tmk.1 - plan9port - [fork] Plan 9 from user space
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tmk.1 (14152B)
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1 .TH MK 1
2 .SH NAME
3 mk \- maintain (make) related files
4 .SH SYNOPSIS
5 .B mk
6 [
7 .B -f
8 .I mkfile
9 ] ...
10 [
11 .I option ...
12 ]
13 [
14 .I target ...
15 ]
16 .SH DESCRIPTION
17 .I Mk
18 uses the dependency rules specified in
19 .I mkfile
20 to control the update (usually by compilation) of
21 .I targets
22 (usually files)
23 from the source files upon which they depend.
24 The
25 .I mkfile
26 (default
27 .LR mkfile )
28 contains a
29 .I rule
30 for each target that identifies the files and other
31 targets upon which it depends and an
32 .IR sh (1)
33 script, a
34 .IR recipe ,
35 to update the target.
36 The script is run if the target does not exist
37 or if it is older than any of the files it depends on.
38 .I Mkfile
39 may also contain
40 .I meta-rules
41 that define actions for updating implicit targets.
42 If no
43 .I target
44 is specified, the target of the first rule (not meta-rule) in
45 .I mkfile
46 is updated.
47 .PP
48 The environment variable
49 .B $NPROC
50 determines how many targets may be updated simultaneously;
51 Some operating systems, e.g., Plan 9, set
52 .B $NPROC
53 automatically to the number of CPUs on the current machine.
54 .PP
55 Options are:
56 .TP \w'\fL-d[egp]\ 'u
57 .B -a
58 Assume all targets to be out of date.
59 Thus, everything is updated.
60 .PD 0
61 .TP
62 .BR -d [ egp ]
63 Produce debugging output
64 .RB ( p
65 is for parsing,
66 .B g
67 for graph building,
68 .B e
69 for execution).
70 .TP
71 .B -e
72 Explain why each target is made.
73 .TP
74 .B -i
75 Force any missing intermediate targets to be made.
76 .TP
77 .B -k
78 Do as much work as possible in the face of errors.
79 .TP
80 .B -n
81 Print, but do not execute, the commands
82 needed to update the targets.
83 .TP
84 .B -s
85 Make the command line arguments sequentially rather than in parallel.
86 .TP
87 .B -t
88 Touch (update the modified date of) file targets, without
89 executing any recipes.
90 .TP
91 .BI -w target1 , target2,...
92 Pretend the modify time for each
93 .I target
94 is the current time; useful in conjunction with
95 .B -n
96 to learn what updates would be triggered by
97 modifying the
98 .IR targets .
99 .PD
100 .SS The \fLmkfile\fP
101 A
102 .I mkfile
103 consists of
104 .I assignments
105 (described under `Environment') and
106 .IR rules .
107 A rule contains
108 .I targets
109 and a
110 .IR tail .
111 A target is a literal string
112 and is normally a file name.
113 The tail contains zero or more
114 .I prerequisites
115 and an optional
116 .IR recipe ,
117 which is an
118 .B shell
119 script.
120 Each line of the recipe must begin with white space.
121 A rule takes the form
122 .IP
123 .EX
124 target: prereq1 prereq2
125 \f2recipe using\fP prereq1, prereq2 \f2to build\fP target
126 .EE
127 .PP
128 When the recipe is executed,
129 the first character on every line is elided.
130 .PP
131 After the colon on the target line, a rule may specify
132 .IR attributes ,
133 described below.
134 .PP
135 A
136 .I meta-rule
137 has a target of the form
138 .IB A % B
139 where
140 .I A
141 and
142 .I B
143 are (possibly empty) strings.
144 A meta-rule acts as a rule for any potential target whose
145 name matches
146 .IB A % B
147 with
148 .B %
149 replaced by an arbitrary string, called the
150 .IR stem .
151 In interpreting a meta-rule,
152 the stem is substituted for all occurrences of
153 .B %
154 in the prerequisite names.
155 In the recipe of a meta-rule, the environment variable
156 .B $stem
157 contains the string matched by the
158 .BR % .
159 For example, a meta-rule to compile a C program
160 might be:
161 .IP
162 .EX
163 %: %.c
164 cc -c $stem.c
165 ld -o $stem $stem.o
166 .EE
167 .PP
168 Meta-rules may contain an ampersand
169 .B &
170 rather than a percent sign
171 .BR % .
172 A
173 .B %
174 matches a maximal length string of any characters;
175 an
176 .B &
177 matches a maximal length string of any characters except period
178 or slash.
179 .PP
180 The text of the
181 .I mkfile
182 is processed as follows.
183 Lines beginning with
184 .B <
185 followed by a file name are replaced by the contents of the named
186 file.
187 Lines beginning with
188 .B "<|"
189 followed by a file name are replaced by the output
190 of the execution of the named
191 file.
192 Blank lines and comments, which run from unquoted
193 .B #
194 characters to the following newline, are deleted.
195 The character sequence backslash-newline is deleted,
196 so long lines in
197 .I mkfile
198 may be folded.
199 Non-recipe lines are processed by substituting for
200 .BI `{ command }
201 the output of the
202 .I command
203 when run by
204 .IR sh .
205 References to variables are replaced by the variables' values.
206 Special characters may be quoted using single quotes
207 .BR \&''
208 as in
209 .IR sh (1).
210 .PP
211 Assignments and rules are distinguished by
212 the first unquoted occurrence of
213 .B :
214 (rule)
215 or
216 .B =
217 (assignment).
218 .PP
219 A later rule may modify or override an existing rule under the
220 following conditions:
221 .TP
222 \-
223 If the targets of the rules exactly match and one rule
224 contains only a prerequisite clause and no recipe, the
225 clause is added to the prerequisites of the other rule.
226 If either or both targets are virtual, the recipe is
227 always executed.
228 .TP
229 \-
230 If the targets of the rules match exactly and the
231 prerequisites do not match and both rules
232 contain recipes,
233 .I mk
234 reports an ``ambiguous recipe'' error.
235 .TP
236 \-
237 If the target and prerequisites of both rules match exactly,
238 the second rule overrides the first.
239 .SS Environment
240 Rules may make use of
241 shell
242 environment variables.
243 A legal reference of the form
244 .B $OBJ
245 or
246 .B ${name}
247 is expanded as in
248 .IR sh (1).
249 A reference of the form
250 .BI ${name: A % B = C\fL%\fID\fL}\fR,
251 where
252 .I A, B, C, D
253 are (possibly empty) strings,
254 has the value formed by expanding
255 .B $name
256 and substituting
257 .I C
258 for
259 .I A
260 and
261 .I D
262 for
263 .I B
264 in each word in
265 .B $name
266 that matches pattern
267 .IB A % B\f1.
268 .PP
269 Variables can be set by
270 assignments of the form
271 .I
272 var\fL=\fR[\fIattr\fL=\fR]\fIvalue\fR
273 .br
274 Blanks in the
275 .I value
276 break it into words.
277 Such variables are exported
278 to the environment of
279 recipes as they are executed, unless
280 .BR U ,
281 the only legal attribute
282 .IR attr ,
283 is present.
284 The initial value of a variable is
285 taken from (in increasing order of precedence)
286 the default values below,
287 .I mk's
288 environment, the
289 .IR mkfiles ,
290 and any command line assignment as an argument to
291 .IR mk .
292 A variable assignment argument overrides the first (but not any subsequent)
293 assignment to that variable.
294 .PP
295 The variable
296 .B MKFLAGS
297 contains all the option arguments (arguments starting with
298 .L -
299 or containing
300 .LR = )
301 and
302 .B MKARGS
303 contains all the targets in the call to
304 .IR mk .
305 .PP
306 The variable
307 .B MKSHELL
308 contains the shell command line
309 .I mk
310 uses to run recipes.
311 If the first word of the command ends in
312 .B rc
313 or
314 .BR rcsh ,
315 .I mk
316 uses
317 .IR rc (1)'s
318 quoting rules; otherwise it uses
319 .IR sh (1)'s.
320 The
321 .B MKSHELL
322 variable is consulted when the mkfile is read, not when it is executed,
323 so that different shells can be used within a single mkfile:
324 .IP
325 .EX
326 MKSHELL=$PLAN9/bin/rc
327 use-rc:V:
328 for(i in a b c) echo $i
329
330 MKSHELL=sh
331 use-sh:V:
332 for i in a b c; do echo $i; done
333 .EE
334 .LP
335 Mkfiles included via
336 .B <
337 or
338 .B <|
339 .RI ( q.v. )
340 see their own private copy of
341 .BR MKSHELL ,
342 which always starts set to
343 .B sh .
344 .PP
345 Dynamic information may be included in the mkfile by using a line of the form
346 .IP
347 \fR<|\fIcommand\fR \fIargs\fR
348 .LP
349 This runs the command
350 .I command
351 with the given arguments
352 .I args
353 and pipes its standard output to
354 .I mk
355 to be included as part of the mkfile. For instance, the Inferno kernels
356 use this technique
357 to run a shell command with an awk script and a configuration
358 file as arguments in order for
359 the
360 .I awk
361 script to process the file and output a set of variables and their values.
362 .SS Execution
363 .PP
364 During execution,
365 .I mk
366 determines which targets must be updated, and in what order,
367 to build the
368 .I names
369 specified on the command line.
370 It then runs the associated recipes.
371 .PP
372 A target is considered up to date if it has no prerequisites or
373 if all its prerequisites are up to date and it is newer
374 than all its prerequisites.
375 Once the recipe for a target has executed, the target is
376 considered up to date.
377 .PP
378 The date stamp
379 used to determine if a target is up to date is computed
380 differently for different types of targets.
381 If a target is
382 .I virtual
383 (the target of a rule with the
384 .B V
385 attribute),
386 its date stamp is initially zero; when the target is
387 updated the date stamp is set to
388 the most recent date stamp of its prerequisites.
389 Otherwise, if a target does not exist as a file,
390 its date stamp is set to the most recent date stamp of its prerequisites,
391 or zero if it has no prerequisites.
392 Otherwise, the target is the name of a file and
393 the target's date stamp is always that file's modification date.
394 The date stamp is computed when the target is needed in
395 the execution of a rule; it is not a static value.
396 .PP
397 Nonexistent targets that have prerequisites
398 and are themselves prerequisites are treated specially.
399 Such a target
400 .I t
401 is given the date stamp of its most recent prerequisite
402 and if this causes all the targets which have
403 .I t
404 as a prerequisite to be up to date,
405 .I t
406 is considered up to date.
407 Otherwise,
408 .I t
409 is made in the normal fashion.
410 The
411 .B -i
412 flag overrides this special treatment.
413 .PP
414 Files may be made in any order that respects
415 the preceding restrictions.
416 .PP
417 A recipe is executed by supplying the recipe as standard input to
418 the command
419 .BR /bin/sh .
420 (Note that unlike
421 .IR make ,
422 .I mk
423 feeds the entire recipe to the shell rather than running each line
424 of the recipe separately.)
425 The environment is augmented by the following variables:
426 .TP 14
427 .B $alltarget
428 all the targets of this rule.
429 .TP
430 .B $newprereq
431 the prerequisites that caused this rule to execute.
432 .TP
433 .B $newmember
434 the prerequisites that are members of an aggregate
435 that caused this rule to execute.
436 When the prerequisites of a rule are members of an
437 aggregate,
438 .B $newprereq
439 contains the name of the aggregate and out of date
440 members, while
441 .B $newmember
442 contains only the name of the members.
443 .TP
444 .B $nproc
445 the process slot for this recipe.
446 It satisfies
447 .RB 0≤ $nproc < $NPROC .
448 .TP
449 .B $pid
450 the process id for the
451 .I mk
452 executing the recipe.
453 .TP
454 .B $prereq
455 all the prerequisites for this rule.
456 .TP
457 .B $stem
458 if this is a meta-rule,
459 .B $stem
460 is the string that matched
461 .B %
462 or
463 .BR & .
464 Otherwise, it is empty.
465 For regular expression meta-rules (see below), the variables
466 .LR stem0 ", ...,"
467 .L stem9
468 are set to the corresponding subexpressions.
469 .TP
470 .B $target
471 the targets for this rule that need to be remade.
472 .PP
473 These variables are available only during the execution of a recipe,
474 not while evaluating the
475 .IR mkfile .
476 .PP
477 Unless the rule has the
478 .B Q
479 attribute,
480 the recipe is printed prior to execution
481 with recognizable environment variables expanded.
482 Commands returning error status
483 cause
484 .I mk
485 to terminate.
486 .PP
487 Recipes and backquoted
488 .B rc
489 commands in places such as assignments
490 execute in a copy of
491 .I mk's
492 environment; changes they make to
493 environment variables are not visible from
494 .IR mk .
495 .PP
496 Variable substitution in a rule is done when
497 the rule is read; variable substitution in the recipe is done
498 when the recipe is executed. For example:
499 .IP
500 .EX
501 bar=a.c
502 foo: $bar
503 $CC -o foo $bar
504 bar=b.c
505 .EE
506 .PP
507 will compile
508 .B b.c
509 into
510 .BR foo ,
511 if
512 .B a.c
513 is newer than
514 .BR foo .
515 .SS Aggregates
516 Names of the form
517 .IR a ( b )
518 refer to member
519 .I b
520 of the aggregate
521 .IR a .
522 .SS Attributes
523 The colon separating the target from the prerequisites
524 may be
525 immediately followed by
526 .I attributes
527 and another colon.
528 The attributes are:
529 .TP
530 .B D
531 If the recipe exits with a non-null status, the target is deleted.
532 .TP
533 .B E
534 Continue execution if the recipe draws errors.
535 .TP
536 .B N
537 If there is no recipe, the target has its time updated.
538 .TP
539 .B n
540 The rule is a meta-rule that cannot be a target of a virtual rule.
541 Only files match the pattern in the target.
542 .TP
543 .B P
544 The characters after the
545 .B P
546 until the terminating
547 .B :
548 are taken as a program name.
549 It will be invoked as
550 .B "sh -c prog 'arg1' 'arg2'"
551 and should return a zero exit status
552 if and only if arg1 is up to date with respect to arg2.
553 Date stamps are still propagated in the normal way.
554 .TP
555 .B Q
556 The recipe is not printed prior to execution.
557 .TP
558 .B R
559 The rule is a meta-rule using regular expressions.
560 In the rule,
561 .B %
562 has no special meaning.
563 The target is interpreted as a regular expression as defined in
564 .IR regexp9 (7).
565 The prerequisites may contain references
566 to subexpressions in form
567 .BI \e n\f1,
568 as in the substitute command of
569 .IR sed (1).
570 .TP
571 .B U
572 The targets are considered to have been updated
573 even if the recipe did not do so.
574 .TP
575 .B V
576 The targets of this rule are marked as virtual.
577 They are distinct from files of the same name.
578 .PD
579 .SH EXAMPLES
580 A simple mkfile to compile a program:
581 .IP
582 .EX
583 .ta 8n +8n +8n +8n +8n +8n +8n
584 </$objtype/mkfile
585
586 prog: a.$O b.$O c.$O
587 $LD $LDFLAGS -o $target $prereq
588
589 %.$O: %.c
590 $CC $CFLAGS $stem.c
591 .EE
592 .PP
593 Override flag settings in the mkfile:
594 .IP
595 .EX
596 % mk target 'CFLAGS=-S -w'
597 .EE
598 .PP
599 Maintain a library:
600 .IP
601 .EX
602 libc.a(%.$O):N: %.$O
603 libc.a: libc.a(abs.$O) libc.a(access.$O) libc.a(alarm.$O) ...
604 ar r libc.a $newmember
605 .EE
606 .PP
607 String expression variables to derive names from a master list:
608 .IP
609 .EX
610 NAMES=alloc arc bquote builtins expand main match mk var word
611 OBJ=${NAMES:%=%.$O}
612 .EE
613 .PP
614 Regular expression meta-rules:
615 .IP
616 .EX
617 ([^/]*)/(.*)\e.$O:R: \e1/\e2.c
618 cd $stem1; $CC $CFLAGS $stem2.c
619 .EE
620 .PP
621 A correct way to deal with
622 .IR yacc (1)
623 grammars.
624 The file
625 .B lex.c
626 includes the file
627 .B x.tab.h
628 rather than
629 .B y.tab.h
630 in order to reflect changes in content, not just modification time.
631 .IP
632 .EX
633 lex.$O: x.tab.h
634 x.tab.h: y.tab.h
635 cmp -s x.tab.h y.tab.h || cp y.tab.h x.tab.h
636 y.tab.c y.tab.h: gram.y
637 $YACC -d gram.y
638 .EE
639 .PP
640 The above example could also use the
641 .B P
642 attribute for the
643 .B x.tab.h
644 rule:
645 .IP
646 .EX
647 x.tab.h:Pcmp -s: y.tab.h
648 cp y.tab.h x.tab.h
649 .EE
650 .SH SOURCE
651 .B https://9fans.github.io/plan9port/unix
652 .SH SEE ALSO
653 .IR sh (1),
654 .IR regexp9 (7)
655 .PP
656 A. Hume,
657 ``Mk: a Successor to Make''
658 (Tenth Edition Research Unix Manuals).
659 .PP
660 Andrew G. Hume and Bob Flandrena,
661 ``Maintaining Files on Plan 9 with Mk''.
662 .BR DOCPREFIX/doc/mk.pdf .
663 .SH HISTORY
664 Andrew Hume wrote
665 .I mk
666 for Tenth Edition Research Unix.
667 It was later ported to Plan 9.
668 This software is a port of the Plan 9 version back to Unix.
669 .SH BUGS
670 Identical recipes for regular expression meta-rules only have one target.
671 .PP
672 Seemingly appropriate input like
673 .B CFLAGS=-DHZ=60
674 is parsed as an erroneous attribute; correct it by inserting
675 a space after the first
676 .LR = .
677 .PP
678 The recipes printed by
679 .I mk
680 before being passed to
681 the shell
682 for execution are sometimes erroneously expanded
683 for printing. Don't trust what's printed; rely
684 on what the shell
685 does.