make supports some variables that have special properties.
Contains the name of each makefile that is parsed by
the order in which it was parsed. The name is appended just
make begins to parse the makefile. Thus, if the first
thing a makefile does is examine the last word in this variable, it
will be the name of the current makefile. Once the current makefile
include, however, the last word will be the
If a makefile named
Makefile has this content:
name1 := $(lastword $(MAKEFILE_LIST)) include inc.mk name2 := $(lastword $(MAKEFILE_LIST)) all: @echo name1 = $(name1) @echo name2 = $(name2)
then you would expect to see this output:
name1 = Makefile name2 = inc.mk
Sets the default goal to be used if no targets were specified on the
command line (see Arguments to Specify the Goals). The
.DEFAULT_GOAL variable allows you to discover the current
default goal, restart the default goal selection algorithm by clearing
its value, or to explicitly set the default goal. The following
example illustrates these cases:
# Query the default goal. ifeq ($(.DEFAULT_GOAL),) $(warning no default goal is set) endif .PHONY: foo foo: ; @echo $@ $(warning default goal is $(.DEFAULT_GOAL)) # Reset the default goal. .DEFAULT_GOAL := .PHONY: bar bar: ; @echo $@ $(warning default goal is $(.DEFAULT_GOAL)) # Set our own. .DEFAULT_GOAL := foo
This makefile prints:
no default goal is set default goal is foo default goal is bar foo
Note that assigning more than one target name to
invalid and will result in an error.
This variable is set only if this instance of
restarted (see How Makefiles Are Remade): it
will contain the number of times this instance has restarted. Note
this is not the same as recursion (counted by the
variable). You should not set, modify, or export this variable.
make starts it will check whether stdout and stderr will
show their output on a terminal. If so, it will set
MAKE_TERMERR, respectively, to the name
of the terminal device (or
true if this cannot be determined).
If set these variables will be marked for export. These variables
will not be changed by
make and they will not be modified if
These values can be used (particularly in combination with output
synchronization (see Output During Parallel
Execution) to determine whether
make itself is writing to a
terminal; they can be tested to decide whether to force recipe
commands to generate colorized output for example.
If you invoke a sub-
make and redirect its stdout or stderr it
is your responsibility to reset or unexport these variables as well,
if your makefiles rely on them.
The first character of the value of this variable is used as the character make assumes is introducing a recipe line. If the variable is empty (as it is by default) that character is the standard tab character. For example, this is a valid makefile:
.RECIPEPREFIX = > all: > @echo Hello, world
The value of
.RECIPEPREFIX can be changed multiple times; once set
it stays in effect for all rules parsed until it is modified.
Expands to a list of the names of all global variables defined so far. This includes variables which have empty values, as well as built-in variables (see Variables Used by Implicit Rules), but does not include any variables which are only defined in a target-specific context. Note that any value you assign to this variable will be ignored; it will always return its special value.
Expands to a list of special features supported by this version of
make. Possible values include, but are not limited to:
ar (archive) files using special file name syntax.
make to Update Archive Files.
See Summary of Options.
Supports “else if” non-nested conditionals. See Syntax of Conditionals.
Supports “job server” enhanced parallel builds. See Parallel Execution.
.ONESHELL special target. See Using
Supports order-only prerequisites. See Types of Prerequisites.
Supports secondary expansion of prerequisite lists.
Uses the “shortest stem” method of choosing which pattern, of multiple applicable options, will be used. See How Patterns Match.
Supports target-specific and pattern-specific variable assignments. See Target-specific Variable Values.
undefine directive. See Undefine Directive.
Has GNU Guile available as an embedded extension language. See GNU Guile Integration.
Supports dynamically loadable objects for creating custom extensions. See Loading Dynamic Objects.
Expands to a list of directories that
make searches for
included makefiles (see Including Other Makefiles).
Each word in this variable is a new prerequisite which is added to targets for which it is set. These prerequisites differ from normal prerequisites in that they do not appear in any of the automatic variables (see Automatic Variables). This allows prerequisites to be defined which do not impact the recipe.
Consider a rule to link a program:
myprog: myprog.o file1.o file2.o $(CC) $(CFLAGS) $(LDFLAGS) -o $@ $^ $(LDLIBS)
Now suppose you want to enhance this makefile to ensure that updates to the compiler cause the program to be re-linked. You can add the compiler as a prerequisite, but you must ensure that it’s not passed as an argument to link command. You’ll need something like this:
myprog: myprog.o file1.o file2.o $(CC) $(CC) $(CFLAGS) $(LDFLAGS) -o $@ $(filter-out $(CC),$^) $(LDLIBS)
Then consider having multiple extra prerequisites: they would all have
to be filtered out. Using
.EXTRA_PREREQS and target-specific
variables provides a simpler solution:
myprog: myprog.o file1.o file2.o $(CC) $(CFLAGS) $(LDFLAGS) -o $@ $^ $(LDLIBS) myprog: .EXTRA_PREREQS = $(CC)
This feature can also be useful if you want to add prerequisites to a makefile you cannot easily modify: you can create a new file such as extra.mk:
myprog: .EXTRA_PREREQS = $(CC)
make -f extra.mk -f Makefile.
.EXTRA_PREREQS globally will cause those prerequisites
to be added to all targets (which did not themselves override it with
a target-specific value). Note
make is smart enough not to add
a prerequisite listed in
.EXTRA_PREREQS as a prerequisite to