(make.info.gz) Special Variables

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(make.info.gz) Suppressing Inheritance

(make.info.gz) Using Variables

 
 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 ( Arguments to Specify the Goals 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
      illegal and will result in an error.
 
 `MAKE_RESTARTS'
      This variable is set only if this instance of `make' has restarted
      ( How Makefiles Are Remade Remaking Makefiles.): 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 ( Variables Used by Implicit Rules
      Implicit Variables.), 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:
 
     `archives'
           Supports `ar' (archive) files using special filename syntax.
            Using `make' to Update Archive Files Archives.
 
     `check-symlink'
           Supports the `-L' (`--check-symlink-times') flag.  
           Summary of Options Options Summary.
 
     `else-if'
           Supports "else if" non-nested conditionals.   Syntax of
           Conditionals Conditional Syntax.
 
     `jobserver'
           Supports "job server" enhanced parallel builds.  
           Parallel Execution Parallel.
 
     `second-expansion'
           Supports secondary expansion of prerequisite lists.
 
     `order-only'
           Supports order-only prerequisites.   Types of
           Prerequisites Prerequisite Types.
 
     `target-specific'
           Supports target-specific and pattern-specific variable
           assignments.   Target-specific Variable Values
           Target-specific.
 
 
 `.INCLUDE_DIRS'
      Expands to a list of directories that `make' searches for included
      makefiles ( Including Other Makefiles Include.).
 
 

Info Catalog

(make.info.gz) Suppressing Inheritance

(make.info.gz) Using Variables