6.14 Other Special Variables

GNU make supports some variables that have special properties.

MAKEFILE_LIST

Contains the name of each makefile that is parsed by make, in the order in which it was parsed. The name is appended just before 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 has used include, however, the last word will be the just-included makefile.

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

.DEFAULT_GOAL

Sets the default goal to be used if no targets were specified on the command line (see section 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 .DEFAULT_GOAL is invalid and will result in an error.

MAKE_RESTARTS

This variable is set only if this instance of make has restarted (see section 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 MAKELEVEL variable). You should not set, modify, or export this variable.

.RECIPEPREFIX

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.

.VARIABLES

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 section 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.

.FEATURES

Expands to a list of special features supported by this version of make. Possible values include, but are not limited to:

‘archives’

Supports ar (archive) files using special file name syntax. See section Using make to Update Archive Files.

‘check-symlink’

Supports the -L (--check-symlink-times) flag. See section Summary of Options.

‘else-if’

Supports “else if” non-nested conditionals. See section Syntax of Conditionals.

‘jobserver’

Supports “job server” enhanced parallel builds. See section Parallel Execution.

‘oneshell’

Supports the .ONESHELL special target. See section Using One Shell.

‘order-only’

Supports order-only prerequisites. See section Types of Prerequisites.

‘second-expansion’

Supports secondary expansion of prerequisite lists.

‘shortest-stem’

Uses the “shortest stem” method of choosing which pattern, of multiple applicable options, will be used. See section How Patterns Match.

‘target-specific’

Supports target-specific and pattern-specific variable assignments. See section Target-specific Variable Values.

‘undefine’

Supports the undefine directive. See section Undefining Variables.

‘guile’

Has GNU Guile available as an embedded extension language. See section GNU Guile Integration.

‘load’

Supports dynamically loadable objects for creating custom extensions. See section Loading Dynamic Objects.

.INCLUDE_DIRS

Expands to a list of directories that make searches for included makefiles (see section Including Other Makefiles).

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