1 .\" Copyright (c) 1988, 1989 by Adam de Boor
2 .\" Copyright (c) 1989 by Berkeley Softworks
3 .\" Copyright (c) 1988, 1989, 1993
4 .\" The Regents of the University of California. All rights reserved.
6 .\" This code is derived from software contributed to Berkeley by
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19 .\" This product includes software developed by the University of
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37 .\" @(#)tutorial.ms 8.1 (Berkeley) 8/18/93
38 .\" $FreeBSD: src/usr.bin/make/PSD.doc/tutorial.ms,v 1.8.2.2 2000/11/24 10:08:45 ru Exp $
39 .\" $DragonFly: src/usr.bin/make/PSD.doc/tutorial.ms,v 1.5 2004/11/24 07:20:51 dillon Exp $
41 .EH 'PSD:12-%''PMake \*- A Tutorial'
42 .OH 'PMake \*- A Tutorial''PSD:12-%'
43 .\" xH is a macro to provide numbered headers that are automatically stuffed
44 .\" into a table-of-contents, properly indented, etc. If the first argument
45 .\" is numeric, it is taken as the depth for numbering (as for .NH), else
46 .\" the default (1) is assumed.
48 .\" @P The initial paragraph distance.
49 .\" @Q The piece of section number to increment (or 0 if none given)
50 .\" @R Section header.
51 .\" @S Indent for toc entry
52 .\" @T Argument to NH (can't use @Q b/c giving 0 to NH resets the counter)
55 \\$2 \\$3 \\$4 \\$5 \\$6 \\$7 \\$8 \\$9
59 \\*(SN \\$2 \\$3 \\$4 \\$5 \\$6 \\$7 \\$8 \\$9
64 .\" CW is used to place a string in fixed-width or switch to a
66 .\" C is a typewriter font for a laserwriter. Use something else if
67 .\" you don't have one...
70 .el \&\\$3\fS\\$1\fP\\$2
72 .\" Anything I put in a display I want to be in fixed-width
76 .\" The stuff in .No produces a little stop sign in the left margin
77 .\" that says NOTE in it. Unfortunately, it does cause a break, but
78 .\" hey. Can't have everything. In case you're wondering how I came
79 .\" up with such weird commands, they came from running grn on a
94 \h'50u'\D'l 71u 0u'\D'l 50u 50u'\D'l 0u 71u'\D'l -50u 50u'\D'l -71u 0u'\D'l -50u -50u'\D'l 0u -71u'\D'l 50u -50u'
99 \h'53u'\D'p 14 68u 0u 46u 46u 0u 68u -46u 46u -68u 0u -47u -46u 0u -68u 47u -46u'
106 \h'85u'\v'0.85n'\h
\a-\w
\a\\*(g9
\au/2u
\a\&\\*(g9
118 .ie !\\n(.$ .IP \(bu 2
128 2150 Shattuck Ave, Penthouse
133 Permission to use, copy, modify, and distribute this software and its
134 documentation for any purpose and without fee is hereby granted,
135 provided that the above copyright notice appears in all copies.
136 The University of California, Berkeley Softworks, and Adam de Boor make no
137 representations about the suitability of this software for any
138 purpose. It is provided "as is" without express or implied warranty.
143 PMake is a program for creating other programs, or anything else you
144 can think of for it to do. The basic idea behind PMake is that, for
145 any given system, be it a program or a document or whatever, there
146 will be some files that depend on the state of other files (on when
147 they were last modified). PMake takes these dependencies, which you
148 must specify, and uses them to build whatever it is you want it to
151 PMake is almost fully-compatible with Make, with which you may already
152 be familiar. PMake's most important feature is its ability to run
153 several different jobs at once, making the creation of systems
154 considerably faster. It also has a great deal more functionality than
155 Make. Throughout the text, whenever something is mentioned that is an
156 important difference between PMake and Make (i.e. something that will
157 cause a makefile to fail if you don't do something about it), or is
158 simply important, it will be flagged with a little sign in the left
162 This tutorial is divided into three main sections corresponding to basic,
163 intermediate and advanced PMake usage. If you already know Make well,
164 you will only need to skim chapter 2 (there are some aspects of
165 PMake that I consider basic to its use that didn't exist in Make).
166 Things in chapter 3 make life much easier, while those in chapter 4
167 are strictly for those who know what they are doing. Chapter 5 has
168 definitions for the jargon I use and chapter 6 contains possible
169 solutions to the problems presented throughout the tutorial.
170 .xH 1 The Basics of PMake
172 PMake takes as input a file that tells a) which files depend on which
173 other files to be complete and b) what to do about files that are
174 ``out-of-date.'' This file is known as a ``makefile'' and is usually
176 kept in the top-most directory of the system to be built. While you
177 can call the makefile anything you want, PMake will look for
181 (in that order) in the current directory if you don't tell it
183 .Ix 0 def makefile default
184 To specify a different makefile, use the
187 .CW "pmake -f program.mk" ''). ``
189 .Ix 0 ref makefile other
191 A makefile has four different types of lines in it:
194 File dependency specifications
200 Comments, include statements and conditional directives
203 Any line may be continued over multiple lines by ending it with a
205 .Ix 0 def "continuation line"
206 The backslash, following newline and any initial whitespace
207 on the following line are compressed into a single space before the
208 input line is examined by PMake.
209 .xH 2 Dependency Lines
211 As mentioned in the introduction, in any system, there are
212 dependencies between the files that make up the system. For instance,
213 in a program made up of several C source files and one header file,
214 the C files will need to be re-compiled should the header file be
215 changed. For a document of several chapters and one macro file, the
216 chapters will need to be reprocessed if any of the macros changes.
217 .Ix 0 def "dependency"
218 These are dependencies and are specified by means of dependency lines in
221 .Ix 0 def "dependency line"
222 On a dependency line, there are targets and sources, separated by a
223 one- or two-character operator.
224 The targets ``depend'' on the sources and are usually created from
229 Any number of targets and sources may be specified on a dependency line.
230 All the targets in the line are made to depend on all the sources.
231 Targets and sources need not be actual files, but every source must be
232 either an actual file or another target in the makefile.
233 If you run out of room, use a backslash at the end of the line to continue onto
236 Any file may be a target and any file may be a source, but the
237 relationship between the two (or however many) is determined by the
238 ``operator'' that separates them.
240 Three types of operators exist: one specifies that the datedness of a
241 target is determined by the state of its sources, while another
242 specifies other files (the sources) that need to be dealt with before
243 the target can be re-created. The third operator is very similar to
244 the first, with the additional condition that the target is
245 out-of-date if it has no sources. These operations are represented by
246 the colon, the exclamation point and the double-colon, respectively, and are
247 mutually exclusive. Their exact semantics are as follows:
249 .Ix 0 def operator colon
251 If a colon is used, a target on the line is considered to be
252 ``out-of-date'' (and in need of creation) if
255 any of the sources has been modified more recently than the target, or
257 the target doesn't exist.
259 .Ix 0 def out-of-date
261 Under this operation, steps will be taken to re-create the target only
262 if it is found to be out-of-date by using these two rules.
264 .Ix 0 def operator force
266 If an exclamation point is used, the target will always be re-created,
267 but this will not happen until all of its sources have been examined
268 and re-created, if necessary.
270 .Ix 0 def operator double-colon
272 If a double-colon is used, a target is out-of-date if:
275 any of the sources has been modified more recently than the target, or
277 the target doesn't exist, or
279 the target has no sources.
282 If the target is out-of-date according to these rules, it will be re-created.
283 This operator also does something else to the targets, but I'll go
284 into that in the next section (``Shell Commands'').
286 Enough words, now for an example. Take that C program I mentioned
287 earlier. Say there are three C files
295 The dependencies between the files could then be expressed as follows:
297 program : a.o b.o c.o
304 You may be wondering at this point, where
313 and the C files don't. The reason is quite simple:
315 cannot be made by linking together .c files \*- it must be
316 made from .o files. Likewise, if you change
318 it isn't the .c files that need to be re-created, it's the .o files.
319 If you think of dependencies in these terms \*- which files (targets)
320 need to be created from which files (sources) \*- you should have no problems.
322 An important thing to notice about the above example, is that all the
323 \&.o files appear as targets on more than one line. This is perfectly
324 all right: the target is made to depend on all the sources mentioned
325 on all the dependency lines. E.g.
334 The order of the dependency lines in the makefile is
335 important: the first target on the first dependency line in the
336 makefile will be the one that gets made if you don't say otherwise.
339 comes first in the example makefile, above.
341 Both targets and sources may contain the standard C-Shell wildcard
350 but the non-curly-brace ones may only appear in the final component
351 (the file portion) of the target or source. The characters mean the
354 These enclose a comma-separated list of options and cause the pattern
355 to be expanded once for each element of the list. Each expansion
356 contains a different element. For example,
357 .CW src/{whiffle,beep,fish}.c
358 expands to the three words
363 These braces may be nested and, unlike the other wildcard characters,
364 the resulting words need not be actual files. All other wildcard
365 characters are expanded using the files that exist when PMake is
368 This matches zero or more characters of any sort.
370 will expand to the same three words as above as long as
372 contains those three files (and no other files that end in
375 Matches any single character.
377 This is known as a character class and contains either a list of
378 single characters, or a series of character ranges
380 for example means all characters between a and z), or both. It matches
381 any single character contained in the list. E.g.
383 will match all letters, while
385 will match all numbers.
388 ``Isn't that nice,'' you say to yourself, ``but how are files
389 actually `re-created,' as he likes to spell it?''
390 The re-creation is accomplished by commands you place in the makefile.
391 These commands are passed to the Bourne shell (better known as
392 ``/bin/sh'') to be executed and are
394 .Ix 0 ref re-creation
396 expected to do what's necessary to update the target file (PMake
397 doesn't actually check to see if the target was created. It just
401 Shell commands in a makefile look a lot like shell commands you would
402 type at a terminal, with one important exception: each command in a
405 be preceded by at least one tab.
407 Each target has associated with it a shell script made up of
408 one or more of these shell commands. The creation script for a target
409 should immediately follow the dependency line for that target. While
410 any given target may appear on more than one dependency line, only one
411 of these dependency lines may be followed by a creation script, unless
412 the `::' operator was used on the dependency line.
413 .Ix 0 ref operator double-colon
417 If the double-colon was used, each dependency line for the target
418 may be followed by a shell script. That script will only be executed
419 if the target on the associated dependency line is out-of-date with
420 respect to the sources on that line, according to the rules I gave
422 I'll give you a good example of this later on.
424 To expand on the earlier makefile, you might add commands as follows:
426 program : a.o b.o c.o
427 cc a.o b.o c.o \-o program
437 Something you should remember when writing a makefile is, the
438 commands will be executed if the
440 on the dependency line is out-of-date, not the sources.
443 .Ix 0 ref out-of-date
444 In this example, the command
445 .CW "cc \-c a.c" '' ``
448 is out-of-date. Because of the `:' operator,
450 .Ix 0 ref operator colon
451 this means that should
455 have been modified more recently than
457 the command will be executed
459 will be considered out-of-date).
460 .Ix 0 ref out-of-date
462 Remember how I said the only difference between a makefile shell
463 command and a regular shell command was the leading tab? I lied. There
464 is another way in which makefile commands differ from regular ones.
465 The first two characters after the initial whitespace are treated
467 If they are any combination of `@' and `\-', they cause PMake to do
470 In most cases, shell commands are printed before they're
471 actually executed. This is to keep you informed of what's going on. If
472 an `@' appears, however, this echoing is suppressed. In the case of an
475 .CW "echo Linking index" ,'' ``
483 so PMake allows you to place an `@' before the command
484 .CW "@echo Linking index" '') (``
485 to prevent the command from being printed.
487 The other special character is the `\-'. In case you didn't know,
488 shell commands finish with a certain ``exit status.'' This status is
489 made available by the operating system to whatever program invoked the
490 command. Normally this status will be 0 if everything went ok and
491 non-zero if something went wrong. For this reason, PMake will consider
492 an error to have occurred if one of the shells it invokes returns a non-zero
493 status. When it detects an error, PMake's usual action is to abort
494 whatever it's doing and exit with a non-zero status itself (any other
495 targets that were being created will continue being made, but nothing
496 new will be started. PMake will exit after the last job finishes).
497 This behavior can be altered, however, by placing a `\-' at the front
499 .CW "\-mv index index.old" ''), (``
500 certain command-line arguments,
501 or doing other things, to be detailed later. In such
502 a case, the non-zero status is simply ignored and PMake keeps chugging
506 Because all the commands are given to a single shell to execute, such
507 things as setting shell variables, changing directories, etc., last
508 beyond the command in which they are found. This also allows shell
509 compound commands (like
511 loops) to be entered in a natural manner.
512 Since this could cause problems for some makefiles that depend on
513 each command being executed by a single shell, PMake has a
515 .Ix 0 ref compatibility
517 flag (it stands for backwards-compatible) that forces each command to
518 be given to a separate shell. It also does several other things, all
519 of which I discourage since they are now old-fashioned.\|.\|.\|.
522 A target's shell script is fed to the shell on its (the shell's) input stream.
523 This means that any commands, such as
525 that need to get input from the terminal won't work right \*- they'll
526 get the shell's input, something they probably won't find to their
527 liking. A simple way around this is to give a command like this:
529 ci $(SRCS) < /dev/tty
531 This would force the program's input to come from the terminal. If you
532 can't do this for some reason, your only other alternative is to use
533 PMake in its fullest compatibility mode. See
536 .Ix 0 ref compatibility
540 PMake, like Make before it, has the ability to save text in variables
541 to be recalled later at your convenience. Variables in PMake are used
542 much like variables in the shell and, by tradition, consist of
543 all upper-case letters (you don't
545 to use all upper-case letters.
546 In fact there's nothing to stop you from calling a variable
548 Just tradition). Variables are assigned-to using lines of the form
549 .Ix 0 def variable assignment
553 .Ix 0 def variable assignment
558 .Ix 0 def variable appending
559 .Ix 0 def variable assignment appended
561 conditionally assigned-to (if the variable isn't already defined) by
565 .Ix 0 def variable assignment conditional
567 and assigned-to with expansion (i.e. the value is expanded (see below)
568 before being assigned to the variable\*-useful for placing a value at
569 the beginning of a variable, or other things) by
573 .Ix 0 def variable assignment expanded
576 Any whitespace before
578 is stripped off. When appending, a space is placed between the old
579 value and the stuff being appended.
581 The final way a variable may be assigned to is using
583 VARIABLE != shell-command
585 .Ix 0 def variable assignment shell-output
589 has all its variables expanded (see below) and is passed off to a
590 shell to execute. The output of the shell is then placed in the
591 variable. Any newlines (other than the final one) are replaced by
592 spaces before the assignment is made. This is typically used to find
593 the current directory via a line like:
599 this is intended to be used to execute commands that produce small amounts
600 of output (e.g. ``pwd''). The implementation is less than intelligent and will
601 likely freeze if you execute something that produces thousands of
602 bytes of output (8 Kb is the limit on many UNIX systems).
604 The value of a variable may be retrieved by enclosing the variable
605 name in parentheses or curly braces and preceding the whole thing
608 For example, to set the variable CFLAGS to the string
609 .CW "\-I/sprite/src/lib/libc \-O" ,'' ``
610 you would place a line
612 CFLAGS = \-I/sprite/src/lib/libc \-O
614 in the makefile and use the word
616 wherever you would like the string
617 .CW "\-I/sprite/src/lib/libc \-O"
618 to appear. This is called variable expansion.
619 .Ix 0 def variable expansion
622 Unlike Make, PMake will not expand a variable unless it knows
623 the variable exists. E.g. if you have a
625 in a shell command and you have not assigned a value to the variable
627 (the empty string is considered a value, by the way), where Make would have
628 substituted the empty string, PMake will leave the
631 To keep PMake from substituting for a variable it knows, precede the
632 dollar sign with another dollar sign.
637 This causes PMake, in effect, to expand the
639 macro, which expands to a single
641 For compatibility, Make's style of variable expansion will be used
642 if you invoke PMake with any of the compatibility flags (\c
649 flag alters just the variable expansion).
653 .Ix 0 ref compatibility
655 .Ix 0 ref variable expansion
656 There are two different times at which variable expansion occurs:
657 When parsing a dependency line, the expansion occurs immediately
658 upon reading the line. If any variable used on a dependency line is
659 undefined, PMake will print a message and exit.
660 Variables in shell commands are expanded when the command is
662 Variables used inside another variable are expanded whenever the outer
663 variable is expanded (the expansion of an inner variable has no effect
664 on the outer variable. I.e. if the outer variable is used on a dependency
665 line and in a shell command, and the inner variable changes value
666 between when the dependency line is read and the shell command is
667 executed, two different values will be substituted for the outer
669 .Ix 0 def variable types
671 Variables come in four flavors, though they are all expanded the same
672 and all look about the same. They are (in order of expanding scope):
676 .Ix 0 ref variable local
678 Command-line variables.
679 .Ix 0 ref variable command-line
682 .Ix 0 ref variable global
684 Environment variables.
685 .Ix 0 ref variable environment
688 The classification of variables doesn't matter much, except that the
689 classes are searched from the top (local) to the bottom (environment)
690 when looking up a variable. The first one found wins.
691 .xH 3 Local Variables
693 .Ix 0 def variable local
694 Each target can have as many as seven local variables. These are
695 variables that are only ``visible'' within that target's shell script
696 and contain such things as the target's name, all of its sources (from
697 all its dependency lines), those sources that were out-of-date, etc.
698 Four local variables are defined for all targets. They are:
701 .Ix 0 def variable local .TARGET
703 The name of the target.
705 .Ix 0 def variable local .OODATE
707 The list of the sources for the target that were considered out-of-date.
708 The order in the list is not guaranteed to be the same as the order in
709 which the dependencies were given.
711 .Ix 0 def variable local .ALLSRC
713 The list of all sources for this target in the order in which they
716 .Ix 0 def variable local .PREFIX
718 The target without its suffix and without any leading path. E.g. for
720 .CW ../../lib/compat/fsRead.c ,
721 this variable would contain
725 Three other local variables are set only for certain targets under
726 special circumstances. These are the ``.IMPSRC,''
727 .Ix 0 ref variable local .IMPSRC
730 .Ix 0 ref variable local .ARCHIVE
733 .Ix 0 ref variable local .MEMBER
735 variables. When they are set and how they are used is described later.
737 Four of these variables may be used in sources as well as in shell
739 .Ix 0 def "dynamic source"
740 .Ix 0 def source dynamic
741 These are ``.TARGET'', ``.PREFIX'', ``.ARCHIVE'' and ``.MEMBER''. The
742 variables in the sources are expanded once for each target on the
743 dependency line, providing what is known as a ``dynamic source,''
745 allowing you to specify several dependency lines at once. For example,
747 $(OBJS) : $(.PREFIX).c
749 will create a dependency between each object file and its
750 corresponding C source file.
751 .xH 3 Command-line Variables
753 .Ix 0 def variable command-line
754 Command-line variables are set when PMake is first invoked by giving a
755 variable assignment as one of the arguments. For example,
757 pmake "CFLAGS = -I/sprite/src/lib/libc -O"
761 be a command-line variable with the given value. Any assignments to
763 in the makefile will have no effect, because once it
764 is set, there is (almost) nothing you can do to change a command-line
765 variable (the search order, you see). Command-line variables may be
766 set using any of the four assignment operators, though only
770 behave as you would expect them to, mostly because assignments to
771 command-line variables are performed before the makefile is read, thus
772 the values set in the makefile are unavailable at the time.
775 .Ix 0 ref variable assignment appended
778 because the old value of the variable is sought only in the scope in
779 which the assignment is taking place (for reasons of efficiency that I
780 won't get into here).
786 .Ix 0 ref variable assignment expanded
787 .Ix 0 ref variable assignment conditional
788 will work if the only variables used are in the environment.
790 is sort of pointless to use from the command line, since the same
791 effect can no doubt be accomplished using the shell's own command
792 substitution mechanisms (backquotes and all that).
793 .xH 3 Global Variables
795 .Ix 0 def variable global
796 Global variables are those set or appended-to in the makefile.
797 There are two classes of global variables: those you set and those PMake sets.
798 As I said before, the ones you set can have any name you want them to have,
799 except they may not contain a colon or an exclamation point.
800 The variables PMake sets (almost) always begin with a
801 period and always contain upper-case letters, only. The variables are
805 .Ix 0 def variable global .PMAKE
807 .Ix 0 def variable global MAKE
809 The name by which PMake was invoked is stored in this variable. For
810 compatibility, the name is also stored in the MAKE variable.
812 .Ix 0 def variable global .MAKEFLAGS
813 .Ix 0 def .MAKEFLAGS variable
814 .Ix 0 def variable global MFLAGS
816 All the relevant flags with which PMake was invoked. This does not
817 include such things as
819 or variable assignments. Again for compatibility, this value is stored
820 in the MFLAGS variable as well.
823 Two other variables, ``.INCLUDES'' and ``.LIBS,'' are covered in the
824 section on special targets in chapter 3.
825 .Ix 0 ref variable global .INCLUDES
826 .Ix 0 ref variable global .LIBS
828 Global variables may be deleted using lines of the form:
830 .Ix 0 def variable deletion
832 #undef \fIvariable\fP
836 must be the first character on the line. Note that this may only be
837 done on global variables.
838 .xH 3 Environment Variables
840 .Ix 0 def variable environment
841 Environment variables are passed by the shell that invoked PMake and
842 are given by PMake to each shell it invokes. They are expanded like
843 any other variable, but they cannot be altered in any way.
845 One special environment variable,
847 .Ix 0 def variable environment PMAKE
848 is examined by PMake for command-line flags, variable assignments,
849 etc., it should always use. This variable is examined before the
850 actual arguments to PMake are. In addition, all flags given to PMake,
853 variable or on the command line, are placed in this environment
854 variable and exported to each shell PMake executes. Thus recursive
855 invocations of PMake automatically receive the same flags as the
858 Using all these variables, you can compress the sample makefile even more:
862 cc $(.ALLSRC) \-o $(.TARGET)
871 .Ix 0 ref variable local .ALLSRC
873 .Ix 0 ref variable local .TARGET
879 Comments in a makefile start with a `#' character and extend to the
880 end of the line. They may appear
881 anywhere you want them, except in a shell command (though the shell
882 will treat it as a comment, too). If, for some reason, you need to use the `#'
883 in a variable or on a dependency line, put a backslash in front of it.
884 PMake will compress the two into a single `#' (Note: this isn't true
885 if PMake is operating in full-compatibility mode).
887 .Ix 0 ref compatibility
891 PMake was specifically designed to re-create several targets at once,
892 when possible. You do not have to do anything special to cause this to
893 happen (unless PMake was configured to not act in parallel, in which
894 case you will have to make use of the
901 but you do have to be careful at times.
903 There are several problems you are likely to encounter. One is
904 that some makefiles (and programs) are written in such a way that it is
905 impossible for two targets to be made at once. The program
908 always modifies the files
912 There is no way to change it. Thus you cannot run two of them at once
913 without something being trashed. Similarly, if you have commands
914 in the makefile that always send output to the same file, you will not
915 be able to make more than one target at once unless you change the
916 file you use. You can, for instance, add a
918 to the end of the file name to tack on the process ID of the shell
919 executing the command (each
923 thus giving you the shell variable
925 Since only one shell is used for all the
926 commands, you'll get the same file name for each command in the
929 The other problem comes from improperly-specified dependencies that
930 worked in Make because of its sequential, depth-first way of examining
931 them. While I don't want to go into depth on how PMake
932 works (look in chapter 4 if you're interested), I will warn you that
933 files in two different ``levels'' of the dependency tree may be
934 examined in a different order in PMake than they were in Make. For
935 example, given the makefile
940 PMake will examine the targets in the order
945 If the makefile's author expected PMake to abort before making
947 if an error occurred while making
951 needed to exist before
954 s/he will be sorely disappointed. The dependencies are
955 incomplete, since in both these cases,
961 Another problem you may face is that, while PMake is set up to handle the
962 output from multiple jobs in a graceful fashion, the same is not so for input.
963 It has no way to regulate input to different jobs,
964 so if you use the redirection from
966 I mentioned earlier, you must be careful not to run two of the jobs at once.
967 .xH 2 Writing and Debugging a Makefile
969 Now you know most of what's in a makefile, what do you do next? There
970 are two choices: (1) use one of the uncommonly-available makefile
971 generators or (2) write your own makefile (I leave out the third choice of
972 ignoring PMake and doing everything by hand as being beyond the bounds
975 When faced with the writing of a makefile, it is usually best to start
976 from first principles: just what
978 you trying to do? What do you want the makefile finally to produce?
980 To begin with a somewhat traditional example, let's say you need to
981 write a makefile to create a program,
983 that takes standard infix expressions and converts them to prefix form (for
984 no readily apparent reason). You've got three source files, in C, that
990 Harking back to my pithy advice about dependency lines, you write the
991 first line of the file:
993 expr : main.o parse.o output.o
1001 files. Similarly for the
1003 files you produce the lines:
1008 main.o parse.o output.o : defs.h
1011 Great. You've now got the dependencies specified. What you need now is
1012 commands. These commands, remember, must produce the target on the
1013 dependency line, usually by using the sources you've listed.
1014 You remember about local variables? Good, so it should come
1015 to you as no surprise when you write
1017 expr : main.o parse.o output.o
1018 cc -o $(.TARGET) $(.ALLSRC)
1020 Why use the variables? If your program grows to produce postfix
1021 expressions too (which, of course, requires a name change or two), it
1022 is one fewer place you have to change the file. You cannot do this for
1023 the object files, however, because they depend on their corresponding
1036 which is wrong. So you round out the makefile with these lines:
1046 The makefile is now complete and will, in fact, create the program you
1047 want it to without unnecessary compilations or excessive typing on
1048 your part. There are two things wrong with it, however (aside from it
1049 being altogether too long, something I'll address in chapter 3):
1052 .CW "main.o parse.o output.o" '' ``
1053 is repeated twice, necessitating two changes when you add postfix
1054 (you were planning on that, weren't you?). This is in direct violation
1055 of de Boor's First Rule of writing makefiles:
1058 Anything that needs to be written more than once
1059 should be placed in a variable.
1061 I cannot emphasize this enough as being very important to the
1062 maintenance of a makefile and its program.
1064 There is no way to alter the way compilations are performed short of
1065 editing the makefile and making the change in all places. This is evil
1066 and violates de Boor's Second Rule, which follows directly from the
1070 Any flags or programs used inside a makefile should be placed in a variable so
1071 they may be changed, temporarily or permanently, with the greatest ease.
1073 The makefile should more properly read:
1075 OBJS = main.o parse.o output.o
1077 $(CC) $(CFLAGS) -o $(.TARGET) $(.ALLSRC)
1079 $(CC) $(CFLAGS) -c main.c
1081 $(CC) $(CFLAGS) -c parse.c
1083 $(CC) $(CFLAGS) -c output.c
1086 Alternatively, if you like the idea of dynamic sources mentioned in
1090 .Ix 0 ref "dynamic source"
1091 .Ix 0 ref source dynamic
1092 you could write it like this:
1094 OBJS = main.o parse.o output.o
1096 $(CC) $(CFLAGS) -o $(.TARGET) $(.ALLSRC)
1097 $(OBJS) : $(.PREFIX).c defs.h
1098 $(CC) $(CFLAGS) -c $(.PREFIX).c
1100 These two rules and examples lead to de Boor's First Corollary:
1103 Variables are your friends.
1105 Once you've written the makefile comes the sometimes-difficult task of
1107 making sure the darn thing works. Your most helpful tool to make sure
1108 the makefile is at least syntactically correct is the
1111 flag, which allows you to see if PMake will choke on the makefile. The
1114 flag lets you do is see what PMake would do without it actually doing
1115 it, thus you can make sure the right commands would be executed were
1116 you to give PMake its head.
1118 When you find your makefile isn't behaving as you hoped, the first
1119 question that comes to mind (after ``What time is it, anyway?'') is
1120 ``Why not?'' In answering this, two flags will serve you well:
1126 The first causes PMake to tell you as it examines each target in the
1127 makefile and indicate why it is deciding whatever it is deciding. You
1128 can then use the information printed for other targets to see where
1131 flag makes PMake print out its internal state when it is done,
1132 allowing you to see that you forgot to make that one chapter depend on
1133 that file of macros you just got a new version of. The output from
1135 is intended to resemble closely a real makefile, but with additional
1136 information provided and with variables expanded in those commands
1137 PMake actually printed or executed.
1139 Something to be especially careful about is circular dependencies.
1140 .Ix 0 def dependency circular
1147 In this case, because of how PMake works,
1149 is the only thing PMake will examine, because
1153 will effectively fall off the edge of the universe, making it
1154 impossible to examine
1156 (or them, for that matter).
1157 PMake will tell you (if run in its normal mode) all the targets
1158 involved in any cycle it looked at (i.e. if you have two cycles in the
1159 graph (naughty, naughty), but only try to make a target in one of
1160 them, PMake will only tell you about that one. You'll have to try to
1161 make the other to find the second cycle). When run as Make, it will
1162 only print the first target in the cycle.
1163 .xH 2 Invoking PMake
1168 PMake comes with a wide variety of flags to choose from.
1169 They may appear in any order, interspersed with command-line variable
1170 assignments and targets to create.
1171 The flags are as follows:
1172 .IP "\fB\-d\fP \fIwhat\fP"
1175 This causes PMake to spew out debugging information that
1176 may prove useful to you. If you can't
1177 figure out why PMake is doing what it's doing, you might try using
1180 parameter is a string of single characters that tell PMake what
1181 aspects you are interested in. Most of what I describe will make
1182 little sense to you, unless you've dealt with Make before. Just
1183 remember where this table is and come back to it as you read on.
1184 The characters and the information they produce are as follows:
1187 Archive searching and caching.
1189 Conditional evaluation.
1191 The searching and caching of directories.
1193 Various snippets of information related to the running of the multiple
1194 shells. Not particularly interesting.
1196 The making of each target: what target is being examined; when it was
1197 last modified; whether it is out-of-date; etc.
1203 The application of suffix-transformation rules. (See chapter 3)
1205 The maintenance of the list of targets.
1207 Variable assignment.
1214 letters will be most useful to you.
1217 is the final argument or the argument from which it would get these
1218 key letters (see below for a note about which argument would be used)
1221 all of these debugging flags will be set, resulting in massive amounts
1223 .IP "\fB\-f\fP \fImakefile\fP"
1225 Specify a makefile to read different from the standard makefiles
1229 .Ix 0 ref makefile default
1230 .Ix 0 ref makefile other
1233 is ``\-'', PMake uses the standard input. This is useful for making
1234 quick and dirty makefiles.\|.\|.
1235 .Ix 0 ref makefile "quick and dirty"
1238 Prints out a summary of the various flags PMake accepts. It can also
1239 be used to find out what level of concurrency was compiled into the
1240 version of PMake you are using (look at
1244 and various other information on how PMake was configured.
1245 .Ix 0 ref configuration
1246 .Ix 0 ref makefilesystem
1249 If you give this flag, PMake will ignore non-zero status returned
1250 by any of its shells. It's like placing a `\-' before all the commands
1256 in that it allows PMake to continue when it sees an error, but unlike
1258 where PMake continues blithely as if nothing went wrong,
1260 causes it to recognize the error and only continue work on those
1261 things that don't depend on the target, either directly or indirectly (through
1262 depending on something that depends on it), whose creation returned the error.
1263 The `k' is for ``keep going''.\|.\|.
1267 PMake has the ability to lock a directory against other
1268 people executing it in the same directory (by means of a file called
1269 ``LOCK.make'' that it creates and checks for in the directory). This
1270 is a Good Thing because two people doing the same thing in the same place
1271 can be disastrous for the final product (too many cooks and all that).
1272 Whether this locking is the default is up to your system
1273 administrator. If locking is on,
1275 will turn it off, and vice versa. Note that this locking will not
1276 prevent \fIyou\fP from invoking PMake twice in the same place \*- if
1277 you own the lock file, PMake will warn you about it but continue to execute.
1278 .IP "\fB\-m\fP \fIdirectory\fP"
1280 Tells PMake another place to search for included makefiles via the <...>
1283 options can be given to form a search path. If this construct is used the
1284 default system makefile search path is completely overridden.
1285 To be explained in chapter 3, section 3.2.
1289 This flag tells PMake not to execute the commands needed to update the
1290 out-of-date targets in the makefile. Rather, PMake will simply print
1291 the commands it would have executed and exit. This is particularly
1292 useful for checking the correctness of a makefile. If PMake doesn't do
1293 what you expect it to, it's a good chance the makefile is wrong.
1294 .IP "\fB\-p\fP \fInumber\fP"
1297 This causes PMake to print its input in a reasonable form, though
1298 not necessarily one that would make immediate sense to anyone but me. The
1300 is a bitwise-or of 1 and 2 where 1 means it should print the input
1301 before doing any processing and 2 says it should print it after
1302 everything has been re-created. Thus
1304 would print it twice\*-once before processing and once after (you
1305 might find the difference between the two interesting). This is mostly
1306 useful to me, but you may find it informative in some bizarre circumstances.
1309 If you give PMake this flag, it will not try to re-create anything. It
1310 will just see if anything is out-of-date and exit non-zero if so.
1313 When PMake starts up, it reads a default makefile that tells it what
1314 sort of system it's on and gives it some idea of what to do if you
1315 don't tell it anything. I'll tell you about it in chapter 3. If you
1316 give this flag, PMake won't read the default makefile.
1319 This causes PMake to not print commands before they're executed. It
1320 is the equivalent of putting an `@' before every command in the
1324 Rather than try to re-create a target, PMake will simply ``touch'' it
1325 so as to make it appear up-to-date. If the target didn't exist before,
1326 it will when PMake finishes, but if the target did exist, it will
1327 appear to have been updated.
1330 This is a mixed-compatibility flag intended to mimic the System V
1331 version of Make. It is the same as giving
1335 as well as turning off directory locking. Targets can still be created
1336 in parallel, however. This is the mode PMake will enter if it is
1343 This tells PMake it's ok to export jobs to other machines, if they're
1344 available. It is used when running in Make mode, as exporting in this
1345 mode tends to make things run slower than if the commands were just
1348 .Ix 0 ref compatibility
1350 Forces PMake to be as backwards-compatible with Make as possible while
1355 Executing one shell per shell command
1357 Expanding anything that looks even vaguely like a variable, with the
1358 empty string replacing any variable PMake doesn't know.
1360 Refusing to allow you to escape a `#' with a backslash.
1362 Permitting undefined variables on dependency lines and conditionals
1363 (see below). Normally this causes PMake to abort.
1367 This nullifies any and all compatibility mode flags you may have given
1368 or implied up to the time the
1370 is encountered. It is useful mostly in a makefile that you wrote for PMake
1371 to avoid bad things happening when someone runs PMake as
1373 or has things set in the environment that tell it to be compatible.
1379 environment variable or the
1384 .Ix 0 ref variable environment PMAKE
1385 .Ix 0 ref variable global .MAKEFLAGS
1386 .Ix 0 ref variable global MFLAGS
1387 .Ix 0 ref .MAKEFLAGS variable
1389 .IP "\fB\-D\fP \fIvariable\fP"
1391 Allows you to define a variable to have
1393 as its value. The variable is a global variable, not a command-line
1394 variable. This is useful mostly for people who are used to the C
1395 compiler arguments and those using conditionals, which I'll get into
1398 .IP "\fB\-I\fP \fIdirectory\fP"
1400 Tells PMake another place to search for included makefiles. Yet
1401 another thing to be explained in chapter 3 (section 3.2, to be
1404 .IP "\fB\-J\fP \fInumber\fP"
1406 Gives the absolute maximum number of targets to create at once on both
1407 local and remote machines.
1408 .IP "\fB\-L\fP \fInumber\fP"
1410 This specifies the maximum number of targets to create on the local
1411 machine at once. This may be 0, though you should be wary of doing
1412 this, as PMake may hang until a remote machine becomes available, if
1413 one is not available when it is started.
1415 .Ix 0 ref compatibility
1417 This is the flag that provides absolute, complete, full compatibility
1418 with Make. It still allows you to use all but a few of the features of
1419 PMake, but it is non-parallel. This is the mode PMake enters if you
1424 .Ix 0 ref "output control"
1425 When creating targets in parallel, several shells are executing at
1426 once, each wanting to write its own two cent's-worth to the screen.
1427 This output must be captured by PMake in some way in order to prevent
1428 the screen from being filled with garbage even more indecipherable
1429 than you usually see. PMake has two ways of doing this, one of which
1430 provides for much cleaner output and a clear separation between the
1431 output of different jobs, the other of which provides a more immediate
1432 response so one can tell what is really happening. The former is done
1433 by notifying you when the creation of a target starts, capturing the
1434 output and transferring it to the screen all at once when the job
1435 finishes. The latter is done by catching the output of the shell (and
1436 its children) and buffering it until an entire line is received, then
1437 printing that line preceded by an indication of which job produced
1438 the output. Since I prefer this second method, it is the one used by
1439 default. The first method will be used if you give the
1444 As mentioned before, the
1446 flag tells PMake to use Make's style of expanding variables,
1447 substituting the empty string for any variable it doesn't know.
1450 There are several times when PMake will print a message at you that is
1451 only a warning, i.e. it can continue to work in spite of your having
1452 done something silly (such as forgotten a leading tab for a shell
1453 command). Sometimes you are well aware of silly things you have done
1454 and would like PMake to stop bothering you. This flag tells it to shut
1455 up about anything non-fatal.
1458 This flag causes PMake to not attempt to export any jobs to another
1461 Several flags may follow a single `\-'. Those flags that require
1462 arguments take them from successive parameters. E.g.
1464 pmake -fDnI server.mk DEBUG /chip2/X/server/include
1466 will cause PMake to read
1468 as the input makefile, define the variable
1470 as a global variable and look for included makefiles in the directory
1471 .CW /chip2/X/server/include .
1474 A makefile is made of four types of lines:
1481 Variable assignments
1483 Comments, include statements and conditional directives
1486 A dependency line is a list of one or more targets, an operator
1491 and a list of zero or more sources. Sources may contain wildcards and
1492 certain local variables.
1494 A creation command is a regular shell command preceded by a tab. In
1495 addition, if the first two characters after the tab (and other
1496 whitespace) are a combination of
1500 PMake will cause the command to not be printed (if the character is
1502 or errors from it to be ignored (if
1504 A blank line, dependency line or variable assignment terminates a
1505 creation script. There may be only one creation script for each target
1512 Variables are places to store text. They may be unconditionally
1513 assigned-to using the
1516 .Ix 0 ref variable assignment
1517 operator, appended-to using the
1520 .Ix 0 ref variable assignment appended
1521 operator, conditionally (if the variable is undefined) assigned-to
1525 .Ix 0 ref variable assignment conditional
1526 operator, and assigned-to with variable expansion with the
1529 .Ix 0 ref variable assignment expanded
1530 operator. The output of a shell command may be assigned to a variable
1534 .Ix 0 ref variable assignment shell-output
1535 operator. Variables may be expanded (their value inserted) by enclosing
1536 their name in parentheses or curly braces, preceded by a dollar sign.
1537 A dollar sign may be escaped with another dollar sign. Variables are
1538 not expanded if PMake doesn't know about them. There are seven local
1554 may be used to specify ``dynamic sources.''
1555 .Ix 0 ref "dynamic source"
1556 .Ix 0 ref source dynamic
1557 Variables are good. Know them. Love them. Live them.
1559 Debugging of makefiles is best accomplished using the
1568 .xH 1 Short-cuts and Other Nice Things
1570 Based on what I've told you so far, you may have gotten the impression
1571 that PMake is just a way of storing away commands and making sure you
1572 don't forget to compile something. Good. That's just what it is.
1573 However, the ways I've described have been inelegant, at best, and
1575 This chapter contains things that make the
1576 writing of makefiles easier and the makefiles themselves shorter and
1577 easier to modify (and, occasionally, simpler). In this chapter, I
1578 assume you are somewhat more
1579 familiar with Sprite (or UNIX, if that's what you're using) than I did
1580 in chapter 2, just so you're on your toes.
1581 So without further ado...
1582 .xH 2 Transformation Rules
1584 As you know, a file's name consists of two parts: a base name, which
1585 gives some hint as to the contents of the file, and a suffix, which
1586 usually indicates the format of the file.
1590 naming conventions, with regard to suffixes, have also developed that have
1591 become almost as incontrovertible as Law. E.g. a file ending in
1593 is assumed to contain C source code; one with a
1595 suffix is assumed to be a compiled, relocatable object file that may
1596 be linked into any program; a file with a
1598 suffix is usually a text file to be processed by Troff with the \-ms
1599 macro package, and so on.
1600 One of the best aspects of both Make and PMake comes from their
1601 understanding of how the suffix of a file pertains to its contents and
1602 their ability to do things with a file based solely on its suffix. This
1603 ability comes from something known as a transformation rule. A
1604 transformation rule specifies how to change a file with one suffix
1605 into a file with another suffix.
1607 A transformation rule looks much like a dependency line, except the
1608 target is made of two known suffixes stuck together. Suffixes are made
1609 known to PMake by placing them as sources on a dependency line whose
1610 target is the special target
1616 $(CC) $(CFLAGS) -c $(.IMPSRC)
1618 The creation script attached to the target is used to transform a file with
1619 the first suffix (in this case,
1621 into a file with the second suffix (here,
1623 In addition, the target inherits whatever attributes have been applied
1624 to the transformation rule.
1625 The simple rule given above says that to transform a C source file
1626 into an object file, you compile it using
1631 This rule is taken straight from the system makefile. Many
1632 transformation rules (and suffixes) are defined there, and I refer you
1633 to it for more examples (type
1634 .CW "pmake -h" '' ``
1635 to find out where it is).
1637 There are several things to note about the transformation rule given
1644 .Ix 0 def variable local .IMPSRC
1646 This variable is set to the ``implied source'' (the file from which
1647 the target is being created; the one with the first suffix), which, in this
1648 case, is the .c file.
1652 variable. Almost all of the transformation rules in the system
1653 makefile are set up using variables that you can alter in your
1654 makefile to tailor the rule to your needs. In this case, if you want
1655 all your C files to be compiled with the
1657 flag, to provide information for
1663 .CW "CFLAGS = -g" '') (``
1664 and PMake would take care of the rest.
1667 To give you a quick example, the makefile in 2.3.4
1669 could be changed to this:
1673 $(CC) -o $(.TARGET) $(.ALLSRC)
1676 The transformation rule I gave above takes the place of the 6 lines\**
1678 This is also somewhat cleaner, I think, than the dynamic source
1679 solution presented in 2.6
1691 Now you may be wondering about the dependency between the
1695 files \*- it's not mentioned anywhere in the new makefile. This is
1696 because it isn't needed: one of the effects of applying a
1697 transformation rule is the target comes to depend on the implied
1698 source. That's why it's called the implied
1701 For a more detailed example. Say you have a makefile like this:
1706 and a directory set up like this:
1709 -rw-rw-r-- 1 deboor 34 Sep 7 00:43 Makefile
1710 -rw-rw-r-- 1 deboor 119 Oct 3 19:39 a.c
1711 -rw-rw-r-- 1 deboor 201 Sep 7 00:43 a.o
1712 -rw-rw-r-- 1 deboor 69 Sep 7 00:43 b.c
1716 will do the right thing, it's much more informative to type
1717 .CW "pmake -d s" ''. ``
1718 This will show you what PMake is up to as it processes the files. In
1719 this case, PMake prints the following:
1721 Suff_FindDeps (a.out)
1722 using existing source a.o
1723 applying .o -> .out to "a.o"
1726 applying .c -> .o to "a.c"
1729 applying .c -> .o to "b.c"
1731 trying a.y...not there
1732 trying a.l...not there
1733 trying a.c,v...not there
1734 trying a.y,v...not there
1735 trying a.l,v...not there
1737 trying b.y...not there
1738 trying b.l...not there
1739 trying b.c,v...not there
1740 trying b.y,v...not there
1741 trying b.l,v...not there
1751 is the name of a function in PMake that is called to check for implied
1752 sources for a target using transformation rules.
1753 The transformations it tries are, naturally
1754 enough, limited to the ones that have been defined (a transformation
1755 may be defined multiple times, by the way, but only the most recent
1756 one will be used). You will notice, however, that there is a definite
1757 order to the suffixes that are tried. This order is set by the
1758 relative positions of the suffixes on the
1760 line \*- the earlier a suffix appears, the earlier it is checked as
1761 the source of a transformation. Once a suffix has been defined, the
1762 only way to change its position in the pecking order is to remove all
1763 the suffixes (by having a
1765 dependency line with no sources) and redefine them in the order you
1766 want. (Previously-defined transformation rules will be automatically
1767 redefined as the suffixes they involve are re-entered.)
1769 Another way to affect the search order is to make the dependency
1770 explicit. In the above example,
1776 Since a transformation exists from
1780 PMake uses that, as indicated by the
1781 .CW "using existing source a.o" '' ``
1784 The search for a transformation starts from the suffix of the target
1785 and continues through all the defined transformations, in the order
1786 dictated by the suffix ranking, until an existing file with the same
1787 base (the target name minus the suffix and any leading directories) is
1788 found. At that point, one or more transformation rules will have been
1789 found to change the one existing file into the target.
1791 For example, ignoring what's in the system makefile for now, say you
1792 have a makefile like this:
1794 \&.SUFFIXES : .out .o .c .y .l
1797 mv lex.yy.c $(.TARGET)
1800 mv y.tab.c $(.TARGET)
1804 cc -o $(.TARGET) $(.IMPSRC)
1809 .CW "pmake -rd ms jive.out" ,'' ``
1810 you would get the following output for
1813 Suff_FindDeps (jive.out)
1814 trying jive.o...not there
1815 trying jive.c...not there
1816 trying jive.y...not there
1817 trying jive.l...got it
1818 applying .l -> .c to "jive.l"
1819 applying .c -> .o to "jive.c"
1820 applying .o -> .out to "jive.o"
1822 and this is why: PMake starts with the target
1824 figures out its suffix
1826 and looks for things it can transform to a
1828 file. In this case, it only finds
1830 so it looks for the file
1832 It fails to find it, so it looks for transformations into a
1834 file. Again it has only one choice:
1838 and, as you know, fails to find it. At this point it has two choices:
1851 first, but can't find it, so it looks for
1853 and, lo and behold, there it is.
1854 At this point, it has defined a transformation path as follows:
1862 and applies the transformation rules accordingly. For completeness,
1863 and to give you a better idea of what PMake actually did with this
1864 three-step transformation, this is what PMake printed for the rest of
1867 Suff_FindDeps (jive.o)
1868 using existing source jive.c
1869 applying .c -> .o to "jive.c"
1870 Suff_FindDeps (jive.c)
1871 using existing source jive.l
1872 applying .l -> .c to "jive.l"
1873 Suff_FindDeps (jive.l)
1874 Examining jive.l...modified 17:16:01 Oct 4, 1987...up-to-date
1875 Examining jive.c...non-existent...out-of-date
1878 \&.\|.\|. meaningless lex output deleted .\|.\|.
1880 Examining jive.o...non-existent...out-of-date
1883 Examining jive.out...non-existent...out-of-date
1885 cc -o jive.out jive.o
1888 One final question remains: what does PMake do with targets that have
1889 no known suffix? PMake simply pretends it actually has a known suffix
1890 and searches for transformations accordingly.
1891 The suffix it chooses is the source for the
1894 target mentioned later. In the system makefile,
1896 is chosen as the ``null suffix''
1897 .Ix 0 def suffix null
1898 .Ix 0 def "null suffix"
1899 because most people use PMake to create programs. You are, however,
1900 free and welcome to change it to a suffix of your own choosing.
1901 The null suffix is ignored, however, when PMake is in compatibility
1902 mode (see chapter 4).
1903 .xH 2 Including Other Makefiles
1904 .Ix 0 def makefile inclusion
1907 Just as for programs, it is often useful to extract certain parts of a
1908 makefile into another file and just include it in other makefiles
1909 somehow. Many compilers allow you say something like
1913 to include the contents of
1915 in the source file. PMake allows you to do the same thing for
1916 makefiles, with the added ability to use variables in the filenames.
1917 An include directive in a makefile looks either like this:
1925 The difference between the two is where PMake searches for the file:
1926 the first way, PMake will look for
1927 the file only in the system makefile directory (or directories)
1928 (to find out what that directory is, give PMake the
1932 The system makefile directory search path can be overridden via the
1936 For files in double-quotes, the search is more complex:
1939 The directory of the makefile that's including the file.
1941 The current directory (the one in which you invoked PMake).
1943 The directories given by you using
1945 flags, in the order in which you gave them.
1947 Directories given by
1949 dependency lines (see chapter 4).
1951 The system makefile directory.
1956 You are free to use PMake variables in the filename\*-PMake will
1957 expand them before searching for the file. You must specify the
1958 searching method with either angle brackets or double-quotes
1960 of a variable expansion. I.e. the following
1962 SYSTEM = <command.mk>
1967 .xH 2 Saving Commands
1970 There may come a time when you will want to save certain commands to
1971 be executed when everything else is done. For instance: you're
1972 making several different libraries at one time and you want to create the
1973 members in parallel. Problem is,
1975 is another one of those programs that can't be run more than once in
1976 the same directory at the same time (each one creates a file called
1978 into which it stuffs information for the linker to use. Two of them
1979 running at once will overwrite each other's file and the result will
1980 be garbage for both parties). You might want a way to save the ranlib
1981 commands til the end so they can be run one after the other, thus
1982 keeping them from trashing each other's file. PMake allows you to do
1983 this by inserting an ellipsis (``.\|.\|.'') as a command between
1984 commands to be run at once and those to be run later.
1988 case above, you might do this:
1991 lib1.a : $(LIB1OBJS)
1993 ar cr $(.TARGET) $(.ALLSRC)
1997 lib2.a : $(LIB2OBJS)
1999 ar cr $(.TARGET) $(.ALLSRC)
2003 .Ix 0 ref variable local .TARGET
2004 .Ix 0 ref variable local .ALLSRC
2005 This would save both
2009 commands until the end, when they would run one after the other
2010 (using the correct value for the
2012 variable, of course).
2014 Commands saved in this manner are only executed if PMake manages to
2015 re-create everything without an error.
2016 .xH 2 Target Attributes
2018 PMake allows you to give attributes to targets by means of special
2019 sources. Like everything else PMake uses, these sources begin with a
2020 period and are made up of all upper-case letters. There are various
2021 reasons for using them, and I will try to give examples for most of
2022 them. Others you'll have to find uses for yourself. Think of it as ``an
2023 exercise for the reader.'' By placing one (or more) of these as a source on a
2024 dependency line, you are ``marking the target(s) with that
2025 attribute.'' That's just the way I phrase it, so you know.
2027 Any attributes given as sources for a transformation rule are applied
2028 to the target of the transformation rule when the rule is applied.
2029 .Ix 0 def attributes
2034 .Ix 0 def attributes .DONTCARE
2036 If a target is marked with this attribute and PMake can't figure out
2037 how to create it, it will ignore this fact and assume the file isn't
2038 really needed or actually exists and PMake just can't find it. This may prove
2039 wrong, but the error will be noted later on, not when PMake tries to create
2040 the target so marked. This attribute also prevents PMake from
2041 attempting to touch the target if it is given the
2046 .Ix 0 def attributes .EXEC
2048 This attribute causes its shell script to be executed while having no
2049 effect on targets that depend on it. This makes the target into a sort
2050 of subroutine. An example. Say you have some LISP files that need to
2051 be compiled and loaded into a LISP process. To do this, you echo LISP
2052 commands into a file and execute a LISP with this file as its input
2053 when everything's done. Say also that you have to load other files
2054 from another system before you can compile your files and further,
2055 that you don't want to go through the loading and dumping unless one
2058 files has changed. Your makefile might look a little bit
2059 like this (remember, this is an educational example, and don't worry
2062 rule, all will soon become clear, grasshopper):
2064 system : init a.fasl b.fasl c.fasl
2065 for i in $(.ALLSRC);
2067 echo -n '(load "' >> input
2068 echo -n ${i} >> input
2071 echo '(dump "$(.TARGET)")' >> input
2074 a.fasl : a.l init COMPILE
2075 b.fasl : b.l init COMPILE
2076 c.fasl : c.l init COMPILE
2078 echo '(compile "$(.ALLSRC)")' >> input
2080 echo '(load-system)' > input
2083 .Ix 0 ref attributes .USE
2084 .Ix 0 ref variable local .ALLSRC
2087 sources, don't appear in the local variables of targets that depend on
2088 them (nor are they touched if PMake is given the
2092 Note that all the rules, not just that for
2096 as a source. This is because none of the other targets can be made
2099 has been made, thus they depend on it.
2101 .Ix 0 def attributes .EXPORT
2103 This is used to mark those targets whose creation should be sent to
2104 another machine if at all possible. This may be used by some
2105 exportation schemes if the exportation is expensive. You should ask
2106 your system administrator if it is necessary.
2107 .IP .EXPORTSAME \n(pw
2108 .Ix 0 def attributes .EXPORTSAME
2109 .Ix 0 def .EXPORTSAME
2110 Tells the export system that the job should be exported to a machine
2111 of the same architecture as the current one. Certain operations (e.g.
2112 running text through
2114 can be performed the same on any architecture (CPU and
2115 operating system type), while others (e.g. compiling a program with
2117 must be performed on a machine with the same architecture. Not all
2118 export systems will support this attribute.
2120 .Ix 0 def attributes .IGNORE
2121 .Ix 0 def .IGNORE attribute
2124 attribute causes PMake to ignore errors from any of the target's commands, as
2125 if they all had `\-' before them.
2126 .IP .INVISIBLE \n(pw
2127 .Ix 0 def attributes .INVISIBLE
2128 .Ix 0 def .INVISIBLE
2129 This allows you to specify one target as a source for another without
2130 the one affecting the other's local variables. Useful if, say, you
2131 have a makefile that creates two programs, one of which is used to
2132 create the other, so it must exist before the other is created. You
2135 prog1 : $(PROG1OBJS) prog2 MAKEINSTALL
2136 prog2 : $(PROG2OBJS) .INVISIBLE MAKEINSTALL
2140 is some complex .USE rule (see below) that depends on the
2143 variable containing the right things. Without the
2149 rule couldn't be applied. This is not as useful as it should be, and
2150 the semantics may change (or the whole thing go away) in the
2151 not-too-distant future.
2153 .Ix 0 def attributes .JOIN
2155 This is another way to avoid performing some operations in parallel
2156 while permitting everything else to be done so. Specifically it
2157 forces the target's shell script to be executed only if one or more of the
2158 sources was out-of-date. In addition, the target's name,
2161 variable and all the local variables of any target that depends on it,
2162 is replaced by the value of its
2165 As an example, suppose you have a program that has four libraries that
2166 compile in the same directory along with, and at the same time as, the
2167 program. You again have the problem with
2169 that I mentioned earlier, only this time it's more severe: you
2170 can't just put the ranlib off to the end since the program
2171 will need those libraries before it can be re-created. You can do
2172 something like this:
2174 program : $(OBJS) libraries
2175 cc -o $(.TARGET) $(.ALLSRC)
2177 libraries : lib1.a lib2.a lib3.a lib4.a .JOIN
2180 .Ix 0 ref variable local .TARGET
2181 .Ix 0 ref variable local .ALLSRC
2182 .Ix 0 ref variable local .OODATE
2186 In this case, PMake will re-create the
2188 as necessary, along with
2194 It will then execute
2196 on any library that was changed and set
2199 variable to contain what's in
2202 .CW "lib1.a lib2.a lib3.a lib4.a" .'' ``
2203 In case you're wondering, it's called
2205 because it joins together different threads of the ``input graph'' at
2206 the target marked with the attribute.
2207 Another aspect of the .JOIN attribute is it keeps the target from
2208 being created if the
2213 .Ix 0 def attributes .MAKE
2217 attribute marks its target as being a recursive invocation of PMake.
2218 This forces PMake to execute the script associated with the target (if
2219 it's out-of-date) even if you gave the
2223 flag. By doing this, you can start at the top of a system and type
2227 and have it descend the directory tree (if your makefiles are set up
2228 correctly), printing what it would have executed if you hadn't
2233 .Ix 0 def attributes .NOEXPORT
2234 .Ix 0 def .NOEXPORT attribute
2235 If possible, PMake will attempt to export the creation of all targets to
2236 another machine (this depends on how PMake was configured). Sometimes,
2237 the creation is so simple, it is pointless to send it to another
2238 machine. If you give the target the
2240 attribute, it will be run locally, even if you've given PMake the
2244 .Ix 0 def attributes .NOTMAIN
2246 Normally, if you do not specify a target to make in any other way,
2247 PMake will take the first target on the first dependency line of a
2248 makefile as the target to create. That target is known as the ``Main
2249 Target'' and is labeled as such if you print the dependencies out
2254 Giving a target this attribute tells PMake that the target is
2258 This allows you to place targets in an included makefile and
2259 have PMake create something else by default.
2261 .Ix 0 def attributes .PRECIOUS
2262 .Ix 0 def .PRECIOUS attribute
2263 When PMake is interrupted (you type control-C at the keyboard), it
2264 will attempt to clean up after itself by removing any half-made
2265 targets. If a target has the
2267 attribute, however, PMake will leave it alone. An additional side
2268 effect of the `::' operator is to mark the targets as
2270 .Ix 0 ref operator double-colon
2273 .Ix 0 def attributes .SILENT
2274 .Ix 0 def .SILENT attribute
2275 Marking a target with this attribute keeps its commands from being
2276 printed when they're executed, just as if they had an `@' in front of them.
2278 .Ix 0 def attributes .USE
2280 By giving a target this attribute, you turn it into PMake's equivalent
2281 of a macro. When the target is used as a source for another target,
2282 the other target acquires the commands, sources and attributes (except
2285 If the target already has commands, the
2287 target's commands are added to the end. If more than one .USE-marked
2288 source is given to a target, the rules are applied sequentially.
2290 The typical .USE rule (as I call them) will use the sources of the
2291 target to which it is applied (as stored in the
2293 variable for the target) as its ``arguments,'' if you will.
2294 For example, you probably noticed that the commands for creating
2298 in the example in section 3.3
2300 were exactly the same. You can use the
2302 attribute to eliminate the repetition, like so:
2304 lib1.a : $(LIB1OBJS) MAKELIB
2305 lib2.a : $(LIB2OBJS) MAKELIB
2309 ar cr $(.TARGET) $(.ALLSRC)
2313 .Ix 0 ref variable local .TARGET
2314 .Ix 0 ref variable local .ALLSRC
2316 Several system makefiles (not to be confused with The System Makefile)
2317 make use of these .USE rules to make your
2318 life easier (they're in the default, system makefile directory...take a look).
2319 Note that the .USE rule source itself
2321 does not appear in any of the targets's local variables.
2322 There is no limit to the number of times I could use the
2324 rule. If there were more libraries, I could continue with
2325 .CW "lib3.a : $(LIB3OBJS) MAKELIB" '' ``
2326 and so on and so forth.
2327 .xH 2 Special Targets
2329 As there were in Make, so there are certain targets that have special
2330 meaning to PMake. When you use one on a dependency line, it is the
2331 only target that may appear on the left-hand-side of the operator.
2334 As for the attributes and variables, all the special targets
2335 begin with a period and consist of upper-case letters only.
2336 I won't describe them all in detail because some of them are rather
2337 complex and I'll describe them in more detail than you'll want in
2339 The targets are as follows:
2343 Any commands attached to this target are executed before anything else
2344 is done. You can use it for any initialization that needs doing.
2347 This is sort of a .USE rule for any target (that was used only as a
2348 source) that PMake can't figure out any other way to create. It's only
2349 ``sort of'' a .USE rule because only the shell script attached to the
2353 variable of a target that inherits
2355 commands is set to the target's own name.
2357 .Ix 0 ref variable local .IMPSRC
2360 This serves a function similar to
2362 in that commands attached to it are executed once everything has been
2363 re-created (so long as no errors occurred). It also serves the extra
2364 function of being a place on which PMake can hang commands you put off
2365 to the end. Thus the script for this target will be executed before
2366 any of the commands you save with the ``.\|.\|.''.
2369 The sources for this target are passed to the exportation system compiled
2370 into PMake. Some systems will use these sources to configure
2371 themselves. You should ask your system administrator about this.
2373 .Ix 0 def .IGNORE target
2374 .Ix 0 ref .IGNORE attribute
2375 .Ix 0 ref attributes .IGNORE
2376 This target marks each of its sources with the
2378 attribute. If you don't give it any sources, then it is like
2381 flag when you invoke PMake \*- errors are ignored for all commands.
2384 .Ix 0 def .INCLUDES target
2385 .Ix 0 def variable global .INCLUDES
2386 .Ix 0 def .INCLUDES variable
2387 The sources for this target are taken to be suffixes that indicate a
2388 file that can be included in a program source file.
2389 The suffix must have already been declared with
2392 Any suffix so marked will have the directories on its search path
2395 below) placed in the
2397 variable, each preceded by a
2399 flag. This variable can then be used as an argument for the compiler
2400 in the normal fashion. The
2402 suffix is already marked in this way in the system makefile.
2403 .Ix 0 ref makefilesystem
2406 \&.SUFFIXES : .bitmap
2407 \&.PATH.bitmap : /usr/local/X/lib/bitmaps
2408 \&.INCLUDES : .bitmap
2411 .CW "-I/usr/local/X/lib/bitmaps" '' ``
2414 variable and you can then say
2416 cc $(.INCLUDES) -c xprogram.c
2420 variable is not actually filled in until the entire makefile has been read.)
2421 .IP .INTERRUPT \n(pw
2422 .Ix 0 def .INTERRUPT
2423 When PMake is interrupted,
2424 it will execute the commands in the script for this target, if it
2427 .Ix 0 def .LIBS target
2428 .Ix 0 def .LIBS variable
2429 .Ix 0 def variable global .LIBS
2430 This does for libraries what
2432 does for include files, except the flag used is
2434 as required by those linkers that allow you to tell them where to find
2435 libraries. The variable used is
2437 Be forewarned that PMake may not have been compiled to do this if the
2438 linker on your system doesn't accept the
2442 variable will always be defined once the makefile has been read.
2445 If you didn't give a target (or targets) to create when you invoked
2446 PMake, it will take the sources of this target as the targets to
2448 .IP .MAKEFLAGS \n(pw
2449 .Ix 0 def .MAKEFLAGS target
2450 This target provides a way for you to always specify flags for PMake
2451 when the makefile is used. The flags are just as they would be typed
2452 to the shell (except you can't use shell variables unless they're in
2458 flags have no effect.
2461 .Ix 0 ref suffix null
2462 .Ix 0 ref "null suffix"
2463 This allows you to specify what suffix PMake should pretend a file has
2464 if, in fact, it has no known suffix. Only one suffix may be so
2465 designated. The last source on the dependency line is the suffix that
2466 is used (you should, however, only give one suffix.\|.\|.).
2469 If you give sources for this target, PMake will take them as
2470 directories in which to search for files it cannot find in the current
2471 directory. If you give no sources, it will clear out any directories
2472 added to the search path before. Since the effects of this all get
2473 very complex, I'll leave it til chapter four to give you a complete
2475 .IP .PATH\fIsuffix\fP \n(pw
2477 This does a similar thing to
2479 but it does it only for files with the given suffix. The suffix must
2480 have been defined already. Look at
2484 for more information.
2486 .Ix 0 def .PRECIOUS target
2487 .Ix 0 ref .PRECIOUS attribute
2488 .Ix 0 ref attributes .PRECIOUS
2493 attribute to each source on the dependency line, unless there are no
2494 sources, in which case the
2496 attribute is given to every target in the file.
2497 .IP .RECURSIVE \n(pw
2498 .Ix 0 def .RECURSIVE
2499 .Ix 0 ref attributes .MAKE
2501 This target applies the
2503 attribute to all its sources. It does nothing if you don't give it any sources.
2506 PMake is not constrained to only using the Bourne shell to execute
2507 the commands you put in the makefile. You can tell it some other shell
2508 to use with this target. Check out
2509 .B "A Shell is a Shell is a Shell"
2512 for more information.
2514 .Ix 0 def .SILENT target
2515 .Ix 0 ref .SILENT attribute
2516 .Ix 0 ref attributes .SILENT
2519 as a target, it applies the
2521 attribute to each of its sources. If there are no sources on the
2522 dependency line, then it is as if you gave PMake the
2524 flag and no commands will be echoed.
2527 This is used to give new file suffixes for PMake to handle. Each
2528 source is a suffix PMake should recognize. If you give a
2530 dependency line with no sources, PMake will forget about all the
2531 suffixes it knew (this also nukes the null suffix).
2532 For those targets that need to have suffixes defined, this is how you do it.
2534 In addition to these targets, a line of the form
2536 \fIattribute\fP : \fIsources\fP
2540 to all the targets listed as
2542 .xH 2 Modifying Variable Expansion
2544 .Ix 0 def variable expansion modified
2545 .Ix 0 ref variable expansion
2546 .Ix 0 def variable modifiers
2547 Variables need not always be expanded verbatim. PMake defines several
2548 modifiers that may be applied to a variable's value before it is
2549 expanded. You apply a modifier by placing it after the variable name
2550 with a colon between the two, like so:
2552 ${\fIVARIABLE\fP:\fImodifier\fP}
2554 Each modifier is a single character followed by something specific to
2555 the modifier itself.
2556 You may apply as many modifiers as you want \*- each one is applied to
2557 the result of the previous and is separated from the previous by
2560 There are seven ways to modify a variable's expansion, most of which
2561 come from the C shell variable modification characters:
2563 .IP "M\fIpattern\fP"
2565 .Ix 0 def modifier match
2566 This is used to select only those words (a word is a series of
2567 characters that are neither spaces nor tabs) that match the given
2569 The pattern is a wildcard pattern like that used by the shell, where
2571 means 0 or more characters of any sort;
2573 is any single character;
2575 matches any single character that is either `a', `b', `c' or `d'
2576 (there may be any number of characters between the brackets);
2578 matches any single character that is between `0' and `9' (i.e. any
2579 digit. This form may be freely mixed with the other bracket form), and
2580 `\\' is used to escape any of the characters `*', `?', `[' or `:',
2581 leaving them as regular characters to match themselves in a word.
2582 For example, the system makefile
2585 .CW "$(CFLAGS:M-[ID]*)" '' ``
2590 flags that would be passed to the C compiler. This allows it to
2591 properly locate include files and generate the correct dependencies.
2592 .IP "N\fIpattern\fP"
2594 .Ix 0 def modifier nomatch
2595 This is identical to
2597 except it substitutes all words that don't match the given pattern.
2598 .IP "S/\fIsearch-string\fP/\fIreplacement-string\fP/[g]"
2600 .Ix 0 def modifier substitute
2601 Causes the first occurrence of
2603 in the variable to be replaced by
2604 .I replacement-string ,
2607 flag is given at the end, in which case all occurrences of the string
2608 are replaced. The substitution is performed on each word in the
2609 variable in turn. If
2613 the string must match starting at the beginning of the word. If
2617 the string must match to the end of the word (these two may be
2618 combined to force an exact match). If a backslash precedes these two
2619 characters, however, they lose their special meaning. Variable
2620 expansion also occurs in the normal fashion inside both the
2623 .I replacement-string ,
2625 that a backslash is used to prevent the expansion of a
2627 not another dollar sign, as is usual.
2630 is just a string, not a pattern, so none of the usual
2631 regular-expression/wildcard characters have any special meaning save
2635 In the replacement string,
2638 character is replaced by the
2640 unless it is preceded by a backslash.
2641 You are allowed to use any character except
2642 colon or exclamation point to separate the two strings. This so-called
2643 delimiter character may be placed in either string by preceding it
2647 .Ix 0 def modifier tail
2648 Replaces each word in the variable expansion by its last
2649 component (its ``tail''). For example, given
2651 OBJS = ../lib/a.o b /usr/lib/libm.a
2657 .CW "a.o b libm.a" .'' ``
2660 .Ix 0 def modifier head
2663 except that every word is replaced by everything but the tail (the
2664 ``head''). Using the same definition of
2667 .CW "$(OBJS:H)" '' ``
2669 .CW "../lib /usr/lib" .'' ``
2670 Note that the final slash on the heads is removed and
2671 anything without a head is replaced by the empty string.
2674 .Ix 0 def modifier extension
2675 .Ix 0 def modifier suffix
2676 .Ix 0 ref suffix "variable modifier"
2678 replaces each word by its suffix (``extension''). So
2679 .CW "$(OBJS:E)" '' ``
2684 .Ix 0 def modifier root
2685 .Ix 0 def modifier base
2686 This replaces each word by everything but the suffix (the ``root'' of
2688 .CW "$(OBJS:R)" '' ``
2690 .CW "../lib/a b /usr/lib/libm" .''
2693 In addition, the System V style of substitution is also supported.
2696 $(\fIVARIABLE\fP:\fIsearch-string\fP=\fIreplacement\fP)
2698 It must be the last modifier in the chain. The search is anchored at
2699 the end of each word, so only suffixes or whole words may be replaced.
2700 .xH 2 More on Debugging
2701 .xH 2 More Exercises
2703 You've got a set programs, each of which is created from its own
2704 assembly-language source file (suffix
2706 Each program can be assembled into two versions, one with error-checking
2707 code assembled in and one without. You could assemble them into files
2708 with different suffixes
2712 for instance), but your linker only understands files that end in
2714 To top it all off, the final executables
2718 How can you still use transformation rules to make your life easier
2719 (Hint: assume the error-checking versions have
2721 tacked onto their prefix)?
2723 Assume, for a moment or two, you want to perform a sort of
2724 ``indirection'' by placing the name of a variable into another one,
2725 then you want to get the value of the first by expanding the second
2726 somehow. Unfortunately, PMake doesn't allow constructs like
2730 What do you do? Hint: no further variable expansion is performed after
2731 modifiers are applied, thus if you cause a $ to occur in the
2732 expansion, that's what will be in the result.
2733 .xH 1 PMake for Gods
2735 This chapter is devoted to those facilities in PMake that allow you to
2736 do a great deal in a makefile with very little work, as well as do
2737 some things you couldn't do in Make without a great deal of work (and
2738 perhaps the use of other programs). The problem with these features,
2739 is they must be handled with care, or you will end up with a mess.
2741 Once more, I assume a greater familiarity with
2743 or Sprite than I did in the previous two chapters.
2747 PMake supports the dispersal of files into multiple directories by
2748 allowing you to specify places to look for sources with
2750 targets in the makefile. The directories you give as sources for these
2751 targets make up a ``search path.'' Only those files used exclusively
2752 as sources are actually sought on a search path, the assumption being
2753 that anything listed as a target in the makefile can be created by the
2754 makefile and thus should be in the current directory.
2756 There are two types of search paths
2757 in PMake: one is used for all types of files (including included
2758 makefiles) and is specified with a plain
2761 .CW ".PATH : RCS" ''), ``
2762 while the other is specific to a certain type of file, as indicated by
2763 the file's suffix. A specific search path is indicated by immediately following
2766 with the suffix of the file. For instance
2768 \&.PATH.h : /sprite/lib/include /sprite/att/lib/include
2770 would tell PMake to look in the directories
2771 .CW /sprite/lib/include
2773 .CW /sprite/att/lib/include
2774 for any files whose suffix is
2777 The current directory is always consulted first to see if a file
2778 exists. Only if it cannot be found there are the directories in the
2779 specific search path, followed by those in the general search path,
2782 A search path is also used when expanding wildcard characters. If the
2783 pattern has a recognizable suffix on it, the path for that suffix will
2784 be used for the expansion. Otherwise the default search path is employed.
2786 When a file is found in some directory other than the current one, all
2787 local variables that would have contained the target's name
2791 will instead contain the path to the file, as found by PMake.
2792 Thus if you have a file
2798 $(CC) -o $(.TARGET) $(.ALLSRC)
2800 the command executed to create
2803 .CW "cc -o mumble ../lib/mumble.c" .'' ``
2804 (As an aside, the command in this case isn't strictly necessary, since
2805 it will be found using transformation rules if it isn't given. This is because
2807 is the null suffix by default and a transformation exists from
2811 Just thought I'd throw that in.)
2813 If a file exists in two directories on the same search path, the file
2814 in the first directory on the path will be the one PMake uses. So if
2815 you have a large system spread over many directories, it would behoove
2816 you to follow a naming convention that avoids such conflicts.
2818 Something you should know about the way search paths are implemented
2819 is that each directory is read, and its contents cached, exactly once
2820 \&\*- when it is first encountered \*- so any changes to the
2821 directories while PMake is running will not be noted when searching
2822 for implicit sources, nor will they be found when PMake attempts to
2823 discover when the file was last modified, unless the file was created in the
2824 current directory. While people have suggested that PMake should read
2825 the directories each time, my experience suggests that the caching seldom
2826 causes problems. In addition, not caching the directories slows things
2827 down enormously because of PMake's attempts to apply transformation
2828 rules through non-existent files \*- the number of extra file-system
2829 searches is truly staggering, especially if many files without
2830 suffixes are used and the null suffix isn't changed from
2832 .xH 2 Archives and Libraries
2835 and Sprite allow you to merge files into an archive using the
2837 command. Further, if the files are relocatable object files, you can
2840 on the archive and get yourself a library that you can link into any
2841 program you want. The main problem with archives is they double the
2842 space you need to store the archived files, since there's one copy in
2843 the archive and one copy out by itself. The problem with libraries is
2844 you usually think of them as
2848 and the linker thinks they're out-of-date if you so much as look at
2851 PMake solves the problem with archives by allowing you to tell it to
2852 examine the files in the archives (so you can remove the individual
2853 files without having to regenerate them later). To handle the problem
2854 with libraries, PMake adds an additional way of deciding if a library
2857 If the table of contents is older than the library, or is missing, the
2858 library is out-of-date.
2860 A library is any target that looks like
2862 or that ends in a suffix that was marked as a library using the
2866 is so marked in the system makefile.
2868 Members of an archive are specified as
2869 ``\fIarchive\fP(\fImember\fP[ \fImember\fP...])''.
2871 .CW libdix.a(window.o) '' ``'
2876 You may also use wildcards to specify the members of the archive. Just
2877 remember that most the wildcard characters will only find
2881 A file that is a member of an archive is treated specially. If the
2882 file doesn't exist, but it is in the archive, the modification time
2883 recorded in the archive is used for the file when determining if the
2884 file is out-of-date. When figuring out how to make an archived member target
2885 (not the file itself, but the file in the archive \*- the
2886 \fIarchive\fP(\fImember\fP) target), special care is
2887 taken with the transformation rules, as follows:
2889 \&\fIarchive\fP(\fImember\fP) is made to depend on \fImember\fP.
2891 The transformation from the \fImember\fP's suffix to the
2892 \fIarchive\fP's suffix is applied to the \fIarchive\fP(\fImember\fP) target.
2894 The \fIarchive\fP(\fImember\fP)'s
2896 variable is set to the name of the \fImember\fP if \fImember\fP is
2897 actually a target, or the path to the member file if \fImember\fP is
2902 variable for the \fIarchive\fP(\fImember\fP) target is set to the name
2903 of the \fIarchive\fP.
2904 .Ix 0 def variable local .ARCHIVE
2909 variable is set to the actual string inside the parentheses. In most
2910 cases, this will be the same as the
2913 .Ix 0 def variable local .MEMBER
2916 The \fIarchive\fP(\fImember\fP)'s place in the local variables of the
2917 targets that depend on it is taken by the value of its
2921 Thus, a program library could be created with the following makefile:
2926 OBJS = obj1.o obj2.o obj3.o
2927 libprog.a : libprog.a($(OBJS))
2928 ar cru $(.TARGET) $(.OODATE)
2931 This will cause the three object files to be compiled (if the
2932 corresponding source files were modified after the object file or, if
2933 that doesn't exist, the archived object file), the out-of-date ones
2936 a table of contents placed in the archive and the newly-archived
2937 object files to be removed.
2939 All this is used in the
2941 system makefile to create a single library with ease. This makefile
2946 # Rules for making libraries. The object files that make up the library
2947 # are removed once they are archived.
2949 # To make several libraries in parallel, you should define the variable
2950 # "many_libraries". This will serialize the invocations of ranlib.
2952 # To use, do something like this:
2954 # OBJECTS = <files in the library>
2956 # fish.a: fish.a($(OBJECTS)) MAKELIB
2972 # Re-archive the out-of-date members and recreate the library's table of
2973 # contents using ranlib. If many_libraries is defined, put the ranlib
2974 # off til the end so many libraries can be made at once.
2976 MAKELIB : .USE .PRECIOUS
2977 ar $(ARFLAGS) $(.TARGET) $(.OODATE)
2979 # ifdef many_libraries
2981 # endif many_libraries
2987 .xH 2 On the Condition...
2990 Like the C compiler before it, PMake allows you to configure the makefile,
2991 based on the current environment, using conditional statements. A
2992 conditional looks like this:
2994 #if \fIboolean expression\fP
2996 #elif \fIanother boolean expression\fP
2999 \fIstill more lines\fP
3002 They may be nested to a maximum depth of 30 and may occur anywhere
3003 (except in a comment, of course). The
3005 must the very first character on the line.
3008 .I "boolean expression"
3009 is made up of terms that look like function calls, the standard C
3015 and the standard relational operators
3027 being overloaded to allow string comparisons as well.
3029 represents logical AND;
3033 is logical NOT. The arithmetic and string operators take precedence
3034 over all three of these operators, while NOT takes precedence over
3035 AND, which takes precedence over OR. This precedence may be
3036 overridden with parentheses, and an expression may be parenthesized to
3037 your heart's content. Each term looks like a call on one of four
3041 .Ix 0 def conditional make
3045 .CW make( \fItarget\fP\c
3049 is a target in the makefile. This is true if the given target was
3050 specified on the command line, or as the source for a
3052 target (note that the sources for
3054 are only used if no targets were given on the command line).
3057 .Ix 0 def conditional defined
3058 .Ix 0 def if defined
3060 .CW defined( \fIvariable\fP\c
3064 is defined. Certain variables are defined in the system makefile that
3065 identify the system on which PMake is being run.
3068 .Ix 0 def conditional exists
3071 .CW exists( \fIfile\fP\c
3073 and is true if the file can be found on the global search path (i.e.
3077 .CW .PATH \fIsuffix\fP
3081 .Ix 0 def conditional empty
3083 This syntax is much like the others, except the string inside the
3084 parentheses is of the same form as you would put between parentheses
3085 when expanding a variable, complete with modifiers and everything. The
3086 function returns true if the resulting string is empty (NOTE: an undefined
3087 variable in this context will cause at the very least a warning
3088 message about a malformed conditional, and at the worst will cause the
3089 process to stop once it has read the makefile. If you want to check
3090 for a variable being defined or empty, use the expression
3091 .CW !defined( \fIvar\fP\c ``
3092 .CW ") || empty(" \fIvar\fP\c
3094 as the definition of
3098 from being evaluated and causing an error, if the variable is
3099 undefined). This can be used to see if a variable contains a given
3102 #if !empty(\fIvar\fP:M\fIword\fP)
3105 The arithmetic and string operators may only be used to test the value
3106 of a variable. The lefthand side must contain the variable expansion,
3107 while the righthand side contains either a string, enclosed in
3108 double-quotes, or a number. The standard C numeric conventions (except
3109 for specifying an octal number) apply to both sides. E.g.
3113 #if $(MACHINE) == "sun3"
3115 #if $(LOAD_ADDR) < 0xc000
3117 are all valid conditionals. In addition, the numeric value of a
3118 variable can be tested as a boolean as follows:
3124 contains a non-zero value and
3130 contains a zero value.
3132 In addition to the bare
3134 there are other forms that apply one of the first two functions to each
3135 term. They are as follows:
3138 ifndef \fR!defined\fP
3142 There are also the ``else if'' forms:
3150 For instance, if you wish to create two versions of a program, one of which
3151 is optimized (the production version) and the other of which is for debugging
3152 (has symbols for dbx), you have two choices: you can create two
3153 makefiles, one of which uses the
3155 flag for the compilation, while the other uses the
3157 flag, or you can use another target (call it
3159 to create the debug version. The construct below will take care of
3160 this for you. I have also made it so defining the variable
3163 .CW "pmake -D DEBUG" )
3164 will also cause the debug version to be made.
3166 #if defined(DEBUG) || make(debug)
3172 There are, of course, problems with this approach. The most glaring
3173 annoyance is that if you want to go from making a debug version to
3174 making a production version, you have to remove all the object files,
3175 or you will get some optimized and some debug versions in the same
3176 program. Another annoyance is you have to be careful not to make two
3177 targets that ``conflict'' because of some conditionals in the
3178 makefile. For instance
3181 FORMATTER = ditroff -Plaser_printer
3184 FORMATTER = nroff -Pdot_matrix_printer
3187 would wreak havoc if you tried
3188 .CW "pmake draft print" '' ``
3189 since you would use the same formatter for each target. As I said,
3190 this all gets somewhat complicated.
3191 .xH 2 A Shell is a Shell is a Shell
3194 In normal operation, the Bourne Shell (better known as
3196 is used to execute the commands to re-create targets. PMake also allows you
3197 to specify a different shell for it to use when executing these
3198 commands. There are several things PMake must know about the shell you
3199 wish to use. These things are specified as the sources for the
3202 .Ix 0 ref target .SHELL
3203 target by keyword, as follows:
3204 .IP "\fBpath=\fP\fIpath\fP"
3205 PMake needs to know where the shell actually resides, so it can
3206 execute it. If you specify this and nothing else, PMake will use the
3207 last component of the path and look in its table of the shells it
3208 knows and use the specification it finds, if any. Use this if you just
3209 want to use a different version of the Bourne or C Shell (yes, PMake knows
3210 how to use the C Shell too).
3211 .IP "\fBname=\fP\fIname\fP"
3212 This is the name by which the shell is to be known. It is a single
3213 word and, if no other keywords are specified (other than
3215 it is the name by which PMake attempts to find a specification for
3216 it (as mentioned above). You can use this if you would just rather use
3217 the C Shell than the Bourne Shell
3218 .CW ".SHELL: name=csh" '' (``
3220 .IP "\fBquiet=\fP\fIecho-off command\fP"
3221 As mentioned before, PMake actually controls whether commands are
3222 printed by introducing commands into the shell's input stream. This
3223 keyword, and the next two, control what those commands are. The
3225 keyword is the command used to turn echoing off. Once it is turned
3226 off, echoing is expected to remain off until the echo-on command is given.
3227 .IP "\fBecho=\fP\fIecho-on command\fP"
3228 The command PMake should give to turn echoing back on again.
3229 .IP "\fBfilter=\fP\fIprinted echo-off command\fP"
3230 Many shells will echo the echo-off command when it is given. This
3231 keyword tells PMake in what format the shell actually prints the
3232 echo-off command. Wherever PMake sees this string in the shell's
3233 output, it will delete it and any following whitespace, up to and
3234 including the next newline. See the example at the end of this section
3236 .IP "\fBechoFlag=\fP\fIflag to turn echoing on\fP"
3237 Unless a target has been marked
3239 PMake wants to start the shell running with echoing on. To do this, it
3240 passes this flag to the shell as one of its arguments. If either this
3241 or the next flag begins with a `\-', the flags will be passed to the
3242 shell as separate arguments. Otherwise, the two will be concatenated
3243 (if they are used at the same time, of course).
3244 .IP "\fBerrFlag=\fP\fIflag to turn error checking on\fP"
3245 Likewise, unless a target is marked
3247 PMake wishes error-checking to be on from the very start. To this end,
3248 it will pass this flag to the shell as an argument. The same rules for
3249 an initial `\-' apply as for the
3251 .IP "\fBcheck=\fP\fIcommand to turn error checking on\fP"
3252 Just as for echo-control, error-control is achieved by inserting
3253 commands into the shell's input stream. This is the command to make
3254 the shell check for errors. It also serves another purpose if the
3255 shell doesn't have error-control as commands, but I'll get into that
3256 in a minute. Again, once error checking has been turned on, it is
3257 expected to remain on until it is turned off again.
3258 .IP "\fBignore=\fP\fIcommand to turn error checking off\fP"
3259 This is the command PMake uses to turn error checking off. It has
3260 another use if the shell doesn't do error-control, but I'll tell you
3261 about that.\|.\|.\|now.
3262 .IP "\fBhasErrCtl=\fP\fIyes or no\fP"
3263 This takes a value that is either
3267 Now you might think that the existence of the
3271 keywords would be enough to tell PMake if the shell can do
3272 error-control, but you'd be wrong. If
3276 PMake uses the check and ignore commands in a straight-forward manner.
3279 however, their use is rather different. In this case, the check
3280 command is used as a template, in which the string
3282 is replaced by the command that's about to be executed, to produce a
3283 command for the shell that will echo the command to be executed. The
3284 ignore command is also used as a template, again with
3286 replaced by the command to be executed, to produce a command that will
3287 execute the command to be executed and ignore any error it returns.
3288 When these strings are used as templates, you must provide newline(s)
3290 in the appropriate place(s).
3292 The strings that follow these keywords may be enclosed in single or
3293 double quotes (the quotes will be stripped off) and may contain the
3294 usual C backslash-characters (\en is newline, \er is return, \eb is
3295 backspace, \e' escapes a single-quote inside single-quotes, \e"
3296 escapes a double-quote inside double-quotes). Now for an example.
3298 This is actually the contents of the
3300 system makefile, and causes PMake to use the Bourne Shell in such a
3301 way that each command is printed as it is executed. That is, if more
3302 than one command is given on a line, each will be printed separately.
3303 Similarly, each time the body of a loop is executed, the commands
3304 within that loop will be printed, etc. The specification runs like
3308 # This is a shell specification to have the Bourne shell echo
3309 # the commands just before executing them, rather than when it reads
3310 # them. Useful if you want to see how variables are being expanded, etc.
3312 \&.SHELL : path=/bin/sh \e
3315 filter="+ set - " \e
3323 It tells PMake the following:
3325 The shell is located in the file
3327 It need not tell PMake that the name of the shell is
3329 as PMake can figure that out for itself (it's the last component of
3332 The command to stop echoing is
3335 The command to start echoing is
3338 When the echo off command is executed, the shell will print
3340 (The `+' comes from using the
3342 flag (rather than the
3344 flag PMake usually uses)). PMake will remove all occurrences of this
3345 string from the output, so you don't notice extra commands you didn't
3348 The flag the Bourne Shell will take to start echoing in this way is
3351 flag. The Bourne Shell will only take its flag arguments concatenated
3352 as its first argument, so neither this nor the
3354 specification begins with a \-.
3356 The flag to use to turn error-checking on from the start is
3359 The shell can turn error-checking on and off, and the commands to do
3366 I should note that this specification is for Bourne Shells that are
3367 not part of Berkeley
3369 as shells from Berkeley don't do error control. You can get a similar
3370 effect, however, by changing the last three lines to be:
3373 check="echo \e"+ %s\e"\en" \e
3374 ignore="sh -c '%s || exit 0\en"
3377 This will cause PMake to execute the two commands
3380 sh -c '\fIcmd\fP || true'
3382 for each command for which errors are to be ignored. (In case you are
3383 wondering, the thing for
3385 tells the shell to execute another shell without error checking on and
3386 always exit 0, since the
3390 to be executed only if the first command exited non-zero, and if the
3391 first command exited zero, the shell will also exit zero, since that's
3392 the last command it executed).
3394 .Ix 0 ref compatibility
3396 There are three (well, 3 \(12) levels of backwards-compatibility built
3397 into PMake. Most makefiles will need none at all. Some may need a
3398 little bit of work to operate correctly when run in parallel. Each
3399 level encompasses the previous levels (e.g.
3401 (one shell per command) implies
3403 The three levels are described in the following three sections.
3404 .xH 3 DEFCON 3 \*- Variable Expansion
3405 .Ix 0 ref compatibility
3407 As noted before, PMake will not expand a variable unless it knows of a
3408 value for it. This can cause problems for makefiles that expect to
3409 leave variables undefined except in special circumstances (e.g. if
3410 more flags need to be passed to the C compiler or the output from a
3411 text processor should be sent to a different printer). If the
3412 variables are enclosed in curly braces
3413 .CW ${PRINTER} ''), (``
3414 the shell will let them pass. If they are enclosed in parentheses,
3415 however, the shell will declare a syntax error and the make will come
3418 You have two choices: change the makefile to define the variables
3419 (their values can be overridden on the command line, since that's
3420 where they would have been set if you used Make, anyway) or always give the
3422 flag (this can be done with the
3424 target, if you want).
3425 .xH 3 DEFCON 2 \*- The Number of the Beast
3426 .Ix 0 ref compatibility
3428 Then there are the makefiles that expect certain commands, such as
3429 changing to a different directory, to not affect other commands in a
3430 target's creation script. You can solve this is either by going
3431 back to executing one shell per command (which is what the
3433 flag forces PMake to do), which slows the process down a good bit and
3434 requires you to use semicolons and escaped newlines for shell constructs, or
3435 by changing the makefile to execute the offending command(s) in a subshell
3436 (by placing the line inside parentheses), like so:
3439 (cd src; $(.PMAKE) install)
3440 (cd lib; $(.PMAKE) install)
3441 (cd man; $(.PMAKE) install)
3443 .Ix 0 ref operator double-colon
3444 .Ix 0 ref variable global .PMAKE
3447 .Ix 0 ref attribute .MAKE
3448 This will always execute the three makes (even if the
3450 flag was given) because of the combination of the ``::'' operator and
3453 attribute. Each command will change to the proper directory to perform
3454 the install, leaving the main shell in the directory in which it started.
3455 .xH 3 "DEFCON 1 \*- Imitation is the Not the Highest Form of Flattery"
3456 .Ix 0 ref compatibility
3458 The final category of makefile is the one where every command requires
3459 input, the dependencies are incompletely specified, or you simply
3460 cannot create more than one target at a time, as mentioned earlier. In
3461 addition, you may not have the time or desire to upgrade the makefile
3462 to run smoothly with PMake. If you are the conservative sort, this is
3463 the compatibility mode for you. It is entered either by giving PMake
3466 flag (for Make), or by executing PMake as
3468 In either case, PMake performs things exactly like Make (while still
3469 supporting most of the nice new features PMake provides). This
3472 No parallel execution.
3474 Targets are made in the exact order specified by the makefile. The
3475 sources for each target are made in strict left-to-right order, etc.
3477 A single Bourne shell is used to execute each command, thus the
3480 variable is useless, changing directories doesn't work across command
3483 If no special characters exist in a command line, PMake will break the
3484 command into words itself and execute the command directly, without
3485 executing a shell first. The characters that cause PMake to execute a
3508 You should notice that these are all the characters that are given
3509 special meaning by the shell (except
3513 which PMake deals with all by its lonesome).
3515 The use of the null suffix is turned off.
3516 .Ix 0 ref "null suffix"
3517 .Ix 0 ref suffix null
3518 .xH 2 The Way Things Work
3520 When PMake reads the makefile, it parses sources and targets into
3521 nodes in a graph. The graph is directed only in the sense that PMake
3522 knows which way is up. Each node contains not only links to all its
3523 parents and children (the nodes that depend on it and those on which
3524 it depends, respectively), but also a count of the number of its
3525 children that have already been processed.
3527 The most important thing to know about how PMake uses this graph is
3528 that the traversal is breadth-first and occurs in two passes.
3530 After PMake has parsed the makefile, it begins with the nodes the user
3531 has told it to make (either on the command line, or via a
3533 target, or by the target being the first in the file not labeled with
3536 attribute) placed in a queue. It continues to take the node off the
3537 front of the queue, mark it as something that needs to be made, pass
3540 (mentioned earlier) to find any implicit sources for the node, and
3541 place all the node's children that have yet to be marked at the end of
3542 the queue. If any of the children is a
3544 rule, its attributes are applied to the parent, then its commands are
3545 appended to the parent's list of commands and its children are linked
3546 to its parent. The parent's unmade children counter is then decremented
3549 node has been processed). You will note that this allows a
3551 node to have children that are
3553 nodes and the rules will be applied in sequence.
3554 If the node has no children, it is placed at the end of
3555 another queue to be examined in the second pass. This process
3556 continues until the first queue is empty.
3558 At this point, all the leaves of the graph are in the examination
3559 queue. PMake removes the node at the head of the queue and sees if it
3560 is out-of-date. If it is, it is passed to a function that will execute
3561 the commands for the node asynchronously. When the commands have
3562 completed, all the node's parents have their unmade children counter
3563 decremented and, if the counter is then 0, they are placed on the
3564 examination queue. Likewise, if the node is up-to-date. Only those
3565 parents that were marked on the downward pass are processed in this
3566 way. Thus PMake traverses the graph back up to the nodes the user
3567 instructed it to create. When the examination queue is empty and no
3568 shells are running to create a target, PMake is finished.
3570 Once all targets have been processed, PMake executes the commands
3573 target, either explicitly or through the use of an ellipsis in a shell
3574 script. If there were no errors during the entire process but there
3575 are still some targets unmade (PMake keeps a running count of how many
3576 targets are left to be made), there is a cycle in the graph. PMake does
3577 a depth-first traversal of the graph to find all the targets that
3578 weren't made and prints them out one by one.
3579 .xH 1 Answers to Exercises
3581 This is something of a trick question, for which I apologize. The
3582 trick comes from the UNIX definition of a suffix, which PMake doesn't
3583 necessarily share. You will have noticed that all the suffixes used in
3584 this tutorial (and in UNIX in general) begin with a period
3587 etc.). Now, PMake's idea of a suffix is more like English's: it's the
3588 characters at the end of a word. With this in mind, one possible
3590 solution to this problem goes as follows:
3592 \&.SUFFIXES : ec.exe .exe ec.obj .obj .asm
3593 ec.objec.exe .obj.exe :
3594 link -o $(.TARGET) $(.IMPSRC)
3596 asm -o $(.TARGET) -DDO_ERROR_CHECKING $(.IMPSRC)
3598 asm -o $(.TARGET) $(.IMPSRC)
3601 The trick to this one lies in the ``:='' variable-assignment operator
3602 and the ``:S'' variable-expansion modifier.
3603 .Ix 0 ref variable assignment expanded
3604 .Ix 0 ref variable expansion modified
3605 .Ix 0 ref modifier substitute
3608 Basically what you want is to take the pointer variable, so to speak,
3609 and transform it into an invocation of the variable at which it
3610 points. You might try something like
3612 $(PTR:S/^/\e$(/:S/$/))
3616 at the front of the variable name and
3618 at the end, thus transforming
3622 which is just what we want. Unfortunately (as you know if you've tried
3623 it), since, as it says in the hint, PMake does no further substitution
3624 on the result of a modified expansion, that's \fIall\fP you get. The
3625 solution is to make use of ``:='' to place that string into yet
3626 another variable, then invoke the other variable directly:
3628 *PTR := $(PTR:S/^/\e$(/:S/$/)/)
3632 to your heart's content.
3637 .xH 1 Glossary of Jargon
3639 A property given to a target that causes PMake to treat it differently.
3640 .Gp "command script"
3641 The lines immediately following a dependency line that specify
3642 commands to execute to create each of the targets on the dependency
3643 line. Each line in the command script must begin with a tab.
3644 .Gp "command-line variable"
3645 A variable defined in an argument when PMake is first executed.
3646 Overrides all assignments to the same variable name in the makefile.
3648 A construct much like that used in C that allows a makefile to be
3649 configured on the fly based on the local environment, or on what is being
3650 made by that invocation of PMake.
3651 .Gp "creation script"
3652 Commands used to create a target. See ``command script.''
3654 The relationship between a source and a target. This comes in three
3655 flavors, as indicated by the operator between the target and the
3656 source. `:' gives a straight time-wise dependency (if the target is
3657 older than the source, the target is out-of-date), while `!' provides
3658 simply an ordering and always considers the target out-of-date. `::'
3659 is much like `:', save it creates multiple instances of a target each
3660 of which depends on its own list of sources.
3661 .Gp "dynamic source"
3662 This refers to a source that has a local variable invocation in it. It
3663 allows a single dependency line to specify a different source for each
3665 .Gp "global variable"
3666 Any variable defined in a makefile. Takes precedence over variables
3667 defined in the environment, but not over command-line or local variables.
3669 What PMake constructs from a makefile. Consists of nodes made of the
3670 targets in the makefile, and the links between them (the
3671 dependencies). The links are directed (from source to target) and
3672 there may not be any cycles (loops) in the graph.
3673 .Gp "local variable"
3674 A variable defined by PMake visible only in a target's shell script.
3675 There are seven local variables, not all of which are defined for
3690 may be used on dependency lines to create ``dynamic sources.''
3692 A file that describes how a system is built. If you don't know what it
3693 is after reading this tutorial.\|.\|.\|.
3695 A letter, following a colon, used to alter how a variable is expanded.
3696 It has no effect on the variable itself.
3698 What separates a source from a target (on a dependency line) and specifies
3699 the relationship between the two. There are three:
3705 A list of directories in which a file should be sought. PMake's view
3706 of the contents of directories in a search path does not change once
3707 the makefile has been read. A file is sought on a search path only if
3708 it is exclusively a source.
3710 A program to which commands are passed in order to create targets.
3712 Anything to the right of an operator on a dependency line. Targets on
3713 the dependency line are usually created from the sources.
3714 .Gp "special target"
3715 A target that causes PMake to do special things when it's encountered.
3717 The tail end of a file name. Usually begins with a period,
3723 A word to the left of the operator on a dependency line. More
3724 generally, any file that PMake might create. A file may be (and often
3725 is) both a target and a source (what it is depends on how PMake is
3726 looking at it at the time \*- sort of like the wave/particle duality
3727 of light, you know).
3728 .Gp "transformation rule"
3729 A special construct in a makefile that specifies how to create a file
3730 of one type from a file of another, as indicated by their suffixes.
3731 .Gp "variable expansion"
3732 The process of substituting the value of a variable for a reference to
3733 it. Expansion may be altered by means of modifiers.
3735 A place in which to store text that may be retrieved later. Also used
3736 to define the local environment. Conditionals exist that test whether
3737 a variable is defined or not.
3739 .\" Output table of contents last, with an entry for the index, making
3740 .\" sure to save and restore the last real page number for the index...
3742 .\" We are not generating an index
tuxillo's projects / dragonfly.git / blob