functions noted with `*' is computed from
341 the first address present in the header component.
345 .ta \w'Fformataddr 'u +\w'Aboolean 'u +\w'Rboolean 'u
346 .I Function Argument Return Description
347 proper addr string official 822 rendering
348 friendly addr string user-friendly rendering
349 addr addr string mbox@host or host!mbox rendering*
350 pers addr string the personal name*
351 note addr string commentary text*
352 mbox addr string the local mailbox*
353 mymbox addr integer List has the user's address? (0 or 1)
354 host addr string the host domain*
355 nohost addr integer no host was present (0 or 1)*
356 type addr integer host type* (0=local,1=network,
358 path addr string any leading host route*
359 ingrp addr integer address was inside a group (0 or 1)*
360 gname addr string name of group*
364 (A clarification on (\fImymbox\fR\^{\fIcomp\fR\^}) is in order.
365 This function checks each of the addresses in the header component
366 \*(lq\fIcomp\fR\*(rq against the user's mailbox name and any
367 .RI \*(lq Alternate-Mailboxes \*(rq.
368 It returns true if any address matches,
369 however, it also returns true if the \*(lq\fIcomp\fR\*(rq header is not
370 present in the message. If needed, the (\fInull\fR\^) function can be
371 used to explicitly test for this case.)
373 When a function or component escape is interpreted and the result will
374 be immediately printed, an optional field width can be specified to
375 print the field in exactly a given number of characters. For example, a
376 numeric escape like %4(\fIsize\fR\^) will print at most 4 digits of the
377 message size; overflow will be indicated by a `?' in the first position
378 (like `?234'). A string escape like %4(\fIme\fR\^) will print the first 4
379 characters and truncate at the end. Short fields are padded at the right
380 with the fill character (normally, a blank). If the field width argument
381 begins with a leading zero, then the fill character is set to a zero.
383 The functions (\fIputnumf\fR\^) and (\fIputstrf\fR\^)
384 print their result in exactly the number of characters
385 specified by their leading field width argument. For example,
386 %06(\fIputnumf\fR\^(\fIsize\fR\^)) will print the message
387 size in a field six characters wide filled with leading zeros;
388 %14(\fIputstrf\^\fR{\fIfrom\^\fR}) will print the \*(lqFrom:\*(rq header
389 component in fourteen characters with trailing spaces added as needed.
390 For \fIputstrf\fR, using a negative value for the field width causes
391 right-justification of the string within the field, with padding on
392 the left up to the field width.
393 The functions (\fIputnum\fR\^) and
394 (\fIputstr\fR\^) are somewhat special: they print their result in the minimum number of characters
395 required, and ignore any leading field width argument. The (\fIputlit\fR\^)
396 function outputs the exact contents of str register without any changes
397 such as duplicate space removal or control character conversion.
399 The available output width is kept in an internal register; any output
400 past this width will be truncated.
402 A few functions have different behavior depending on what command they are
407 the (\fIformataddr\fR\^) function stores all email addresses encountered into
408 an internal cache and will use this cache to suppress duplicate addresses.
409 If you need to create an address list that includes previously-seen
410 addresses you may use the (\fIconcataddr\fR\^) function, which is identical
411 to (\fIformataddr\fR\^) in all other respects. Note that (\fIconcataddr\fR\^)
412 will NOT add addresses to the duplicate-suppression cache.
414 With all this in mind,
415 here's the default format string for
417 It's been divided into several pieces for readability.
422 %4(msg)%<(cur)+%| %>%<{replied}\-%?{encrypted}E%| %>
426 which says that the message number should be printed in four digits.
427 If the message is the current message then a `+' else a space should
428 be printed; if a \*(lqReplied:\*(rq field is present then a `\-'
429 else if an \*(lqEncrypted:\*(rq field is present then an `E' otherwise
430 a space should be printed. Next:
434 %02(mon{date})/%02(mday{date})
438 the month and date are printed in two digits (zero filled) separated by
447 If a \*(lqDate:\*(rq field was present,
448 then a space is printed, otherwise a `*'.
453 %<(mymbox{from})%<{to}To:%14(decode(friendly{to}))%>%>
457 if the message is from me, and there is a \*(lqTo:\*(rq header,
458 print \*(lqTo:\*(rq followed by a \*(lquser-friendly\*(rq rendering of the
459 first address in the \*(lqTo:\*(rq field; any MIME-encoded
460 characters are decoded into the actual characters.
465 %<(zero)%17(decode(friendly{from}))%>
469 if either of the above two tests failed,
470 then the \*(lqFrom:\*(rq address is printed
471 in a mime-decoded, \*(lquser-friendly\*(rq format.
476 %(decode{subject})%<{body}<<%{body}>>%>
480 the mime-decoded subject and initial body (if any) are printed.
482 For a more complicated example, next consider
489 %(lit)%(formataddr %<{reply-to}
495 and formats the \*(lqReply-To:\*(rq header
496 if present. If not present, the else-if clause is executed.
500 %?{from}%?{sender}%?{return-path}%>)\\
505 \*(lqFrom:\*(rq, \*(lqSender:\*(rq and \*(lqReturn-Path:\*(rq
506 headers, stopping as soon as one of them is present. Next:
510 %<(nonnull)%(void(width))%(putaddr To: )\\n%>\\
514 If the \fIformataddr\fR result is non-null, it is printed as
515 an address (with line folding if needed) in a field \fIwidth\fR
516 wide with a leading label of \*(lqTo:\*(rq.
520 %(lit)%(formataddr{to})%(formataddr{cc})%(formataddr(me))\\
525 is cleared, and the \*(lqTo:\*(rq and \*(lqCc:\*(rq headers, along with the user's
526 address (depending on what was specified with
527 the \*(lq\-cc\*(rq switch to \fIrepl\fR\^) are formatted.
531 %<(nonnull)%(void(width))%(putaddr cc: )\\n%>\\
535 If the result is non-null, it is printed as above with a
536 leading label of \*(lqcc:\*(rq.
540 %<{fcc}Fcc: %{fcc}\\n%>\\
551 for more details about %{\fIfcc\fR\^}),
552 an \*(lqFcc:\*(rq header is output.
556 %<{subject}Subject: Re: %{subject}\\n%>\\
560 If a subject component was present,
561 a suitable reply subject is output.
565 %<{message-id}In-Reply-To: %{message-id}\\n%>\\
566 %<{message-id}References: %<{references} %{references}%>\\
572 If a message-id component was present, an \*(lqIn-Reply-To:\*(rq header is
573 output including the message-id, followed by a \*(lqReferences:\*(rq
574 header with references, if present, and the message-id.
576 plain-text, the row of dashes are output as-is.
578 This last part is a good example for a little more elaboration.
579 Here's that part again in pseudo-code:
584 if (comp_exists(message-id)) then
585 print (\*(lqIn-reply-to: \*(rq)
586 print (message-id.value)
587 print (\*(lq\\n\*(rq)
589 if (comp_exists(message-id)) then
590 print (\*(lqReferences: \*(rq)
591 if (comp_exists(references)) then
592 print(references.value);
594 print (message-id.value)
595 print (\*(lq\\n\*(rq)
600 .\" (Note that this pseudocode begs the question ``why not just
601 .\" support this syntax?'' MH has been hacked on for a long time...)
603 One more example: Currently,
606 large message numbers, and it is not uncommon for a folder
607 to have far more than 10000 messages.
608 .\" (Indeed, the original MH
609 .\" tutorial document by Rose and Romine is entitled "How to
610 .\" process 200 messages a day and still get some real work
611 .\" done." The authors apparently only planned to get
612 .\" real work done for about 50 days per folder.)
613 Nontheless (as noted above)
614 the various scan format strings are inherited
615 from older MH versions, and are generally hard-coded to 4
616 digits of message number before formatting problems
618 The nmh format strings can be modified to behave more sensibly with larger
623 %(void(msg))%<(gt 9999)%(msg)%|%4(msg)%>
627 The current message number is placed in \fInum\fP.
630 is an int function, not a component.)
634 is used to test whether the message number
637 If so, it is printed at full width: otherwise
640 scan(1), repl(1), ap(8), dp(8)