Info Catalog make: Flavor Function make: Functions make: Shell Function

make: Make Control Functions

 
 8.12 Functions That Control Make
 ================================
 
 These functions control the way make runs.  Generally, they are used to
 provide information to the user of the makefile or to cause make to stop
 if some sort of environmental error is detected.
 
 '$(error TEXT...)'
      Generates a fatal error where the message is TEXT.  Note that the
      error is generated whenever this function is evaluated.  So, if you
      put it inside a recipe or on the right side of a recursive variable
      assignment, it won't be evaluated until later.  The TEXT will be
      expanded before the error is generated.
 
      For example,
 
           ifdef ERROR1
           $(error error is $(ERROR1))
           endif
 
      will generate a fatal error during the read of the makefile if the
      'make' variable 'ERROR1' is defined.  Or,
 
           ERR = $(error found an error!)
 
           .PHONY: err
           err: ; $(ERR)
 
      will generate a fatal error while 'make' is running, if the 'err'
      target is invoked.
 
 '$(warning TEXT...)'
      This function works similarly to the 'error' function, above,
      except that 'make' doesn't exit.  Instead, TEXT is expanded and the
      resulting message is displayed, but processing of the makefile
      continues.
 
      The result of the expansion of this function is the empty string.
 
 '$(info TEXT...)'
      This function does nothing more than print its (expanded)
      argument(s) to standard output.  No makefile name or line number is
      added.  The result of the expansion of this function is the empty
      string.
 

Info Catalog make: Flavor Function make: Functions make: Shell Function