xref: /freebsd/contrib/bmake/bmake.cat1 (revision 7fdf597e96a02165cfe22ff357b857d5fa15ed8a)
1BMAKE(1)                FreeBSD General Commands Manual               BMAKE(1)
2
3NNAAMMEE
4     bbmmaakkee - maintain program dependencies
5
6SSYYNNOOPPSSIISS
7     bbmmaakkee [--BBeeiikkNNnnqqrrSSssttWWwwXX] [--CC _d_i_r_e_c_t_o_r_y] [--DD _v_a_r_i_a_b_l_e] [--dd _f_l_a_g_s]
8           [--ff _m_a_k_e_f_i_l_e] [--II _d_i_r_e_c_t_o_r_y] [--JJ _p_r_i_v_a_t_e] [--jj _m_a_x___j_o_b_s]
9           [--mm _d_i_r_e_c_t_o_r_y] [--TT _f_i_l_e] [--VV _v_a_r_i_a_b_l_e] [--vv _v_a_r_i_a_b_l_e]
10           [_v_a_r_i_a_b_l_e==_v_a_l_u_e] [_t_a_r_g_e_t ...]
11
12DDEESSCCRRIIPPTTIIOONN
13     bbmmaakkee is a program designed to simplify the maintenance of other
14     programs.  Its input is a list of specifications as to the files upon
15     which programs and other files depend.  If no --ff _m_a_k_e_f_i_l_e option is
16     given, bbmmaakkee tries to open `_m_a_k_e_f_i_l_e' then `_M_a_k_e_f_i_l_e' in order to find
17     the specifications.  If the file `_._d_e_p_e_n_d' exists, it is read, see
18     mkdep(1).
19
20     This manual page is intended as a reference document only.  For a more
21     thorough description of bbmmaakkee and makefiles, please refer to _P_M_a_k_e _- _A
22     _T_u_t_o_r_i_a_l (from 1993).
23
24     bbmmaakkee prepends the contents of the MAKEFLAGS environment variable to the
25     command line arguments before parsing them.
26
27     The options are as follows:
28
29     --BB      Try to be backwards compatible by executing a single shell per
30             command and by making the sources of a dependency line in
31             sequence.
32
33     --CC _d_i_r_e_c_t_o_r_y
34             Change to _d_i_r_e_c_t_o_r_y before reading the makefiles or doing
35             anything else.  If multiple --CC options are specified, each is
36             interpreted relative to the previous one: --CC _/ --CC _e_t_c is
37             equivalent to --CC _/_e_t_c.
38
39     --DD _v_a_r_i_a_b_l_e
40             Define _v_a_r_i_a_b_l_e to be 1, in the global scope.
41
42     --dd [--]_f_l_a_g_s
43             Turn on debugging, and specify which portions of bbmmaakkee are to
44             print debugging information.  Unless the flags are preceded by
45             `-', they are added to the MAKEFLAGS environment variable and are
46             passed on to any child make processes.  By default, debugging
47             information is printed to standard error, but this can be changed
48             using the FF debugging flag.  The debugging output is always
49             unbuffered; in addition, if debugging is enabled but debugging
50             output is not directed to standard output, the standard output is
51             line buffered.  The available _f_l_a_g_s are:
52
53             AA       Print all possible debugging information; equivalent to
54                     specifying all of the debugging flags.
55
56             aa       Print debugging information about archive searching and
57                     caching.
58
59             CC       Print debugging information about the current working
60                     directory.
61
62             cc       Print debugging information about conditional evaluation.
63
64             dd       Print debugging information about directory searching and
65                     caching.
66
67             ee       Print debugging information about failed commands and
68                     targets.
69
70             FF[++]_f_i_l_e_n_a_m_e
71                     Specify where debugging output is written.  This must be
72                     the last flag, because it consumes the remainder of the
73                     argument.  If the character immediately after the FF flag
74                     is `+', the file is opened in append mode; otherwise the
75                     file is overwritten.  If the file name is `stdout' or
76                     `stderr', debugging output is written to the standard
77                     output or standard error output respectively (and the `+'
78                     option has no effect).  Otherwise, the output is written
79                     to the named file.  If the file name ends with `.%d', the
80                     `%d' is replaced by the pid.
81
82             ff       Print debugging information about loop evaluation.
83
84             gg11      Print the input graph before making anything.
85
86             gg22      Print the input graph after making everything, or before
87                     exiting on error.
88
89             gg33      Print the input graph before exiting on error.
90
91             hh       Print debugging information about hash table operations.
92
93             jj       Print debugging information about running multiple
94                     shells.
95
96             LL       Turn on lint checks.  This throws errors for variable
97                     assignments that do not parse correctly, at the time of
98                     assignment, so the file and line number are available.
99
100             ll       Print commands in Makefiles regardless of whether or not
101                     they are prefixed by `@' or other "quiet" flags.  Also
102                     known as "loud" behavior.
103
104             MM       Print debugging information about "meta" mode decisions
105                     about targets.
106
107             mm       Print debugging information about making targets,
108                     including modification dates.
109
110             nn       Don't delete the temporary command scripts created when
111                     running commands.  These temporary scripts are created in
112                     the directory referred to by the TMPDIR environment
113                     variable, or in _/_t_m_p if TMPDIR is unset or set to the
114                     empty string.  The temporary scripts are created by
115                     mkstemp(3), and have names of the form _m_a_k_e_X_X_X_X_X_X.  _N_O_T_E:
116                     This can create many files in TMPDIR or _/_t_m_p, so use with
117                     care.
118
119             pp       Print debugging information about makefile parsing.
120
121             ss       Print debugging information about suffix-transformation
122                     rules.
123
124             tt       Print debugging information about target list
125                     maintenance.
126
127             VV       Force the --VV option to print raw values of variables,
128                     overriding the default behavior set via
129                     _._M_A_K_E_._E_X_P_A_N_D___V_A_R_I_A_B_L_E_S.
130
131             vv       Print debugging information about variable assignment and
132                     expansion.
133
134             xx       Run shell commands with --xx so the actual commands are
135                     printed as they are executed.
136
137     --ee      Let environment variables override global variables within
138             makefiles.
139
140     --ff _m_a_k_e_f_i_l_e
141             Specify a makefile to read instead of the default _m_a_k_e_f_i_l_e or
142             _M_a_k_e_f_i_l_e.  If _m_a_k_e_f_i_l_e is `-', standard input is read.  Multiple
143             makefiles may be specified, and are read in the order specified.
144
145     --II _d_i_r_e_c_t_o_r_y
146             Specify a directory in which to search for makefiles and included
147             makefiles.  The system makefile directory (or directories, see
148             the --mm option) is automatically included as part of this list.
149
150     --ii      Ignore non-zero exit of shell commands in the makefile.
151             Equivalent to specifying `-' before each command line in the
152             makefile.
153
154     --JJ _p_r_i_v_a_t_e
155             This option should _n_o_t be specified by the user.
156
157             When the --jj option is in use in a recursive build, this option is
158             passed by a make to child makes to allow all the make processes
159             in the build to cooperate to avoid overloading the system.
160
161     --jj _m_a_x___j_o_b_s
162             Specify the maximum number of jobs that bbmmaakkee may have running at
163             any one time.  If _m_a_x___j_o_b_s is a floating point number, or ends
164             with `C', then the value is multiplied by the number of CPUs
165             reported online by sysconf(3).  The value of _m_a_x___j_o_b_s is saved in
166             _._M_A_K_E_._J_O_B_S.  Turns compatibility mode off, unless the --BB option
167             is also specified.  When compatibility mode is off, all commands
168             associated with a target are executed in a single shell
169             invocation as opposed to the traditional one shell invocation per
170             line.  This can break traditional scripts which change
171             directories on each command invocation and then expect to start
172             with a fresh environment on the next line.  It is more efficient
173             to correct the scripts rather than turn backwards compatibility
174             on.
175
176             A job token pool with _m_a_x___j_o_b_s tokens is used to control the
177             total number of jobs running.  Each instance of bbmmaakkee will wait
178             for a token from the pool before running a new job.
179
180     --kk      Continue processing after errors are encountered, but only on
181             those targets that do not depend on the target whose creation
182             caused the error.
183
184     --mm _d_i_r_e_c_t_o_r_y
185             Specify a directory in which to search for _s_y_s_._m_k and makefiles
186             included via the <_f_i_l_e>-style include statement.  The --mm option
187             can be used multiple times to form a search path.  This path
188             overrides the default system include path _/_u_s_r_/_s_h_a_r_e_/_m_k.
189             Furthermore, the system include path is appended to the search
190             path used for "_f_i_l_e"-style include statements (see the --II
191             option).  The system include path can be referenced via the read-
192             only variable _._S_Y_S_P_A_T_H.
193
194             If a directory name in the --mm argument (or the MAKESYSPATH
195             environment variable) starts with the string `.../', bbmmaakkee
196             searches for the specified file or directory named in the
197             remaining part of the argument string.  The search starts with
198             the current directory and then works upward towards the root of
199             the file system.  If the search is successful, the resulting
200             directory replaces the `.../' specification in the --mm argument.
201             This feature allows bbmmaakkee to easily search in the current source
202             tree for customized _s_y_s_._m_k files (e.g., by using `.../mk/sys.mk'
203             as an argument).
204
205     --nn      Display the commands that would have been executed, but do not
206             actually execute them unless the target depends on the _._M_A_K_E
207             special source (see below) or the command is prefixed with `++'.
208
209     --NN      Display the commands that would have been executed, but do not
210             actually execute any of them; useful for debugging top-level
211             makefiles without descending into subdirectories.
212
213     --qq      Do not execute any commands, instead exit 0 if the specified
214             targets are up to date, and 1 otherwise.
215
216     --rr      Do not use the built-in rules specified in the system makefile.
217
218     --SS      Stop processing if an error is encountered.  This is the default
219             behavior and the opposite of --kk.
220
221     --ss      Do not echo any commands as they are executed.  Equivalent to
222             specifying `@@' before each command line in the makefile.
223
224     --TT _t_r_a_c_e_f_i_l_e
225             When used with the --jj flag, append a trace record to _t_r_a_c_e_f_i_l_e
226             for each job started and completed.
227
228     --tt      Rather than re-building a target as specified in the makefile,
229             create it or update its modification time to make it appear up-
230             to-date.
231
232     --VV _v_a_r_i_a_b_l_e
233             Print the value of _v_a_r_i_a_b_l_e.  Do not build any targets.  Multiple
234             instances of this option may be specified; the variables are
235             printed one per line, with a blank line for each null or
236             undefined variable.  The value printed is extracted from the
237             global scope after all makefiles have been read.
238
239             By default, the raw variable contents (which may include
240             additional unexpanded variable references) are shown.  If
241             _v_a_r_i_a_b_l_e contains a `$', it is not interpreted as a variable name
242             but rather as an expression.  Its value is expanded before
243             printing.  The value is also expanded before printing if
244             _._M_A_K_E_._E_X_P_A_N_D___V_A_R_I_A_B_L_E_S is set to true and the --ddVV option has not
245             been used to override it.
246
247             Note that loop-local and target-local variables, as well as
248             values taken temporarily by global variables during makefile
249             processing, are not accessible via this option.  The --ddvv debug
250             mode can be used to see these at the cost of generating
251             substantial extraneous output.
252
253     --vv _v_a_r_i_a_b_l_e
254             Like --VV, but all printed variables are always expanded to their
255             complete value.  The last occurrence of --VV or --vv decides whether
256             all variables are expanded or not.
257
258     --WW      Treat any warnings during makefile parsing as errors.
259
260     --ww      Print entering and leaving directory messages, pre and post
261             processing.
262
263     --XX      Don't export variables passed on the command line to the
264             environment individually.  Variables passed on the command line
265             are still exported via the MAKEFLAGS environment variable.  This
266             option may be useful on systems which have a small limit on the
267             size of command arguments.
268
269     _v_a_r_i_a_b_l_e==_v_a_l_u_e
270             Set the value of the variable _v_a_r_i_a_b_l_e to _v_a_l_u_e.  Normally, all
271             values passed on the command line are also exported to sub-makes
272             in the environment.  The --XX flag disables this behavior.
273             Variable assignments should follow options for POSIX
274             compatibility but no ordering is enforced.
275
276     There are several different types of lines in a makefile: dependency
277     specifications, shell commands, variable assignments, include statements,
278     conditional directives, for loops, other directives, and comments.
279
280     Lines may be continued from one line to the next by ending them with a
281     backslash (`\').  The trailing newline character and initial whitespace
282     on the following line are compressed into a single space.
283
284FFIILLEE DDEEPPEENNDDEENNCCYY SSPPEECCIIFFIICCAATTIIOONNSS
285     Dependency lines consist of one or more targets, an operator, and zero or
286     more sources.  This creates a relationship where the targets "depend" on
287     the sources and are customarily created from them.  A target is
288     considered out of date if it does not exist, or if its modification time
289     is less than that of any of its sources.  An out-of-date target is re-
290     created, but not until all sources have been examined and themselves re-
291     created as needed.  Three operators may be used:
292
293     ::     Many dependency lines may name this target but only one may have
294           attached shell commands.  All sources named in all dependency lines
295           are considered together, and if needed the attached shell commands
296           are run to create or re-create the target.  If bbmmaakkee is
297           interrupted, the target is removed.
298
299     !!     The same, but the target is always re-created whether or not it is
300           out of date.
301
302     ::::    Any dependency line may have attached shell commands, but each one
303           is handled independently: its sources are considered and the
304           attached shell commands are run if the target is out of date with
305           respect to (only) those sources.  Thus, different groups of the
306           attached shell commands may be run depending on the circumstances.
307           Furthermore, unlike ::, for dependency lines with no sources, the
308           attached shell commands are always run.  Also unlike ::, the target
309           is not removed if bbmmaakkee is interrupted.
310
311     All dependency lines mentioning a particular target must use the same
312     operator.
313
314     Targets and sources may contain the shell wildcard values `?', `*', `[]',
315     and `{}'.  The values `?', `*', and `[]' may only be used as part of the
316     final component of the target or source, and only match existing files.
317     The value `{}' need not necessarily be used to describe existing files.
318     Expansion is in directory order, not alphabetically as done in the shell.
319
320SSHHEELLLL CCOOMMMMAANNDDSS
321     Each target may have associated with it one or more lines of shell
322     commands, normally used to create the target.  Each of the lines in this
323     script _m_u_s_t be preceded by a tab.  (For historical reasons, spaces are
324     not accepted.)  While targets can occur in many dependency lines if
325     desired, by default only one of these rules may be followed by a creation
326     script.  If the `::::' operator is used, however, all rules may include
327     scripts, and the respective scripts are executed in the order found.
328
329     Each line is treated as a separate shell command, unless the end of line
330     is escaped with a backslash `\', in which case that line and the next are
331     combined.  If the first characters of the command are any combination of
332     `@@', `++', or `--', the command is treated specially.
333
334           @@       causes the command not to be echoed before it is executed.
335
336           ++       causes the command to be executed even when --nn is given.
337                   This is similar to the effect of the _._M_A_K_E special source,
338                   except that the effect can be limited to a single line of a
339                   script.
340
341           --       in compatibility mode causes any non-zero exit status of
342                   the command line to be ignored.
343
344     When bbmmaakkee is run in jobs mode with --jj _m_a_x___j_o_b_s, the entire script for
345     the target is fed to a single instance of the shell.  In compatibility
346     (non-jobs) mode, each command is run in a separate process.  If the
347     command contains any shell meta characters (`#=|^(){};&<>*?[]:$`\\n'), it
348     is passed to the shell; otherwise bbmmaakkee attempts direct execution.  If a
349     line starts with `--' and the shell has ErrCtl enabled, failure of the
350     command line is ignored as in compatibility mode.  Otherwise `--' affects
351     the entire job; the script stops at the first command line that fails,
352     but the target is not deemed to have failed.
353
354     Makefiles should be written so that the mode of bbmmaakkee operation does not
355     change their behavior.  For example, any command which uses "cd" or
356     "chdir" without the intention of changing the directory for subsequent
357     commands should be put in parentheses so it executes in a subshell.  To
358     force the use of a single shell, escape the line breaks so as to make the
359     whole script one command.  For example:
360
361           avoid-chdir-side-effects:
362                   @echo "Building $@ in $$(pwd)"
363                   @(cd ${.CURDIR} && ${MAKE} $@)
364                   @echo "Back in $$(pwd)"
365
366           ensure-one-shell-regardless-of-mode:
367                   @echo "Building $@ in $$(pwd)"; \
368                   (cd ${.CURDIR} && ${MAKE} $@); \
369                   echo "Back in $$(pwd)"
370
371     Since bbmmaakkee changes the current working directory to `_._O_B_J_D_I_R' before
372     executing any targets, each child process starts with that as its current
373     working directory.
374
375VVAARRIIAABBLLEE AASSSSIIGGNNMMEENNTTSS
376     Variables in make behave much like macros in the C preprocessor.
377
378     Variable assignments have the form `_N_A_M_E _o_p _v_a_l_u_e', where:
379
380           _N_A_M_E    is a single-word variable name, consisting, by tradition,
381                   of all upper-case letters,
382
383           _o_p      is one of the variable assignment operators described
384                   below, and
385
386           _v_a_l_u_e   is interpreted according to the variable assignment
387                   operator.
388
389     Whitespace around _N_A_M_E, _o_p and _v_a_l_u_e is discarded.
390
391   VVaarriiaabbllee aassssiiggnnmmeenntt ooppeerraattoorrss
392     The five operators that assign values to variables are:
393
394     ==       Assign the value to the variable.  Any previous value is
395             overwritten.
396
397     ++==      Append the value to the current value of the variable, separating
398             them by a single space.
399
400     ??==      Assign the value to the variable if it is not already defined.
401
402     ::==      Expand the value, then assign it to the variable.
403
404             _N_O_T_E: References to undefined variables are _n_o_t expanded.  This
405             can cause problems when variable modifiers are used.
406
407     !!==      Expand the value and pass it to the shell for execution, then
408             assign the output from the child's standard output to the
409             variable.  Any newlines in the result are replaced with spaces.
410
411   EExxppaannssiioonn ooff vvaarriiaabblleess
412     In most contexts where variables are expanded, `$$' expands to a single
413     dollar sign.  In other contexts (most variable modifiers, string literals
414     in conditions), `\$' expands to a single dollar sign.
415
416     References to variables have the form $${{_n_a_m_e[::_m_o_d_i_f_i_e_r_s]}} or
417     $$((_n_a_m_e[::_m_o_d_i_f_i_e_r_s])).  If the variable name consists of only a single
418     character and the expression contains no modifiers, the surrounding curly
419     braces or parentheses are not required.  This shorter form is not
420     recommended.
421
422     If the variable name contains a dollar, the name itself is expanded
423     first.  This allows almost arbitrary variable names, however names
424     containing dollar, braces, parentheses or whitespace are really best
425     avoided.
426
427     If the result of expanding a nested variable expression contains a dollar
428     sign (`$'), the result is subject to further expansion.
429
430     Variable substitution occurs at four distinct times, depending on where
431     the variable is being used.
432
433     1.   Variables in dependency lines are expanded as the line is read.
434
435     2.   Variables in conditionals are expanded individually, but only as far
436          as necessary to determine the result of the conditional.
437
438     3.   Variables in shell commands are expanded when the shell command is
439          executed.
440
441     4.   ..ffoorr loop index variables are expanded on each loop iteration.  Note
442          that other variables are not expanded when composing the body of a
443          loop, so the following example code:
444
445                .for i in 1 2 3
446                a+=     ${i}
447                j=      ${i}
448                b+=     ${j}
449                .endfor
450
451                all:
452                        @echo ${a}
453                        @echo ${b}
454
455          prints:
456
457                1 2 3
458                3 3 3
459
460          After the loop is executed:
461
462                _a       contains `${:U1} ${:U2} ${:U3}', which expands to `1 2
463                        3'.
464
465                _j       contains `${:U3}', which expands to `3'.
466
467                _b       contains `${j} ${j} ${j}', which expands to `${:U3}
468                        ${:U3} ${:U3}' and further to `3 3 3'.
469
470   VVaarriiaabbllee ccllaasssseess
471     The four different classes of variables (in order of increasing
472     precedence) are:
473
474     Environment variables
475             Variables defined as part of bbmmaakkee's environment.
476
477     Global variables
478             Variables defined in the makefile or in included makefiles.
479
480     Command line variables
481             Variables defined as part of the command line.
482
483     Local variables
484             Variables that are defined specific to a certain target.
485
486     Local variables can be set on a dependency line, unless
487     _._M_A_K_E_._T_A_R_G_E_T___L_O_C_A_L___V_A_R_I_A_B_L_E_S is set to `false'.  The rest of the line
488     (which already has had global variables expanded) is the variable value.
489     For example:
490
491           COMPILER_WRAPPERS= ccache distcc icecc
492
493           ${OBJS}: .MAKE.META.CMP_FILTER=${COMPILER_WRAPPERS:S,^,N,}
494
495     Only the targets `${OBJS}' are impacted by that filter (in "meta" mode)
496     and simply enabling/disabling any of the compiler wrappers does not
497     render all of those targets out-of-date.
498
499     _N_O_T_E: target-local variable assignments behave differently in that;
500
501           ++==      Only appends to a previous local assignment for the same
502                   target and variable.
503
504           ::==      Is redundant with respect to global variables, which have
505                   already been expanded.
506
507     The seven built-in local variables are:
508
509           _._A_L_L_S_R_C   The list of all sources for this target; also known as
510                     `_>'.
511
512           _._A_R_C_H_I_V_E  The name of the archive file; also known as `_!'.
513
514           _._I_M_P_S_R_C   In suffix-transformation rules, the name/path of the
515                     source from which the target is to be transformed (the
516                     "implied" source); also known as `_<'.  It is not defined
517                     in explicit rules.
518
519           _._M_E_M_B_E_R   The name of the archive member; also known as `_%'.
520
521           _._O_O_D_A_T_E   The list of sources for this target that were deemed out-
522                     of-date; also known as `_?'.
523
524           _._P_R_E_F_I_X   The name of the target with suffix (if declared in
525                     ..SSUUFFFFIIXXEESS) removed; also known as `_*'.
526
527           _._T_A_R_G_E_T   The name of the target; also known as `_@'.  For
528                     compatibility with other makes this is an alias for
529                     _._A_R_C_H_I_V_E in archive member rules.
530
531     The shorter forms (`_>', `_!', `_<', `_%', `_?', `_*', and `_@') are permitted
532     for backward compatibility with historical makefiles and legacy POSIX
533     make and are not recommended.
534
535     Variants of these variables with the punctuation followed immediately by
536     `D' or `F', e.g. `$(@D)', are legacy forms equivalent to using the `:H'
537     and `:T' modifiers.  These forms are accepted for compatibility with AT&T
538     System V UNIX makefiles and POSIX but are not recommended.
539
540     Four of the local variables may be used in sources on dependency lines
541     because they expand to the proper value for each target on the line.
542     These variables are `_._T_A_R_G_E_T', `_._P_R_E_F_I_X', `_._A_R_C_H_I_V_E', and `_._M_E_M_B_E_R'.
543
544   AAddddiittiioonnaall bbuuiilltt--iinn vvaarriiaabblleess
545     In addition, bbmmaakkee sets or knows about the following variables:
546
547     _._A_L_L_T_A_R_G_E_T_S
548             The list of all targets encountered in the makefiles.  If
549             evaluated during makefile parsing, lists only those targets
550             encountered thus far.
551
552     _._C_U_R_D_I_R
553             A path to the directory where bbmmaakkee was executed.  Refer to the
554             description of `_P_W_D' for more details.
555
556     _._E_R_R_O_R___C_M_D
557             Is used in error handling, see _M_A_K_E___P_R_I_N_T___V_A_R___O_N___E_R_R_O_R.
558
559     _._E_R_R_O_R___C_W_D
560             Is used in error handling, see _M_A_K_E___P_R_I_N_T___V_A_R___O_N___E_R_R_O_R.
561
562     _._E_R_R_O_R___E_X_I_T
563             Is used in error handling, see _M_A_K_E___P_R_I_N_T___V_A_R___O_N___E_R_R_O_R.
564
565     _._E_R_R_O_R___M_E_T_A___F_I_L_E
566             Is used in error handling in "meta" mode, see
567             _M_A_K_E___P_R_I_N_T___V_A_R___O_N___E_R_R_O_R.
568
569     _._E_R_R_O_R___T_A_R_G_E_T
570             Is used in error handling, see _M_A_K_E___P_R_I_N_T___V_A_R___O_N___E_R_R_O_R.
571
572     _._I_N_C_L_U_D_E_D_F_R_O_M_D_I_R
573             The directory of the file this makefile was included from.
574
575     _._I_N_C_L_U_D_E_D_F_R_O_M_F_I_L_E
576             The filename of the file this makefile was included from.
577
578     _M_A_C_H_I_N_E
579             The machine hardware name, see uname(1).
580
581     _M_A_C_H_I_N_E___A_R_C_H
582             The machine processor architecture name, see uname(1).
583
584     _M_A_K_E    The name that bbmmaakkee was executed with (_a_r_g_v_[_0_]).
585
586     _._M_A_K_E   The same as _M_A_K_E, for compatibility.  The preferred variable to
587             use is the environment variable MAKE because it is more
588             compatible with other make variants and cannot be confused with
589             the special target with the same name.
590
591     _._M_A_K_E_._D_E_P_E_N_D_F_I_L_E
592             Names the makefile (default `_._d_e_p_e_n_d') from which generated
593             dependencies are read.
594
595     _._M_A_K_E_._D_I_E___Q_U_I_E_T_L_Y
596             If set to `true', do not print error information at the end.
597
598     _._M_A_K_E_._E_X_P_A_N_D___V_A_R_I_A_B_L_E_S
599             A boolean that controls the default behavior of the --VV option.
600             If true, variable values printed with --VV are fully expanded; if
601             false, the raw variable contents (which may include additional
602             unexpanded variable references) are shown.
603
604     _._M_A_K_E_._E_X_P_O_R_T_E_D
605             The list of variables exported by bbmmaakkee.
606
607     _M_A_K_E_F_I_L_E
608             The top-level makefile that is currently read, as given in the
609             command line.
610
611     _._M_A_K_E_F_L_A_G_S
612             The environment variable `MAKEFLAGS' may contain anything that
613             may be specified on bbmmaakkee's command line.  Anything specified on
614             bbmmaakkee's command line is appended to the _._M_A_K_E_F_L_A_G_S variable,
615             which is then added to the environment for all programs that
616             bbmmaakkee executes.
617
618     _._M_A_K_E_._G_I_D
619             The numeric group ID of the user running bbmmaakkee.  It is read-only.
620
621     _._M_A_K_E_._J_O_B_._P_R_E_F_I_X
622             If bbmmaakkee is run with --jj, the output for each target is prefixed
623             with a token
624                   --- _t_a_r_g_e_t ---
625             the first part of which can be controlled via _._M_A_K_E_._J_O_B_._P_R_E_F_I_X.
626             If _._M_A_K_E_._J_O_B_._P_R_E_F_I_X is empty, no token is printed.  For example,
627             setting _._M_A_K_E_._J_O_B_._P_R_E_F_I_X to
628             `${.newline}---${.MAKE:T}[${.MAKE.PID}]' would produce tokens
629             like
630                   ---make[1234] _t_a_r_g_e_t ---
631             making it easier to track the degree of parallelism being
632             achieved.
633
634     _._M_A_K_E_._J_O_B_S
635             The argument to the --jj option.
636
637     _._M_A_K_E_._J_O_B_S_._C
638             A read-only boolean that indicates whether the --jj option supports
639             use of `C'.
640
641     _._M_A_K_E_._L_E_V_E_L
642             The recursion depth of bbmmaakkee.  The top-level instance of bbmmaakkee
643             has level 0, and each child make has its parent level plus 1.
644             This allows tests like: .if ${.MAKE.LEVEL} == 0 to protect things
645             which should only be evaluated in the top-level instance of
646             bbmmaakkee.
647
648     _._M_A_K_E_._L_E_V_E_L_._E_N_V
649             The name of the environment variable that stores the level of
650             nested calls to bbmmaakkee.
651
652     _._M_A_K_E_._M_A_K_E_F_I_L_E___P_R_E_F_E_R_E_N_C_E
653             The ordered list of makefile names (default `_m_a_k_e_f_i_l_e',
654             `_M_a_k_e_f_i_l_e') that bbmmaakkee looks for.
655
656     _._M_A_K_E_._M_A_K_E_F_I_L_E_S
657             The list of makefiles read by bbmmaakkee, which is useful for tracking
658             dependencies.  Each makefile is recorded only once, regardless of
659             the number of times read.
660
661     _._M_A_K_E_._M_E_T_A_._B_A_I_L_I_W_I_C_K
662             In "meta" mode, provides a list of prefixes which match the
663             directories controlled by bbmmaakkee.  If a file that was generated
664             outside of _._O_B_J_D_I_R but within said bailiwick is missing, the
665             current target is considered out-of-date.
666
667     _._M_A_K_E_._M_E_T_A_._C_M_P___F_I_L_T_E_R
668             In "meta" mode, it can (very rarely!) be useful to filter command
669             lines before comparison.  This variable can be set to a set of
670             modifiers that are applied to each line of the old and new
671             command that differ, if the filtered commands still differ, the
672             target is considered out-of-date.
673
674     _._M_A_K_E_._M_E_T_A_._C_R_E_A_T_E_D
675             In "meta" mode, this variable contains a list of all the meta
676             files updated.  If not empty, it can be used to trigger
677             processing of _._M_A_K_E_._M_E_T_A_._F_I_L_E_S.
678
679     _._M_A_K_E_._M_E_T_A_._F_I_L_E_S
680             In "meta" mode, this variable contains a list of all the meta
681             files used (updated or not).  This list can be used to process
682             the meta files to extract dependency information.
683
684     _._M_A_K_E_._M_E_T_A_._I_G_N_O_R_E___F_I_L_T_E_R
685             Provides a list of variable modifiers to apply to each pathname.
686             Ignore if the expansion is an empty string.
687
688     _._M_A_K_E_._M_E_T_A_._I_G_N_O_R_E___P_A_T_H_S
689             Provides a list of path prefixes that should be ignored; because
690             the contents are expected to change over time.  The default list
691             includes: `_/_d_e_v _/_e_t_c _/_p_r_o_c _/_t_m_p _/_v_a_r_/_r_u_n _/_v_a_r_/_t_m_p'
692
693     _._M_A_K_E_._M_E_T_A_._I_G_N_O_R_E___P_A_T_T_E_R_N_S
694             Provides a list of patterns to match against pathnames.  Ignore
695             any that match.
696
697     _._M_A_K_E_._M_E_T_A_._P_R_E_F_I_X
698             Defines the message printed for each meta file updated in "meta
699             verbose" mode.  The default value is:
700                   Building ${.TARGET:H:tA}/${.TARGET:T}
701
702     _._M_A_K_E_._M_O_D_E
703             Processed after reading all makefiles.  Affects the mode that
704             bbmmaakkee runs in.  It can contain these keywords:
705
706             ccoommppaatt  Like --BB, puts bbmmaakkee into "compat" mode.
707
708             mmeettaa    Puts bbmmaakkee into "meta" mode, where meta files are created
709                     for each target to capture the command run, the output
710                     generated, and if filemon(4) is available, the system
711                     calls which are of interest to bbmmaakkee.  The captured
712                     output can be useful when diagnosing errors.
713
714             ccuurrddiirrOOkk==_b_f
715                     By default, bbmmaakkee does not create _._m_e_t_a files in
716                     `_._C_U_R_D_I_R'.  This can be overridden by setting _b_f to a
717                     value which represents true.
718
719             mmiissssiinngg--mmeettaa==_b_f
720                     If _b_f is true, a missing _._m_e_t_a file makes the target out-
721                     of-date.
722
723             mmiissssiinngg--ffiilleemmoonn==_b_f
724                     If _b_f is true, missing filemon data makes the target out-
725                     of-date.
726
727             nnooffiilleemmoonn
728                     Do not use filemon(4).
729
730             eennvv     For debugging, it can be useful to include the
731                     environment in the _._m_e_t_a file.
732
733             vveerrbboossee
734                     If in "meta" mode, print a clue about the target being
735                     built.  This is useful if the build is otherwise running
736                     silently.  The message printed is the expanded value of
737                     _._M_A_K_E_._M_E_T_A_._P_R_E_F_I_X.
738
739             iiggnnoorree--ccmmdd
740                     Some makefiles have commands which are simply not stable.
741                     This keyword causes them to be ignored for determining
742                     whether a target is out of date in "meta" mode.  See also
743                     ..NNOOMMEETTAA__CCMMPP.
744
745             ssiilleenntt==_b_f
746                     If _b_f is true, when a .meta file is created, mark the
747                     target ..SSIILLEENNTT.
748
749             rraannddoommiizzee--ttaarrggeettss
750                     In both compat and parallel mode, do not make the targets
751                     in the usual order, but instead randomize their order.
752                     This mode can be used to detect undeclared dependencies
753                     between files.
754
755     _M_A_K_E_O_B_J_D_I_R
756             Used to create files in a separate directory, see _._O_B_J_D_I_R.
757
758     _M_A_K_E___O_B_J_D_I_R___C_H_E_C_K___W_R_I_T_A_B_L_E
759             When true, bbmmaakkee will check that _._O_B_J_D_I_R is writable, and issue a
760             warning if not.
761
762     _M_A_K_E___D_E_B_U_G___O_B_J_D_I_R___C_H_E_C_K___W_R_I_T_A_B_L_E
763             When true and bbmmaakkee is warning about an unwritable _._O_B_J_D_I_R,
764             report the variables listed in _M_A_K_E___P_R_I_N_T___V_A_R___O_N___E_R_R_O_R to help
765             debug.
766
767     _M_A_K_E_O_B_J_D_I_R_P_R_E_F_I_X
768             Used to create files in a separate directory, see _._O_B_J_D_I_R.
769
770     _._M_A_K_E_._O_S
771             The name of the operating system, see uname(1).  It is read-only.
772
773     _._M_A_K_E_O_V_E_R_R_I_D_E_S
774             This variable is used to record the names of variables assigned
775             to on the command line, so that they may be exported as part of
776             `MAKEFLAGS'.  This behavior can be disabled by assigning an empty
777             value to `_._M_A_K_E_O_V_E_R_R_I_D_E_S' within a makefile.  Extra variables can
778             be exported from a makefile by appending their names to
779             `_._M_A_K_E_O_V_E_R_R_I_D_E_S'.  `MAKEFLAGS' is re-exported whenever
780             `_._M_A_K_E_O_V_E_R_R_I_D_E_S' is modified.
781
782     _._M_A_K_E_._P_A_T_H___F_I_L_E_M_O_N
783             If bbmmaakkee was built with filemon(4) support, this is set to the
784             path of the device node.  This allows makefiles to test for this
785             support.
786
787     _._M_A_K_E_._P_I_D
788             The process ID of bbmmaakkee.  It is read-only.
789
790     _._M_A_K_E_._P_P_I_D
791             The parent process ID of bbmmaakkee.  It is read-only.
792
793     _M_A_K_E___P_R_I_N_T___V_A_R___O_N___E_R_R_O_R
794             When bbmmaakkee stops due to an error, it sets `_._E_R_R_O_R___T_A_R_G_E_T' to the
795             name of the target that failed, `_._E_R_R_O_R___E_X_I_T' to the exit status
796             of the failed target, `_._E_R_R_O_R___C_M_D' to the commands of the failed
797             target, and in "meta" mode, it also sets `_._E_R_R_O_R___C_W_D' to the
798             getcwd(3), and `_._E_R_R_O_R___M_E_T_A___F_I_L_E' to the path of the meta file
799             (if any) describing the failed target.  It then prints its name
800             and the value of `_._C_U_R_D_I_R' as well as the value of any variables
801             named in `_M_A_K_E___P_R_I_N_T___V_A_R___O_N___E_R_R_O_R'.
802
803     _._M_A_K_E_._S_A_V_E___D_O_L_L_A_R_S
804             If true, `$$' are preserved when doing `:=' assignments.  The
805             default is false, for backwards compatibility.  Set to true for
806             compatability with other makes.  If set to false, `$$' becomes
807             `$' per normal evaluation rules.
808
809     _._M_A_K_E_._T_A_R_G_E_T___L_O_C_A_L___V_A_R_I_A_B_L_E_S
810             If set to `false', apparent variable assignments in dependency
811             lines are treated as normal sources.
812
813     _._M_A_K_E_._U_I_D
814             The numeric ID of the user running bbmmaakkee.  It is read-only.
815
816     _._n_e_w_l_i_n_e
817             This variable is simply assigned a newline character as its
818             value.  It is read-only.  This allows expansions using the ::@@
819             modifier to put a newline between iterations of the loop rather
820             than a space.  For example, in case of an error, bbmmaakkee prints the
821             variable names and their values using:
822                   ${MAKE_PRINT_VAR_ON_ERROR:@v@$v='${$v}'${.newline}@}
823
824     _._O_B_J_D_I_R
825             A path to the directory where the targets are built.  Its value
826             is determined by trying to chdir(2) to the following directories
827             in order and using the first match:
828
829             1.   $${{MMAAKKEEOOBBJJDDIIRRPPRREEFFIIXX}}$${{..CCUURRDDIIRR}}
830
831                  (Only if `MAKEOBJDIRPREFIX' is set in the environment or on
832                  the command line.)
833
834             2.   $${{MMAAKKEEOOBBJJDDIIRR}}
835
836                  (Only if `MAKEOBJDIR' is set in the environment or on the
837                  command line.)
838
839             3.   $${{..CCUURRDDIIRR}}_/_o_b_j_.$${{MMAACCHHIINNEE}}
840
841             4.   $${{..CCUURRDDIIRR}}_/_o_b_j
842
843             5.   _/_u_s_r_/_o_b_j_/$${{..CCUURRDDIIRR}}
844
845             6.   $${{..CCUURRDDIIRR}}
846
847             Variable expansion is performed on the value before it is used,
848             so expressions such as $${{..CCUURRDDIIRR::SS,,^^//uussrr//ssrrcc,,//vvaarr//oobbjj,,}} may be
849             used.  This is especially useful with `MAKEOBJDIR'.
850
851             `_._O_B_J_D_I_R' may be modified in the makefile via the special target
852             `..OOBBJJDDIIRR'.  In all cases, bbmmaakkee changes to the specified
853             directory if it exists, and sets `_._O_B_J_D_I_R' and `_P_W_D' to that
854             directory before executing any targets.
855
856             Except in the case of an explicit `..OOBBJJDDIIRR' target, bbmmaakkee checks
857             that the specified directory is writable and ignores it if not.
858             This check can be skipped by setting the environment variable
859             `MAKE_OBJDIR_CHECK_WRITABLE' to "no".
860
861     _._P_A_R_S_E_D_I_R
862             The directory name of the current makefile being parsed.
863
864     _._P_A_R_S_E_F_I_L_E
865             The basename of the current makefile being parsed.  This variable
866             and `_._P_A_R_S_E_D_I_R' are both set only while the makefiles are being
867             parsed.  To retain their current values, assign them to a
868             variable using assignment with expansion `::=='.
869
870     _._P_A_T_H   The space-separated list of directories that bbmmaakkee searches for
871             files.  To update this search list, use the special target
872             `..PPAATTHH' rather than modifying the variable directly.
873
874     _%_P_O_S_I_X  Is set in POSIX mode, see the special `_._P_O_S_I_X' target.
875
876     _P_W_D     Alternate path to the current directory.  bbmmaakkee normally sets
877             `_._C_U_R_D_I_R' to the canonical path given by getcwd(3).  However, if
878             the environment variable `PWD' is set and gives a path to the
879             current directory, bbmmaakkee sets `_._C_U_R_D_I_R' to the value of `PWD'
880             instead.  This behavior is disabled if `MAKEOBJDIRPREFIX' is set
881             or `MAKEOBJDIR' contains a variable transform.  `_P_W_D' is set to
882             the value of `_._O_B_J_D_I_R' for all programs which bbmmaakkee executes.
883
884     _._S_H_E_L_L  The pathname of the shell used to run target scripts.  It is
885             read-only.
886
887     _._S_U_F_F_I_X_E_S
888             The list of known suffixes.  It is read-only.
889
890     _._S_Y_S_P_A_T_H
891             The space-separated list of directories that bbmmaakkee searches for
892             makefiles, referred to as the system include path.  To update
893             this search list, use the special target `..SSYYSSPPAATTHH' rather than
894             modifying the variable which is read-only.
895
896     _._T_A_R_G_E_T_S
897             The list of targets explicitly specified on the command line, if
898             any.
899
900     _V_P_A_T_H   The colon-separated (":") list of directories that bbmmaakkee searches
901             for files.  This variable is supported for compatibility with old
902             make programs only, use `_._P_A_T_H' instead.
903
904   VVaarriiaabbllee mmooddiiffiieerrss
905     The general format of a variable expansion is:
906
907           $${{_v_a_r_i_a_b_l_e[::_m_o_d_i_f_i_e_r[::...]]}}
908
909     Each modifier begins with a colon.  To escape a colon, precede it with a
910     backslash `\'.
911
912     A list of indirect modifiers can be specified via a variable, as follows:
913
914           _m_o_d_i_f_i_e_r___v_a_r_i_a_b_l_e = _m_o_d_i_f_i_e_r[::...]
915
916           $${{_v_a_r_i_a_b_l_e::$${{_m_o_d_i_f_i_e_r___v_a_r_i_a_b_l_e}}[::...]}}
917
918     In this case, the first modifier in the _m_o_d_i_f_i_e_r___v_a_r_i_a_b_l_e does not start
919     with a colon, since that colon already occurs in the referencing
920     variable.  If any of the modifiers in the _m_o_d_i_f_i_e_r___v_a_r_i_a_b_l_e contains a
921     dollar sign (`$'), these must be doubled to avoid early expansion.
922
923     Some modifiers interpret the expression value as a single string, others
924     treat the expression value as a whitespace-separated list of words.  When
925     splitting a string into words, whitespace can be escaped using double
926     quotes, single quotes and backslashes, like in the shell.  The quotes and
927     backslashes are retained in the words.
928
929     The supported modifiers are:
930
931     ::EE   Replaces each word with its suffix.
932
933     ::HH   Replaces each word with its dirname.
934
935     ::MM_p_a_t_t_e_r_n
936          Selects only those words that match _p_a_t_t_e_r_n.  The standard shell
937          wildcard characters (`*', `?', and `[]') may be used.  The wildcard
938          characters may be escaped with a backslash (`\').  As a consequence
939          of the way values are split into words, matched, and then joined,
940          the construct `${VAR:M*}' removes all leading and trailing
941          whitespace and normalizes the inter-word spacing to a single space.
942
943     ::NN_p_a_t_t_e_r_n
944          This is the opposite of `::MM', selecting all words which do _n_o_t match
945          _p_a_t_t_e_r_n.
946
947     ::OO   Orders the words lexicographically.
948
949     ::OOnn  Orders the words numerically.  A number followed by one of `k', `M'
950          or `G' is multiplied by the appropriate factor, which is 1024 for
951          `k', 1048576 for `M', or 1073741824 for `G'.  Both upper- and lower-
952          case letters are accepted.
953
954     ::OOrr  Orders the words in reverse lexicographical order.
955
956     ::OOrrnn
957          Orders the words in reverse numerical order.
958
959     ::OOxx  Shuffles the words.  The results are different each time you are
960          referring to the modified variable; use the assignment with
961          expansion `::==' to prevent such behavior.  For example,
962
963                LIST=                   uno due tre quattro
964                RANDOM_LIST=            ${LIST:Ox}
965                STATIC_RANDOM_LIST:=    ${LIST:Ox}
966
967                all:
968                        @echo "${RANDOM_LIST}"
969                        @echo "${RANDOM_LIST}"
970                        @echo "${STATIC_RANDOM_LIST}"
971                        @echo "${STATIC_RANDOM_LIST}"
972          may produce output similar to:
973
974                quattro due tre uno
975                tre due quattro uno
976                due uno quattro tre
977                due uno quattro tre
978
979     ::QQ   Quotes every shell meta-character in the value, so that it can be
980          passed safely to the shell.
981
982     ::qq   Quotes every shell meta-character in the value, and also doubles `$'
983          characters so that it can be passed safely through recursive
984          invocations of bbmmaakkee.  This is equivalent to `::SS//\\$$//&&&&//gg::QQ'.
985
986     ::RR   Replaces each word with everything but its suffix.
987
988     ::rraannggee[==_c_o_u_n_t]
989          The value is an integer sequence representing the words of the
990          original value, or the supplied _c_o_u_n_t.
991
992     ::ggmmttiimmee[==_t_i_m_e_s_t_a_m_p]
993          The value is interpreted as a format string for strftime(3), using
994          gmtime(3), producing the formatted timestamp.  Note: the `%s' format
995          should only be used with `::llooccaallttiimmee'.  If a _t_i_m_e_s_t_a_m_p value is not
996          provided or is 0, the current time is used.
997
998     ::hhaasshh
999          Computes a 32-bit hash of the value and encodes it as 8 hex digits.
1000
1001     ::llooccaallttiimmee[==_t_i_m_e_s_t_a_m_p]
1002          The value is interpreted as a format string for strftime(3), using
1003          localtime(3), producing the formatted timestamp.  If a _t_i_m_e_s_t_a_m_p
1004          value is not provided or is 0, the current time is used.
1005
1006     ::mmttiimmee[==_t_i_m_e_s_t_a_m_p]
1007          Call stat(2) with each word as pathname; use `st_mtime' as the new
1008          value.  If stat(2) fails; use _t_i_m_e_s_t_a_m_p or current time.  If
1009          _t_i_m_e_s_t_a_m_p is set to `error', then stat(2) failure will cause an
1010          error.
1011
1012     ::ttAA  Attempts to convert the value to an absolute path using realpath(3).
1013          If that fails, the value is unchanged.
1014
1015     ::ttll  Converts the value to lower-case letters.
1016
1017     ::ttss_c
1018          When joining the words after a modifier that treats the value as
1019          words, the words are normally separated by a space.  This modifier
1020          changes the separator to the character _c.  If _c is omitted, no
1021          separator is used.  The common escapes (including octal numeric
1022          codes) work as expected.
1023
1024     ::tttt  Converts the first character of each word to upper-case, and the
1025          rest to lower-case letters.
1026
1027     ::ttuu  Converts the value to upper-case letters.
1028
1029     ::ttWW  Causes subsequent modifiers to treat the value as a single word
1030          (possibly containing embedded whitespace).  See also `::[[**]]'.
1031
1032     ::ttww  Causes the value to be treated as a list of words.  See also `::[[@@]]'.
1033
1034     ::SS/_o_l_d___s_t_r_i_n_g/_n_e_w___s_t_r_i_n_g/[11ggWW]
1035          Modifies the first occurrence of _o_l_d___s_t_r_i_n_g in each word of the
1036          value, replacing it with _n_e_w___s_t_r_i_n_g.  If a `g' is appended to the
1037          last delimiter of the pattern, all occurrences in each word are
1038          replaced.  If a `1' is appended to the last delimiter of the
1039          pattern, only the first occurrence is affected.  If a `W' is
1040          appended to the last delimiter of the pattern, the value is treated
1041          as a single word.  If _o_l_d___s_t_r_i_n_g begins with a caret (`^'),
1042          _o_l_d___s_t_r_i_n_g is anchored at the beginning of each word.  If _o_l_d___s_t_r_i_n_g
1043          ends with a dollar sign (`$'), it is anchored at the end of each
1044          word.  Inside _n_e_w___s_t_r_i_n_g, an ampersand (`&') is replaced by
1045          _o_l_d___s_t_r_i_n_g (without the anchoring `^' or `$').  Any character may be
1046          used as the delimiter for the parts of the modifier string.  The
1047          anchoring, ampersand and delimiter characters can be escaped with a
1048          backslash (`\').
1049
1050          Both _o_l_d___s_t_r_i_n_g and _n_e_w___s_t_r_i_n_g may contain nested expressions.  To
1051          prevent a dollar sign from starting a nested expression, escape it
1052          with a backslash.
1053
1054     ::CC/_p_a_t_t_e_r_n/_r_e_p_l_a_c_e_m_e_n_t/[11ggWW]
1055          The ::CC modifier works like the ::SS modifier except that the old and
1056          new strings, instead of being simple strings, are an extended
1057          regular expression _p_a_t_t_e_r_n (see regex(3)) and an ed(1)-style
1058          _r_e_p_l_a_c_e_m_e_n_t.  Normally, the first occurrence of the pattern _p_a_t_t_e_r_n
1059          in each word of the value is substituted with _r_e_p_l_a_c_e_m_e_n_t.  The `1'
1060          modifier causes the substitution to apply to at most one word; the
1061          `g' modifier causes the substitution to apply to as many instances
1062          of the search pattern _p_a_t_t_e_r_n as occur in the word or words it is
1063          found in; the `W' modifier causes the value to be treated as a
1064          single word (possibly containing embedded whitespace).
1065
1066          As for the ::SS modifier, the _p_a_t_t_e_r_n and _r_e_p_l_a_c_e_m_e_n_t are subjected to
1067          variable expansion before being parsed as regular expressions.
1068
1069     ::TT   Replaces each word with its last path component (basename).
1070
1071     ::uu   Removes adjacent duplicate words (like uniq(1)).
1072
1073     ::??_t_r_u_e___s_t_r_i_n_g::_f_a_l_s_e___s_t_r_i_n_g
1074          If the variable name (not its value), when parsed as a ..iiff
1075          conditional expression, evaluates to true, return as its value the
1076          _t_r_u_e___s_t_r_i_n_g, otherwise return the _f_a_l_s_e___s_t_r_i_n_g.  Since the variable
1077          name is used as the expression, :? must be the first modifier after
1078          the variable name itself--which, of course, usually contains
1079          variable expansions.  A common error is trying to use expressions
1080          like
1081                ${NUMBERS:M42:?match:no}
1082          which actually tests defined(NUMBERS).  To determine if any words
1083          match "42", you need to use something like:
1084                ${"${NUMBERS:M42}" != "":?match:no}.
1085
1086     ::_o_l_d___s_t_r_i_n_g==_n_e_w___s_t_r_i_n_g
1087          This is the AT&T System V UNIX style substitution.  It can only be
1088          the last modifier specified, as a `:' in either _o_l_d___s_t_r_i_n_g or
1089          _n_e_w___s_t_r_i_n_g is treated as a regular character, not as the end of the
1090          modifier.
1091
1092          If _o_l_d___s_t_r_i_n_g does not contain the pattern matching character `%',
1093          and the word ends with _o_l_d___s_t_r_i_n_g or equals it, that suffix is
1094          replaced with _n_e_w___s_t_r_i_n_g.
1095
1096          Otherwise, the first `%' in _o_l_d___s_t_r_i_n_g matches a possibly empty
1097          substring of arbitrary characters, and if the whole pattern is found
1098          in the word, the matching part is replaced with _n_e_w___s_t_r_i_n_g, and the
1099          first occurrence of `%' in _n_e_w___s_t_r_i_n_g (if any) is replaced with the
1100          substring matched by the `%'.
1101
1102          Both _o_l_d___s_t_r_i_n_g and _n_e_w___s_t_r_i_n_g may contain nested expressions.  To
1103          prevent a dollar sign from starting a nested expression, escape it
1104          with a backslash.
1105
1106     ::@@_v_a_r_n_a_m_e@@_s_t_r_i_n_g@@
1107          This is the loop expansion mechanism from the OSF Development
1108          Environment (ODE) make.  Unlike ..ffoorr loops, expansion occurs at the
1109          time of reference.  For each word in the value, assign the word to
1110          the variable named _v_a_r_n_a_m_e and evaluate _s_t_r_i_n_g.  The ODE convention
1111          is that _v_a_r_n_a_m_e should start and end with a period, for example:
1112                ${LINKS:@.LINK.@${LN} ${TARGET} ${.LINK.}@}
1113
1114          However, a single-letter variable is often more readable:
1115                ${MAKE_PRINT_VAR_ON_ERROR:@v@$v='${$v}'${.newline}@}
1116
1117     ::__[==_v_a_r]
1118          Saves the current variable value in `$_' or the named _v_a_r for later
1119          reference.  Example usage:
1120
1121                M_cmpv.units = 1 1000 1000000
1122                M_cmpv = S,., ,g:_:range:@i@+ $${_:[-$$i]} \
1123                \* $${M_cmpv.units:[$$i]}@:S,^,expr 0 ,1:sh
1124
1125                .if ${VERSION:${M_cmpv}} < ${3.1.12:L:${M_cmpv}}
1126
1127          Here `$_' is used to save the result of the `:S' modifier which is
1128          later referenced using the index values from `:range'.
1129
1130     ::UU_n_e_w_v_a_l
1131          If the variable is undefined, the optional _n_e_w_v_a_l (which may be
1132          empty) is the value.  If the variable is defined, the existing value
1133          is returned.  This is another ODE make feature.  It is handy for
1134          setting per-target CFLAGS for instance:
1135                ${_${.TARGET:T}_CFLAGS:U${DEF_CFLAGS}}
1136          If a value is only required if the variable is undefined, use:
1137                ${VAR:D:Unewval}
1138
1139     ::DD_n_e_w_v_a_l
1140          If the variable is defined, _n_e_w_v_a_l (which may be empty) is the
1141          value.
1142
1143     ::LL   The name of the variable is the value.
1144
1145     ::PP   The path of the node which has the same name as the variable is the
1146          value.  If no such node exists or its path is null, the name of the
1147          variable is used.  In order for this modifier to work, the name
1148          (node) must at least have appeared on the right-hand side of a
1149          dependency.
1150
1151     ::!!_c_m_d!!
1152          The output of running _c_m_d is the value.
1153
1154     ::sshh  The value is run as a command, and the output becomes the new value.
1155
1156     ::::==_s_t_r
1157          The variable is assigned the value _s_t_r after substitution.  This
1158          modifier and its variations are useful in obscure situations such as
1159          wanting to set a variable at a point where a target's shell commands
1160          are being parsed.  These assignment modifiers always expand to
1161          nothing.
1162
1163          The `::::' helps avoid false matches with the AT&T System V UNIX style
1164          `:=' modifier and since substitution always occurs, the `::=' form
1165          is vaguely appropriate.
1166
1167     ::::??==_s_t_r
1168          As for ::::== but only if the variable does not already have a value.
1169
1170     ::::++==_s_t_r
1171          Append _s_t_r to the variable.
1172
1173     ::::!!==_c_m_d
1174          Assign the output of _c_m_d to the variable.
1175
1176     ::[[_r_a_n_g_e]]
1177          Selects one or more words from the value, or performs other
1178          operations related to the way in which the value is split into
1179          words.
1180
1181          An empty value, or a value that consists entirely of white-space, is
1182          treated as a single word.  For the purposes of the `::[[]]' modifier,
1183          the words are indexed both forwards using positive integers (where
1184          index 1 represents the first word), and backwards using negative
1185          integers (where index -1 represents the last word).
1186
1187          The _r_a_n_g_e is subjected to variable expansion, and the expanded
1188          result is then interpreted as follows:
1189
1190          _i_n_d_e_x  Selects a single word from the value.
1191
1192          _s_t_a_r_t...._e_n_d
1193                 Selects all words from _s_t_a_r_t to _e_n_d, inclusive.  For example,
1194                 `::[[22....--11]]' selects all words from the second word to the last
1195                 word.  If _s_t_a_r_t is greater than _e_n_d, the words are output in
1196                 reverse order.  For example, `::[[--11....11]]' selects all the words
1197                 from last to first.  If the list is already ordered, this
1198                 effectively reverses the list, but it is more efficient to
1199                 use `::OOrr' instead of `::OO::[[--11....11]]'.
1200
1201          **      Causes subsequent modifiers to treat the value as a single
1202                 word (possibly containing embedded whitespace).  Analogous to
1203                 the effect of $* in Bourne shell.
1204
1205          0      Means the same as `::[[**]]'.
1206
1207          @@      Causes subsequent modifiers to treat the value as a sequence
1208                 of words delimited by whitespace.  Analogous to the effect of
1209                 $@ in Bourne shell.
1210
1211          ##      Returns the number of words in the value.
1212
1213DDIIRREECCTTIIVVEESS
1214     bbmmaakkee offers directives for including makefiles, conditionals and for
1215     loops.  All these directives are identified by a line beginning with a
1216     single dot (`.') character, followed by the keyword of the directive,
1217     such as iinncclluuddee or iiff.
1218
1219   FFiillee iinncclluussiioonn
1220     Files are included with either ..iinncclluuddee <<_f_i_l_e>> or ..iinncclluuddee ""_f_i_l_e"".
1221     Variables between the angle brackets or double quotes are expanded to
1222     form the file name.  If angle brackets are used, the included makefile is
1223     expected to be in the system makefile directory.  If double quotes are
1224     used, the including makefile's directory and any directories specified
1225     using the --II option are searched before the system makefile directory.
1226
1227     For compatibility with other make variants, `iinncclluuddee _f_i_l_e ...' (without
1228     leading dot) is also accepted.
1229
1230     If the include statement is written as ..--iinncclluuddee or as ..ssiinncclluuddee, errors
1231     locating and/or opening include files are ignored.
1232
1233     If the include statement is written as ..ddiinncclluuddee, not only are errors
1234     locating and/or opening include files ignored, but stale dependencies
1235     within the included file are ignored just like in _._M_A_K_E_._D_E_P_E_N_D_F_I_L_E.
1236
1237   EExxppoorrttiinngg vvaarriiaabblleess
1238     The directives for exporting and unexporting variables are:
1239
1240     ..eexxppoorrtt _v_a_r_i_a_b_l_e ...
1241             Export the specified global variable.
1242
1243             For compatibility with other make programs, eexxppoorrtt _v_a_r_i_a_b_l_e==_v_a_l_u_e
1244             (without leading dot) is also accepted.
1245
1246             Appending a variable name to _._M_A_K_E_._E_X_P_O_R_T_E_D is equivalent to
1247             exporting a variable.
1248
1249     ..eexxppoorrtt--aallll
1250             Export all globals except for internal variables (those that
1251             start with `.').  This is not affected by the --XX flag, so should
1252             be used with caution.
1253
1254     ..eexxppoorrtt--eennvv _v_a_r_i_a_b_l_e ...
1255             The same as `.export', except that the variable is not appended
1256             to _._M_A_K_E_._E_X_P_O_R_T_E_D.  This allows exporting a value to the
1257             environment which is different from that used by bbmmaakkee
1258             internally.
1259
1260     ..eexxppoorrtt--lliitteerraall _v_a_r_i_a_b_l_e ...
1261             The same as `.export-env', except that variables in the value are
1262             not expanded.
1263
1264     ..uunneexxppoorrtt _v_a_r_i_a_b_l_e ...
1265             The opposite of `.export'.  The specified global _v_a_r_i_a_b_l_e is
1266             removed from _._M_A_K_E_._E_X_P_O_R_T_E_D.  If no variable list is provided,
1267             all globals are unexported, and _._M_A_K_E_._E_X_P_O_R_T_E_D deleted.
1268
1269     ..uunneexxppoorrtt--eennvv
1270             Unexport all globals previously exported and clear the
1271             environment inherited from the parent.  This operation causes a
1272             memory leak of the original environment, so should be used
1273             sparingly.  Testing for _._M_A_K_E_._L_E_V_E_L being 0 would make sense.
1274             Also note that any variables which originated in the parent
1275             environment should be explicitly preserved if desired.  For
1276             example:
1277
1278                   .if ${.MAKE.LEVEL} == 0
1279                   PATH := ${PATH}
1280                   .unexport-env
1281                   .export PATH
1282                   .endif
1283
1284             Would result in an environment containing only `PATH', which is
1285             the minimal useful environment.  Actually `_._M_A_K_E_._L_E_V_E_L' is also
1286             pushed into the new environment.
1287
1288   MMeessssaaggeess
1289     The directives for printing messages to the output are:
1290
1291     ..iinnffoo _m_e_s_s_a_g_e
1292             The message is printed along with the name of the makefile and
1293             line number.
1294
1295     ..wwaarrnniinngg _m_e_s_s_a_g_e
1296             The message prefixed by `warning:' is printed along with the name
1297             of the makefile and line number.
1298
1299     ..eerrrroorr _m_e_s_s_a_g_e
1300             The message is printed along with the name of the makefile and
1301             line number, bbmmaakkee exits immediately.
1302
1303   CCoonnddiittiioonnaallss
1304     The directives for conditionals are:
1305
1306     ..iiff [!!]_e_x_p_r_e_s_s_i_o_n [_o_p_e_r_a_t_o_r _e_x_p_r_e_s_s_i_o_n ...]
1307             Test the value of an expression.
1308
1309     ..iiffddeeff [!!]_v_a_r_i_a_b_l_e [_o_p_e_r_a_t_o_r _v_a_r_i_a_b_l_e ...]
1310             Test whether a variable is defined.
1311
1312     ..iiffnnddeeff [!!]_v_a_r_i_a_b_l_e [_o_p_e_r_a_t_o_r _v_a_r_i_a_b_l_e ...]
1313             Test whether a variable is not defined.
1314
1315     ..iiffmmaakkee [!!]_t_a_r_g_e_t [_o_p_e_r_a_t_o_r _t_a_r_g_e_t ...]
1316             Test the target being requested.
1317
1318     ..iiffnnmmaakkee [!!]_t_a_r_g_e_t [_o_p_e_r_a_t_o_r _t_a_r_g_e_t ...]
1319             Test the target being requested.
1320
1321     ..eellssee   Reverse the sense of the last conditional.
1322
1323     ..eelliiff [!!]_e_x_p_r_e_s_s_i_o_n [_o_p_e_r_a_t_o_r _e_x_p_r_e_s_s_i_o_n ...]
1324             A combination of `..eellssee' followed by `..iiff'.
1325
1326     ..eelliiffddeeff [!!]_v_a_r_i_a_b_l_e [_o_p_e_r_a_t_o_r _v_a_r_i_a_b_l_e ...]
1327             A combination of `..eellssee' followed by `..iiffddeeff'.
1328
1329     ..eelliiffnnddeeff [!!]_v_a_r_i_a_b_l_e [_o_p_e_r_a_t_o_r _v_a_r_i_a_b_l_e ...]
1330             A combination of `..eellssee' followed by `..iiffnnddeeff'.
1331
1332     ..eelliiffmmaakkee [!!]_t_a_r_g_e_t [_o_p_e_r_a_t_o_r _t_a_r_g_e_t ...]
1333             A combination of `..eellssee' followed by `..iiffmmaakkee'.
1334
1335     ..eelliiffnnmmaakkee [!!]_t_a_r_g_e_t [_o_p_e_r_a_t_o_r _t_a_r_g_e_t ...]
1336             A combination of `..eellssee' followed by `..iiffnnmmaakkee'.
1337
1338     ..eennddiiff  End the body of the conditional.
1339
1340     The _o_p_e_r_a_t_o_r may be any one of the following:
1341
1342     ||||      Logical OR.
1343
1344     &&&&      Logical AND; of higher precedence than `||||'.
1345
1346     bbmmaakkee only evaluates a conditional as far as is necessary to determine
1347     its value.  Parentheses can be used to override the operator precedence.
1348     The boolean operator `!!' may be used to logically negate an expression,
1349     typically a function call.  It is of higher precedence than `&&&&'.
1350
1351     The value of _e_x_p_r_e_s_s_i_o_n may be any of the following function call
1352     expressions:
1353
1354     ddeeffiinneedd(_v_a_r_n_a_m_e)
1355             Evaluates to true if the variable _v_a_r_n_a_m_e has been defined.
1356
1357     mmaakkee(_t_a_r_g_e_t)
1358             Evaluates to true if the target was specified as part of bbmmaakkee's
1359             command line or was declared the default target (either
1360             implicitly or explicitly, see _._M_A_I_N) before the line containing
1361             the conditional.
1362
1363     eemmppttyy(_v_a_r_n_a_m_e[:_m_o_d_i_f_i_e_r_s])
1364             Evaluates to true if the expansion of the variable, after
1365             applying the modifiers, results in an empty string.
1366
1367     eexxiissttss(_p_a_t_h_n_a_m_e)
1368             Evaluates to true if the given pathname exists.  If relative, the
1369             pathname is searched for on the system search path (see _._P_A_T_H).
1370
1371     ttaarrggeett(_t_a_r_g_e_t)
1372             Evaluates to true if the target has been defined.
1373
1374     ccoommmmaannddss(_t_a_r_g_e_t)
1375             Evaluates to true if the target has been defined and has commands
1376             associated with it.
1377
1378     _E_x_p_r_e_s_s_i_o_n may also be an arithmetic or string comparison.  Variable
1379     expansion is performed on both sides of the comparison.  If both sides
1380     are numeric and neither is enclosed in quotes, the comparison is done
1381     numerically, otherwise lexicographically.  A string is interpreted as a
1382     hexadecimal integer if it is preceded by 0x, otherwise it is interpreted
1383     as a decimal floating-point number; octal numbers are not supported.
1384
1385     All comparisons may use the operators `====' and `!!=='.  Numeric comparisons
1386     may also use the operators `<<', `<<==', `>>' and `>>=='.
1387
1388     If the comparison has neither a comparison operator nor a right side, the
1389     expression evaluates to true if it is nonempty and its numeric value (if
1390     any) is not zero.
1391
1392     When bbmmaakkee is evaluating one of these conditional expressions, and it
1393     encounters a (whitespace-separated) word it doesn't recognize, either the
1394     "make" or "defined" function is applied to it, depending on the form of
1395     the conditional.  If the form is `..iiffddeeff', `..iiffnnddeeff' or `..iiff', the
1396     "defined" function is applied.  Similarly, if the form is `..iiffmmaakkee' or
1397     `..iiffnnmmaakkee', the "make" function is applied.
1398
1399     If the conditional evaluates to true, parsing of the makefile continues
1400     as before.  If it evaluates to false, the following lines until the
1401     corresponding `..eelliiff' variant, `..eellssee' or `..eennddiiff' are skipped.
1402
1403   FFoorr llooooppss
1404     For loops are typically used to apply a set of rules to a list of files.
1405     The syntax of a for loop is:
1406
1407     ..ffoorr _v_a_r_i_a_b_l_e [_v_a_r_i_a_b_l_e ...] iinn _e_x_p_r_e_s_s_i_o_n
1408     <_m_a_k_e_-_l_i_n_e_s>
1409     ..eennddffoorr
1410
1411     The _e_x_p_r_e_s_s_i_o_n is expanded and then split into words.  On each iteration
1412     of the loop, one word is taken and assigned to each _v_a_r_i_a_b_l_e, in order,
1413     and these _v_a_r_i_a_b_l_e_s are substituted into the _m_a_k_e_-_l_i_n_e_s inside the body
1414     of the for loop.  The number of words must come out even; that is, if
1415     there are three iteration variables, the number of words provided must be
1416     a multiple of three.
1417
1418     If `..bbrreeaakk' is encountered within a ..ffoorr loop, it causes early
1419     termination of the loop, otherwise a parse error.
1420
1421   OOtthheerr ddiirreeccttiivveess
1422     ..uunnddeeff _v_a_r_i_a_b_l_e ...
1423             Un-define the specified global variables.  Only global variables
1424             can be un-defined.
1425
1426CCOOMMMMEENNTTSS
1427     Comments begin with a hash (`#') character, anywhere but in a shell
1428     command line, and continue to the end of an unescaped new line.
1429
1430SSPPEECCIIAALL SSOOUURRCCEESS ((AATTTTRRIIBBUUTTEESS))
1431     ..EEXXEECC     Target is never out of date, but always execute commands
1432               anyway.
1433
1434     ..IIGGNNOORREE   Ignore any errors from the commands associated with this
1435               target, exactly as if they all were preceded by a dash (`-').
1436
1437     ..MMAADDEE     Mark all sources of this target as being up to date.
1438
1439     ..MMAAKKEE     Execute the commands associated with this target even if the --nn
1440               or --tt options were specified.  Normally used to mark recursive
1441               bbmmaakkees.
1442
1443     ..MMEETTAA     Create a meta file for the target, even if it is flagged as
1444               ..PPHHOONNYY, ..MMAAKKEE, or ..SSPPEECCIIAALL.  Usage in conjunction with ..MMAAKKEE is
1445               the most likely case.  In "meta" mode, the target is out-of-
1446               date if the meta file is missing.
1447
1448     ..NNOOMMEETTAA   Do not create a meta file for the target.  Meta files are also
1449               not created for ..PPHHOONNYY, ..MMAAKKEE, or ..SSPPEECCIIAALL targets.
1450
1451     ..NNOOMMEETTAA__CCMMPP
1452               Ignore differences in commands when deciding if target is out
1453               of date.  This is useful if the command contains a value which
1454               always changes.  If the number of commands change, though, the
1455               target is still considered out of date.  The same effect
1456               applies to any command line that uses the variable _._O_O_D_A_T_E,
1457               which can be used for that purpose even when not otherwise
1458               needed or desired:
1459
1460
1461                     skip-compare-for-some:
1462                             @echo this is compared
1463                             @echo this is not ${.OODATE:M.NOMETA_CMP}
1464                             @echo this is also compared
1465
1466               The ::MM pattern suppresses any expansion of the unwanted
1467               variable.
1468
1469     ..NNOOPPAATTHH   Do not search for the target in the directories specified by
1470               _._P_A_T_H.
1471
1472     ..NNOOTTMMAAIINN  Normally bbmmaakkee selects the first target it encounters as the
1473               default target to be built if no target was specified.  This
1474               source prevents this target from being selected.
1475
1476     ..OOPPTTIIOONNAALL
1477               If a target is marked with this attribute and bbmmaakkee can't
1478               figure out how to create it, it ignores this fact and assumes
1479               the file isn't needed or already exists.
1480
1481     ..PPHHOONNYY    The target does not correspond to an actual file; it is always
1482               considered to be out of date, and is not created with the --tt
1483               option.  Suffix-transformation rules are not applied to ..PPHHOONNYY
1484               targets.
1485
1486     ..PPRREECCIIOOUUSS
1487               When bbmmaakkee is interrupted, it normally removes any partially
1488               made targets.  This source prevents the target from being
1489               removed.
1490
1491     ..RREECCUURRSSIIVVEE
1492               Synonym for ..MMAAKKEE.
1493
1494     ..SSIILLEENNTT   Do not echo any of the commands associated with this target,
1495               exactly as if they all were preceded by an at sign (`@').
1496
1497     ..UUSSEE      Turn the target into bbmmaakkee's version of a macro.  When the
1498               target is used as a source for another target, the other target
1499               acquires the commands, sources, and attributes (except for
1500               ..UUSSEE) of the source.  If the target already has commands, the
1501               ..UUSSEE target's commands are appended to them.
1502
1503     ..UUSSEEBBEEFFOORREE
1504               Like ..UUSSEE, but instead of appending, prepend the ..UUSSEEBBEEFFOORREE
1505               target commands to the target.
1506
1507     ..WWAAIITT     If ..WWAAIITT appears in a dependency line, the sources that precede
1508               it are made before the sources that succeed it in the line.
1509               Since the dependents of files are not made until the file
1510               itself could be made, this also stops the dependents being
1511               built unless they are needed for another branch of the
1512               dependency tree.  So given:
1513
1514               x: a .WAIT b
1515                       echo x
1516               a:
1517                       echo a
1518               b: b1
1519                       echo b
1520               b1:
1521                       echo b1
1522
1523               the output is always `a', `b1', `b', `x'.
1524
1525               The ordering imposed by ..WWAAIITT is only relevant for parallel
1526               makes.
1527
1528SSPPEECCIIAALL TTAARRGGEETTSS
1529     Special targets may not be included with other targets, i.e. they must be
1530     the only target specified.
1531
1532     ..BBEEGGIINN   Any command lines attached to this target are executed before
1533              anything else is done.
1534
1535     ..DDEEFFAAUULLTT
1536              This is sort of a ..UUSSEE rule for any target (that was used only
1537              as a source) that bbmmaakkee can't figure out any other way to
1538              create.  Only the shell script is used.  The _._I_M_P_S_R_C variable of
1539              a target that inherits ..DDEEFFAAUULLTT's commands is set to the
1540              target's own name.
1541
1542     ..DDEELLEETTEE__OONN__EERRRROORR
1543              If this target is present in the makefile, it globally causes
1544              make to delete targets whose commands fail.  (By default, only
1545              targets whose commands are interrupted during execution are
1546              deleted.  This is the historical behavior.)  This setting can be
1547              used to help prevent half-finished or malformed targets from
1548              being left around and corrupting future rebuilds.
1549
1550     ..EENNDD     Any command lines attached to this target are executed after
1551              everything else is done successfully.
1552
1553     ..EERRRROORR   Any command lines attached to this target are executed when
1554              another target fails.  See _M_A_K_E___P_R_I_N_T___V_A_R___O_N___E_R_R_O_R for the
1555              variables that will be set.
1556
1557     ..IIGGNNOORREE  Mark each of the sources with the ..IIGGNNOORREE attribute.  If no
1558              sources are specified, this is the equivalent of specifying the
1559              --ii option.
1560
1561     ..IINNTTEERRRRUUPPTT
1562              If bbmmaakkee is interrupted, the commands for this target are
1563              executed.
1564
1565     ..MMAAIINN    If no target is specified when bbmmaakkee is invoked, this target is
1566              built.
1567
1568     ..MMAAKKEEFFLLAAGGSS
1569              This target provides a way to specify flags for bbmmaakkee at the
1570              time when the makefiles are read.  The flags are as if typed to
1571              the shell, though the --ff option has no effect.
1572
1573     ..NNOOPPAATTHH  Apply the ..NNOOPPAATTHH attribute to any specified sources.
1574
1575     ..NNOOTTPPAARRAALLLLEELL
1576              Disable parallel mode.
1577
1578     ..NNOO__PPAARRAALLLLEELL
1579              Synonym for ..NNOOTTPPAARRAALLLLEELL, for compatibility with other pmake
1580              variants.
1581
1582     ..NNOORREEAADDOONNLLYY
1583              clear the read-only attribute from the global variables
1584              specified as sources.
1585
1586     ..OOBBJJDDIIRR  The source is a new value for `_._O_B_J_D_I_R'.  If it exists, bbmmaakkee
1587              changes the current working directory to it and updates the
1588              value of `_._O_B_J_D_I_R'.
1589
1590     ..OORRDDEERR   In parallel mode, the named targets are made in sequence.  This
1591              ordering does not add targets to the list of targets to be made.
1592
1593              Since the dependents of a target do not get built until the
1594              target itself could be built, unless `a' is built by another
1595              part of the dependency graph, the following is a dependency
1596              loop:
1597
1598              .ORDER: b a
1599              b: a
1600
1601     ..PPAATTHH    The sources are directories which are to be searched for files
1602              not found in the current directory.  If no sources are
1603              specified, any previously specified directories are removed from
1604              the search path.  If the source is the special ..DDOOTTLLAASSTT target,
1605              the current working directory is searched last.
1606
1607     ..PPAATTHH.._s_u_f_f_i_x
1608              Like ..PPAATTHH but applies only to files with a particular suffix.
1609              The suffix must have been previously declared with ..SSUUFFFFIIXXEESS.
1610
1611     ..PPHHOONNYY   Apply the ..PPHHOONNYY attribute to any specified sources.
1612
1613     ..PPOOSSIIXX   If this is the first non-comment line in the main makefile, the
1614              variable _%_P_O_S_I_X is set to the value `1003.2' and the makefile
1615              `<posix.mk>' is included if it exists, to provide POSIX-
1616              compatible default rules.  If bbmmaakkee is run with the --rr flag,
1617              only `posix.mk' contributes to the default rules.
1618
1619     ..PPRREECCIIOOUUSS
1620              Apply the ..PPRREECCIIOOUUSS attribute to any specified sources.  If no
1621              sources are specified, the ..PPRREECCIIOOUUSS attribute is applied to
1622              every target in the file.
1623
1624     ..RREEAADDOONNLLYY
1625              set the read-only attribute on the global variables specified as
1626              sources.
1627
1628     ..SSHHEELLLL   Sets the shell that bbmmaakkee uses to execute commands.  The sources
1629              are a set of _f_i_e_l_d==_v_a_l_u_e pairs.
1630
1631              name        This is the minimal specification, used to select
1632                          one of the built-in shell specs; sh, ksh, and csh.
1633
1634              path        Specifies the absolute path to the shell.
1635
1636              hasErrCtl   Indicates whether the shell supports exit on error.
1637
1638              check       The command to turn on error checking.
1639
1640              ignore      The command to disable error checking.
1641
1642              echo        The command to turn on echoing of commands executed.
1643
1644              quiet       The command to turn off echoing of commands
1645                          executed.
1646
1647              filter      The output to filter after issuing the quiet
1648                          command.  It is typically identical to quiet.
1649
1650              errFlag     The flag to pass the shell to enable error checking.
1651
1652              echoFlag    The flag to pass the shell to enable command
1653                          echoing.
1654
1655              newline     The string literal to pass the shell that results in
1656                          a single newline character when used outside of any
1657                          quoting characters.
1658              Example:
1659
1660              .SHELL: name=ksh path=/bin/ksh hasErrCtl=true \
1661                      check="set -e" ignore="set +e" \
1662                      echo="set -v" quiet="set +v" filter="set +v" \
1663                      echoFlag=v errFlag=e newline="'\n'"
1664
1665     ..SSIILLEENNTT  Apply the ..SSIILLEENNTT attribute to any specified sources.  If no
1666              sources are specified, the ..SSIILLEENNTT attribute is applied to every
1667              command in the file.
1668
1669     ..SSTTAALLEE   This target gets run when a dependency file contains stale
1670              entries, having _._A_L_L_S_R_C set to the name of that dependency file.
1671
1672     ..SSUUFFFFIIXXEESS
1673              Each source specifies a suffix to bbmmaakkee.  If no sources are
1674              specified, any previously specified suffixes are deleted.  It
1675              allows the creation of suffix-transformation rules.
1676
1677              Example:
1678
1679              .SUFFIXES: .c .o
1680              .c.o:
1681                      cc -o ${.TARGET} -c ${.IMPSRC}
1682
1683     ..SSYYSSPPAATTHH
1684              The sources are directories which are to be added to the system
1685              include path which bbmmaakkee searches for makefiles.  If no sources
1686              are specified, any previously specified directories are removed
1687              from the system include path.
1688
1689EENNVVIIRROONNMMEENNTT
1690     bbmmaakkee uses the following environment variables, if they exist: MACHINE,
1691     MACHINE_ARCH, MAKE, MAKEFLAGS, MAKEOBJDIR, MAKEOBJDIRPREFIX, MAKESYSPATH,
1692     PWD, and TMPDIR.
1693
1694     MAKEOBJDIRPREFIX and MAKEOBJDIR may only be set in the environment or on
1695     the command line to bbmmaakkee and not as makefile variables; see the
1696     description of `_._O_B_J_D_I_R' for more details.
1697
1698FFIILLEESS
1699     .depend        list of dependencies
1700     makefile       first default makefile if no makefile is specified on the
1701                    command line
1702     Makefile       second default makefile if no makefile is specified on the
1703                    command line
1704     sys.mk         system makefile
1705     /usr/share/mk  system makefile directory
1706
1707CCOOMMPPAATTIIBBIILLIITTYY
1708     The basic make syntax is compatible between different make variants;
1709     however the special variables, variable modifiers and conditionals are
1710     not.
1711
1712   OOllddeerr vveerrssiioonnss
1713     An incomplete list of changes in older versions of bbmmaakkee:
1714
1715     The way that .for loop variables are substituted changed after NetBSD 5.0
1716     so that they still appear to be variable expansions.  In particular this
1717     stops them being treated as syntax, and removes some obscure problems
1718     using them in .if statements.
1719
1720     The way that parallel makes are scheduled changed in NetBSD 4.0 so that
1721     .ORDER and .WAIT apply recursively to the dependent nodes.  The
1722     algorithms used may change again in the future.
1723
1724   OOtthheerr mmaakkee ddiiaalleeccttss
1725     Other make dialects (GNU make, SVR4 make, POSIX make, etc.) do not
1726     support most of the features of bbmmaakkee as described in this manual.  Most
1727     notably:
1728
1729           ++oo   The ..WWAAIITT and ..OORRDDEERR declarations and most functionality
1730               pertaining to parallelization.  (GNU make supports
1731               parallelization but lacks the features needed to control it
1732               effectively.)
1733
1734           ++oo   Directives, including for loops and conditionals and most of
1735               the forms of include files.  (GNU make has its own incompatible
1736               and less powerful syntax for conditionals.)
1737
1738           ++oo   All built-in variables that begin with a dot.
1739
1740           ++oo   Most of the special sources and targets that begin with a dot,
1741               with the notable exception of ..PPHHOONNYY, ..PPRREECCIIOOUUSS, and ..SSUUFFFFIIXXEESS.
1742
1743           ++oo   Variable modifiers, except for the `:old=new' string
1744               substitution, which does not portably support globbing with `%'
1745               and historically only works on declared suffixes.
1746
1747           ++oo   The $$>> variable even in its short form; most makes support this
1748               functionality but its name varies.
1749
1750     Some features are somewhat more portable, such as assignment with ++==, ??==,
1751     and !!==.  The _._P_A_T_H functionality is based on an older feature VVPPAATTHH found
1752     in GNU make and many versions of SVR4 make; however, historically its
1753     behavior is too ill-defined (and too buggy) to rely upon.
1754
1755     The $$@@ and $$<< variables are more or less universally portable, as is the
1756     $$((MMAAKKEE)) variable.  Basic use of suffix rules (for files only in the
1757     current directory, not trying to chain transformations together, etc.) is
1758     also reasonably portable.
1759
1760SSEEEE AALLSSOO
1761     mkdep(1)
1762
1763HHIISSTTOORRYY
1764     bbmmaakkee is derived from NetBSD make(1).  It uses autoconf to facilitate
1765     portability to other platforms.
1766
1767     A make command appeared in Version 7 AT&T UNIX.  This make implementation
1768     is based on Adam de Boor's pmake program, which was written for Sprite at
1769     Berkeley.  It was designed to be a parallel distributed make running jobs
1770     on different machines using a daemon called "customs".
1771
1772     Historically the target/dependency FFRRCC has been used to FoRCe rebuilding
1773     (since the target/dependency does not exist ... unless someone creates an
1774     _F_R_C file).
1775
1776BBUUGGSS
1777     The make syntax is difficult to parse.  For instance, finding the end of
1778     a variable's use should involve scanning each of the modifiers, using the
1779     correct terminator for each field.  In many places make just counts {}
1780     and () in order to find the end of a variable expansion.
1781
1782     There is no way of escaping a space character in a filename.
1783
1784     In jobs mode, when a target fails; make will put an error token into the
1785     job token pool.  This will cause all other instances of make using that
1786     token pool to abort the build and exit with error code 6.  Sometimes the
1787     attempt to suppress a cascade of unnecessary errors, can result in a
1788     seemingly unexplained `*** Error code 6'
1789
1790FreeBSD 14.1-RELEASE             July 1, 2024             FreeBSD 14.1-RELEASE
1791