xref: /freebsd/contrib/bmake/make.1 (revision 13de33a5dc2304b13d595d75d48c51793958474f)
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30.\"	from: @(#)make.1	8.4 (Berkeley) 3/19/94
31.\"
32.Dd August 11, 2013
33.Dt MAKE 1
34.Os
35.Sh NAME
36.Nm make
37.Nd maintain program dependencies
38.Sh SYNOPSIS
39.Nm
40.Op Fl BeikNnqrstWwX
41.Op Fl C Ar directory
42.Op Fl D Ar variable
43.Op Fl d Ar flags
44.Op Fl f Ar makefile
45.Op Fl I Ar directory
46.Op Fl J Ar private
47.Op Fl j Ar max_jobs
48.Op Fl m Ar directory
49.Op Fl T Ar file
50.Op Fl V Ar variable
51.Op Ar variable=value
52.Op Ar target ...
53.Sh DESCRIPTION
54.Nm
55is a program designed to simplify the maintenance of other programs.
56Its input is a list of specifications as to the files upon which programs
57and other files depend.
58If no
59.Fl f Ar makefile
60makefile option is given,
61.Nm
62will try to open
63.Ql Pa makefile
64then
65.Ql Pa Makefile
66in order to find the specifications.
67If the file
68.Ql Pa .depend
69exists, it is read (see
70.Xr mkdep 1 ) .
71.Pp
72This manual page is intended as a reference document only.
73For a more thorough description of
74.Nm
75and makefiles, please refer to
76.%T "PMake \- A Tutorial" .
77.Pp
78.Nm
79will prepend the contents of the
80.Va MAKEFLAGS
81environment variable to the command line arguments before parsing them.
82.Pp
83The options are as follows:
84.Bl -tag -width Ds
85.It Fl B
86Try to be backwards compatible by executing a single shell per command and
87by executing the commands to make the sources of a dependency line in sequence.
88.It Fl C Ar directory
89Change to
90.Ar directory
91before reading the makefiles or doing anything else.
92If multiple
93.Fl C
94options are specified, each is interpreted relative to the previous one:
95.Fl C Pa / Fl C Pa etc
96is equivalent to
97.Fl C Pa /etc .
98.It Fl D Ar variable
99Define
100.Ar variable
101to be 1, in the global context.
102.It Fl d Ar [-]flags
103Turn on debugging, and specify which portions of
104.Nm
105are to print debugging information.
106Unless the flags are preceded by
107.Ql \-
108they are added to the
109.Va MAKEFLAGS
110environment variable and will be processed by any child make processes.
111By default, debugging information is printed to standard error,
112but this can be changed using the
113.Ar F
114debugging flag.
115The debugging output is always unbuffered; in addition, if debugging
116is enabled but debugging output is not directed to standard output,
117then the standard output is line buffered.
118.Ar Flags
119is one or more of the following:
120.Bl -tag -width Ds
121.It Ar A
122Print all possible debugging information;
123equivalent to specifying all of the debugging flags.
124.It Ar a
125Print debugging information about archive searching and caching.
126.It Ar C
127Print debugging information about current working directory.
128.It Ar c
129Print debugging information about conditional evaluation.
130.It Ar d
131Print debugging information about directory searching and caching.
132.It Ar e
133Print debugging information about failed commands and targets.
134.It Ar F Ns Oo Sy \&+ Oc Ns Ar filename
135Specify where debugging output is written.
136This must be the last flag, because it consumes the remainder of
137the argument.
138If the character immediately after the
139.Ql F
140flag is
141.Ql \&+ ,
142then the file will be opened in append mode;
143otherwise the file will be overwritten.
144If the file name is
145.Ql stdout
146or
147.Ql stderr
148then debugging output will be written to the
149standard output or standard error output file descriptors respectively
150(and the
151.Ql \&+
152option has no effect).
153Otherwise, the output will be written to the named file.
154If the file name ends
155.Ql .%d
156then the
157.Ql %d
158is replaced by the pid.
159.It Ar f
160Print debugging information about loop evaluation.
161.It Ar "g1"
162Print the input graph before making anything.
163.It Ar "g2"
164Print the input graph after making everything, or before exiting
165on error.
166.It Ar "g3"
167Print the input graph before exiting on error.
168.It Ar j
169Print debugging information about running multiple shells.
170.It Ar l
171Print commands in Makefiles regardless of whether or not they are prefixed by
172.Ql @
173or other "quiet" flags.
174Also known as "loud" behavior.
175.It Ar M
176Print debugging information about "meta" mode decisions about targets.
177.It Ar m
178Print debugging information about making targets, including modification
179dates.
180.It Ar n
181Don't delete the temporary command scripts created when running commands.
182These temporary scripts are created in the directory
183referred to by the
184.Ev TMPDIR
185environment variable, or in
186.Pa /tmp
187if
188.Ev TMPDIR
189is unset or set to the empty string.
190The temporary scripts are created by
191.Xr mkstemp 3 ,
192and have names of the form
193.Pa makeXXXXXX .
194.Em NOTE :
195This can create many files in
196.Ev TMPDIR
197or
198.Pa /tmp ,
199so use with care.
200.It Ar p
201Print debugging information about makefile parsing.
202.It Ar s
203Print debugging information about suffix-transformation rules.
204.It Ar t
205Print debugging information about target list maintenance.
206.It Ar V
207Force the
208.Fl V
209option to print raw values of variables.
210.It Ar v
211Print debugging information about variable assignment.
212.It Ar w
213Print entering and leaving directory messages, pre and post processing.
214.It Ar x
215Run shell commands with
216.Fl x
217so the actual commands are printed as they are executed.
218.El
219.It Fl e
220Specify that environment variables override macro assignments within
221makefiles.
222.It Fl f Ar makefile
223Specify a makefile to read instead of the default
224.Ql Pa makefile .
225If
226.Ar makefile
227is
228.Ql Fl ,
229standard input is read.
230Multiple makefiles may be specified, and are read in the order specified.
231.It Fl I Ar directory
232Specify a directory in which to search for makefiles and included makefiles.
233The system makefile directory (or directories, see the
234.Fl m
235option) is automatically included as part of this list.
236.It Fl i
237Ignore non-zero exit of shell commands in the makefile.
238Equivalent to specifying
239.Ql Fl
240before each command line in the makefile.
241.It Fl J Ar private
242This option should
243.Em not
244be specified by the user.
245.Pp
246When the
247.Ar j
248option is in use in a recursive build, this option is passed by a make
249to child makes to allow all the make processes in the build to
250cooperate to avoid overloading the system.
251.It Fl j Ar max_jobs
252Specify the maximum number of jobs that
253.Nm
254may have running at any one time.
255The value is saved in
256.Va .MAKE.JOBS .
257Turns compatibility mode off, unless the
258.Ar B
259flag is also specified.
260When compatibility mode is off, all commands associated with a
261target are executed in a single shell invocation as opposed to the
262traditional one shell invocation per line.
263This can break traditional scripts which change directories on each
264command invocation and then expect to start with a fresh environment
265on the next line.
266It is more efficient to correct the scripts rather than turn backwards
267compatibility on.
268.It Fl k
269Continue processing after errors are encountered, but only on those targets
270that do not depend on the target whose creation caused the error.
271.It Fl m Ar directory
272Specify a directory in which to search for sys.mk and makefiles included
273via the
274.Ao Ar file Ac Ns -style
275include statement.
276The
277.Fl m
278option can be used multiple times to form a search path.
279This path will override the default system include path: /usr/share/mk.
280Furthermore the system include path will be appended to the search path used
281for
282.Qo Ar file Qc Ns -style
283include statements (see the
284.Fl I
285option).
286.Pp
287If a file or directory name in the
288.Fl m
289argument (or the
290.Ev MAKESYSPATH
291environment variable) starts with the string
292.Qq \&.../
293then
294.Nm
295will search for the specified file or directory named in the remaining part
296of the argument string.
297The search starts with the current directory of
298the Makefile and then works upward towards the root of the filesystem.
299If the search is successful, then the resulting directory replaces the
300.Qq \&.../
301specification in the
302.Fl m
303argument.
304If used, this feature allows
305.Nm
306to easily search in the current source tree for customized sys.mk files
307(e.g., by using
308.Qq \&.../mk/sys.mk
309as an argument).
310.It Fl n
311Display the commands that would have been executed, but do not
312actually execute them unless the target depends on the .MAKE special
313source (see below).
314.It Fl N
315Display the commands which would have been executed, but do not
316actually execute any of them; useful for debugging top-level makefiles
317without descending into subdirectories.
318.It Fl q
319Do not execute any commands, but exit 0 if the specified targets are
320up-to-date and 1, otherwise.
321.It Fl r
322Do not use the built-in rules specified in the system makefile.
323.It Fl s
324Do not echo any commands as they are executed.
325Equivalent to specifying
326.Ql Ic @
327before each command line in the makefile.
328.It Fl T Ar tracefile
329When used with the
330.Fl j
331flag,
332append a trace record to
333.Ar tracefile
334for each job started and completed.
335.It Fl t
336Rather than re-building a target as specified in the makefile, create it
337or update its modification time to make it appear up-to-date.
338.It Fl V Ar variable
339Print
340.Nm Ns 's
341idea of the value of
342.Ar variable ,
343in the global context.
344Do not build any targets.
345Multiple instances of this option may be specified;
346the variables will be printed one per line,
347with a blank line for each null or undefined variable.
348If
349.Ar variable
350contains a
351.Ql \&$
352then the value will be expanded before printing.
353.It Fl W
354Treat any warnings during makefile parsing as errors.
355.It Fl X
356Don't export variables passed on the command line to the environment
357individually.
358Variables passed on the command line are still exported
359via the
360.Va MAKEFLAGS
361environment variable.
362This option may be useful on systems which have a small limit on the
363size of command arguments.
364.It Ar variable=value
365Set the value of the variable
366.Ar variable
367to
368.Ar value .
369Normally, all values passed on the command line are also exported to
370sub-makes in the environment.
371The
372.Fl X
373flag disables this behavior.
374Variable assignments should follow options for POSIX compatibility
375but no ordering is enforced.
376.El
377.Pp
378There are seven different types of lines in a makefile: file dependency
379specifications, shell commands, variable assignments, include statements,
380conditional directives, for loops, and comments.
381.Pp
382In general, lines may be continued from one line to the next by ending
383them with a backslash
384.Pq Ql \e .
385The trailing newline character and initial whitespace on the following
386line are compressed into a single space.
387.Sh FILE DEPENDENCY SPECIFICATIONS
388Dependency lines consist of one or more targets, an operator, and zero
389or more sources.
390This creates a relationship where the targets
391.Dq depend
392on the sources
393and are usually created from them.
394The exact relationship between the target and the source is determined
395by the operator that separates them.
396The three operators are as follows:
397.Bl -tag -width flag
398.It Ic \&:
399A target is considered out-of-date if its modification time is less than
400those of any of its sources.
401Sources for a target accumulate over dependency lines when this operator
402is used.
403The target is removed if
404.Nm
405is interrupted.
406.It Ic \&!
407Targets are always re-created, but not until all sources have been
408examined and re-created as necessary.
409Sources for a target accumulate over dependency lines when this operator
410is used.
411The target is removed if
412.Nm
413is interrupted.
414.It Ic \&::
415If no sources are specified, the target is always re-created.
416Otherwise, a target is considered out-of-date if any of its sources has
417been modified more recently than the target.
418Sources for a target do not accumulate over dependency lines when this
419operator is used.
420The target will not be removed if
421.Nm
422is interrupted.
423.El
424.Pp
425Targets and sources may contain the shell wildcard values
426.Ql \&? ,
427.Ql * ,
428.Ql [] ,
429and
430.Ql {} .
431The values
432.Ql \&? ,
433.Ql * ,
434and
435.Ql []
436may only be used as part of the final
437component of the target or source, and must be used to describe existing
438files.
439The value
440.Ql {}
441need not necessarily be used to describe existing files.
442Expansion is in directory order, not alphabetically as done in the shell.
443.Sh SHELL COMMANDS
444Each target may have associated with it a series of shell commands, normally
445used to create the target.
446Each of the commands in this script
447.Em must
448be preceded by a tab.
449While any target may appear on a dependency line, only one of these
450dependencies may be followed by a creation script, unless the
451.Ql Ic \&::
452operator is used.
453.Pp
454If the first characters of the command line are any combination of
455.Ql Ic @ ,
456.Ql Ic + ,
457or
458.Ql Ic \- ,
459the command is treated specially.
460A
461.Ql Ic @
462causes the command not to be echoed before it is executed.
463A
464.Ql Ic +
465causes the command to be executed even when
466.Fl n
467is given.
468This is similar to the effect of the .MAKE special source,
469except that the effect can be limited to a single line of a script.
470A
471.Ql Ic \-
472causes any non-zero exit status of the command line to be ignored.
473.Pp
474When
475.Nm
476is run in jobs mode with
477.Fl j Ar max_jobs ,
478the entire script for the target is fed to a
479single instance of the shell.
480.Pp
481In compatibility (non-jobs) mode, each command is run in a separate process.
482If the command contains any shell meta characters
483.Pq Ql #=|^(){};&<>*?[]:$`\e\en
484it will be passed to the shell, otherwise
485.Nm
486will attempt direct execution.
487.Pp
488Since
489.Nm
490will
491.Xr chdir 2
492to
493.Ql Va .OBJDIR
494before executing any targets, each child process
495starts with that as its current working directory.
496.Pp
497Makefiles should be written so that the mode of
498.Nm
499operation does not change their behavior.
500For example, any command which needs to use
501.Dq cd
502or
503.Dq chdir ,
504without side-effect should be put in parenthesis:
505.Bd -literal -offset indent
506
507avoid-chdir-side-effects:
508	@echo Building $@ in `pwd`
509	@(cd ${.CURDIR} && ${.MAKE} $@)
510	@echo Back in `pwd`
511
512ensure-one-shell-regardless-of-mode:
513	@echo Building $@ in `pwd`; \\
514	(cd ${.CURDIR} && ${.MAKE} $@); \\
515	echo Back in `pwd`
516.Ed
517.Sh VARIABLE ASSIGNMENTS
518Variables in make are much like variables in the shell, and, by tradition,
519consist of all upper-case letters.
520.Ss Variable assignment modifiers
521The five operators that can be used to assign values to variables are as
522follows:
523.Bl -tag -width Ds
524.It Ic \&=
525Assign the value to the variable.
526Any previous value is overridden.
527.It Ic \&+=
528Append the value to the current value of the variable.
529.It Ic \&?=
530Assign the value to the variable if it is not already defined.
531.It Ic \&:=
532Assign with expansion, i.e. expand the value before assigning it
533to the variable.
534Normally, expansion is not done until the variable is referenced.
535.Em NOTE :
536References to undefined variables are
537.Em not
538expanded.
539This can cause problems when variable modifiers are used.
540.It Ic \&!=
541Expand the value and pass it to the shell for execution and assign
542the result to the variable.
543Any newlines in the result are replaced with spaces.
544.El
545.Pp
546Any white-space before the assigned
547.Ar value
548is removed; if the value is being appended, a single space is inserted
549between the previous contents of the variable and the appended value.
550.Pp
551Variables are expanded by surrounding the variable name with either
552curly braces
553.Pq Ql {}
554or parentheses
555.Pq Ql ()
556and preceding it with
557a dollar sign
558.Pq Ql \&$ .
559If the variable name contains only a single letter, the surrounding
560braces or parentheses are not required.
561This shorter form is not recommended.
562.Pp
563If the variable name contains a dollar, then the name itself is expanded first.
564This allows almost arbitrary variable names, however names containing dollar,
565braces, parenthesis, or whitespace are really best avoided!
566.Pp
567If the result of expanding a variable contains a dollar sign
568.Pq Ql \&$
569the string is expanded again.
570.Pp
571Variable substitution occurs at three distinct times, depending on where
572the variable is being used.
573.Bl -enum
574.It
575Variables in dependency lines are expanded as the line is read.
576.It
577Variables in shell commands are expanded when the shell command is
578executed.
579.It
580.Dq .for
581loop index variables are expanded on each loop iteration.
582Note that other variables are not expanded inside loops so
583the following example code:
584.Bd -literal -offset indent
585
586.Dv .for i in 1 2 3
587a+=     ${i}
588j=      ${i}
589b+=     ${j}
590.Dv .endfor
591
592all:
593	@echo ${a}
594	@echo ${b}
595
596.Ed
597will print:
598.Bd -literal -offset indent
5991 2 3
6003 3 3
601
602.Ed
603Because while ${a} contains
604.Dq 1 2 3
605after the loop is executed, ${b}
606contains
607.Dq ${j} ${j} ${j}
608which expands to
609.Dq 3 3 3
610since after the loop completes ${j} contains
611.Dq 3 .
612.El
613.Ss Variable classes
614The four different classes of variables (in order of increasing precedence)
615are:
616.Bl -tag -width Ds
617.It Environment variables
618Variables defined as part of
619.Nm Ns 's
620environment.
621.It Global variables
622Variables defined in the makefile or in included makefiles.
623.It Command line variables
624Variables defined as part of the command line.
625.It Local variables
626Variables that are defined specific to a certain target.
627The seven local variables are as follows:
628.Bl -tag -width ".ARCHIVE"
629.It Va .ALLSRC
630The list of all sources for this target; also known as
631.Ql Va \&\*[Gt] .
632.It Va .ARCHIVE
633The name of the archive file.
634.It Va .IMPSRC
635In suffix-transformation rules, the name/path of the source from which the
636target is to be transformed (the
637.Dq implied
638source); also known as
639.Ql Va \&\*[Lt] .
640It is not defined in explicit rules.
641.It Va .MEMBER
642The name of the archive member.
643.It Va .OODATE
644The list of sources for this target that were deemed out-of-date; also
645known as
646.Ql Va \&? .
647.It Va .PREFIX
648The file prefix of the target, containing only the file portion, no suffix
649or preceding directory components; also known as
650.Ql Va * .
651.It Va .TARGET
652The name of the target; also known as
653.Ql Va @ .
654.El
655.Pp
656The shorter forms
657.Ql Va @ ,
658.Ql Va \&? ,
659.Ql Va \&\*[Lt] ,
660.Ql Va \&\*[Gt] ,
661and
662.Ql Va *
663are permitted for backward
664compatibility with historical makefiles and are not recommended.
665The six variables
666.Ql Va "@F" ,
667.Ql Va "@D" ,
668.Ql Va "\*[Lt]F" ,
669.Ql Va "\*[Lt]D" ,
670.Ql Va "*F" ,
671and
672.Ql Va "*D"
673are permitted for compatibility with
674.At V
675makefiles and are not recommended.
676.Pp
677Four of the local variables may be used in sources on dependency lines
678because they expand to the proper value for each target on the line.
679These variables are
680.Ql Va .TARGET ,
681.Ql Va .PREFIX ,
682.Ql Va .ARCHIVE ,
683and
684.Ql Va .MEMBER .
685.El
686.Ss Additional built-in variables
687In addition,
688.Nm
689sets or knows about the following variables:
690.Bl -tag -width .MAKEOVERRIDES
691.It Va \&$
692A single dollar sign
693.Ql \&$ ,
694i.e.
695.Ql \&$$
696expands to a single dollar
697sign.
698.It Va .ALLTARGETS
699The list of all targets encountered in the Makefile.
700If evaluated during
701Makefile parsing, lists only those targets encountered thus far.
702.It Va .CURDIR
703A path to the directory where
704.Nm
705was executed.
706Refer to the description of
707.Ql Ev PWD
708for more details.
709.It Ev MAKE
710The name that
711.Nm
712was executed with
713.Pq Va argv[0] .
714For compatibility
715.Nm
716also sets
717.Va .MAKE
718with the same value.
719The preferred variable to use is the environment variable
720.Ev MAKE
721because it is more compatible with other versions of
722.Nm
723and cannot be confused with the special target with the same name.
724.It Va .MAKE.ALWAYS_PASS_JOB_QUEUE
725Tells
726.Nm
727whether to pass the descriptors of the job token queue
728even if the target is not tagged with
729.Ic .MAKE
730The default is
731.Ql Pa yes
732for backwards compatability with
733.Fx 9.0
734and earlier.
735.It Va .MAKE.DEPENDFILE
736Names the makefile (default
737.Ql Pa .depend )
738from which generated dependencies are read.
739.It Va .MAKE.EXPAND_VARIABLES
740A boolean that controls the default behavior of the
741.Fl V
742option.
743.It Va .MAKE.EXPORTED
744The list of variables exported by
745.Nm .
746.It Va .MAKE.JOBS
747The argument to the
748.Fl j
749option.
750.It Va .MAKE.JOB.PREFIX
751If
752.Nm
753is run with
754.Ar j
755then output for each target is prefixed with a token
756.Ql --- target ---
757the first part of which can be controlled via
758.Va .MAKE.JOB.PREFIX .
759If
760.Va .MAKE.JOB.PREFIX
761is empty, no token is printed.
762.br
763For example:
764.Li .MAKE.JOB.PREFIX=${.newline}---${.MAKE:T}[${.MAKE.PID}]
765would produce tokens like
766.Ql ---make[1234] target ---
767making it easier to track the degree of parallelism being achieved.
768.It Ev MAKEFLAGS
769The environment variable
770.Ql Ev MAKEFLAGS
771may contain anything that
772may be specified on
773.Nm Ns 's
774command line.
775Anything specified on
776.Nm Ns 's
777command line is appended to the
778.Ql Ev MAKEFLAGS
779variable which is then
780entered into the environment for all programs which
781.Nm
782executes.
783.It Va .MAKE.LEVEL
784The recursion depth of
785.Nm .
786The initial instance of
787.Nm
788will be 0, and an incremented value is put into the environment
789to be seen by the next generation.
790This allows tests like:
791.Li .if ${.MAKE.LEVEL} == 0
792to protect things which should only be evaluated in the initial instance of
793.Nm .
794.It Va .MAKE.MAKEFILE_PREFERENCE
795The ordered list of makefile names
796(default
797.Ql Pa makefile ,
798.Ql Pa Makefile )
799that
800.Nm
801will look for.
802.It Va .MAKE.MAKEFILES
803The list of makefiles read by
804.Nm ,
805which is useful for tracking dependencies.
806Each makefile is recorded only once, regardless of the number of times read.
807.It Va .MAKE.MODE
808Processed after reading all makefiles.
809Can affect the mode that
810.Nm
811runs in.
812It can contain a number of keywords:
813.Bl -hang -width ignore-cmd
814.It Pa compat
815Like
816.Fl B ,
817puts
818.Nm
819into "compat" mode.
820.It Pa meta
821Puts
822.Nm
823into "meta" mode, where meta files are created for each target
824to capture the command run, the output generated and if
825.Xr filemon 4
826is available, the system calls which are of interest to
827.Nm .
828The captured output can be very useful when diagnosing errors.
829.It Pa curdirOk= Ar bf
830Normally
831.Nm
832will not create .meta files in
833.Ql Va .CURDIR .
834This can be overridden by setting
835.Va bf
836to a value which represents True.
837.It Pa env
838For debugging, it can be useful to inlcude the environment
839in the .meta file.
840.It Pa verbose
841If in "meta" mode, print a clue about the target being built.
842This is useful if the build is otherwise running silently.
843The message printed the value of:
844.Va .MAKE.META.PREFIX .
845.It Pa ignore-cmd
846Some makefiles have commands which are simply not stable.
847This keyword causes them to be ignored for
848determining whether a target is out of date in "meta" mode.
849See also
850.Ic .NOMETA_CMP .
851.It Pa silent= Ar bf
852If
853.Va bf
854is True, when a .meta file is created, mark the target
855.Ic .SILENT .
856.El
857.It Va .MAKE.META.BAILIWICK
858In "meta" mode, provides a list of prefixes which
859match the directories controlled by
860.Nm .
861If a file that was generated outside of
862.Va .OBJDIR
863but within said bailiwick is missing,
864the current target is considered out-of-date.
865.It Va .MAKE.META.CREATED
866In "meta" mode, this variable contains a list of all the meta files
867updated.
868If not empty, it can be used to trigger processing of
869.Va .MAKE.META.FILES .
870.It Va .MAKE.META.FILES
871In "meta" mode, this variable contains a list of all the meta files
872used (updated or not).
873This list can be used to process the meta files to extract dependency
874information.
875.It Va .MAKE.META.IGNORE_PATHS
876Provides a list of path prefixes that should be ignored;
877because the contents are expected to change over time.
878The default list includes:
879.Ql Pa /dev /etc /proc /tmp /var/run /var/tmp
880.It Va .MAKE.META.PREFIX
881Defines the message printed for each meta file updated in "meta verbose" mode.
882The default value is:
883.Dl Building ${.TARGET:H:tA}/${.TARGET:T}
884.It Va .MAKEOVERRIDES
885This variable is used to record the names of variables assigned to
886on the command line, so that they may be exported as part of
887.Ql Ev MAKEFLAGS .
888This behaviour can be disabled by assigning an empty value to
889.Ql Va .MAKEOVERRIDES
890within a makefile.
891Extra variables can be exported from a makefile
892by appending their names to
893.Ql Va .MAKEOVERRIDES .
894.Ql Ev MAKEFLAGS
895is re-exported whenever
896.Ql Va .MAKEOVERRIDES
897is modified.
898.It Va .MAKE.PATH_FILEMON
899If
900.Nm
901was built with
902.Xr filemon 4
903support, this is set to the path of the device node.
904This allows makefiles to test for this support.
905.It Va .MAKE.PID
906The process-id of
907.Nm .
908.It Va .MAKE.PPID
909The parent process-id of
910.Nm .
911.It Va MAKE_PRINT_VAR_ON_ERROR
912When
913.Nm
914stops due to an error, it prints its name and the value of
915.Ql Va .CURDIR
916as well as the value of any variables named in
917.Ql Va MAKE_PRINT_VAR_ON_ERROR .
918.It Va .newline
919This variable is simply assigned a newline character as its value.
920This allows expansions using the
921.Cm \&:@
922modifier to put a newline between
923iterations of the loop rather than a space.
924For example, the printing of
925.Ql Va MAKE_PRINT_VAR_ON_ERROR
926could be done as ${MAKE_PRINT_VAR_ON_ERROR:@v@$v='${$v}'${.newline}@}.
927.It Va .OBJDIR
928A path to the directory where the targets are built.
929Its value is determined by trying to
930.Xr chdir 2
931to the following directories in order and using the first match:
932.Bl -enum
933.It
934.Ev ${MAKEOBJDIRPREFIX}${.CURDIR}
935.Pp
936(Only if
937.Ql Ev MAKEOBJDIRPREFIX
938is set in the environment or on the command line.)
939.It
940.Ev ${MAKEOBJDIR}
941.Pp
942(Only if
943.Ql Ev MAKEOBJDIR
944is set in the environment or on the command line.)
945.It
946.Ev ${.CURDIR} Ns Pa /obj. Ns Ev ${MACHINE}
947.It
948.Ev ${.CURDIR} Ns Pa /obj
949.It
950.Pa /usr/obj/ Ns Ev ${.CURDIR}
951.It
952.Ev ${.CURDIR}
953.El
954.Pp
955Variable expansion is performed on the value before it's used,
956so expressions such as
957.Dl ${.CURDIR:S,^/usr/src,/var/obj,}
958may be used.
959This is especially useful with
960.Ql Ev MAKEOBJDIR .
961.Pp
962.Ql Va .OBJDIR
963may be modified in the makefile as a global variable.
964In all cases,
965.Nm
966will
967.Xr chdir 2
968to
969.Ql Va .OBJDIR
970and set
971.Ql Ev PWD
972to that directory before executing any targets.
973.
974.It Va .PARSEDIR
975A path to the directory of the current
976.Ql Pa Makefile
977being parsed.
978.It Va .PARSEFILE
979The basename of the current
980.Ql Pa Makefile
981being parsed.
982This variable and
983.Ql Va .PARSEDIR
984are both set only while the
985.Ql Pa Makefiles
986are being parsed.
987If you want to retain their current values, assign them to a variable
988using assignment with expansion:
989.Pq Ql Cm \&:= .
990.It Va .PATH
991A variable that represents the list of directories that
992.Nm
993will search for files.
994The search list should be updated using the target
995.Ql Va .PATH
996rather than the variable.
997.It Ev PWD
998Alternate path to the current directory.
999.Nm
1000normally sets
1001.Ql Va .CURDIR
1002to the canonical path given by
1003.Xr getcwd 3 .
1004However, if the environment variable
1005.Ql Ev PWD
1006is set and gives a path to the current directory, then
1007.Nm
1008sets
1009.Ql Va .CURDIR
1010to the value of
1011.Ql Ev PWD
1012instead.
1013This behaviour is disabled if
1014.Ql Ev MAKEOBJDIRPREFIX
1015is set or
1016.Ql Ev MAKEOBJDIR
1017contains a variable transform.
1018.Ql Ev PWD
1019is set to the value of
1020.Ql Va .OBJDIR
1021for all programs which
1022.Nm
1023executes.
1024.It Ev .TARGETS
1025The list of targets explicitly specified on the command line, if any.
1026.It Ev VPATH
1027Colon-separated
1028.Pq Dq \&:
1029lists of directories that
1030.Nm
1031will search for files.
1032The variable is supported for compatibility with old make programs only,
1033use
1034.Ql Va .PATH
1035instead.
1036.El
1037.Ss Variable modifiers
1038Variable expansion may be modified to select or modify each word of the
1039variable (where a
1040.Dq word
1041is white-space delimited sequence of characters).
1042The general format of a variable expansion is as follows:
1043.Pp
1044.Dl ${variable[:modifier[:...]]}
1045.Pp
1046Each modifier begins with a colon,
1047which may be escaped with a backslash
1048.Pq Ql \e .
1049.Pp
1050A set of modifiers can be specified via a variable, as follows:
1051.Pp
1052.Dl modifier_variable=modifier[:...]
1053.Dl ${variable:${modifier_variable}[:...]}
1054.Pp
1055In this case the first modifier in the modifier_variable does not
1056start with a colon, since that must appear in the referencing
1057variable.
1058If any of the modifiers in the modifier_variable contain a dollar sign
1059.Pq Ql $ ,
1060these must be doubled to avoid early expansion.
1061.Pp
1062The supported modifiers are:
1063.Bl -tag -width EEE
1064.It Cm \&:E
1065Replaces each word in the variable with its suffix.
1066.It Cm \&:H
1067Replaces each word in the variable with everything but the last component.
1068.It Cm \&:M Ns Ar pattern
1069Select only those words that match
1070.Ar pattern .
1071The standard shell wildcard characters
1072.Pf ( Ql * ,
1073.Ql \&? ,
1074and
1075.Ql Oo Oc )
1076may
1077be used.
1078The wildcard characters may be escaped with a backslash
1079.Pq Ql \e .
1080.It Cm \&:N Ns Ar pattern
1081This is identical to
1082.Ql Cm \&:M ,
1083but selects all words which do not match
1084.Ar pattern .
1085.It Cm \&:O
1086Order every word in variable alphabetically.
1087To sort words in
1088reverse order use the
1089.Ql Cm \&:O:[-1..1]
1090combination of modifiers.
1091.It Cm \&:Ox
1092Randomize words in variable.
1093The results will be different each time you are referring to the
1094modified variable; use the assignment with expansion
1095.Pq Ql Cm \&:=
1096to prevent such behaviour.
1097For example,
1098.Bd -literal -offset indent
1099LIST=			uno due tre quattro
1100RANDOM_LIST=		${LIST:Ox}
1101STATIC_RANDOM_LIST:=	${LIST:Ox}
1102
1103all:
1104	@echo "${RANDOM_LIST}"
1105	@echo "${RANDOM_LIST}"
1106	@echo "${STATIC_RANDOM_LIST}"
1107	@echo "${STATIC_RANDOM_LIST}"
1108.Ed
1109may produce output similar to:
1110.Bd -literal -offset indent
1111quattro due tre uno
1112tre due quattro uno
1113due uno quattro tre
1114due uno quattro tre
1115.Ed
1116.It Cm \&:Q
1117Quotes every shell meta-character in the variable, so that it can be passed
1118safely through recursive invocations of
1119.Nm .
1120.It Cm \&:R
1121Replaces each word in the variable with everything but its suffix.
1122.It Cm \&:gmtime
1123The value is a format string for
1124.Xr strftime 3 ,
1125using the current
1126.Xr gmtime 3 .
1127.It Cm \&:hash
1128Compute a 32bit hash of the value and encode it as hex digits.
1129.It Cm \&:localtime
1130The value is a format string for
1131.Xr strftime 3 ,
1132using the current
1133.Xr localtime 3 .
1134.It Cm \&:tA
1135Attempt to convert variable to an absolute path using
1136.Xr realpath 3 ,
1137if that fails, the value is unchanged.
1138.It Cm \&:tl
1139Converts variable to lower-case letters.
1140.It Cm \&:ts Ns Ar c
1141Words in the variable are normally separated by a space on expansion.
1142This modifier sets the separator to the character
1143.Ar c .
1144If
1145.Ar c
1146is omitted, then no separator is used.
1147The common escapes (including octal numeric codes), work as expected.
1148.It Cm \&:tu
1149Converts variable to upper-case letters.
1150.It Cm \&:tW
1151Causes the value to be treated as a single word
1152(possibly containing embedded white space).
1153See also
1154.Ql Cm \&:[*] .
1155.It Cm \&:tw
1156Causes the value to be treated as a sequence of
1157words delimited by white space.
1158See also
1159.Ql Cm \&:[@] .
1160.Sm off
1161.It Cm \&:S No \&/ Ar old_string No \&/ Ar new_string No \&/ Op Cm 1gW
1162.Sm on
1163Modify the first occurrence of
1164.Ar old_string
1165in the variable's value, replacing it with
1166.Ar new_string .
1167If a
1168.Ql g
1169is appended to the last slash of the pattern, all occurrences
1170in each word are replaced.
1171If a
1172.Ql 1
1173is appended to the last slash of the pattern, only the first word
1174is affected.
1175If a
1176.Ql W
1177is appended to the last slash of the pattern,
1178then the value is treated as a single word
1179(possibly containing embedded white space).
1180If
1181.Ar old_string
1182begins with a caret
1183.Pq Ql ^ ,
1184.Ar old_string
1185is anchored at the beginning of each word.
1186If
1187.Ar old_string
1188ends with a dollar sign
1189.Pq Ql \&$ ,
1190it is anchored at the end of each word.
1191Inside
1192.Ar new_string ,
1193an ampersand
1194.Pq Ql \*[Am]
1195is replaced by
1196.Ar old_string
1197(without any
1198.Ql ^
1199or
1200.Ql \&$ ) .
1201Any character may be used as a delimiter for the parts of the modifier
1202string.
1203The anchoring, ampersand and delimiter characters may be escaped with a
1204backslash
1205.Pq Ql \e .
1206.Pp
1207Variable expansion occurs in the normal fashion inside both
1208.Ar old_string
1209and
1210.Ar new_string
1211with the single exception that a backslash is used to prevent the expansion
1212of a dollar sign
1213.Pq Ql \&$ ,
1214not a preceding dollar sign as is usual.
1215.Sm off
1216.It Cm \&:C No \&/ Ar pattern No \&/ Ar replacement No \&/ Op Cm 1gW
1217.Sm on
1218The
1219.Cm \&:C
1220modifier is just like the
1221.Cm \&:S
1222modifier except that the old and new strings, instead of being
1223simple strings, are a regular expression (see
1224.Xr regex 3 )
1225string
1226.Ar pattern
1227and an
1228.Xr ed 1 Ns \-style
1229string
1230.Ar replacement .
1231Normally, the first occurrence of the pattern
1232.Ar pattern
1233in each word of the value is substituted with
1234.Ar replacement .
1235The
1236.Ql 1
1237modifier causes the substitution to apply to at most one word; the
1238.Ql g
1239modifier causes the substitution to apply to as many instances of the
1240search pattern
1241.Ar pattern
1242as occur in the word or words it is found in; the
1243.Ql W
1244modifier causes the value to be treated as a single word
1245(possibly containing embedded white space).
1246Note that
1247.Ql 1
1248and
1249.Ql g
1250are orthogonal; the former specifies whether multiple words are
1251potentially affected, the latter whether multiple substitutions can
1252potentially occur within each affected word.
1253.It Cm \&:T
1254Replaces each word in the variable with its last component.
1255.It Cm \&:u
1256Remove adjacent duplicate words (like
1257.Xr uniq 1 ) .
1258.Sm off
1259.It Cm \&:\&? Ar true_string Cm \&: Ar false_string
1260.Sm on
1261If the variable name (not its value), when parsed as a .if conditional
1262expression, evaluates to true, return as its value the
1263.Ar true_string ,
1264otherwise return the
1265.Ar false_string .
1266Since the variable name is used as the expression, \&:\&? must be the
1267first modifier after the variable name itself - which will, of course,
1268usually contain variable expansions.
1269A common error is trying to use expressions like
1270.Dl ${NUMBERS:M42:?match:no}
1271which actually tests defined(NUMBERS),
1272to determine is any words match "42" you need to use something like:
1273.Dl ${"${NUMBERS:M42}" != \&"\&":?match:no} .
1274.It Ar :old_string=new_string
1275This is the
1276.At V
1277style variable substitution.
1278It must be the last modifier specified.
1279If
1280.Ar old_string
1281or
1282.Ar new_string
1283do not contain the pattern matching character
1284.Ar %
1285then it is assumed that they are
1286anchored at the end of each word, so only suffixes or entire
1287words may be replaced.
1288Otherwise
1289.Ar %
1290is the substring of
1291.Ar old_string
1292to be replaced in
1293.Ar new_string .
1294.Pp
1295Variable expansion occurs in the normal fashion inside both
1296.Ar old_string
1297and
1298.Ar new_string
1299with the single exception that a backslash is used to prevent the
1300expansion of a dollar sign
1301.Pq Ql \&$ ,
1302not a preceding dollar sign as is usual.
1303.Sm off
1304.It Cm \&:@ Ar temp Cm @ Ar string Cm @
1305.Sm on
1306This is the loop expansion mechanism from the OSF Development
1307Environment (ODE) make.
1308Unlike
1309.Cm \&.for
1310loops expansion occurs at the time of
1311reference.
1312Assign
1313.Ar temp
1314to each word in the variable and evaluate
1315.Ar string .
1316The ODE convention is that
1317.Ar temp
1318should start and end with a period.
1319For example.
1320.Dl ${LINKS:@.LINK.@${LN} ${TARGET} ${.LINK.}@}
1321.Pp
1322However a single character variable is often more readable:
1323.Dl ${MAKE_PRINT_VAR_ON_ERROR:@v@$v='${$v}'${.newline}@}
1324.It Cm \&:U Ns Ar newval
1325If the variable is undefined
1326.Ar newval
1327is the value.
1328If the variable is defined, the existing value is returned.
1329This is another ODE make feature.
1330It is handy for setting per-target CFLAGS for instance:
1331.Dl ${_${.TARGET:T}_CFLAGS:U${DEF_CFLAGS}}
1332If a value is only required if the variable is undefined, use:
1333.Dl ${VAR:D:Unewval}
1334.It Cm \&:D Ns Ar newval
1335If the variable is defined
1336.Ar newval
1337is the value.
1338.It Cm \&:L
1339The name of the variable is the value.
1340.It Cm \&:P
1341The path of the node which has the same name as the variable
1342is the value.
1343If no such node exists or its path is null, then the
1344name of the variable is used.
1345In order for this modifier to work, the name (node) must at least have
1346appeared on the rhs of a dependency.
1347.Sm off
1348.It Cm \&:\&! Ar cmd Cm \&!
1349.Sm on
1350The output of running
1351.Ar cmd
1352is the value.
1353.It Cm \&:sh
1354If the variable is non-empty it is run as a command and the output
1355becomes the new value.
1356.It Cm \&::= Ns Ar str
1357The variable is assigned the value
1358.Ar str
1359after substitution.
1360This modifier and its variations are useful in
1361obscure situations such as wanting to set a variable when shell commands
1362are being parsed.
1363These assignment modifiers always expand to
1364nothing, so if appearing in a rule line by themselves should be
1365preceded with something to keep
1366.Nm
1367happy.
1368.Pp
1369The
1370.Ql Cm \&::
1371helps avoid false matches with the
1372.At V
1373style
1374.Cm \&:=
1375modifier and since substitution always occurs the
1376.Cm \&::=
1377form is vaguely appropriate.
1378.It Cm \&::?= Ns Ar str
1379As for
1380.Cm \&::=
1381but only if the variable does not already have a value.
1382.It Cm \&::+= Ns Ar str
1383Append
1384.Ar str
1385to the variable.
1386.It Cm \&::!= Ns Ar cmd
1387Assign the output of
1388.Ar cmd
1389to the variable.
1390.It Cm \&:\&[ Ns Ar range Ns Cm \&]
1391Selects one or more words from the value,
1392or performs other operations related to the way in which the
1393value is divided into words.
1394.Pp
1395Ordinarily, a value is treated as a sequence of words
1396delimited by white space.
1397Some modifiers suppress this behaviour,
1398causing a value to be treated as a single word
1399(possibly containing embedded white space).
1400An empty value, or a value that consists entirely of white-space,
1401is treated as a single word.
1402For the purposes of the
1403.Ql Cm \&:[]
1404modifier, the words are indexed both forwards using positive integers
1405(where index 1 represents the first word),
1406and backwards using negative integers
1407(where index \-1 represents the last word).
1408.Pp
1409The
1410.Ar range
1411is subjected to variable expansion, and the expanded result is
1412then interpreted as follows:
1413.Bl -tag -width index
1414.\" :[n]
1415.It Ar index
1416Selects a single word from the value.
1417.\" :[start..end]
1418.It Ar start Ns Cm \&.. Ns Ar end
1419Selects all words from
1420.Ar start
1421to
1422.Ar end ,
1423inclusive.
1424For example,
1425.Ql Cm \&:[2..-1]
1426selects all words from the second word to the last word.
1427If
1428.Ar start
1429is greater than
1430.Ar end ,
1431then the words are output in reverse order.
1432For example,
1433.Ql Cm \&:[-1..1]
1434selects all the words from last to first.
1435.\" :[*]
1436.It Cm \&*
1437Causes subsequent modifiers to treat the value as a single word
1438(possibly containing embedded white space).
1439Analogous to the effect of
1440\&"$*\&"
1441in Bourne shell.
1442.\" :[0]
1443.It 0
1444Means the same as
1445.Ql Cm \&:[*] .
1446.\" :[*]
1447.It Cm \&@
1448Causes subsequent modifiers to treat the value as a sequence of words
1449delimited by white space.
1450Analogous to the effect of
1451\&"$@\&"
1452in Bourne shell.
1453.\" :[#]
1454.It Cm \&#
1455Returns the number of words in the value.
1456.El \" :[range]
1457.El
1458.Sh INCLUDE STATEMENTS, CONDITIONALS AND FOR LOOPS
1459Makefile inclusion, conditional structures and for loops  reminiscent
1460of the C programming language are provided in
1461.Nm .
1462All such structures are identified by a line beginning with a single
1463dot
1464.Pq Ql \&.
1465character.
1466Files are included with either
1467.Cm \&.include Aq Ar file
1468or
1469.Cm \&.include Pf \*q Ar file Ns \*q .
1470Variables between the angle brackets or double quotes are expanded
1471to form the file name.
1472If angle brackets are used, the included makefile is expected to be in
1473the system makefile directory.
1474If double quotes are used, the including makefile's directory and any
1475directories specified using the
1476.Fl I
1477option are searched before the system
1478makefile directory.
1479For compatibility with other versions of
1480.Nm
1481.Ql include file ...
1482is also accepted.
1483If the include statement is written as
1484.Cm .-include
1485or as
1486.Cm .sinclude
1487then errors locating and/or opening include files are ignored.
1488.Pp
1489Conditional expressions are also preceded by a single dot as the first
1490character of a line.
1491The possible conditionals are as follows:
1492.Bl -tag -width Ds
1493.It Ic .error Ar message
1494The message is printed along with the name of the makefile and line number,
1495then
1496.Nm
1497will exit.
1498.It Ic .export Ar variable ...
1499Export the specified global variable.
1500If no variable list is provided, all globals are exported
1501except for internal variables (those that start with
1502.Ql \&. ) .
1503This is not affected by the
1504.Fl X
1505flag, so should be used with caution.
1506For compatibility with other
1507.Nm
1508programs
1509.Ql export variable=value
1510is also accepted.
1511.Pp
1512Appending a variable name to
1513.Va .MAKE.EXPORTED
1514is equivalent to exporting a variable.
1515.It Ic .export-env Ar variable ...
1516The same as
1517.Ql .export ,
1518except that the variable is not appended to
1519.Va .MAKE.EXPORTED .
1520This allows exporting a value to the environment which is different from that
1521used by
1522.Nm
1523internally.
1524.It Ic .info Ar message
1525The message is printed along with the name of the makefile and line number.
1526.It Ic .undef Ar variable
1527Un-define the specified global variable.
1528Only global variables may be un-defined.
1529.It Ic .unexport Ar variable ...
1530The opposite of
1531.Ql .export .
1532The specified global
1533.Va variable
1534will be removed from
1535.Va .MAKE.EXPORTED .
1536If no variable list is provided, all globals are unexported,
1537and
1538.Va .MAKE.EXPORTED
1539deleted.
1540.It Ic .unexport-env
1541Unexport all globals previously exported and
1542clear the environment inherited from the parent.
1543This operation will cause a memory leak of the original environment,
1544so should be used sparingly.
1545Testing for
1546.Va .MAKE.LEVEL
1547being 0, would make sense.
1548Also note that any variables which originated in the parent environment
1549should be explicitly preserved if desired.
1550For example:
1551.Bd -literal -offset indent
1552.Li .if ${.MAKE.LEVEL} == 0
1553PATH := ${PATH}
1554.Li .unexport-env
1555.Li .export PATH
1556.Li .endif
1557.Pp
1558.Ed
1559Would result in an environment containing only
1560.Ql Ev PATH ,
1561which is the minimal useful environment.
1562Actually
1563.Ql Ev .MAKE.LEVEL
1564will also be pushed into the new environment.
1565.It Ic .warning Ar message
1566The message prefixed by
1567.Ql Pa warning:
1568is printed along with the name of the makefile and line number.
1569.It Ic \&.if Oo \&! Oc Ns Ar expression Op Ar operator expression ...
1570Test the value of an expression.
1571.It Ic .ifdef Oo \&! Oc Ns Ar variable Op Ar operator variable ...
1572Test the value of a variable.
1573.It Ic .ifndef Oo \&! Oc Ns Ar variable Op Ar operator variable ...
1574Test the value of a variable.
1575.It Ic .ifmake Oo \&! Oc Ns Ar target Op Ar operator target ...
1576Test the target being built.
1577.It Ic .ifnmake Oo \&! Ns Oc Ar target Op Ar operator target ...
1578Test the target being built.
1579.It Ic .else
1580Reverse the sense of the last conditional.
1581.It Ic .elif Oo \&! Ns Oc Ar expression Op Ar operator expression ...
1582A combination of
1583.Ql Ic .else
1584followed by
1585.Ql Ic .if .
1586.It Ic .elifdef Oo \&! Oc Ns Ar variable Op Ar operator variable ...
1587A combination of
1588.Ql Ic .else
1589followed by
1590.Ql Ic .ifdef .
1591.It Ic .elifndef Oo \&! Oc Ns Ar variable Op Ar operator variable ...
1592A combination of
1593.Ql Ic .else
1594followed by
1595.Ql Ic .ifndef .
1596.It Ic .elifmake Oo \&! Oc Ns Ar target Op Ar operator target ...
1597A combination of
1598.Ql Ic .else
1599followed by
1600.Ql Ic .ifmake .
1601.It Ic .elifnmake Oo \&! Oc Ns Ar target Op Ar operator target ...
1602A combination of
1603.Ql Ic .else
1604followed by
1605.Ql Ic .ifnmake .
1606.It Ic .endif
1607End the body of the conditional.
1608.El
1609.Pp
1610The
1611.Ar operator
1612may be any one of the following:
1613.Bl -tag -width "Cm XX"
1614.It Cm \&|\&|
1615Logical OR.
1616.It Cm \&\*[Am]\*[Am]
1617Logical
1618.Tn AND ;
1619of higher precedence than
1620.Dq \&|\&| .
1621.El
1622.Pp
1623As in C,
1624.Nm
1625will only evaluate a conditional as far as is necessary to determine
1626its value.
1627Parentheses may be used to change the order of evaluation.
1628The boolean operator
1629.Ql Ic \&!
1630may be used to logically negate an entire
1631conditional.
1632It is of higher precedence than
1633.Ql Ic \&\*[Am]\*[Am] .
1634.Pp
1635The value of
1636.Ar expression
1637may be any of the following:
1638.Bl -tag -width defined
1639.It Ic defined
1640Takes a variable name as an argument and evaluates to true if the variable
1641has been defined.
1642.It Ic make
1643Takes a target name as an argument and evaluates to true if the target
1644was specified as part of
1645.Nm Ns 's
1646command line or was declared the default target (either implicitly or
1647explicitly, see
1648.Va .MAIN )
1649before the line containing the conditional.
1650.It Ic empty
1651Takes a variable, with possible modifiers, and evaluates to true if
1652the expansion of the variable would result in an empty string.
1653.It Ic exists
1654Takes a file name as an argument and evaluates to true if the file exists.
1655The file is searched for on the system search path (see
1656.Va .PATH ) .
1657.It Ic target
1658Takes a target name as an argument and evaluates to true if the target
1659has been defined.
1660.It Ic commands
1661Takes a target name as an argument and evaluates to true if the target
1662has been defined and has commands associated with it.
1663.El
1664.Pp
1665.Ar Expression
1666may also be an arithmetic or string comparison.
1667Variable expansion is
1668performed on both sides of the comparison, after which the integral
1669values are compared.
1670A value is interpreted as hexadecimal if it is
1671preceded by 0x, otherwise it is decimal; octal numbers are not supported.
1672The standard C relational operators are all supported.
1673If after
1674variable expansion, either the left or right hand side of a
1675.Ql Ic ==
1676or
1677.Ql Ic "!="
1678operator is not an integral value, then
1679string comparison is performed between the expanded
1680variables.
1681If no relational operator is given, it is assumed that the expanded
1682variable is being compared against 0 or an empty string in the case
1683of a string comparison.
1684.Pp
1685When
1686.Nm
1687is evaluating one of these conditional expressions, and it encounters
1688a (white-space separated) word it doesn't recognize, either the
1689.Dq make
1690or
1691.Dq defined
1692expression is applied to it, depending on the form of the conditional.
1693If the form is
1694.Ql Ic .ifdef ,
1695.Ql Ic .ifndef ,
1696or
1697.Ql Ic .if
1698the
1699.Dq defined
1700expression is applied.
1701Similarly, if the form is
1702.Ql Ic .ifmake
1703or
1704.Ql Ic .ifnmake , the
1705.Dq make
1706expression is applied.
1707.Pp
1708If the conditional evaluates to true the parsing of the makefile continues
1709as before.
1710If it evaluates to false, the following lines are skipped.
1711In both cases this continues until a
1712.Ql Ic .else
1713or
1714.Ql Ic .endif
1715is found.
1716.Pp
1717For loops are typically used to apply a set of rules to a list of files.
1718The syntax of a for loop is:
1719.Pp
1720.Bl -tag -compact -width Ds
1721.It Ic \&.for Ar variable Oo Ar variable ... Oc Ic in Ar expression
1722.It Aq make-rules
1723.It Ic \&.endfor
1724.El
1725.Pp
1726After the for
1727.Ic expression
1728is evaluated, it is split into words.
1729On each iteration of the loop, one word is taken and assigned to each
1730.Ic variable ,
1731in order, and these
1732.Ic variables
1733are substituted into the
1734.Ic make-rules
1735inside the body of the for loop.
1736The number of words must come out even; that is, if there are three
1737iteration variables, the number of words provided must be a multiple
1738of three.
1739.Sh COMMENTS
1740Comments begin with a hash
1741.Pq Ql \&#
1742character, anywhere but in a shell
1743command line, and continue to the end of an unescaped new line.
1744.Sh SPECIAL SOURCES (ATTRIBUTES)
1745.Bl -tag -width .IGNOREx
1746.It Ic .EXEC
1747Target is never out of date, but always execute commands anyway.
1748.It Ic .IGNORE
1749Ignore any errors from the commands associated with this target, exactly
1750as if they all were preceded by a dash
1751.Pq Ql \- .
1752.\" .It Ic .INVISIBLE
1753.\" XXX
1754.\" .It Ic .JOIN
1755.\" XXX
1756.It Ic .MADE
1757Mark all sources of this target as being up-to-date.
1758.It Ic .MAKE
1759Execute the commands associated with this target even if the
1760.Fl n
1761or
1762.Fl t
1763options were specified.
1764Normally used to mark recursive
1765.Nm Ns 's .
1766.It Ic .META
1767Create a meta file for the target, even if it is flagged as
1768.Ic .PHONY ,
1769.Ic .MAKE ,
1770or
1771.Ic .SPECIAL .
1772Usage in conjunction with
1773.Ic .MAKE
1774is the most likely case.
1775In "meta" mode, the target is out-of-date if the meta file is missing.
1776.It Ic .NOMETA
1777Do not create a meta file for the target.
1778Meta files are also not created for
1779.Ic .PHONY ,
1780.Ic .MAKE ,
1781or
1782.Ic .SPECIAL
1783targets.
1784.It Ic .NOMETA_CMP
1785Ignore differences in commands when deciding if target is out of date.
1786This is useful if the command contains a value which always changes.
1787If the number of commands change, though, the target will still be out of date.
1788The same effect applies to any command line that uses the variable
1789.Va .OODATE ,
1790which can be used for that purpose even when not otherwise needed or desired:
1791.Bd -literal -offset indent
1792
1793skip-compare-for-some:
1794	@echo this will be compared
1795	@echo this will not ${.OODATE:M.NOMETA_CMP}
1796	@echo this will also be compared
1797
1798.Ed
1799The
1800.Cm \&:M
1801pattern suppresses any expansion of the unwanted variable.
1802.It Ic .NOPATH
1803Do not search for the target in the directories specified by
1804.Ic .PATH .
1805.It Ic .NOTMAIN
1806Normally
1807.Nm
1808selects the first target it encounters as the default target to be built
1809if no target was specified.
1810This source prevents this target from being selected.
1811.It Ic .OPTIONAL
1812If a target is marked with this attribute and
1813.Nm
1814can't figure out how to create it, it will ignore this fact and assume
1815the file isn't needed or already exists.
1816.It Ic .PHONY
1817The target does not
1818correspond to an actual file; it is always considered to be out of date,
1819and will not be created with the
1820.Fl t
1821option.
1822Suffix-transformation rules are not applied to
1823.Ic .PHONY
1824targets.
1825.It Ic .PRECIOUS
1826When
1827.Nm
1828is interrupted, it normally removes any partially made targets.
1829This source prevents the target from being removed.
1830.It Ic .RECURSIVE
1831Synonym for
1832.Ic .MAKE .
1833.It Ic .SILENT
1834Do not echo any of the commands associated with this target, exactly
1835as if they all were preceded by an at sign
1836.Pq Ql @ .
1837.It Ic .USE
1838Turn the target into
1839.Nm Ns 's
1840version of a macro.
1841When the target is used as a source for another target, the other target
1842acquires the commands, sources, and attributes (except for
1843.Ic .USE )
1844of the
1845source.
1846If the target already has commands, the
1847.Ic .USE
1848target's commands are appended
1849to them.
1850.It Ic .USEBEFORE
1851Exactly like
1852.Ic .USE ,
1853but prepend the
1854.Ic .USEBEFORE
1855target commands to the target.
1856.It Ic .WAIT
1857If
1858.Ic .WAIT
1859appears in a dependency line, the sources that precede it are
1860made before the sources that succeed it in the line.
1861Since the dependents of files are not made until the file itself
1862could be made, this also stops the dependents being built unless they
1863are needed for another branch of the dependency tree.
1864So given:
1865.Bd -literal
1866x: a .WAIT b
1867	echo x
1868a:
1869	echo a
1870b: b1
1871	echo b
1872b1:
1873	echo b1
1874
1875.Ed
1876the output is always
1877.Ql a ,
1878.Ql b1 ,
1879.Ql b ,
1880.Ql x .
1881.br
1882The ordering imposed by
1883.Ic .WAIT
1884is only relevant for parallel makes.
1885.El
1886.Sh SPECIAL TARGETS
1887Special targets may not be included with other targets, i.e. they must be
1888the only target specified.
1889.Bl -tag -width .BEGINx
1890.It Ic .BEGIN
1891Any command lines attached to this target are executed before anything
1892else is done.
1893.It Ic .DEFAULT
1894This is sort of a
1895.Ic .USE
1896rule for any target (that was used only as a
1897source) that
1898.Nm
1899can't figure out any other way to create.
1900Only the shell script is used.
1901The
1902.Ic .IMPSRC
1903variable of a target that inherits
1904.Ic .DEFAULT Ns 's
1905commands is set
1906to the target's own name.
1907.It Ic .END
1908Any command lines attached to this target are executed after everything
1909else is done.
1910.It Ic .ERROR
1911Any command lines attached to this target are executed when another target fails.
1912The
1913.Ic .ERROR_TARGET
1914variable is set to the target that failed.
1915See also
1916.Ic MAKE_PRINT_VAR_ON_ERROR .
1917.It Ic .IGNORE
1918Mark each of the sources with the
1919.Ic .IGNORE
1920attribute.
1921If no sources are specified, this is the equivalent of specifying the
1922.Fl i
1923option.
1924.It Ic .INTERRUPT
1925If
1926.Nm
1927is interrupted, the commands for this target will be executed.
1928.It Ic .MAIN
1929If no target is specified when
1930.Nm
1931is invoked, this target will be built.
1932.It Ic .MAKEFLAGS
1933This target provides a way to specify flags for
1934.Nm
1935when the makefile is used.
1936The flags are as if typed to the shell, though the
1937.Fl f
1938option will have
1939no effect.
1940.\" XXX: NOT YET!!!!
1941.\" .It Ic .NOTPARALLEL
1942.\" The named targets are executed in non parallel mode.
1943.\" If no targets are
1944.\" specified, then all targets are executed in non parallel mode.
1945.It Ic .NOPATH
1946Apply the
1947.Ic .NOPATH
1948attribute to any specified sources.
1949.It Ic .NOTPARALLEL
1950Disable parallel mode.
1951.It Ic .NO_PARALLEL
1952Synonym for
1953.Ic .NOTPARALLEL ,
1954for compatibility with other pmake variants.
1955.It Ic .ORDER
1956The named targets are made in sequence.
1957This ordering does not add targets to the list of targets to be made.
1958Since the dependents of a target do not get built until the target itself
1959could be built, unless
1960.Ql a
1961is built by another part of the dependency graph,
1962the following is a dependency loop:
1963.Bd -literal
1964\&.ORDER: b a
1965b: a
1966.Ed
1967.Pp
1968The ordering imposed by
1969.Ic .ORDER
1970is only relevant for parallel makes.
1971.\" XXX: NOT YET!!!!
1972.\" .It Ic .PARALLEL
1973.\" The named targets are executed in parallel mode.
1974.\" If no targets are
1975.\" specified, then all targets are executed in parallel mode.
1976.It Ic .PATH
1977The sources are directories which are to be searched for files not
1978found in the current directory.
1979If no sources are specified, any previously specified directories are
1980deleted.
1981If the source is the special
1982.Ic .DOTLAST
1983target, then the current working
1984directory is searched last.
1985.It Ic .PATH. Ns Va suffix
1986Like
1987.Ic .PATH
1988but applies only to files with a particular suffix.
1989The suffix must have been previously declared with
1990.Ic .SUFFIXES .
1991.It Ic .PHONY
1992Apply the
1993.Ic .PHONY
1994attribute to any specified sources.
1995.It Ic .PRECIOUS
1996Apply the
1997.Ic .PRECIOUS
1998attribute to any specified sources.
1999If no sources are specified, the
2000.Ic .PRECIOUS
2001attribute is applied to every
2002target in the file.
2003.It Ic .SHELL
2004Sets the shell that
2005.Nm
2006will use to execute commands.
2007The sources are a set of
2008.Ar field=value
2009pairs.
2010.Bl -tag -width hasErrCtls
2011.It Ar name
2012This is the minimal specification, used to select one of the builtin
2013shell specs;
2014.Ar sh ,
2015.Ar ksh ,
2016and
2017.Ar csh .
2018.It Ar path
2019Specifies the path to the shell.
2020.It Ar hasErrCtl
2021Indicates whether the shell supports exit on error.
2022.It Ar check
2023The command to turn on error checking.
2024.It Ar ignore
2025The command to disable error checking.
2026.It Ar echo
2027The command to turn on echoing of commands executed.
2028.It Ar quiet
2029The command to turn off echoing of commands executed.
2030.It Ar filter
2031The output to filter after issuing the
2032.Ar quiet
2033command.
2034It is typically identical to
2035.Ar quiet .
2036.It Ar errFlag
2037The flag to pass the shell to enable error checking.
2038.It Ar echoFlag
2039The flag to pass the shell to enable command echoing.
2040.It Ar newline
2041The string literal to pass the shell that results in a single newline
2042character when used outside of any quoting characters.
2043.El
2044Example:
2045.Bd -literal
2046\&.SHELL: name=ksh path=/bin/ksh hasErrCtl=true \e
2047	check="set \-e" ignore="set +e" \e
2048	echo="set \-v" quiet="set +v" filter="set +v" \e
2049	echoFlag=v errFlag=e newline="'\en'"
2050.Ed
2051.It Ic .SILENT
2052Apply the
2053.Ic .SILENT
2054attribute to any specified sources.
2055If no sources are specified, the
2056.Ic .SILENT
2057attribute is applied to every
2058command in the file.
2059.It Ic .STALE
2060This target gets run when a dependency file contains stale entries, having
2061.Va .ALLSRC
2062set to the name of that dependency file.
2063.It Ic .SUFFIXES
2064Each source specifies a suffix to
2065.Nm .
2066If no sources are specified, any previously specified suffixes are deleted.
2067It allows the creation of suffix-transformation rules.
2068.Pp
2069Example:
2070.Bd -literal
2071\&.SUFFIXES: .o
2072\&.c.o:
2073	cc \-o ${.TARGET} \-c ${.IMPSRC}
2074.Ed
2075.El
2076.Sh ENVIRONMENT
2077.Nm
2078uses the following environment variables, if they exist:
2079.Ev MACHINE ,
2080.Ev MACHINE_ARCH ,
2081.Ev MAKE ,
2082.Ev MAKEFLAGS ,
2083.Ev MAKEOBJDIR ,
2084.Ev MAKEOBJDIRPREFIX ,
2085.Ev MAKESYSPATH ,
2086.Ev PWD ,
2087and
2088.Ev TMPDIR .
2089.Pp
2090.Ev MAKEOBJDIRPREFIX
2091and
2092.Ev MAKEOBJDIR
2093may only be set in the environment or on the command line to
2094.Nm
2095and not as makefile variables;
2096see the description of
2097.Ql Va .OBJDIR
2098for more details.
2099.Sh FILES
2100.Bl -tag -width /usr/share/mk -compact
2101.It .depend
2102list of dependencies
2103.It Makefile
2104list of dependencies
2105.It makefile
2106list of dependencies
2107.It sys.mk
2108system makefile
2109.It /usr/share/mk
2110system makefile directory
2111.El
2112.Sh COMPATIBILITY
2113The basic make syntax is compatible between different versions of make,
2114however the special variables, variable modifiers and conditionals are not.
2115.Pp
2116The way that parallel makes are scheduled changed in
2117.Nx 4.0
2118so that .ORDER and .WAIT apply recursively to the dependent nodes.
2119The algorithms used may change again in the future.
2120.Pp
2121The way that .for loop variables are substituted changed after
2122.Nx 5.0
2123so that they still appear to be variable expansions.
2124In particular this stops them being treated as syntax, and removes some
2125obscure problems using them in .if statements.
2126.Sh SEE ALSO
2127.Xr mkdep 1
2128.Sh HISTORY
2129A
2130.Nm
2131command appeared in
2132.At v7 .
2133This
2134.Nm
2135implementation is based on Adam De Boor's pmake program which was written
2136for Sprite at Berkeley.
2137It was designed to be a parallel distributed make running jobs on different
2138machines using a daemon called
2139.Dq customs .
2140.Pp
2141Historically the target/dependency
2142.Dq FRC
2143has been used to FoRCe rebuilding (since the target/dependency
2144does not exist... unless someone creates an
2145.Dq FRC
2146file).
2147.Sh BUGS
2148The
2149.Nm
2150syntax is difficult to parse without actually acting of the data.
2151For instance finding the end of a variable use should involve scanning each
2152the modifiers using the correct terminator for each field.
2153In many places
2154.Nm
2155just counts {} and () in order to find the end of a variable expansion.
2156.Pp
2157There is no way of escaping a space character in a filename.
2158