Variable assignment operators

The five operators that assign values to variables are:

=

Assign the value to the variable. Any previous value is overwritten.

+=

Append the value to the current value of the variable, separating them by a single space.

?=

Assign the value to the variable if it is not already defined.

:=

Expand the value, then assign it to the variable.

NOTE: References to undefined variables are not expanded. This can cause problems when variable modifiers are used.

!=

Expand the value and pass it to the shell for execution, then assign the output from the child's standard output to the variable. Any newlines in the result are replaced with spaces.

Expansion of variables

In most contexts where variables are expanded, ‘$$’ expands to a single dollar sign. In other contexts (most variable modifiers, string literals in conditions), ‘\$’ expands to a single dollar sign.

References to variables have the form ${name[:modifiers]} or $(name[:modifiers]). If the variable name consists of only a single character and the expression contains no modifiers, the surrounding curly braces or parentheses are not required. This shorter form is not recommended.

If the variable name contains a dollar, the name itself is expanded first. This allows almost arbitrary variable names, however names containing dollar, braces, parentheses or whitespace are really best avoided.

If the result of expanding a nested variable expression contains a dollar sign (‘$’), the result is subject to further expansion.

Variable substitution occurs at four distinct times, depending on where the variable is being used.

1. Variables in dependency lines are expanded as the line is read.
2. Variables in conditionals are expanded individually, but only as far as necessary to determine the result of the conditional.
3. Variables in shell commands are expanded when the shell command is executed.
4. .for loop index variables are expanded on each loop iteration. Note that other variables are not expanded when composing the body of a loop, so the following example code:

   .for i in 1 2 3
   a+=     ${i}
   j=      ${i}
   b+=     ${j}
   .endfor
   
   all:
   	@echo ${a}
   	@echo ${b}

   prints:

   1 2 3
   3 3 3

   After the loop is executed:

   a

   contains ‘${:U1} ${:U2} ${:U3}’, which expands to ‘1 2 3’.

   j

   contains ‘${:U3}’, which expands to ‘3’.

   b

   contains ‘${j} ${j} ${j}’, which expands to ‘${:U3} ${:U3} ${:U3}’ and further to ‘3 3 3’.

Variable classes

The four different classes of variables (in order of increasing precedence) are:

Environment variables

Variables defined as part of bmake's environment.

Global variables

Variables defined in the makefile or in included makefiles.

Command line variables

Variables defined as part of the command line.

Local variables

Variables that are defined specific to a certain target.

Local variables can be set on a dependency line, unless .MAKE.TARGET_LOCAL_VARIABLES is set to ‘false’. The rest of the line (which already has had global variables expanded) is the variable value. For example:

COMPILER_WRAPPERS= ccache distcc icecc

${OBJS}: .MAKE.META.CMP_FILTER=${COMPILER_WRAPPERS:S,^,N,}

Only the targets ‘${OBJS}’ are impacted by that filter (in “meta” mode) and simply enabling/disabling any of the compiler wrappers does not render all of those targets out-of-date.

NOTE: target-local variable assignments behave differently in that;

The seven built-in local variables are:

The shorter forms (‘>’, ‘!’, ‘<’, ‘%’, ‘?’, ‘*’, and ‘@’) are permitted for backward compatibility with historical makefiles and legacy POSIX make and are not recommended.

Variants of these variables with the punctuation followed immediately by ‘D’ or ‘F’, e.g. ‘$(@D)’, are legacy forms equivalent to using the ‘:H’ and ‘:T’ modifiers. These forms are accepted for compatibility with AT&T System V UNIX makefiles and POSIX but are not recommended.

Four of the local variables may be used in sources on dependency lines because they expand to the proper value for each target on the line. These variables are ‘.TARGET’, ‘.PREFIX’, ‘.ARCHIVE’, and ‘.MEMBER’.

Additional built-in variables

In addition, bmake sets or knows about the following variables:

.ALLTARGETS

The list of all targets encountered in the makefiles. If evaluated during makefile parsing, lists only those targets encountered thus far.

.CURDIR

A path to the directory where bmake was executed. Refer to the description of ‘PWD’ for more details.

.ERROR_CMD

Is used in error handling, see MAKE_PRINT_VAR_ON_ERROR.

.ERROR_CWD

Is used in error handling, see MAKE_PRINT_VAR_ON_ERROR.

.ERROR_META_FILE

Is used in error handling in “meta” mode, see MAKE_PRINT_VAR_ON_ERROR.

.ERROR_TARGET

Is used in error handling, see MAKE_PRINT_VAR_ON_ERROR.

.INCLUDEDFROMDIR

The directory of the file this makefile was included from.

.INCLUDEDFROMFILE

The filename of the file this makefile was included from.

MACHINE

The machine hardware name, see uname(1).

MACHINE_ARCH

The machine processor architecture name, see uname(1).

MAKE

The name that bmake was executed with (argv[0]).

.MAKE

The same as MAKE, for compatibility. The preferred variable to use is the environment variable MAKE because it is more compatible with other make variants and cannot be confused with the special target with the same name.

.MAKE.DEPENDFILE

Names the makefile (default ‘.depend’) from which generated dependencies are read.

.MAKE.DIE_QUIETLY

If set to ‘true’, do not print error information at the end.

.MAKE.EXPAND_VARIABLES

A boolean that controls the default behavior of the -V option. If true, variable values printed with -V are fully expanded; if false, the raw variable contents (which may include additional unexpanded variable references) are shown.

.MAKE.EXPORTED

The list of variables exported by bmake.

MAKEFILE

The top-level makefile that is currently read, as given in the command line.

.MAKEFLAGS

The environment variable ‘MAKEFLAGS’ may contain anything that may be specified on bmake's command line. Anything specified on bmake's command line is appended to the .MAKEFLAGS variable, which is then added to the environment for all programs that bmake executes.

.MAKE.GID

The numeric group ID of the user running bmake. It is read-only.

.MAKE.JOB.PREFIX

If bmake is run with -j, the output for each target is prefixed with a token

--- target ---

the first part of which can be controlled via .MAKE.JOB.PREFIX. If .MAKE.JOB.PREFIX is empty, no token is printed. For example, setting .MAKE.JOB.PREFIX to ‘${.newline}---${.MAKE:T}[${.MAKE.PID}]’ would produce tokens like

---make[1234] target ---

making it easier to track the degree of parallelism being achieved.

.MAKE.JOBS

The argument to the -j option.

.MAKE.LEVEL

The recursion depth of bmake. The top-level instance of bmake has level 0, and each child make has its parent level plus 1. This allows tests like: .if ${.MAKE.LEVEL} == 0 to protect things which should only be evaluated in the top-level instance of bmake.

.MAKE.LEVEL.ENV

The name of the environment variable that stores the level of nested calls to bmake.

.MAKE.MAKEFILE_PREFERENCE

The ordered list of makefile names (default ‘makefile’, ‘Makefile’) that bmake looks for.

.MAKE.MAKEFILES

The list of makefiles read by bmake, which is useful for tracking dependencies. Each makefile is recorded only once, regardless of the number of times read.

.MAKE.META.BAILIWICK

In “meta” mode, provides a list of prefixes which match the directories controlled by bmake. If a file that was generated outside of .OBJDIR but within said bailiwick is missing, the current target is considered out-of-date.

.MAKE.META.CMP_FILTER

In “meta” mode, it can (very rarely!) be useful to filter command lines before comparison. This variable can be set to a set of modifiers that are applied to each line of the old and new command that differ, if the filtered commands still differ, the target is considered out-of-date.

.MAKE.META.CREATED

In “meta” mode, this variable contains a list of all the meta files updated. If not empty, it can be used to trigger processing of .MAKE.META.FILES.

.MAKE.META.FILES

In “meta” mode, this variable contains a list of all the meta files used (updated or not). This list can be used to process the meta files to extract dependency information.

.MAKE.META.IGNORE_FILTER

Provides a list of variable modifiers to apply to each pathname. Ignore if the expansion is an empty string.

.MAKE.META.IGNORE_PATHS

Provides a list of path prefixes that should be ignored; because the contents are expected to change over time. The default list includes: ‘/dev /etc /proc /tmp /var/run /var/tmp’

.MAKE.META.IGNORE_PATTERNS

Provides a list of patterns to match against pathnames. Ignore any that match.

.MAKE.META.PREFIX

Defines the message printed for each meta file updated in “meta verbose” mode. The default value is:

Building ${.TARGET:H:tA}/${.TARGET:T}

.MAKE.MODE

Processed after reading all makefiles. Affects the mode that bmake runs in. It can contain these keywords:

compat

Like -B, puts bmake into “compat” mode.

meta

Puts bmake into “meta” mode, where meta files are created for each target to capture the command run, the output generated, and if filemon(4) is available, the system calls which are of interest to bmake. The captured output can be useful when diagnosing errors.

curdirOk=bf

By default, bmake does not create .meta files in ‘.CURDIR’. This can be overridden by setting bf to a value which represents true.

missing-meta=bf

If bf is true, a missing .meta file makes the target out-of-date.

missing-filemon=bf

If bf is true, missing filemon data makes the target out-of-date.

nofilemon

Do not use filemon(4).

env

For debugging, it can be useful to include the environment in the .meta file.

verbose

If in “meta” mode, print a clue about the target being built. This is useful if the build is otherwise running silently. The message printed is the expanded value of .MAKE.META.PREFIX.

ignore-cmd

Some makefiles have commands which are simply not stable. This keyword causes them to be ignored for determining whether a target is out of date in “meta” mode. See also .NOMETA_CMP.

silent=bf

If bf is true, when a .meta file is created, mark the target .SILENT.

randomize-targets

In both compat and parallel mode, do not make the targets in the usual order, but instead randomize their order. This mode can be used to detect undeclared dependencies between files.

MAKEOBJDIR

Used to create files in a separate directory, see .OBJDIR.

MAKE_OBJDIR_CHECK_WRITABLE

Used to force a separate directory for the created files, even if that directory is not writable, see .OBJDIR.

MAKEOBJDIRPREFIX

Used to create files in a separate directory, see .OBJDIR.

.MAKE.OS

The name of the operating system, see uname(1). It is read-only.

.MAKEOVERRIDES

This variable is used to record the names of variables assigned to on the command line, so that they may be exported as part of ‘MAKEFLAGS’. This behavior can be disabled by assigning an empty value to ‘.MAKEOVERRIDES’ within a makefile. Extra variables can be exported from a makefile by appending their names to ‘.MAKEOVERRIDES’. ‘MAKEFLAGS’ is re-exported whenever ‘.MAKEOVERRIDES’ is modified.

.MAKE.PATH_FILEMON

If bmake was built with filemon(4) support, this is set to the path of the device node. This allows makefiles to test for this support.

.MAKE.PID

The process ID of bmake. It is read-only.

.MAKE.PPID

The parent process ID of bmake. It is read-only.

MAKE_PRINT_VAR_ON_ERROR

When bmake stops due to an error, it sets ‘.ERROR_TARGET’ to the name of the target that failed, ‘.ERROR_CMD’ to the commands of the failed target, and in “meta” mode, it also sets ‘.ERROR_CWD’ to the getcwd(3), and ‘.ERROR_META_FILE’ to the path of the meta file (if any) describing the failed target. It then prints its name and the value of ‘.CURDIR’ as well as the value of any variables named in ‘MAKE_PRINT_VAR_ON_ERROR’.

.MAKE.SAVE_DOLLARS

If true, ‘$$’ are preserved when doing ‘:=’ assignments. The default is false, for backwards compatibility. Set to true for compatability with other makes. If set to false, ‘$$’ becomes ‘$’ per normal evaluation rules.

.MAKE.TARGET_LOCAL_VARIABLES

If set to ‘false’, apparent variable assignments in dependency lines are treated as normal sources.

.MAKE.UID

The numeric ID of the user running bmake. It is read-only.

.newline

This variable is simply assigned a newline character as its value. It is read-only. This allows expansions using the :@ modifier to put a newline between iterations of the loop rather than a space. For example, in case of an error, bmake prints the variable names and their values using:

${MAKE_PRINT_VAR_ON_ERROR:@v@$v='${$v}'${.newline}@}

.OBJDIR

A path to the directory where the targets are built. Its value is determined by trying to chdir(2) to the following directories in order and using the first match:

1. ${MAKEOBJDIRPREFIX}${.CURDIR}

   (Only if ‘MAKEOBJDIRPREFIX’ is set in the environment or on the command line.)

2. ${MAKEOBJDIR}

   (Only if ‘MAKEOBJDIR’ is set in the environment or on the command line.)

3. ${.CURDIR}/obj.${MACHINE}
4. ${.CURDIR}/obj
5. /usr/obj/${.CURDIR}
6. ${.CURDIR}

Variable expansion is performed on the value before it is used, so expressions such as ${.CURDIR:S,^/usr/src,/var/obj,} may be used. This is especially useful with ‘MAKEOBJDIR’.

‘.OBJDIR’ may be modified in the makefile via the special target ‘.OBJDIR’. In all cases, bmake changes to the specified directory if it exists, and sets ‘.OBJDIR’ and ‘PWD’ to that directory before executing any targets.

Except in the case of an explicit ‘.OBJDIR’ target, bmake checks that the specified directory is writable and ignores it if not. This check can be skipped by setting the environment variable ‘MAKE_OBJDIR_CHECK_WRITABLE’ to “no”.

.PARSEDIR

The directory name of the current makefile being parsed.

.PARSEFILE

The basename of the current makefile being parsed. This variable and ‘.PARSEDIR’ are both set only while the makefiles are being parsed. To retain their current values, assign them to a variable using assignment with expansion ‘:=’.

.PATH

The space-separated list of directories that bmake searches for files. To update this search list, use the special target ‘.PATH’ rather than modifying the variable directly.

%POSIX

Is set in POSIX mode, see the special ‘.POSIX’ target.

PWD

Alternate path to the current directory. bmake normally sets ‘.CURDIR’ to the canonical path given by getcwd(3). However, if the environment variable ‘PWD’ is set and gives a path to the current directory, bmake sets ‘.CURDIR’ to the value of ‘PWD’ instead. This behavior is disabled if ‘MAKEOBJDIRPREFIX’ is set or ‘MAKEOBJDIR’ contains a variable transform. ‘PWD’ is set to the value of ‘.OBJDIR’ for all programs which bmake executes.

.SHELL

The pathname of the shell used to run target scripts. It is read-only.

.SUFFIXES

The list of known suffixes. It is read-only.

.SYSPATH

The space-separated list of directories that bmake searches for makefiles, referred to as the system include path. To update this search list, use the special target ‘.SYSPATH’ rather than modifying the variable which is read-only.

.TARGETS

The list of targets explicitly specified on the command line, if any.

VPATH

The colon-separated (“:”) list of directories that bmake searches for files. This variable is supported for compatibility with old make programs only, use ‘.PATH’ instead.

Variable modifiers

The general format of a variable expansion is:

Each modifier begins with a colon. To escape a colon, precede it with a backslash ‘\’.

A list of indirect modifiers can be specified via a variable, as follows:

modifier_variable = modifier[:...]

${variable:${modifier_variable}[:...]}

In this case, the first modifier in the modifier_variable does not start with a colon, since that colon already occurs in the referencing variable. If any of the modifiers in the modifier_variable contains a dollar sign (‘$’), these must be doubled to avoid early expansion.

Some modifiers interpret the expression value as a single string, others treat the expression value as a whitespace-separated list of words. When splitting a string into words, whitespace can be escaped using double quotes, single quotes and backslashes, like in the shell. The quotes and backslashes are retained in the words.

The supported modifiers are:

:E

Replaces each word with its suffix.

:H

Replaces each word with its dirname.

:Mpattern

Selects only those words that match pattern. The standard shell wildcard characters (‘*’, ‘?’, and ‘[]’) may be used. The wildcard characters may be escaped with a backslash (‘\’). As a consequence of the way values are split into words, matched, and then joined, the construct ‘${VAR:M*}’ removes all leading and trailing whitespace and normalizes the inter-word spacing to a single space.

:Npattern

This is the opposite of ‘:M’, selecting all words which do not match pattern.

:O

Orders the words lexicographically.

:On

Orders the words numerically. A number followed by one of ‘k’, ‘M’ or ‘G’ is multiplied by the appropriate factor, which is 1024 for ‘k’, 1048576 for ‘M’, or 1073741824 for ‘G’. Both upper- and lower-case letters are accepted.

:Or

Orders the words in reverse lexicographical order.

:Orn

Orders the words in reverse numerical order.

:Ox

Shuffles the words. The results are different each time you are referring to the modified variable; use the assignment with expansion ‘:=’ to prevent such behavior. For example,

LIST=			uno due tre quattro
RANDOM_LIST=		${LIST:Ox}
STATIC_RANDOM_LIST:=	${LIST:Ox}

all:
	@echo "${RANDOM_LIST}"
	@echo "${RANDOM_LIST}"
	@echo "${STATIC_RANDOM_LIST}"
	@echo "${STATIC_RANDOM_LIST}"

may produce output similar to:

quattro due tre uno
tre due quattro uno
due uno quattro tre
due uno quattro tre

:Q

Quotes every shell meta-character in the value, so that it can be passed safely to the shell.

:q

Quotes every shell meta-character in the value, and also doubles ‘$’ characters so that it can be passed safely through recursive invocations of bmake. This is equivalent to ‘:S/\$/&&/g:Q’.

:R

Replaces each word with everything but its suffix.

:range[=count]

The value is an integer sequence representing the words of the original value, or the supplied count.

:gmtime[=timestamp]

The value is interpreted as a format string for strftime(3), using gmtime(3), producing the formatted timestamp. If a timestamp value is not provided or is 0, the current time is used.

:hash

Computes a 32-bit hash of the value and encodes it as 8 hex digits.

:localtime[=timestamp]

The value is interpreted as a format string for strftime(3), using localtime(3), producing the formatted timestamp. If a timestamp value is not provided or is 0, the current time is used.

:mtime[=timestamp]

Call stat(2) with each word as pathname; use ‘st_mtime’ as the new value. If stat(2) fails; use timestamp or current time. If timestamp is set to ‘error’, then stat(2) failure will cause an error.

:tA

Attempts to convert the value to an absolute path using realpath(3). If that fails, the value is unchanged.

:tl

Converts the value to lower-case letters.

:tsc

When joining the words after a modifier that treats the value as words, the words are normally separated by a space. This modifier changes the separator to the character c. If c is omitted, no separator is used. The common escapes (including octal numeric codes) work as expected.

:tu

Converts the value to upper-case letters.

:tW

Causes subsequent modifiers to treat the value as a single word (possibly containing embedded whitespace). See also ‘:[*]’.

:tw

Causes the value to be treated as a list of words. See also ‘:[@]’.

:S/old_string/new_string/[1gW]

Modifies the first occurrence of old_string in each word of the value, replacing it with new_string. If a ‘g’ is appended to the last delimiter of the pattern, all occurrences in each word are replaced. If a ‘1’ is appended to the last delimiter of the pattern, only the first occurrence is affected. If a ‘W’ is appended to the last delimiter of the pattern, the value is treated as a single word. If old_string begins with a caret (‘^’), old_string is anchored at the beginning of each word. If old_string ends with a dollar sign (‘$’), it is anchored at the end of each word. Inside new_string, an ampersand (‘&’) is replaced by old_string (without the anchoring ‘^’ or ‘$’). Any character may be used as the delimiter for the parts of the modifier string. The anchoring, ampersand and delimiter characters can be escaped with a backslash (‘\’).

Both old_string and new_string may contain nested expressions. To prevent a dollar sign from starting a nested expression, escape it with a backslash.

:C/pattern/replacement/[1gW]

The :C modifier works like the :S modifier except that the old and new strings, instead of being simple strings, are an extended regular expression pattern (see regex(3)) and an ed(1)-style replacement. Normally, the first occurrence of the pattern pattern in each word of the value is substituted with replacement. The ‘1’ modifier causes the substitution to apply to at most one word; the ‘g’ modifier causes the substitution to apply to as many instances of the search pattern pattern as occur in the word or words it is found in; the ‘W’ modifier causes the value to be treated as a single word (possibly containing embedded whitespace).

As for the :S modifier, the pattern and replacement are subjected to variable expansion before being parsed as regular expressions.

:T

Replaces each word with its last path component (basename).

:u

Removes adjacent duplicate words (like uniq(1)).

:?true_string:false_string

If the variable name (not its value), when parsed as a .if conditional expression, evaluates to true, return as its value the true_string, otherwise return the false_string. Since the variable name is used as the expression, :? must be the first modifier after the variable name itself—which, of course, usually contains variable expansions. A common error is trying to use expressions like

${NUMBERS:M42:?match:no}

which actually tests defined(NUMBERS). To determine if any words match “42”, you need to use something like:

${"${NUMBERS:M42}" != "":?match:no}

.

:old_string=new_string

This is the AT&T System V UNIX style substitution. It can only be the last modifier specified, as a ‘:’ in either old_string or new_string is treated as a regular character, not as the end of the modifier.

If old_string does not contain the pattern matching character ‘%’, and the word ends with old_string or equals it, that suffix is replaced with new_string.

Otherwise, the first ‘%’ in old_string matches a possibly empty substring of arbitrary characters, and if the whole pattern is found in the word, the matching part is replaced with new_string, and the first occurrence of ‘%’ in new_string (if any) is replaced with the substring matched by the ‘%’.

Both old_string and new_string may contain nested expressions. To prevent a dollar sign from starting a nested expression, escape it with a backslash.

:@varname@string@

This is the loop expansion mechanism from the OSF Development Environment (ODE) make. Unlike .for loops, expansion occurs at the time of reference. For each word in the value, assign the word to the variable named varname and evaluate string. The ODE convention is that varname should start and end with a period, for example:

${LINKS:@.LINK.@${LN} ${TARGET} ${.LINK.}@}

However, a single-letter variable is often more readable:

${MAKE_PRINT_VAR_ON_ERROR:@v@$v='${$v}'${.newline}@}

:_[=var]

Saves the current variable value in ‘$_’ or the named var for later reference. Example usage:

M_cmpv.units = 1 1000 1000000
M_cmpv = S,., ,g:_:range:@i@+ $${_:[-$$i]} \
\* $${M_cmpv.units:[$$i]}@:S,^,expr 0 ,1:sh

.if ${VERSION:${M_cmpv}} < ${3.1.12:L:${M_cmpv}}

    

Here ‘$_’ is used to save the result of the ‘:S’ modifier which is later referenced using the index values from ‘:range’.

:Unewval

If the variable is undefined, newval is the value. If the variable is defined, the existing value is returned. This is another ODE make feature. It is handy for setting per-target CFLAGS for instance:

${_${.TARGET:T}_CFLAGS:U${DEF_CFLAGS}}

If a value is only required if the variable is undefined, use:

${VAR:D:Unewval}

:Dnewval

If the variable is defined, newval is the value.

:L

The name of the variable is the value.

:P

The path of the node which has the same name as the variable is the value. If no such node exists or its path is null, the name of the variable is used. In order for this modifier to work, the name (node) must at least have appeared on the right-hand side of a dependency.

:!cmd!

The output of running cmd is the value.

:sh

The value is run as a command, and the output becomes the new value.

::=str

The variable is assigned the value str after substitution. This modifier and its variations are useful in obscure situations such as wanting to set a variable at a point where a target's shell commands are being parsed. These assignment modifiers always expand to nothing.

The ‘::’ helps avoid false matches with the AT&T System V UNIX style ‘:=’ modifier and since substitution always occurs, the ‘::=’ form is vaguely appropriate.

::?=str

As for ::= but only if the variable does not already have a value.

::+=str

Append str to the variable.

::!=cmd

Assign the output of cmd to the variable.

:[range]

Selects one or more words from the value, or performs other operations related to the way in which the value is split into words.

An empty value, or a value that consists entirely of white-space, is treated as a single word. For the purposes of the ‘:[]’ modifier, the words are indexed both forwards using positive integers (where index 1 represents the first word), and backwards using negative integers (where index -1 represents the last word).

The range is subjected to variable expansion, and the expanded result is then interpreted as follows:

index

Selects a single word from the value.

start..end

Selects all words from start to end, inclusive. For example, ‘:[2..-1]’ selects all words from the second word to the last word. If start is greater than end, the words are output in reverse order. For example, ‘:[-1..1]’ selects all the words from last to first. If the list is already ordered, this effectively reverses the list, but it is more efficient to use ‘:Or’ instead of ‘:O:[-1..1]’.

*

Causes subsequent modifiers to treat the value as a single word (possibly containing embedded whitespace). Analogous to the effect of $* in Bourne shell.

0

Means the same as ‘:[*]’.

@

Causes subsequent modifiers to treat the value as a sequence of words delimited by whitespace. Analogous to the effect of $@ in Bourne shell.

#

Returns the number of words in the value.

File inclusion

Files are included with either .include <file> or .include "file". Variables between the angle brackets or double quotes are expanded to form the file name. If angle brackets are used, the included makefile is expected to be in the system makefile directory. If double quotes are used, the including makefile's directory and any directories specified using the -I option are searched before the system makefile directory.

For compatibility with other make variants, ‘include file ...’ (without leading dot) is also accepted.

If the include statement is written as .-include or as .sinclude, errors locating and/or opening include files are ignored.

If the include statement is written as .dinclude, not only are errors locating and/or opening include files ignored, but stale dependencies within the included file are ignored just like in .MAKE.DEPENDFILE.

Exporting variables

The directives for exporting and unexporting variables are:

.export variable ...

Export the specified global variable. If no variable list is provided, all globals are exported except for internal variables (those that start with ‘.’). This is not affected by the -X flag, so should be used with caution. For compatibility with other make programs, export variable=value (without leading dot) is also accepted.

Appending a variable name to .MAKE.EXPORTED is equivalent to exporting a variable.

.export-env variable ...

The same as ‘.export’, except that the variable is not appended to .MAKE.EXPORTED. This allows exporting a value to the environment which is different from that used by bmake internally.

.export-literal variable ...

The same as ‘.export-env’, except that variables in the value are not expanded.

.unexport variable ...

The opposite of ‘.export’. The specified global variable is removed from .MAKE.EXPORTED. If no variable list is provided, all globals are unexported, and .MAKE.EXPORTED deleted.

.unexport-env

Unexport all globals previously exported and clear the environment inherited from the parent. This operation causes a memory leak of the original environment, so should be used sparingly. Testing for .MAKE.LEVEL being 0 would make sense. Also note that any variables which originated in the parent environment should be explicitly preserved if desired. For example:

.if ${.MAKE.LEVEL} == 0
PATH := ${PATH}
.unexport-env
.export PATH
.endif

    

Would result in an environment containing only ‘PATH’, which is the minimal useful environment. Actually ‘.MAKE.LEVEL’ is also pushed into the new environment.

Messages

The directives for printing messages to the output are:

.info message

The message is printed along with the name of the makefile and line number.

.warning message

The message prefixed by ‘warning:’ is printed along with the name of the makefile and line number.

.error message

The message is printed along with the name of the makefile and line number, bmake exits immediately.

Conditionals

The directives for conditionals are:

.if [!]expression [operator expression ...]

Test the value of an expression.

.ifdef [!]variable [operator variable ...]

Test whether a variable is defined.

.ifndef [!]variable [operator variable ...]

Test whether a variable is not defined.

.ifmake [!]target [operator target ...]

Test the target being requested.

.ifnmake [!]target [operator target ...]

Test the target being requested.

.else

Reverse the sense of the last conditional.

.elif [!]expression [operator expression ...]

A combination of ‘.else’ followed by ‘.if’.

.elifdef [!]variable [operator variable ...]

A combination of ‘.else’ followed by ‘.ifdef’.

.elifndef [!]variable [operator variable ...]

A combination of ‘.else’ followed by ‘.ifndef’.

.elifmake [!]target [operator target ...]

A combination of ‘.else’ followed by ‘.ifmake’.

.elifnmake [!]target [operator target ...]

A combination of ‘.else’ followed by ‘.ifnmake’.

.endif

End the body of the conditional.

The operator may be any one of the following:

||

Logical OR.

&&

Logical AND; of higher precedence than ‘||’.

bmake only evaluates a conditional as far as is necessary to determine its value. Parentheses can be used to override the operator precedence. The boolean operator ‘!’ may be used to logically negate an expression, typically a function call. It is of higher precedence than ‘&&’.

The value of expression may be any of the following function call expressions:

defined(varname)

Evaluates to true if the variable varname has been defined.

make(target)

Evaluates to true if the target was specified as part of bmake's command line or was declared the default target (either implicitly or explicitly, see .MAIN) before the line containing the conditional.

empty(varname[:modifiers])

Evaluates to true if the expansion of the variable, after applying the modifiers, results in an empty string.

exists(pathname)

Evaluates to true if the given pathname exists. If relative, the pathname is searched for on the system search path (see .PATH).

target(target)

Evaluates to true if the target has been defined.

commands(target)

Evaluates to true if the target has been defined and has commands associated with it.

Expression may also be an arithmetic or string comparison. Variable expansion is performed on both sides of the comparison. If both sides are numeric and neither is enclosed in quotes, the comparison is done numerically, otherwise lexicographically. A string is interpreted as a hexadecimal integer if it is preceded by 0x, otherwise it is interpreted as a decimal floating-point number; octal numbers are not supported.

All comparisons may use the operators ‘==’ and ‘!=’. Numeric comparisons may also use the operators ‘<’, ‘<=’, ‘>’ and ‘>=’.

If the comparison has neither a comparison operator nor a right side, the expression evaluates to true if it is nonempty and its numeric value (if any) is not zero.

When bmake is evaluating one of these conditional expressions, and it encounters a (whitespace-separated) word it doesn't recognize, either the “make” or “defined” function is applied to it, depending on the form of the conditional. If the form is ‘.ifdef’, ‘.ifndef’ or ‘.if’, the “defined” function is applied. Similarly, if the form is ‘.ifmake’ or ‘.ifnmake’, the “make” function is applied.

If the conditional evaluates to true, parsing of the makefile continues as before. If it evaluates to false, the following lines until the corresponding ‘.elif’ variant, ‘.else’ or ‘.endif’ are skipped.

For loops

For loops are typically used to apply a set of rules to a list of files. The syntax of a for loop is:

.for variable [variable ...] in expression

 

⟨make-lines⟩

 

.endfor

 

The expression is expanded and then split into words. On each iteration of the loop, one word is taken and assigned to each variable, in order, and these variables are substituted into the make-lines inside the body of the for loop. The number of words must come out even; that is, if there are three iteration variables, the number of words provided must be a multiple of three.

If ‘.break’ is encountered within a .for loop, it causes early termination of the loop, otherwise a parse error.

Other directives

.undef variable ...

Un-define the specified global variables. Only global variables can be un-defined.

Older versions

An incomplete list of changes in older versions of bmake:

The way that .for loop variables are substituted changed after NetBSD 5.0 so that they still appear to be variable expansions. In particular this stops them being treated as syntax, and removes some obscure problems using them in .if statements.

The way that parallel makes are scheduled changed in NetBSD 4.0 so that .ORDER and .WAIT apply recursively to the dependent nodes. The algorithms used may change again in the future.

Other make dialects

Other make dialects (GNU make, SVR4 make, POSIX make, etc.) do not support most of the features of bmake as described in this manual. Most notably:

• The .WAIT and .ORDER declarations and most functionality pertaining to parallelization. (GNU make supports parallelization but lacks the features needed to control it effectively.)
• Directives, including for loops and conditionals and most of the forms of include files. (GNU make has its own incompatible and less powerful syntax for conditionals.)
• All built-in variables that begin with a dot.
• Most of the special sources and targets that begin with a dot, with the notable exception of .PHONY, .PRECIOUS, and .SUFFIXES.
• Variable modifiers, except for the ‘:old=new’ string substitution, which does not portably support globbing with ‘%’ and historically only works on declared suffixes.
• The $> variable even in its short form; most makes support this functionality but its name varies.

Some features are somewhat more portable, such as assignment with +=, ?=, and !=. The .PATH functionality is based on an older feature VPATH found in GNU make and many versions of SVR4 make; however, historically its behavior is too ill-defined (and too buggy) to rely upon.

The $@ and $< variables are more or less universally portable, as is the $(MAKE) variable. Basic use of suffix rules (for files only in the current directory, not trying to chain transformations together, etc.) is also reasonably portable.