Directives

Here is a summary of the directives kmk recognizes:

Define a multi-line, recursively-expanded variable:

define variable
endef

Conditionally evaluate part of the makefile:

ifdef variable
ifndef variable
ifeq (a,b)
ifeq "a" "b"
ifeq 'a' 'b'
ifneq (a,b)
ifneq "a" "b"
ifneq 'a' 'b'
if1of (set-a,set-b)             [1]
ifn1of (set-a,set-b)            [1]
if expression                   [1]
else
endif

Include another makefile:

include file
-include file
sinclude file

Include another dependency file [1]:

includedep file

Define a variable, overriding any previous definition, even one from the command line:

override variable = value
override variable := value
override variable += value
override variable <= value      [1]
override variable ?= value
override define variable
endef

Tell kmk to export all variables to child processes by default:

export

Tell kmk whether or not to export a particular variable to child processes:

export variable
export variable = value
export variable := value
export variable += value
export variable <= value        [1]
export variable ?= value
unexport variable

Define a variable in the local context instead of the global one [1]:

local variable = value
local variable := value
local variable += value
local variable <= value
local variable ?= value
local define variable
endef

Specify a search path for files matching a % pattern:

vpath pattern path

Remove all search paths previously specified for pattern:

vpath pattern

Remove all search paths previously specified in any vpath directive:

vpath

Automatic variables

Here is a summary of the automatic variables.

Variable	Description
$@	The file name of the target.
$<	The name of the first prerequisite.
$?	The names of all the prerequisites that are newer than the target, with spaces between them.
$^	The names of all the prerequisites, duplicates omitted.
$+	The names of all the prerequisites, duplicates and order preserved
$*	The stem with which an implicit rule matches.
$|	The name of all the order only prerequisites.
$(@D)	The directory part of $@.
$(<D)	The directory part of $<.
$(?D)	The directory part of $?.
$(^D)	The directory part of %^.
$(+D)	The directory part of $+.
$(*D)	The directory part of $*.
$(|D)	The directory part of $|.
$(@F)	The file-within-directory part of $@.
$(<F)	The file-within-directory part of $<.
$(?F)	The file-within-directory part of $?.
$(^F)	The file-within-directory part of $^.
$(+F)	The file-within-directory part of $+.
$(*F)	The file-within-directory part of $*.
$(|F)	The file-within-directory part of $|.

Special variables

All variables starting with a . is reserved by kmk. The following variables are specially used or/and defined by kmk:

Variable	Description
.DEFAULT_GOAL	The makefile default goal. You can set this in the makefile, if you don't it will default to the first target that is encountered.
.FEATURES	List of GNU make features. Do not set this.
.INCLUDE_DIRS	List of include directories, -I arguments and defaults. Do not set this.
.RECIPEPREFIX	Recipe prefix, defaults to tab.
.VARIABLES	Special variable which exands to the list of variable. Do not set this.
CURDIR	Set to the pathname of the current working directory (after all -C options are processed, if any). Do not set this.
KBUILD_VERSION, KBUILD_VERSION_MAJOR, KBUILD_VERSION_MINOR, KBUILD_VERSION_PATCH, KBUILD_KMK_REVISION	The kBuild version string and the break down into individual components. [1]
KBUILD_HOST [1]	The host operating system.
KBUILD_HOST_ARCH [1]	The host architecture.
KBUILD_HOST_CPU [1]	The host CPU kmk is built for, set to blend if not any particular CPU.
KBUILD_PATH [1]	Where the kBuild scripts are.
KBUILD_BIN_PATH [1]	Where the host specific kBuild binaries are.
KMK [1], MAKE	The name with which kmk was invoked. Using this variable in recipes has special meaning.
KMK_BUILTIN [1]	List of built-in commands.
KMK_FEATURES [1]	List of kmk specific features.
KMK_FLAGS [1]	The flags given to kmk. You can set this in the environment or a makefile to set flags. It is never appropriate to use KMK_FLAGS directly in a recipe line: its contents may not be quoted correctly for use in the shell. Always allow recursive kmk's to obtain these values through the environment from its parent.
KMK_LEVEL [1]	The number of levels of recursion (sub-makes).
KMK_VERSION [1]	The GNU make version number.
MAKECMDGOALS	The targets given to kmk on the command line. Do not set this.
MAKEFILES	Makefiles to be read on every invocation of kmk.
MAKEFILE_LIST	List of the makefiles that kmk has opened.
MAKESHELL	OS/2 and MS-DOS only, the name of the command interpreter that is to be used by kmk. This value takes precedence over the value of SHELL.
SHELL	The name of the default command interpreter, kmk_ash. You can set SHELL in the makefile to change the shell used to run recipes. The SHELL variable is handled specially when importing from and exporting to the environment.
SUFFIXES	The default list of suffixes before kmk reads any makefiles (always empty).
VPATH	Directory search path for files not found in the current directory.

The following variables reflects kmk options. Do not set these. [1]

Variable	Description
KMK_OPTS_JOBS	-j slots, 0 if not given.
KMK_OPTS_KEEP_GOING	-k indictor (0/1).
KMK_OPTS_JUST_PRINT	-n indicator (0/1).
KMK_OPTS_PRORITY	--priority level, 0 if not given.
KMK_OPTS_AFFINITY	--affinity mask, 0 if not given.
KMK_OPTS_STATISTICS	--statistics indicator (0/1).
KMK_OPTS_PRINT_TIME	The --print-time value.
KMK_OPTS_PRETTY_COMMAND_PRINTING	--pretty-command-printing indicator.

Special Targets

Certain names have special meanings if they appear as targets.

Target	Description
.DEFAULT	The recipe is used for any target for which no rules are found.
.DELETE_ON_ERROR	If mentioned, kmk will delete the targets of a rule if it has changed and its recipe fails or is interrupted.
.EXPORT_ALL_VARIABLES	If mentioned, all variables will by default be exported to child processes.
.IGNORE	Ignore errors in the execution of the recipe for the targets .IGNORE depends on, if no prequisites all targets are affected.
.INTERMEDIATE	The prerequisites are treated as intermediate files (implicite rules).
.LOW_RESOLUTION_TIME	kmk will assume prerequisite files are created with low resolution time stamps.
.NOTPARALLEL	If mentioned without any prerequisites, kmk will run serially as if -j1 was given. If it has prerequisites kmk [1] will only do this for the targets among them.
.PHONY	The prerequisites are considered phony and will be rebuilt unconditionally.
.PRECIOUS	The targets which .PRECIOUS depends will to be deleted if kmk is killed or interrupted while their building.
.SECONDARY	The prerequisites are treated as intermediate files, except that they are never automatically deleted. If used with no prerequisites all targets gets this treatement.
.SECONDEXPANSION	If mentioned, all prerequisite lists after it will be expanded a second time after all makefiles have been read.
.SECONDTARGETEXPANSION [1]	If mentioned, all targets after it will be expanded a second time after all makefiles have been read.
.SILENT	kmk will not print the recipe for targets listed as prerequisites, if none then it applies to all targets.
.SUFFIXES	The prerequisites are the list of suffixes used in checking for suffix rules. If it appears without prerequisites it the suffix will be cleared.

Commands

Builtin commands [1] all start with kmk_builtin_, so in order to save space this prefix has been omitted in the table below. All commands comes in an external edition that can be used by/in the shell, these are prefixed kmk_.

Command	Description
append	Append text to a file. The builtin version can output the value of a variable or the commands of a target.
cat	The BSD cat command.
chmod	The BSD chmod command.
cmp	The BSD cmp command.
cp	The BSD cp command with some twaking.
echo	The BSD echo command.
expr	The BSD expr command.
install	The BSD install command with some tweaking.
kDepIDB	Extract dependencies from a Visual C++ .IDB file.
ln	The BSD ln command.
md5sum	Typical MD5 sum program, custom kBuild version.
mkdir	The BSD mkdir command.
mv	The BSD mv command with some tweaking.
printf	The BSD printf command.
rm	The BSD rm command with some tweaking.
rmdir	The BSD rmdir command with some tweaking.
sleep	Typical sleep program, custom kBuild version.
test	The BSD test program with some tweaking.

Some additional external commands are available in the kmk / kBuild environment (kSomething command are not prefixed with kmk_):

Command	Description
kDepPre	Extract dependencies from the C/C++ preprocessor output.
kObjCache	Simple object file cache program.
ash	Almquist's shell (NetBSD variant).
gmake	Vanilla GNU make from same sources as kmk.
redirect	Shell avoidance tool. Sets up file descriptors, environment variables and current directory before kicking of program.
sed	GNU sed with some tweaks to avoid involving the shell.
time	Stopwatch utility for measuring program execution time(s).

kmk-expression

kmk-expressions [1] are related to the C/C++ preprocessor in some ways as well as nmake and BSD make. There are however some peculiarities because of the way GNU make choose to represent booleans in its function library, so, strings can be turned into boolean by taking any non-empty string as true.

Quoting using single quotes results in hard strings, while double quotes and unquoted string results in soft strings that can be converted to number or boolean to fit the situation.

Here's the operator table in decending precedence order:

Operator	Type	Description
defined	Unary	Checks if the following variable exists.
exists		Checks if the following file exists.
target		Checks if the following target exists.
bool		Casts the following value to boolean.
num		Casts the following value to a number.
str		Casts the following value to a string.
!	Unary	Logical NOT.
+		Pluss prefix.
-		Minus prefix.
~		Bitwise one's complement.
*	Binary	Multiplication (product).
/		Division (quotient).
%		Modulus (remainder).
+	Binary	Addition (sum).
-		Subtraction (difference).
<<	Binary	Bitwise left shift.
>>		Bitwise right shift.
<=	Binary	Less or equal than.
<		Less than.
>=		Greater or equal than.
>		Greater than.
==	Binary	Equal to.
!=		Not equal to.
&	Binary	Bitwise AND.
^	Binary	Bitwise XOR.
|	Binary	Bitwise OR.
&&	Binary	Logical AND.
||	Binary	Logical OR.

Built-in functions

String Manipulation Functions:

Replace from with to in text:

$(subst from,to,text)

Replace words matching pattern with replacement in text:

$(patsubst pattern,replacement,text)

Remove excess whitespace characters from string:

$(strip string)

Locate find in text, returning find if found:

$(findstring find,text)

Select words in text that match one of the pattern words:

$(filter pattern...,text)

Select words in text that do not match any of the pattern words:

$(filter-out pattern...,text)

Sort the words in list lexicographically, removing duplicates:

$(sort list)

Sort the words in list lexicographically in reserve order, removing duplicates [1]:

$(rsort list)

Count the number of words in text:

$(words text)

Extract the nth word (one-origin) of text:

$(word n,text)

Returns the list of words in text from s to e (one-origin):

$(wordlist s,e,text)

Extract the first word of names:

$(firstword names...)

Extract the last word of names:

$(lastword names...)

Join two parallel lists of words:

$(join list1,list2)

Fold text to upper case [1]:

$(toupper text)

Fold text to lower case [1]:

$(tolower text)

String formatting a la the unix printf command [1]:

$(printf fmt, arg...)

Return the length of a string or a (unexpanded) variable [1]:

$(length string)
$(length-var var)

Find the position of needle in haystack, returns 0 if not found. Negative start indices are relative to the end of haystack, while positive ones are one based [1]:

$(pos needle, haystack[, start])
$(lastpos needle, haystack[, start])

Returns the specified substring. The start works like with $(pos ). If the substring is partially outside the string the result will be padded with pad if present [1]:

$(substr string, start[, length[, pad]])

Insert in into str at the specified position. n works like with $(pos ), except that 0 is the end of the string [1]:

$(insert in, str[, n[, length[, pad]]])

Translate string exchanging characters in from-set with to-set, optionally completing to-set with pad-char if specified. If no pad-char characters absent in to-set will be deleted [1]:

$(translate string, from-set[, to-set[, pad-char]])

Functions for file names:

Extract the directory part of each file name:

$(dir names...)

Extract the non-directory part of each file name:

$(notdir names...)

Extract the suffix (the last . and following characters) of each file name:

$(suffix names...)

Extract the base name (name without suffix) of each file name:

$(basename names...)

Extract the root specification of each file name (a bit complicated on Windows & OS/2) [1]:

$(root names...)

Append suffix to each word in names:

$(addsuffix suffix,names...)

Prepend prefix to each word in names:

$(addprefix prefix,names...)

Find file names matching a shell file name pattern (not a % pattern):

$(wildcard pattern...)

For each file name in names, expand to an absolute name that does not contain any ., .., nor symlinks:

$(realpath names...)

For each file name in names, expand to an absolute name that does not contain any . or .. components, but preserves symlinks:

$(abspath names...)

Same as $(abspath ) except that the current directory can be specified as curdir [1]:

$(abspathex names...[, curdir])

Arithmetic Functions:

Returns the sum of the arguments [1]:

$(int-add addend1, addend2[, addendN])

Returns the difference between the first argument and the sum of the rest [1]:

$(int-sub minuend, subtrahend[, subtrahendN])

Returns the product of the arguments [1]:

$(int-mul factor1, factor2[, factorN])

Returns the quotient of first argument and the rest [1]:

$(int-div dividend, divisor[, divisorN])

Returns the modulus of the two arguments [1]:

$(int-mod dividend, divisor)

Returns the bitwise two-complement of argument [1]:

$(int-not val)

Returns the result of a bitwise AND of the arguments [1]:

$(int-and val1, val2[, valN])

Returns the result of a bitwise OR of the arguments [1]:

$(int-or val1, val2[, valN])

Returns the result of a bitwise XOR of the arguments [1]:

$(int-xor val1, val2[, valN])

Returns the kmk boolean (true = non-empty, false = empty) result of val1 == val2 [1]:

$(int-eq val1, val2)

Returns the kmk boolean result of val1 != val2 [1]:

$(int-ne val1, val2)

Returns the kmk boolean result of val1 > val2 [1]:

$(int-gt val1, val2)

Returns the kmk boolean result of val1 >= val2 [1]:

$(int-ge val1, val2)

Returns the kmk boolean result of val1 < val2 [1]:

$(int-lt val1, val2)

Returns the kmk boolean result of val1 <= val2 [1]:

$(int-le val1, val2)

Boolean and Conditional Functions:

Condition is false if the condition evaluates to an empty string (stripped). Evaluate the true-part if the condition is true, otherwise the false-part:

$(if condition,true-part[,false-part])

Test if any of the conditions evalues to non-empty string, returning the first one:

$(or condition1[,condition2[,condition3[...]]])

Test if all of the conditions evaluates to non-empty strings, returning the last one:

$(and condition1[,condition2[,condition3[...]]])

Test if the two strings are identical, returning kmk boolean (true = non-empty, false = empty) [2]:

$(eq str1, str2)

Invert a kmk boolean value [2]:

$(not val)

Test if variable is defined, returning a kmk boolean value [1]:

$(defined variable)

Test if set-a and set-b intersects, returning a kmk boolean value [1]:

$(intersects set-a, set-b)

Same as $(if ) execpt that the condition is a kmk-expression [1]:

$(if-expr kmk-expression,true-part[,false-part])

Select the first true condition (kmk-expression) and expand the following body. Special condition strings default and otherwise [1]:

$(select when1-cond, when1-body[, whenN-cond, whenN-body])

Evalutate the kmk-expression returning what it evalues as. This is the preferred way of doing arithmentic now [1]:

$(expr kmk-expression)

Stack Fuctions:

Push item onto the stack-var, returning the empty string [1]:

$(stack-push stack-var, item)

Pop the top item off the stack-var [1]:

$(stack-pop stack-var)

Pop the top item off the stack-var, returning the empty string [1]:

$(stack-popv stack-var)

Get the top item of the stack-var, returning the empty string [1]:

$(stack-top stack-var)

Advanced Functions:

Evaluates to the contents of the variable var, with no expansion performed on it:

$(value var)

Evaluate body with var bound to each word in words, and concatenate the results (spaced):

$(foreach var,words,body)

C-style for-loop. Start by evaluating init. Each iteration will first check whether the condition (kmk-expression) is true, then expand body concatenating the result to the previous iterations (spaced), and finally evaluate next [1]:

$(for init,conditions,next,body)

C-style while-loop. Each iteration will check whether the condition (kmk-expression) is true, then expand body concatenating the result to the previous iterations [1]:

$(while conditions,body)

Evaluate the variable var replacing any references to $(1), $(2) with the first, second, etc. param values:

$(call var,param,...)

Evaluate text then read the results as makefile commands. Expands to the empty string:

$(eval text)

Same as $(eval text) except that the text is expanded in its own variable context [1]:

$(evalctx text)

Same as $(eval $(value var)) [1]:

$(evalval var)

Same as $(evalctx $(value var)) [1]:

$(evalvalctx var)

A combination of $(eval ), $(call ) and $(value ) [1]:

$(evalcall var)

A combination of $(eval ) and $(call ) [1]:

$(evalcall var)

Remove comments and blank lines from the variable var. Expands to the empty string [1]:

$(eval-opt-var var)

Returns accessing $< of target, either retriving the whole thing or the file at pos (one-origin) [1]:

$(deps target[, pos])

Returns accessing $+ (order + duplicates) of target, either retriving the whole thing or the file at pos (one-origin) [1]:

$(deps-all target[, pos])

Returns accessing $? of target, either retriving the whole thing or the file at pos (one-origin) [1]:

$(deps-newer target[, pos])

Returns accessing $| (order only) of target, either retriving the whole thing or the file at pos (one-origin) [1]:

$(deps-oo target[, pos])

Command Functions:

Create one or more command lines avoiding the max argument length restriction of the host OS [1]:

$(xargs ar cas mylib.a,$(objects))
$(xargs ar cas mylib.a,ar as mylib.a,$(objects))

Returns the commands for the specified target separated by new-line, space, or a user defined string. Note that this might not produce the 100% correct result if any of the prerequisite automatic variables are used [1]:

$(commands target)
$(commands-sc target)
$(commands-usr target,sep)

Compares two commands returning the empty string if equal and the 3rd argument if not. This differs from $(comp-vars v1,v2,ne) in that line by line is stripped of leading spaces, command prefixes and trailing spaces before comparing [1]:

$(comp-cmds cmds-var1, cmds-var2, ne)
$(comp-cmds-ex cmds1, cmd2, ne)

Compares the values of the two variables returning the empty string if equal and the 3rd argument if not. Leading and trailing spaces is ignored [1]:

$(comp-var var1, var2, ne)

Utility functions:

When this function is evaluated, kmk generates a fatal error with the message text:

$(error text...)

When this function is evaluated, kmk generates a warning with the message text:

$(warning text...)

When this function is evaluated, kmk generates a info with the message text:

$(info text...)

Execute a shell command and return its output:

$(shell command)

Return a string describing how the kmk variable variable was defined:

$(origin variable)

Return a string describing the flavor of the kmk variable variable:

$(flavor variable)

Returns the current local time and date formatted in the strftime style specifier fmt. fmt defaults to %Y-%m-%dT%H:%M:%S when not specified [1]:

$(date fmt)

Returns the current UTC time and date formatted in the strftime style specifier fmt. fmt defaults to %Y-%m-%dT%H:%M:%SZ when not specified [1]:

$(date-utc fmt)

Reformats the in time and date using fmt. The in-fmt defaults to fmt if not specified. While fmt defaults to %Y-%m-%dT%H:%M:%SZ if not specified [1]:

$(date-utc fmt,time,in-fmt)

Returns the current nanosecond timestamp (monotonic when possible) [1]:

$(nanots )

Returns the size of the specified file, or -1 if the size could not be obtained. This can be used to check if a file exist or not [1]:

$(file-size file)

Searches the PATH kmk variable for the specified files [1]:

$(which files...)

OS/2: Returns the specified LIBPATH variable value [1]:

$(libpath var)

OS/2: Sets the specified LIBPATH variable value, returning the empty string [1]:

$(libpath var,value)

Debugging Functions:

Returns various make statistics, if no item is specified a default selection is returned [1]:

$(make-stats item[,itemN])

Raise a debug breakpoint. Used for debugging kmk makefile parsing [1]:

$(breakpoint )

Recipes

A typical recipe takes one of the two following forms:

targets : normal-prerequisites | order-only-prerequisites
        command
        ...

targets : normal-prerequisites | order-only-prerequisites ; command
        command
        ...

Specifying more than one file in the targets lists is the same as repeating the recipe for each of the files.

Use + and +| in the list of targets to tell kmk that the recipe has more than one output. [1] The files after a + will always be remade, while the files after a +| don't have to be remade. The latter is frequently employed to update files which prerequisites change wihtout the output files necessarily changing. See also kmk_cp --changed.

Double colon recipes

Double colon recipes are written with :: instead of : and are handled differently from ordinary recipes if the target appears in more than one recipe. First, all the recipes must be of the double colon type. Second, the recipes are executed individually and may be omitted depending on the state of their prerequisites. Double colon recipes without any prerequisites will always be executed.

Pattern rules

A couple of examples:

%.o : %.c
        gcc -o $@ $<
%.tab.c %.tab.h : %.y
        bison -d $<

The latter has two outputs.

---

[1]

(1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28, 29, 30, 31, 32, 33, 34, 35, 36, 37, 38, 39, 40, 41, 42, 43, 44, 45, 46, 47, 48, 49, 50, 51, 52, 53, 54, 55, 56, 57, 58, 59, 60, 61, 62, 63, 64, 65, 66, 67, 68, 69, 70, 71, 72, 73, 74, 75, 76, 77, 78, 79, 80, 81) kmk only feature.

[2]	(1, 2) Experimental GNU make feature that is not enabled by default.

---

Status:	$Id: QuickReference-kmk.html 2340 2009-04-18 12:05:47Z bird $
Copyright:	Copyright (C) 1988, 1989, 1990, 1991, 1992, 1993, 1994, 1995, 1996, 1997, 1998, 1999, 2000, 2002, 2003, 2004, 2005, 2006, 2007 Free Software Foundation, Inc. Copyright (c) 2008-2009 knut st. osmundsen