NAME

make — maintain, update, and regenerate files (DEVELOPMENT)

SYNOPSIS

DESCRIPTION

The make utility shall update files that are derived from other files. A typical case is one where object files are derived from the corresponding source files. The make utility examines time relationships and shall update those derived files (called targets) that have modified times earlier than the modified times of the files (called prerequisites) from which they are derived. A description file (makefile) contains a description of the relationships between files, and the commands that need to be executed to update the targets to reflect changes in their prerequisites. Each specification, or rule, shall consist of a target, optional prerequisites, and optional commands to be executed when a prerequisite is newer than the target. There are two kinds of rule:

1. Inference rules, which have one target name with at least one <period> ( ‘’.) and no <slash> ( ‘/’)
2. Target rules, which can have more than one target name

In addition, make shall have a collection of built-in macros and inference rules that infer prerequisite relationships to simplify maintenance of programs.

To receive exactly the behavior described in this section, a portable makefile shall:

• Include the special target .POSIX
• Omit any special target reserved for implementations (a leading period followed by uppercase letters) that has not been specified by this section

The behavior of make is unspecified if either or both of these conditions are not met.

OPTIONS

The make utility shall conform to XBD V1_chap12(7), except for Guideline 9.

The following options shall be supported:

-e

Cause environment variables, including those with null values, to override macro assignments within makefiles.

-f makefile

Specify a different makefile. The argument makefile is a pathname of a description file, which is also referred to as the makefile . A pathname of '-' shall denote the standard input. There can be multiple instances of this option, and they shall be processed in the order specified. The effect of specifying the same option-argument more than once is unspecified.

-i

Ignore error codes returned by invoked commands. This mode shall be the same as if the special target .IGNORE were specified without prerequisites.

-j maxjobs

Set the maximum number of targets that can be updated concurrently. If this option is specified multiple times, the last value of maxjobs specified shall take precedence. If this option is not specified, or if maxjobs is 1, only one target shall be updated at a time (no parallelization). If the value of maxjobs is non-positive, the behavior is unspecified. When maxjobs is greater than 1, make shall create a pool of up to maxjobs - 1 tokens. (Note that implementations are not required to create a pool of exactly maxjobs - 1 tokens. For example, an implementation could limit the pool size based on the number of processors available.) If the size of the token pool would be 0, make need not implement a token pool.

When all of the following are true:

• There is a target with commands that is not up-to-date
• The target's prerequisites (if any) are up-to-date
• make is not waiting to bring the target up-to-date (see .WAIT)
• make is currently bringing a different target with commands up-to-date
• make is not currently bringing maxjobs targets up-to-date in parallel
• The special target .NOTPARALLEL is not specified
• The token pool is not empty

then make may attempt to remove one token from the pool. If a token is successfully removed, it shall attempt to bring this target up-to-date in parallel, and after this processing completes shall return the token to the pool. When make is bringing a target without commands up-to-date, it need not remove a token from the pool.

If a rule invokes a sub- make either via the MAKE macro or via a command line that begins with ‘+’, the sub- make is the same implementation as the make that invoked the sub- make, and the -j option is passed to the sub- make via the MAKEFLAGS environment variable with the same maxjobs value and is not overridden by a maxjobs value from another source (even if it has the same value), the sub- make shall use the same token pool as its invoking make rather than create a new token pool. Otherwise, it is unspecified whether the sub- make uses the same token pool as its invoking make or creates a new token pool. If a rule executes multiple sub- make processes asynchronously the behavior is unspecified.

-k

Continue to update other targets that do not depend on the current target if a non-ignored error occurs while executing the commands to bring a target up-to-date.

-n

Write commands that would be executed on standard output, but do not execute them. However, lines with a <plus-sign> ( '+' ) prefix, lines that expand the MAKE macro, and lines being processed in order to create an include file or to bring it up-to-date (see Include Lines in the EXTENDED DESCRIPTION section) shall be executed. In this mode, lines with a <commercial-at> ( '@' ) character prefix shall be written to standard output.

-p

Write to standard output the complete set of macro definitions and target descriptions. The output format is unspecified.

-q

Return a zero exit value if the target file is up-to-date; otherwise, return an exit value of 1. Targets shall not be updated if this option is specified. However, a makefile command line (associated with the targets) with a <plus-sign> ( '+' ) prefix shall be executed and it is unspecified whether command lines that do not have a <plus-sign> prefix and either expand the MAKE macro or are being processed in order to create an include file or to bring it up-to-date (see Include Lines in the EXTENDED DESCRIPTION section) are executed.

-r

Clear the suffix list and do not use the built-in rules.

-S

Terminate make if an error occurs while executing the commands to bring a target up-to-date. This shall be the default and the opposite of -k .

-s

Do not write makefile execution lines (see Makefile Execution ) or touch messages (see -t ) to standard output before executing. This mode shall be the same as if the special target .SILENT were specified without prerequisites.

-t

Update the modification time of each target as though a touch target had been executed. Targets that have prerequisites but no commands (see Target Rules ), or that are already up-to-date, shall not be touched in this manner. Write messages to standard output for each target file indicating the name of the file and that it was touched. Normally, the makefile command lines associated with each target are not executed. However, a command line with a <plus-sign> ( '+' ) prefix shall be executed and it is unspecified whether command lines that do not have a <plus-sign> prefix and either expand the MAKE macro or are being processed in order to create an include file or to bring it up-to-date (see Include Lines in the EXTENDED DESCRIPTION section) are executed.

Any options specified in the MAKEFLAGS environment variable shall be evaluated before any options specified on the make utility command line. If the -k and -S options are both specified on the make utility command line or by the MAKEFLAGS environment variable, the last option specified shall take precedence. If the -f or -p options appear in the MAKEFLAGS environment variable, the result is undefined.

OPERANDS

The following operands shall be supported:

target_name

Target names, as defined in the EXTENDED DESCRIPTION section. If no target is specified, while make is processing the makefiles, the first target that make encounters that is not a special target or an inference rule shall be used.

macro=value

 

macro::=value

 

macro:::=value

Delayed and immediate expansion macro definitions, as defined in Macros .

Delayed and immediate expansion macro definitions can be intermixed, and shall be processed in the order specified. If any macro definition appears after a target_name operand on the make utility command line, the results are unspecified.

STDIN

The standard input shall be used only if the makefile option-argument is ‘-’. See the INPUT FILES section.

INPUT FILES

The input file, otherwise known as the makefile, is a text file containing rules, macro definitions, include lines, and comments. See the EXTENDED DESCRIPTION section.

ENVIRONMENT VARIABLES

The following environment variables shall affect the execution of make:

LANG

Provide a default value for the internationalization variables that are unset or null. (See XBD 8.2 Internationalization Variables for the precedence of internationalization variables used to determine the values of locale categories.)

LC_ALL

If set to a non-empty string value, override the values of all the other internationalization variables.

LC_CTYPE

Determine the locale for the interpretation of sequences of bytes of text data as characters (for example, single-byte as opposed to multi-byte characters in arguments and input files).

LC_MESSAGES

Determine the locale that should be used to affect the format and contents of diagnostic messages written to standard error.

MAKEFLAGS

This variable shall be interpreted as a character string representing a series of option characters to be used as the default options. The implementation shall accept both of the following formats (but need not accept them when intermixed):

• The characters are option letters without the leading <hyphen-minus> characters or <blank> separation used on a make utility command line.
• The characters are formatted in a manner similar to the use of the make utility in shell commands: options are preceded by <hyphen-minus> characters and <blank>-separated as described in XBD V1_chap12(7). The macro = value macro definition operands can also be included. The difference between the contents of MAKEFLAGS and the use of the make utility in shell commands is that the contents of the variable shall not be subjected to the word expansions (see 2.6 Word Expansions) associated with parsing shell command lines.

NLSPATH

[ XSI] Determine the location of messages objects and message catalogs.

PROJECTDIR

[ XSI]
Provide a directory to be used to search for SCCS files not found in the current directory. In all of the following cases, the search for SCCS files is made in the directory SCCS in the identified directory. If the value of PROJECTDIR begins with a <slash>, it shall be considered an absolute pathname; otherwise, the value of PROJECTDIR is treated as a user name and that user's initial working directory shall be examined for a subdirectory src or source . If such a directory is found, it shall be used. Otherwise, the value is used as a relative pathname.

If PROJECTDIR is not set or has a null value, the search for SCCS files shall be made in the directory SCCS in the current directory.

The setting of PROJECTDIR affects all files listed in the remainder of this utility description for files with a component named SCCS.

The value of the SHELL environment variable shall not be used as a macro and shall not be modified by defining the SHELL macro in a makefile or on the command line. All other environment variables, including those with null values, shall be used as macros, as defined in Macros.

ASYNCHRONOUS EVENTS

For SIGHUP, SIGINT, SIGQUIT, and SIGTERM signals, if the signal was not inherited as ignored, none of the -n, -p, or -q options was specified, make is currently processing a target or inference rule, and the current target is neither a directory nor a prerequisite of the special targets .PHONY or .PRECIOUS:

• The make utility shall catch the signal and, if the time of last data modification of the current target has changed since make began processing the rule to bring that target up to date, remove that target; it may also remove that target if the time of last data modification has not changed. Any targets removed in this manner shall be reported in diagnostic or informational messages of unspecified format, written to standard error.
• If make writes a diagnostic message to standard error, it shall exit with a status that indicates an error occurred; otherwise, it shall set the signal to default and re-signal itself.

In all other circumstances, make shall take the standard action for all signals; see 1.4 Utility Description Defaults.

STDOUT

If make is invoked without any work needing to be done, it may write a message to standard output indicating that no action was taken. Otherwise, the make utility shall write all commands to be executed (and the filenames of files touched for the -t option in a message of unspecified format) to standard output unless the -s option was specified, the command is prefixed with a <commercial-at> ( ‘@’), or the special target .SILENT has either the current target as a prerequisite or has no prerequisites.

STDERR

The standard error shall be used for diagnostic messages and may be used for informational messages about target removals (see ASYNCHRONOUS EVENTS).

OUTPUT FILES

Files can be created when the -t option is present. Additional files can also be created by the utilities invoked by make.

EXTENDED DESCRIPTION

The make utility attempts to perform the actions, specified in one or more makefiles, required to ensure that specified targets are up-to-date. By default, the following files shall be tried in sequence: ./makefile and ./Makefile. If neither ./makefile nor ./Makefile is found, other implementation-defined files may also be tried. [XSI] On XSI-conformant systems, the additional files ./s.makefile, SCCS/s.makefile, ./s.Makefile, and SCCS/s.Makefile shall also be tried. The -f option shall direct make to ignore any of these default files and use the specified option-argument as a makefile instead. If this option-argument is ‘-’, standard input shall be used.

The term makefile is used to refer to any makefile contents provided by the user, whether in ./makefile or its variants, or specified by the -f option.

A target shall be considered up-to-date if it exists and is newer than all of its prerequisites, or if it has already been made up-to-date by the current invocation of make (regardless of the target's existence or age), except that targets that are made up-to-date in order for them to be processed as include line pathnames (see Include Lines below) need not be considered up-to-date during later processing. A target may also be considered up-to-date if it exists, is the same age as one or more of its prerequisites, and is newer than the remaining prerequisites (if any). The make utility shall treat all prerequisites as targets themselves and recursively ensure that they are up-to-date, processing them in the order in which they appear in the rule. The make utility shall use the modification times of files to determine whether the corresponding targets are out-of-date.

To ensure that a target is up-to-date, make shall ensure that all of the prerequisites of the target are up-to-date, then check to see if the target itself is up-to-date. If the target is not up-to-date, the target shall be made up-to-date by executing the rule's commands (if any). If the target does not exist after the target has been successfully made up-to-date, the target shall be treated as being newer than any target for which it is a prerequisite.

If a target exists and there is neither a target rule nor an inference rule for the target, the target shall be considered up-to-date. It shall be an error if make attempts to ensure that a target is up-to-date but the target does not exist and there is neither a target rule nor an inference rule for the target.

target [target...]: [prerequisite...][;command]
[<tab>command
<tab>command
...]

string1 = [string2]

string1 ::= [string2]

string1 :::= [string2]

string1 != [string2]

string1 ?= [string2]

string1 += [string2]

target:
<tab>command
[<tab>command]
...


line that does not begin with <tab> or #

rule: ;

SPECIAL TARGETS


[XSI]
.SCCS_GET:
    sccs $(SCCSFLAGS) get $(SCCSGETFLAGS) $@



[XSI]
.SUFFIXES: .o .c .y .l .a .sh .c~ .y~ .l~ .sh~


MACROS


AR=ar
ARFLAGS=-rv
YACC=yacc
YFLAGS=
LEX=lex
LFLAGS=
LDFLAGS=
CC=c17
CFLAGS=-O 1
[XSI]
GET=get
GFLAGS=
SCCSFLAGS=
SCCSGETFLAGS=-s



SINGLE-SUFFIX RULES


.c:
    $(CC) $(CFLAGS) $(LDFLAGS) -o $@ $<


.sh:
    cp $< $@
    chmod a+x $@


[XSI]
.c~:
    $(GET) $(GFLAGS) -p $< > $*.c
    $(CC) $(CFLAGS) $(LDFLAGS) -o $@ $*.c


.sh~:
    $(GET) $(GFLAGS) -p $< > $*.sh
    cp $*.sh $@
    chmod a+x $@



DOUBLE-SUFFIX RULES


.c.o:
    $(CC) $(CFLAGS) -c $<


.y.o:
    $(YACC) $(YFLAGS) $<
    $(CC) $(CFLAGS) -c y.tab.c
    rm -f y.tab.c
    mv y.tab.o $@


.l.o:
    $(LEX) $(LFLAGS) $<
    $(CC) $(CFLAGS) -c lex.yy.c
    rm -f lex.yy.c
    mv lex.yy.o $@


.y.c:
    $(YACC) $(YFLAGS) $<
    mv y.tab.c $@


.l.c:
    $(LEX) $(LFLAGS) $<
    mv lex.yy.c $@


[XSI]
.c~.o:
    $(GET) $(GFLAGS) -p $< > $*.c
    $(CC) $(CFLAGS) -c $*.c


.y~.o:
    $(GET) $(GFLAGS) -p $< > $*.y
    $(YACC) $(YFLAGS) $*.y
    $(CC) $(CFLAGS) -c y.tab.c
    rm -f y.tab.c
    mv y.tab.o $@


.l~.o:
    $(GET) $(GFLAGS) -p $< > $*.l
    $(LEX) $(LFLAGS) $*.l
    $(CC) $(CFLAGS) -c lex.yy.c
    rm -f lex.yy.c
    mv lex.yy.o $@


.y~.c:
    $(GET) $(GFLAGS) -p $< > $*.y
    $(YACC) $(YFLAGS) $*.y
    mv y.tab.c $@


.l~.c:
    $(GET) $(GFLAGS) -p $< > $*.l
    $(LEX) $(LFLAGS) $*.l
    mv lex.yy.c $@



.c.a:
    $(CC) -c $(CFLAGS) $<
    $(AR) $(ARFLAGS) $@ $*.o
    rm -f $*.o

EXIT STATUS

When the -q option is specified, the make utility shall exit with one of the following values:

0

All specified targets were already up-to-date.

1

One or more targets were not up-to-date.

>1

An error occurred.

When the -q option is not specified, the make utility shall exit with one of the following values:

0

All specified targets were already up-to-date, or all commands executed to bring targets up-to-date either exited with status 0 or had a non-zero exit status that was specified (via the -i option, the special target .IGNORE , or a '-' command prefix) to be ignored.

>0

An error occurred, or at least one command executed to bring a target up-to-date exited with a non-zero exit status that was not specified to be ignored.

CONSEQUENCES OF ERRORS

Default.

The following sections are informative.

APPLICATION USAGE

If there is a source file (such as ./source.c) and there are two SCCS files corresponding to it ( ./s.source.c and ./SCCS/s.source.c), on XSI-conformant systems make uses the SCCS file in the current directory. However, users are advised to use the underlying SCCS utilities ( admin(1), delta(1), get(1), and so on) or the sccs(1) utility for all source files in a given directory. If both forms are used for a given source file, future developers are very likely to be confused.

It is incumbent upon portable makefiles to specify the .POSIX special target in order to guarantee that they are not affected by local extensions.

The -k and -S options are both present so that the relationship between the command line, the MAKEFLAGS variable, and the makefile can be controlled precisely. If the k flag is passed in MAKEFLAGS and a command is of the form:

$(MAKE) -S foo

then the default behavior is restored for the child make.

When the -n option is specified, it is always added to MAKEFLAGS . This allows a recursive make -n target to be used to see all of the actions that would be taken to update target.

Because of widespread historical practice, interpreting a <number-sign> ( ‘#’) inside a variable as the start of a comment has the unfortunate side-effect of making it impossible to place a <number-sign> in a variable, thus forbidding something like:

CFLAGS = -D "COMMENT_CHAR='#'"

Many historical make utilities stop chaining together inference rules when an intermediate target is nonexistent. For example, it might be possible for a make to determine that both .y.c and .c.o could be used to convert a .y to a .o. Instead, in this case, make requires the use of a .y.o rule.

The standard set of default rules uses only features provided by other parts of this volume of POSIX.1-2024. They include rules for optional utilities in this volume of POSIX.1-2024, but only rules pertaining to utilities that are provided are needed in an implementation's default set.

Although make expands macros that do not exist to an empty string, it is not safe to assume that a macro which has not intentionally been set to a specific value will expand to an empty string for everyone who uses the makefile. There are two reasons for this:

1. When another user executes make, they might happen to have an environment variable of the same name (which they have set for some unrelated purpose) with a non-empty value.
2. A different implementation of make (or a later version of the same implementation) might have a non-empty value for the macro in its default set.

This is one aspect of a more general problem, which is that any macro that is not one for which this standard requires a default value, and is not explicitly set either in the makefile or on the make command line, can have an unexpected value (or unexpectedly not exist) when the makefile is used by a different user or with a different make implementation.

For this reason, it is recommended that makefile authors do not design makefile schemes in which values for non-standard macros are obtained from the user's environment variables. Safer methods of allowing users to configure macro values include:

• Setting the macros to default values in a make include file where the user can edit the values.
• Executing make from one or more wrapper scripts which set macro values on the command line (and which do not obtain those values from environment variables).

Makefile authors who follow this recommendation may wish to check for any macros they have overlooked by using a make implementation that provides, as an extension, a command-line option that causes make to report attempts to expand (or append to) macros that do not exist. Users of makefiles written by others can also benefit from the use of such an option to detect the opposite problem (where the author had a macro being set from an environment variable but the user does not have the variable set). This can avoid misbehaviors that would otherwise be hard to debug, such as a file-processing utility reading from standard input because it was not given any pathnames to process.

Makefile authors who choose not to follow the recommendation can minimize the risk of misbehavior by ensuring all non-standard macros have names that begin with a suitable project-specific prefix.

Use of the -e option is strongly discouraged, as it makes the problem discussed above even more likely by introducing the possibility of unexpected values occurring even for macros set in the makefile. If a specific macro needs a value from the environment to override a value set in the makefile, it is safer to set just that macro on the command line, using for example make MYPROJ_FOO="$MYPROJ_FOO". Alternatively, the makefile can be modified to use the ?= assignment operator for that macro.

Delayed-expansion macros are evaluated when they are used rather than when they are defined. Therefore:

MACRO = value1
Immed ::= $(MACRO)
DELAY = $(MACRO)
MACRO = value2


target:
    echo $(Immed) $(DELAY)

would produce "value1 value2", since Immed was expanded while MACRO was value1, but DELAY was not expanded until it was needed in the echo(1) command line when MACRO was value2.

Because the behavior of the += assignment differs depending on whether the macro being appended to is a delayed-expansion macro or an immediate-expansion macro, it is recommended that when both macro types are used in a set of multiple makefiles and include files, a naming convention is adopted to distinguish the two macro types. This avoids any confusion about whether += will append the expanded or unexpanded value. A suitable convention might be to name delayed-expansion macros using uppercase and underscore characters and immediate-expansion macros using a name that contains at least one lowercase character.

Some historical applications have been known to intermix target_name and macro=name operands on the command line, expecting that all of the macros are processed before any of the targets are dealt with. Conforming applications do not do this, although some backwards-compatibility support may be included in some implementations.

The following characters in filenames may give trouble: ‘=’, ‘’:, ‘`’, single-quote, and ‘@’. In include filenames, pattern matching characters and ‘"’ should also be avoided, as they may be treated as special by some implementations.

For inference rules, the descriptions of $< and $? seem similar. However, an example shows the minor difference. In a makefile containing:

foo.o: foo.h

if foo.h is newer than foo.o, yet foo.c is older than foo.o, the built-in rule to make foo.o from foo.c is used, with $< equal to foo.c and $? equal to foo.h. If foo.c is also newer than foo.o, $< is equal to foo.c and $? is equal to foo.h foo.c.

As a consequence of the general rules for target updating, a useful special case is that if a target has no prerequisites and no commands, and the target of the rule is a nonexistent file, then make acts as if this target has been updated whenever its rule is run.

Note:

This implies that all targets depending on this one will always have their commands run.

Shell command sequences like make; cp original copy; make may have problems on filesystems where the timestamp resolution is the minimum (1 second) required by the standard and where make considers identical timestamps to be up-to-date. Conversely, rules like copy: original; cp -p original copy will result in redundant work on make implementations that consider identical timestamps to be out-of-date.

The requirements relating to dynamic include files (ones that have rules to create or update them) allow two different methods of implementing them, as explained in RATIONALE below. In order to write a set of makefiles and include files (both dynamic and static) that work with both methods, applications need to ensure the following:

• Rules containing commands for creating dynamic include files (and any prerequisites) precede the include line that will cause the file to be read.
• Include lines and rules for creating dynamic include files do not depend on the contents of any earlier dynamic include file. For example, defining a macro in a dynamic include file and using that macro in a later include line should be avoided (unless the later include line is itself inside the dynamic include file).
• One of the rules used in creating a dynamic include file, or a dynamic prerequisite of an include file, contains commands to create its target and does not ignore creation failure.

Note that although the first point above appears at first sight to preclude a dynamic include file that defines its own prerequisites, this can be achieved by having two include lines that name the same file (provided the rules in the file do not contain command lines), as shown in EXAMPLES.

This standard does not specify precedence between macro definition and include directives. Thus, the behavior of:

include =foo.mk

is unspecified. To define a variable named include, either the white space before the <equal-sign> should be removed, or another macro should be used, as in:

INCLUDE_NAME = include
$(INCLUDE_NAME) =foo.mk

On the other hand, if the intent is to include a file which starts with an <equal-sign>, either the filename should be changed to ./=foo.mk, or the makefile should be written as:

INCLUDE_FILE = =foo.mk
include $(INCLUDE_FILE)

It is important to be careful when using parallel execution (the -j option) and archives. If multiple $(AR) commands run at the same time on the same archive file, they will not know about each other and can corrupt the file. If the -j option is used, it is necessary to use .WAIT in between archive member prerequisites to prevent this (see EXAMPLES).

EXAMPLES

1. The following command:

   make

   makes the first target found in the makefile.

2. The following command:

   make junk

   makes the target junk.

3. The following makefile says that pgm depends on two files, a.o and b.o, and that they in turn depend on their corresponding source files ( a.c and b.c), and a common file incl.h:

   .POSIX:
   pgm: a.o b.o
       c17 a.o b.o -o pgm
   a.o: incl.h a.c
       c17 -c a.c
   b.o: incl.h b.c
       c17 -c b.c

4. The following is an extended version of the previous example that generates make include files containing the prerequisites for each object file. The include file also defines its own prerequisites, and the makefile arranges that these are used by including the file twice. With implementations of make that create include files during parsing, the first time make is run the file does not exist but the use of the <hyphen-minus> prefix on the first include line means it is ignored and is then generated by the rule preceding the second include line. On subsequent runs, if any of the source or header files previously identified has changed, the include file will be updated. There are other ways of updating the include file when headers change, but they involve recursive execution of make.

   .POSIX:
   .SUFFIXES: .c .d
   
   OFILES = a.o b.o
   
   pgm: $(OFILES)
       c17 $(OFILES) -o pgm
   a.o:
       c17 -c a.c
   b.o:
       c17 -c b.c
   
   -include $(OFILES:.o=.d)
   .c.d:
       +{ \
         set -o pipefail; cfile=$<; ofile=$${cfile%.c}.o; \
         printf '%s %s: %s ' "$$ofile" $@ $<; \
         c17 -E $< | LC_ALL=C sed -n \
           '/^#[[:blank:]]*[[:digit:]]/s/.*"\([^"]*\.h\)".*/\1/p' | \
           LC_ALL=C sort -u | tr '\n' ' '; \
         echo; \
       } > $@
   include $(OFILES:.o=.d)

   This example does not cope with a header file being removed ( make(1) will complain that it does not know how to make it), necessitating that *.d be removed and the make run again. Alternatively, this can be handled by updating the commands which generate the .d file so that they add an empty target rule for each of its prerequisites.

5. An example for making optimized .o files from .c files is:

   .c.o:
       c17 -c -O 1 $*.c

   or:

   .c.o:
       c17 -c -O 1 $<

6. The most common use of the archive interface follows. Here, it is assumed that the source files are all C-language source:

   lib.a: lib.a(file1.o) .WAIT lib.a(file2.o) .WAIT lib.a(file3.o)
       @echo lib.a is now up-to-date

   The .c.a rule is used to make file1.o, file2.o, and file3.o and insert them into lib.a.

7. The treatment of escaped <newline> characters throughout the makefile is historical practice. For example, the inference rule:

   .c.o\
   :

   works, and the macro:

   f=  bar baz\
       biz
   a:
       echo ==$f==

   echoes "==bar baz biz==".

   If $? were:

   /usr/include/stdio.h /usr/include/unistd.h foo.h

   then $(?D) would be:

   /usr/include /usr/include .

   and $(?F) would be:

   stdio.h unistd.h foo.h

8. The contents of the built-in rules can be viewed by running:

   make -p -f /dev/null 2>/dev/null

9. With the following makefile, make -j 10 all may bring one and two up-to-date in parallel despite the .WAIT in the prerequisite list for foo. This is because the .WAIT does not stop make from recursively processing bar and its prerequisites in parallel. However, if only foo is specified ( make -j 10 foo), make will wait for one to be brought up-to-date before bringing two up-to-date. Note also that the .WAIT does not create a prerequisite relationship between one and two, so make -j 10 two will not build one.

   all: foo bar
   foo: one .WAIT two
   bar: one two
   foo bar one two: ; @echo $@

RATIONALE

The make utility described in this volume of POSIX.1-2024 is intended to provide the means for changing portable source code into executables that can be run on a POSIX.1-2024-conforming system. It reflects the most common features present in System V and BSD make s.

Historically, the make utility has been an especially fertile ground for vendor and research organization-specific syntax modifications and extensions. Examples include:

• Syntax supporting parallel execution (such as from various multi-processor vendors, GNU, and others)
• Additional "operators" separating targets and their prerequisites (System V, BSD, and others)
• Modifications of the meaning of internal macros when referencing libraries (BSD and others)
• Using a single instance of the shell for all of the command lines of the target (BSD and others)
• Allowing <space> characters as well as <tab> characters to delimit command lines (BSD)
• Adding C preprocessor-style "include" and "ifdef" constructs (System V, GNU, BSD, and others)
• Remote execution of command lines (Sprite and others)
• Specifying additional special targets (BSD, System V, and most others)
• Specifying an alternate shell to use to process commands.

Additionally, many vendors and research organizations have rethought the basic concepts of make, creating vastly extended, as well as completely new, syntaxes. Each of these versions of make fulfills the needs of a different community of users; it is unreasonable for this volume of POSIX.1-2024 to require behavior that would be incompatible (and probably inferior) to historical practice for such a community.

In similar circumstances, when the industry has enough sufficiently incompatible formats as to make them irreconcilable, this volume of POSIX.1-2024 has followed one or both of two courses of action. Commands have been renamed ( cksum(1), echo(1), and pax(1)) and/or command line options have been provided to select the desired behavior ( grep(1), od(1), and pax(1)).

Because the syntax specified for the make utility was, by and large, a subset of the syntaxes accepted by almost all versions of make when the original IEEE Std 1003.2-1992 (“POSIX.2”) shell and utilities standard was being developed, it was decided that it would be counter-productive to change the name. And since the makefile itself is a basic unit of portability, it would not be completely effective to reserve a new option letter, such as make -P, to achieve the portable behavior. Therefore, the special target .POSIX was added to the makefile, allowing users to specify "standard" behavior. This special target does not preclude extensions in the make utility, nor does it preclude such extensions being used by the makefile specifying the target; it does, however, preclude any extensions from being applied that could alter the behavior of previously valid syntax; such extensions must be controlled via command line options or new special targets. It is incumbent upon portable makefiles to specify the .POSIX special target in order to guarantee that they are not affected by local extensions.

The portable version of make described in this reference page is not intended to be the state-of-the-art software generation tool and, as such, some newer and more leading-edge features have not been included. An attempt has been made to describe the portable makefile in a manner that does not preclude such extensions as long as they do not disturb the portable behavior described here.

When the -n option is specified, it is always added to MAKEFLAGS . This allows a recursive make -n target to be used to see all of the actions that would be taken to update target.

The definition of MAKEFLAGS allows both the System V letter string and the BSD command line formats. The two formats are sufficiently different to allow implementations to support both without ambiguity.

Early proposals stated that an "unquoted" <number-sign> was treated as the start of a comment. The make utility does not pay any attention to quotes. A <number-sign> starts a comment regardless of its surroundings.

The text about "other implementation-defined pathnames may also be tried" in addition to ./makefile and ./Makefile is to allow such extensions as SCCS/s.Makefile and other variations. It was made an implementation-defined requirement (as opposed to unspecified behavior) to highlight surprising implementations that might select something unexpected like /etc/Makefile. XSI-conformant systems also try ./s.makefile, SCCS/s.makefile, ./s.Makefile, and SCCS/s.Makefile.

The default rules are based on System V. The default CC= value is c17(1) instead of cc because this volume of POSIX.1-2024 does not standardize the utility named cc. Thus, every conforming application would be required to define CC= c17(1) to expect to run. There is no advantage conferred by the hope that the makefile might hit the "preferred" compiler because this cannot be guaranteed to work. Also, since the portable makescript can only use the c17(1) options, no advantage is conferred in terms of what the script can do. It is a quality-of-implementation issue as to whether c17(1) is as valuable as cc.

Implementations are permitted to include any macro of their choosing in the default set. However, they are encouraged to keep such additions to a minimum in order to reduce the risk of name clashes with user macros.

Implementations are encouraged to provide, as an extension, a command-line option that causes make to report attempts to expand (or append to) macros that do not exist. See APPLICATION USAGE for the intended use cases of such an option.

The -d option to make is frequently used to produce debugging information, but is too implementation-defined to add to this volume of POSIX.1-2024.

The -p option is not passed in MAKEFLAGS on most historical implementations and to change this would cause many implementations to break without sufficiently increased portability.

Commands that begin with a <plus-sign> ( ‘+’) are executed even if the -n option is present. Based on the GNU version of make, the behavior of -n when the <plus-sign> prefix is encountered has been extended to apply to -q and -t as well. The System V convention of forcing command execution with -n when the command line of a target expands the MAKE macro was not adopted in earlier versions of this standard, but it is now required because it has become widespread existing practice.

The double <colon> in the target rule format is supported in BSD systems to allow more than one target line containing the same target name to have commands associated with it. Since this is not functionality described in the SVID or XPG3 it has been allowed as an extension, but not mandated.

The default rules are provided with text specifying that the built-in rules shall be the same as if the listed set were used. The intent is that implementations should be able to use the rules without change, but will be allowed to alter them in ways that do not affect the primary behavior.

One point of discussion was whether to drop the default rules list from this volume of POSIX.1-2024. They provide convenience, but do not enhance portability of applications. The prime benefit is in portability of users who wish to type make command and have the command build from a command.c file.

The historical MAKESHELL feature, and related features provided by other make implementations, were omitted. In some implementations it is used to let a user override the shell to be used to run make commands. This was confusing; for a portable make, the shell should be chosen by the makefile writer. Further, a makefile writer cannot require an alternate shell to be used and still consider the makefile portable. While it would be possible to standardize a mechanism for specifying an alternate shell, existing implementations do not agree on such a mechanism, and makefile writers can already invoke an alternate shell by specifying the shell name in the rule for a target; for example:

python -c "foo"

The make utilities in most historical implementations process the prerequisites of a target in left-to-right order, and the makefile format requires this. It supports the standard idiom used in many makefiles that produce yacc(1) programs; for example:

foo: y.tab.o lex.o main.o
    $(CC) $(CFLAGS) -o $@ y.tab.o lex.o main.o

In this example, if make chose any arbitrary order, the lex.o might not be made with the correct y.tab.h. Although there may be better ways to express this relationship, it is widely used historically. Implementations that desire to update prerequisites in parallel should require an explicit extension to make or the makefile format to accomplish it, as described previously.

The algorithm for determining a new entry for target rules is partially unspecified. Some historical make s allow comment lines (including blank and empty lines) within the collection of commands marked by leading <tab> characters. A conforming makefile must ensure that each command starts with a <tab>, but implementations are free to ignore comments without triggering the start of a new entry.

The ASYNCHRONOUS EVENTS section includes having SIGTERM and SIGHUP, along with the more traditional SIGINT and SIGQUIT, remove the current target unless directed not to do so. SIGTERM and SIGHUP were added to parallel other utilities that have historically cleaned up their work as a result of these signals. When make receives any signal other than SIGQUIT, it is required to resend itself the signal it received so that it exits with a status that reflects the signal. The results from SIGQUIT are partially unspecified because, on systems that create a file named core upon receipt of SIGQUIT, the core file from make would conflict with a core file from the command that was running when the SIGQUIT arrived. The main concern was to prevent damaged files from appearing up-to-date when make is rerun.

The .PRECIOUS special target was extended to affect all targets globally (by specifying no prerequisites). The .IGNORE and .SILENT special targets were extended to allow prerequisites; it was judged to be more useful in some cases to be able to turn off errors or echoing for a list of targets than for the entire makefile. These extensions to make in System V were made to match historical practice from the BSD make.

Macros are not exported to the environment of commands to be run. This was never the case in any historical make and would have serious consequences. The environment is the same as the environment to make except that MAKEFLAGS and macros defined on the make command line are added, and except that macros defined by the MAKEFLAGS environment variable and macros defined in the makefile(s) may update the value of an existing environment variable (other than SHELL ).

Some implementations do not use system(3) for all command lines, as required by the portable makefile format; as a performance enhancement, they select lines without shell metacharacters for direct execution by execve(3). There is no requirement that system(3) be used specifically, but merely that the same results be achieved. The metacharacters typically used to bypass the direct execve(3) execution have been any of:

=  |  ^  (  )  ;  &  <  >  *  ?  [  ]  :  $  `  '  "  \  \n

The default in some advanced versions of make is to group all the command lines for a target and execute them using a single shell invocation; the System V method is to pass each line individually to a separate shell. The single-shell method has the advantages in performance and the lack of a requirement for many continued lines. However, converting to this newer method has caused portability problems with many historical makefiles, so the behavior with the POSIX makefile is specified to be the same as that of System V. It is suggested that the special target .ONESHELL be used as an implementation extension to achieve the single-shell grouping for a target or group of targets.

Novice users of make have had difficulty with the historical need to start commands with a <tab>. Since it is often difficult to discern differences between <tab> and <space> characters on terminals or printed listings, confusing bugs can arise. In early proposals, an attempt was made to correct this problem by allowing leading <blank> characters instead of <tab> characters. However, implementors reported many makefiles that failed in subtle ways following this change, and it is difficult to implement a make that unambiguously can differentiate between macro and command lines. There is extensive historical practice of allowing leading <space> characters before macro definitions. Forcing macro lines into column 1 would be a significant backwards-compatibility problem for some makefiles. Therefore, historical practice was restored.

There is substantial variation in the handling of include lines by different implementations. However, there is enough commonality for the standard to be able to specify a minimum set of requirements that allow the feature to be used portably. Known variations have been explicitly called out as unspecified behavior in the description.

The System V dynamic dependency feature was not included. It would support:

cat: $$@.c

that would expand to;

cat: cat.c

This feature exists only in the new version of System V make and, while useful, is not in wide usage. This means that macros are expanded twice for prerequisites: once at makefile parse time and once at target update time.

Consideration was given to adding metarules to the POSIX make. This would make %.o: %.c the same as .c.o:. This is quite useful and available from some vendors, but it would cause too many changes to this make to support. It would have introduced rule chaining and new substitution rules. However, the rules for target names have been set to reserve the ‘%’ and ‘"’ characters. These are traditionally used to implement metarules and quoting of target names, respectively. Implementors are strongly encouraged to use these characters only for these purposes.

A request was made to extend the suffix delimiter character from a <period> to any character. The metarules feature in newer make s solves this problem in a more general way. This volume of POSIX.1-2024 is staying with the more conservative historical definition.

The standard output format for the -p option is not described because it is primarily a debugging option and because the format is not generally useful to programs. In historical implementations the output is not suitable for use in generating makefiles. The -p format has been variable across historical implementations. Therefore, the definition of -p was only to provide a consistently named option for obtaining make script debugging information.

Some historical implementations have not cleared the suffix list with -r.

Implementations should be aware that some historical applications have intermixed target_name and macro = value operands on the command line, expecting that all of the macros are processed before any of the targets are dealt with. Conforming applications do not do this, but some backwards-compatibility support may be warranted.

Empty inference rules are specified with a <semicolon> command rather than omitting all commands, as described in an early proposal. The latter case has no traditional meaning and is reserved for implementation extensions, such as in GNU make.

Earlier versions of this standard defined comment lines only as lines with ‘#’ as the first character. Many places then talked about comments, blank lines, and empty lines; but some places inadvertently only mentioned comments when blank lines and empty lines had also been accepted in all known implementations. The standard now defines comment lines to be blank lines, empty lines, and lines starting with a ‘#’ character and explicitly lists cases where blank lines and empty lines are not acceptable.

On most historic systems, the make utility considered a target with a prerequisite that had an identical timestamp as up-to-date. One implementation of make treated it as out-of-date. Note that up-to-date and out-of-date are antonyms. The standard now allows either behavior, but implementations are encouraged to treat such targets as out-of-date. This is especially important on file systems where the timestamp resolution is the minimum (1 second) required by the standard. All implementations of make should make full use of the finest timestamp resolution available on the file systems holding targets and prerequisites to ensure that targets are up-to-date even for prerequisite files with timestamps that were updated within the same second. However, if the timestamp resolutions of the file systems containing a target and a prerequisite are different, the timestamp with the more precise resolution should be rounded down to the resolution of the less precise timestamp for the comparison.

The traditional semantics of delayed-expansion macros have often been the source of subtle bugs for makefile writers not aware of those semantics. Furthermore, in implementations that support an extension of assigning the output of an arbitrary command to a macro definition, the use of delayed-expansion macros could result in an undesirable growth in execution time, as each use of the macro would re-run the arbitrary command. Historically, several implementations independently developed a form of immediate expansion, usually via the operator ":=", so that execution of an arbitrary command happens once at the definition of the macro rather than each use of the macro; however, there are subtle differences in the expansion rules of those various implementations when the expanded value of string2 contained a ‘$’. Other implementations used the operator ":=" for conditional expansion, altogether unrelated to immediate-expansion macro definition.

The standard developers felt that immediate-expansion semantics were useful enough to standardize, but requiring the semantics of any one implementation of ":=" would cause confusion in makefiles written for other implementation semantics, necessitating a reader to determine if .POSIX: had been specified at the beginning of the file (or worse, at the beginning of some other file that then includes the fragment in question) to know which semantics would be in use. Therefore, the standard developers opted to require two new operators, "::=" and ":::=", with specific semantics; the "::=" operator has semantics closest to the GNU make implementation of ":=", where ‘$’ characters occurring in the immediate expansion of string2 are not further expanded in subsequent use of the macro, and the ":::=" operator has semantics closest to the BSD make and smake implementations of ":=", where immediate expansion is performed when assigning to a delayed-expansion macro and "$$" is preserved. It was felt that other implementations could easily support the required semantics.

Implementations that previously provided ":=" as an extension are encouraged to leave this extension intact, with no change in the implementation's particular semantics, to avoid breaking non-portable makefiles that had been targeting that particular implementation. A portable makefile, with .POSIX: specified at the beginning, should not use the ":=" operator.

Traditionally, constructs such as

DIR: FORCE
        (commands)
FORCE:

were used to allow make DIR to always run (commands); however, this depended on the user never creating a file named FORCE. The addition of the .B~.PHONY special target provides a more efficient manner of providing a target whose commands are always run, and where the user cannot create a file that influences the behavior in an unexpected manner.

This standard allows two different methods of creating include files or bringing them up-to-date, reflecting established practice in SunPro make and GNU make. The former performs this action during parsing, before the include file is opened. The latter delays performing the action until after all makefiles have been read. Implementors who opt for the "delayed remaking" method should be aware of the following potential issues:

• Diagnostic messages about missing include files must be deferred until the final exit status is known. Note that this is a conformance issue, not just a quality of implementation issue.
• If the way make handles using updated include file contents is to start over after include files have been made up-to-date, it is possible for a poorly written makefile to cause make to enter a sequence of restarts where nothing changes each time, resulting in the sequence continuing indefinitely unless the situation is detected. Implementors are encouraged to include a mechanism for detecting and reporting this, rather than allowing make to consume an arbitrary amount of system resource until it is forcibly terminated.
• If make uses this start-over method, makefile contents read from a pipe on standard input or from a FIFO must be copied to a temporary file, and when make starts over it must use this file instead.
• If make starts over by executing itself using the exec family of functions, the need to replace ‘-’ or the pathnames of FIFOs with the pathnames of temporary files can lead to the exec call failing with an [E2BIG] error if the original execution was close to the {ARG_MAX} limit. Although this is a quality of implementation issue, not a conformance issue (since the general rules for utility errors allow utilities to fail when they encounter a variety of internal errors - see 1.4 Utility Description Defaults), implementors are encouraged to explore ways to prevent it, such as passing information via a temporary file instead of on the command line when an [E2BIG] error has occurred. Another solution might be to jump (e.g. using siglongjmp(3)) back to the start of main () as the way to start over. Making a recursive call to main () is not recommended, as that would run into the stack limit if sufficiently many restarts are needed.

This standard specifies that a non-existent include file is first created if possible, and only if not possible can other directories be searched. Historical versions of GNU make first searched the include directories, then attempted to create the include file. This behavior was not considered suitable for standardization as it means writers of portable applications have to use absolute pathnames for all include files that need to be created via a rule (because they can never be sure what relative pathnames are safe to use, since a file with the same relative pathname might happen to exist in one of the searched directories when installing the application on a new system). Note, however, that this only applies to directories searched by default. If an application uses an extension to specify that one or more directories are searched, this standard does not place any constraints on when the specified directories are searched.

This standard specifies a way for portable applications to request parallel updating of targets with commands by using the -j maxjobs option. This feature is described in terms of a token pool initially containing up to maxjobs - 1 tokens. Note that this is not intended to prescribe a particular implementation design; the usual "as if" rule applies.

Implementations are permitted to silently limit the pool size for a few reasons, including:

• Implementations that do not support parallelism can support the -j option by simply ignoring the option (other than passing it to sub- make invocations via the MAKEFLAGS environment variable). In effect, such an implementation silently restricts the size of the token pool to zero (and therefore need not create a token pool).
• Some historical implementations dynamically limit the token pool size based on the current system load to avoid overloading the system.
• Implementations may want to limit the token pool size based on the number of processors available.
• Implementations may want to limit the token pool size based on resource limits.

Limiting the pool size does not change the value of maxjobs that is passed to sub- make invocations via the MAKEFLAGS environment variable.

When a different maxjobs value is passed to a sub- make, some historical make implementations created a separate pool of tokens while other historical make implementations continued to obtain tokens from the invoking make but limited the number of tokens held at a time to the new value of maxjobs - 1. Both behaviors are believed to have merit in different situations: the former gives a sub- make complete control the amount of parallelism, while the latter allows the user to control the overall system load. This standard permits either behavior.

This standard calls for a token pool of size maxjobs - 1, and for removal from that pool only for the second and subsequent tasks in a set of parallel tasks. This design was chosen because this is effectively what existing implementations do, and also because the token consumed by a parallel task that invokes a sub- make is effectively lent to the sub- make. Lending the token to the sub- make has the following advantages:

• It prevents the sub- make from being completely idle due to token starvation, allowing it to always make some progress regardless of how many tokens other sub- make invocations have consumed.
• It prevents token pool exhaustion caused by a long chain of sub- make invocations. If the token consumed by the invoking rule was not effectively lent to the sub- make, then the pool would be exhausted by a chain of sub- make invocations that is maxjobs long. Such a chain would never accomplish any work, and would thus never complete.

When a rule invokes multiple sub- make processes asynchronously (for example by using an asynchronous list in the shell), some implementations allow each sub- make to execute at least one rule even though this would cause the total number of parallel rule executions across all make instances to exceed maxjobs (after discounting the rules that execute sub- make processes). This behavior may not be ideal, but it is easier to implement and is unlikely to cause problems in practice because applications typically do not have any rules that invoke multiple sub- make processes asynchronously. For this reason the behavior is unspecified if a rule executes multiple sub- make processes asynchronously.

When multiple sub- make processes are running in parallel there is no requirement placed on the ordering of output from these processes. Some implementations of make attempt to serialize output from each sub- make; others make no such attempt. If diagnostic messages from failed commands are intermixed, the usual way to deal with this is to repeat the make without -j (or with -j 1) so that intermixing will not occur.

FUTURE DIRECTIONS

If this utility is directed to create a new directory entry that contains any bytes that have the encoded value of a <newline> character, implementations are encouraged to treat this as an error. A future version of this standard may require implementations to treat this as an error.

Some implementations of make include an export directive to add specified make variables to the environment. This may be considered for standardization in a future version.

A future version of this standard may add a command-line option that causes make to report attempts to expand (or append to) macros that do not exist.

A future version of this standard may require that a target with a prerequisite with an identical timestamp is considered out-of-date.

SEE ALSO

2. Shell Command Language, ar(1), c17(1), get(1), lex(1), sccs(1), sh(1), yacc(1)

XBD V1_chap06(7), V1_chap08(7), V1_chap12(7)

XSH exec(3), system(3)

CHANGE HISTORY

First released in Issue 2.

Issue 5

The FUTURE DIRECTIONS section is added.

Issue 6

This utility is marked as part of the Software Development Utilities option.

The Open Group Corrigendum U029/1 is applied, correcting a typographical error in the SPECIAL TARGETS section.

In the ENVIRONMENT VARIABLES section, the PROJECTDIR description is updated from "otherwise, the home directory of a user of that name is examined" to "otherwise, the value of PROJECTDIR is treated as a user name and that user's initial working directory is examined".

It is specified whether the command line is related to the makefile or to the make command, and the macro processing rules are updated to align with the IEEE P1003.2b draft standard.

The normative text is reworded to avoid use of the term "must" for application requirements.

PASC Interpretation 1003.2 #193 is applied.

Issue 7

SD5-XCU-ERN-6 is applied, clarifying that Guideline 9 of the Utility Syntax Guidelines does not apply.

SD5-XCU-ERN-97 is applied, updating the SYNOPSIS.

Include lines in makefiles are introduced.

Austin Group Interpretation 1003.1-2001 #131 is applied, changing the Makefile Execution section.

POSIX.1-2008, Technical Corrigendum 1, XCU/TC1-2008/0121 [257] is applied.

POSIX.1-2008, Technical Corrigendum 2, XCU/TC2-2008/0122 [509], XCU/TC2-2008/0123 [584], XCU/TC2-2008/0124 [857], XCU/TC2-2008/0125 [505], XCU/TC2-2008/0126 [584], XCU/TC2-2008/0127 [505], XCU/TC2-2008/0128 [865], XCU/TC2-2008/0129 [693], XCU/TC2-2008/0130 [602], XCU/TC2-2008/0131 [848], XCU/TC2-2008/0132 [763], XCU/TC2-2008/0133 [857], XCU/TC2-2008/0134 [866], XCU/TC2-2008/0135 [525], XCU/TC2-2008/0136 [848], XCU/TC2-2008/0137 [769], XCU/TC2-2008/0138 [525], XCU/TC2-2008/0139 [769], XCU/TC2-2008/0140 [505], XCU/TC2-2008/0141 [693], XCU/TC2-2008/0142 [505], XCU/TC2-2008/0143 [857], and XCU/TC2-2008/0144 [693,865] are applied.

Issue 8

Austin Group Defect 251 is applied, encouraging implementations to disallow the creation of filenames containing any bytes that have the encoded value of a <newline> character.

Austin Group Defects 330, 1417, 1422, 1709, and 1710 are applied, adding new forms of macro assignment using the "::=", "?=", and "+=" operators.

Austin Group Defect 333 is applied, adding support for "silent includes" using -include.

Austin Group Defects 336 and 1711 are applied, specifying the behavior when string1 in a macro expansion contains a macro expansion.

Austin Group Defect 337 is applied, adding a new form of macro assignment using the "!=" operator.

Austin Group Defects 373 and 1417 are applied, changing the set of characters that portable applications can use in macro names to the entire portable filename character set (thus adding <hyphen-minus> to the set that could previously be used).

Austin Group Defects 514 and 1520 are applied, adding the $+ and $^ internal macros.

Austin Group Defect 518 is applied, allowing multiple files to be specified on an include line.

Austin Group Defects 519, 1712, and 1715 are applied, adding support for pattern macro expansions.

Austin Group Defects 523, 1708, and 1749 are applied, adding the .B~.PHONY special target.

Austin Group Defect 875 is applied, clarifying the requirements for inference rules.

Austin Group Defect 1104 is applied, changing " s2.a " to " .s2.a ".

Austin Group Defect 1122 is applied, changing the description of NLSPATH .

Austin Group Defect 1141 is applied, changing "core files" to "a file named core".

Austin Group Defect 1155 is applied, clarifying the handling of the MAKE macro.

Austin Group Defect 1325 is applied, adding requirements relating to the creation of include files.

Austin Group Defect 1330 is applied, removing obsolescent interfaces.

Austin Group Defect 1419 is applied, updating the .SCCS_GET default rule.

Austin Group Defect 1420 is applied, clarifying where internal macros can be used.

Austin Group Defect 1421 is applied, changing the APPLICATION USAGE section.

Austin Group Defects 1424, 1658, 1690, 1701, 1702, 1703, 1704, 1707, 1719, 1720, 1721, 1722, and 1750 are applied, making various minor editorial wording changes.

Austin Group Defects 1436, 1437, 1652, 1660, 1661, and 1733 are applied, adding the -j maxjobs option and the .NOTPARALLEL and .WAIT special targets, and changing the -n option.

Austin Group Defects 1471 and 1513 are applied, adding a new form of macro assignment using the ":::=" operator.

Austin Group Defect 1479 is applied, clarifying the requirements for default rules and macro values.

Austin Group Defect 1492 is applied, changing the EXIT STATUS section.

Austin Group Defect 1505 is applied, clarifying the requirements for expansion of macros that do not exist.

Austin Group Defect 1510 is applied, correcting a typographic error in the RATIONALE section.

Austin Group Defect 1549 is applied, clarifying the requirements for an escaped <newline> in a command line.

Austin Group Defect 1615 is applied, allowing target names to contain slashes and hyphens.

Austin Group Defect 1626 is applied, adding the CURDIR macro.

Austin Group Defect 1631 is applied, adding information about use of the -j option with the .c.a default rule to the APPLICATION USAGE and EXAMPLES sections.

Austin Group Defect 1650 is applied, changing the few occurrences of "dependencies" to use the more common "prerequisites".

Austin Group Defect 1653 is applied, clarifying the difference between how MAKEFLAGS is parsed compared to shell commands that use the make utility.

Austin Group Defects 1654 and 1655 are applied, changing the APPLICATION USAGE section.

Austin Group Defect 1656 is applied, changing the NAME section.

Austin Group Defect 1657 is applied, moving some requirements unrelated to makefile syntax from the Makefile Syntax subsection to the beginning of the EXTENDED DESCRIPTION section.

Austin Group Defect 1689 is applied, removing some redundant wording from the DESCRIPTION section.

Austin Group Defect 1692 is applied, allowing make, when invoked with the -q or -t option, to execute command lines (without a <plus-sign> prefix) that expand the MAKE macro.

Austin Group Defect 1693 is applied, changing "command lines" to "execution lines" in the description of the -s option.

Austin Group Defect 1694 is applied, changing "in the order they appear" to "in the order specified" in the OPERANDS section.

Austin Group Defect 1696 is applied, changing the STDOUT section.

Austin Group Defect 1697 is applied, changing the RATIONALE and FUTURE DIRECTIONS sections.

Austin Group Defect 1698 is applied, changing "of a target" to "of the target" in the EXTENDED DESCRIPTION section.

Austin Group Defect 1699 is applied, addressing some inconsistencies in the use of the term "rules".

Austin Group Defect 1706 is applied, removing a line from the format specified for target rules.

Austin Group Defect 1714 is applied, changing "beginning of the line" to "beginning of the value".

Austin Group Defect 1716 is applied, changing the typographic convention used for variable elements within target names, in particular the inference rule suffixes s1 and s2.

Austin Group Defect 1723 is applied, adding historical context to a paragraph in the RATIONALE section.

Austin Group Defect 1772 is applied, clarifying the ASYNCHRONOUS EVENTS section.

End of informative text.