3 mk \- maintain (make) related files
18 uses the dependency rules specified in
20 to control the update (usually by compilation) of
23 from the source files upon which they depend.
30 for each target that identifies the files and other
31 targets upon which it depends and an
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.
41 that define actions for updating implicit targets.
44 is specified, the target of the first rule (not meta-rule) in
48 The environment variable
50 determines how many targets may be updated simultaneously;
51 Some operating systems, e.g., Plan 9, set
53 automatically to the number of CPUs on the current machine.
58 Assume all targets to be out of date.
59 Thus, everything is updated.
63 Produce debugging output
72 Explain why each target is made.
75 Force any missing intermediate targets to be made.
78 Do as much work as possible in the face of errors.
81 Print, but do not execute, the commands
82 needed to update the targets.
85 Make the command line arguments sequentially rather than in parallel.
88 Touch (update the modified date of) file targets, without
89 executing any recipes.
91 .BI -w target1 , target2,...
92 Pretend the modify time for each
94 is the current time; useful in conjunction with
96 to learn what updates would be triggered by
105 (described under `Environment') and
111 A target is a literal string
112 and is normally a file name.
113 The tail contains zero or more
120 Each line of the recipe must begin with white space.
121 A rule takes the form
124 target: prereq1 prereq2
125 \f2recipe using\fP prereq1, prereq2 \f2to build\fP target
128 When the recipe is executed,
129 the first character on every line is elided.
131 After the colon on the target line, a rule may specify
137 has a target of the form
143 are (possibly empty) strings.
144 A meta-rule acts as a rule for any potential target whose
149 replaced by an arbitrary string, called the
151 In interpreting a meta-rule,
152 the stem is substituted for all occurrences of
154 in the prerequisite names.
155 In the recipe of a meta-rule, the environment variable
157 contains the string matched by the
159 For example, a meta-rule to compile a C program using
169 Meta-rules may contain an ampersand
171 rather than a percent sign
175 matches a maximal length string of any characters;
178 matches a maximal length string of any characters except period
183 is processed as follows.
186 followed by a file name are replaced by the contents of the named
190 followed by a file name are replaced by the output
191 of the execution of the named
193 Blank lines and comments, which run from unquoted
195 characters to the following newline, are deleted.
196 The character sequence backslash-newline is deleted,
200 Non-recipe lines are processed by substituting for
206 References to variables are replaced by the variables' values.
207 Special characters may be quoted using single quotes
212 Assignments and rules are distinguished by
213 the first unquoted occurrence of
220 A later rule may modify or override an existing rule under the
221 following conditions:
224 If the targets of the rules exactly match and one rule
225 contains only a prerequisite clause and no recipe, the
226 clause is added to the prerequisites of the other rule.
227 If either or both targets are virtual, the recipe is
231 If the targets of the rules match exactly and the
232 prerequisites do not match and both rules
235 reports an ``ambiguous recipe'' error.
238 If the target and prerequisites of both rules match exactly,
239 the second rule overrides the first.
241 Rules may make use of
243 environment variables.
244 A legal reference of the form
250 A reference of the form
251 .BI ${name: A % B = C\fL%\fID\fL}\fR,
254 are (possibly empty) strings,
255 has the value formed by expanding
270 Variables can be set by
271 assignments of the form
273 var\fL=\fR[\fIattr\fL=\fR]\fIvalue\fR
278 Such variables are exported
279 to the environment of
280 recipes as they are executed, unless
282 the only legal attribute
285 The initial value of a variable is
286 taken from (in increasing order of precedence)
287 the default values below,
291 and any command line assignment as an argument to
293 A variable assignment argument overrides the first (but not any subsequent)
294 assignment to that variable.
298 contains all the option arguments (arguments starting with
304 contains all the targets in the call to
309 contains the shell command line
312 If the first word of the command ends in
319 quoting rules; otherwise it uses
323 variable is consulted when the mkfile is read, not when it is executed,
324 so that different shells can be used within a single mkfile:
327 MKSHELL=$PLAN9/bin/rc
329 for(i in a b c) echo $i
333 for i in a b c; do echo $i; done
341 see their own private copy of
343 which always starts set to
346 Dynamic information may be included in the mkfile by using a line of the form
348 \fR<|\fIcommand\fR \fIargs\fR
350 This runs the command
352 with the given arguments
354 and pipes its standard output to
356 to be included as part of the mkfile. For instance, the Inferno kernels
358 to run a shell command with an awk script and a configuration
359 file as arguments in order for
362 script to process the file and output a set of variables and their values.
367 determines which targets must be updated, and in what order,
370 specified on the command line.
371 It then runs the associated recipes.
373 A target is considered up to date if it has no prerequisites or
374 if all its prerequisites are up to date and it is newer
375 than all its prerequisites.
376 Once the recipe for a target has executed, the target is
377 considered up to date.
380 used to determine if a target is up to date is computed
381 differently for different types of targets.
384 (the target of a rule with the
387 its date stamp is initially zero; when the target is
388 updated the date stamp is set to
389 the most recent date stamp of its prerequisites.
390 Otherwise, if a target does not exist as a file,
391 its date stamp is set to the most recent date stamp of its prerequisites,
392 or zero if it has no prerequisites.
393 Otherwise, the target is the name of a file and
394 the target's date stamp is always that file's modification date.
395 The date stamp is computed when the target is needed in
396 the execution of a rule; it is not a static value.
398 Nonexistent targets that have prerequisites
399 and are themselves prerequisites are treated specially.
402 is given the date stamp of its most recent prerequisite
403 and if this causes all the targets which have
405 as a prerequisite to be up to date,
407 is considered up to date.
410 is made in the normal fashion.
413 flag overrides this special treatment.
415 Files may be made in any order that respects
416 the preceding restrictions.
418 A recipe is executed by supplying the recipe as standard input to
424 feeds the entire recipe to the shell rather than running each line
425 of the recipe separately.)
426 The environment is augmented by the following variables:
429 all the targets of this rule.
432 the prerequisites that caused this rule to execute.
435 the prerequisites that are members of an aggregate
436 that caused this rule to execute.
437 When the prerequisites of a rule are members of an
440 contains the name of the aggregate and out of date
443 contains only the name of the members.
446 the process slot for this recipe.
448 .RB 0≤ $nproc < $NPROC .
451 the process id for the
453 executing the recipe.
456 all the prerequisites for this rule.
459 if this is a meta-rule,
461 is the string that matched
465 Otherwise, it is empty.
466 For regular expression meta-rules (see below), the variables
469 are set to the corresponding subexpressions.
472 the targets for this rule that need to be remade.
474 These variables are available only during the execution of a recipe,
475 not while evaluating the
478 Unless the rule has the
481 the recipe is printed prior to execution
482 with recognizable environment variables expanded.
483 Commands returning error status
488 Recipes and backquoted
490 commands in places such as assignments
493 environment; changes they make to
494 environment variables are not visible from
497 Variable substitution in a rule is done when
498 the rule is read; variable substitution in the recipe is done
499 when the recipe is executed. For example:
523 Currently, the only aggregates supported are
529 The colon separating the target from the prerequisites
531 immediately followed by
537 If the recipe exits with a non-null status, the target is deleted.
540 Continue execution if the recipe draws errors.
543 If there is no recipe, the target has its time updated.
546 The rule is a meta-rule that cannot be a target of a virtual rule.
547 Only files match the pattern in the target.
550 The characters after the
552 until the terminating
554 are taken as a program name.
555 It will be invoked as
556 .B "sh -c prog 'arg1' 'arg2'"
557 and should return a zero exit status
558 if and only if arg1 is up to date with respect to arg2.
559 Date stamps are still propagated in the normal way.
562 The recipe is not printed prior to execution.
565 The rule is a meta-rule using regular expressions.
568 has no special meaning.
569 The target is interpreted as a regular expression as defined in
571 The prerequisites may contain references
572 to subexpressions in form
574 as in the substitute command of
578 The targets are considered to have been updated
579 even if the recipe did not do so.
582 The targets of this rule are marked as virtual.
583 They are distinct from files of the same name.
586 A simple mkfile to compile a program:
589 .ta 8n +8n +8n +8n +8n +8n +8n
593 $LD $LDFLAGS -o $target $prereq
599 Override flag settings in the mkfile:
602 % mk target 'CFLAGS=-S -w'
609 libc.a: libc.a(abs.$O) libc.a(access.$O) libc.a(alarm.$O) ...
610 ar r libc.a $newmember
613 String expression variables to derive names from a master list:
616 NAMES=alloc arc bquote builtins expand main match mk var word
620 Regular expression meta-rules:
623 ([^/]*)/(.*)\e.$O:R: \e1/\e2.c
624 cd $stem1; $CC $CFLAGS $stem2.c
627 A correct way to deal with
636 in order to reflect changes in content, not just modification time.
641 cmp -s x.tab.h y.tab.h || cp y.tab.h x.tab.h
642 y.tab.c y.tab.h: gram.y
646 The above example could also use the
653 x.tab.h:Pcmp -s: y.tab.h
663 ``Mk: a Successor to Make''
664 (Tenth Edition Research Unix Manuals).
666 Andrew G. Hume and Bob Flandrena,
667 ``Maintaining Files on Plan 9 with Mk''.
672 for Tenth Edition Research Unix.
673 It was later ported to Plan 9.
674 This software is a port of the Plan 9 version back to Unix.
676 Identical recipes for regular expression meta-rules only have one target.
678 Seemingly appropriate input like
680 is parsed as an erroneous attribute; correct it by inserting
681 a space after the first
684 The recipes printed by
686 before being passed to
688 for execution are sometimes erroneously expanded
689 for printing. Don't trust what's printed; rely
