Automatic Compilation with Make

Explicit Makefile for program chi: 

chi: chi.o euler.o f90 -n32 -o chi chi.o euler.o chi.o: chi.f90 EULER.kmo f90 -n32 -c chi.f90 euler.o: euler.f90 f90 -n32 -c euler.f90 EULER.kmo: euler.f90 f90 -n32 -c euler.f90 clean: rm -f *.o *.kmo core clobber: clean rm -f chi

General syntax of a Makefile rule: target: dependencies <tab> command_1 <tab> command_2 ...

Makefile for program chi using automatic variables: 

F90         = f90
F90_OPTS    = -n32

chi: chi.o euler.o
        $(F90) $(F90_OPTS) -o $@ $^

chi.o: chi.f90 EULER.kmo
        $(F90) $(F90_OPTS) -c $<

euler.o: euler.f90
        $(F90) $(F90_OPTS) -c $<

EULER.kmo: euler.f90
        $(F90) $(F90_OPTS) -c $<

clean:
        rm -f *.o *.kmo core

clobber: clean
        rm -f chi

The meaning of some automatic and defined variables:

• $(F90): whatever F90 has been defined to be
• $(F90_OPTS): whatever F90_OPTS has been defined to be
• $@: a target, e.g., chi in the first instruction
• $^: all explicitly listed dependencies for that target, e.g., chi.o and euler.o in the first instruction
• $<: the first dependency, e.g., chi.f90 in the second instruction

Automatic variables are a mixed blessing: they can be hard to read.

• If there is no target all then the first target encountered in the Makefile is assumed to be the goal. Otherwise all defines what needs to be made.

Portable Makefiles: 

• Our Makefile is non-portable, because the module interface file under SunOS is called euler.M. So for SunOS the Makefile would have to replace every occurrence of EULER.kmo with EULER.M and every occurrence of *.kmo with *.M. Also, for SunOS we don't need the -n32 flag.
• The Makefile can be made more portable by calling the shell function. This feature is available in GNU make only:

  OS = $(shell uname -s)
  

• Once we know what the $(OS) is we can use Makefile conditionals to make it more portable. This feature is available in GNU make only.

OS             = $(shell uname -s)
F90            = f90

ifeq ($(OS), IRIX)
   F90_OPTS    = -n32 -g
else
   F90_OPTS    = -g
endif

ifeq ($(OS), IRIX)
   MODULE_IFC  = EULER.kmo
else
   ifeq ($(OS), SunOS)
      MODULE_IFC  = euler.M
   else
      MODULE_IFC  =
   endif
endif

chi: chi.o euler.o
        $(F90) $(F90_OPTS) -o $@ $^

chi.o: chi.f90 $(MODULE_IFC)
        $(F90) $(F90_OPTS) -c $<

euler.o: euler.f90
        $(F90) $(F90_OPTS) -c $<

$(MODULE_IFC): euler.f90
        $(F90) $(F90_OPTS) -c $<

clean:
ifeq ($(OS), IRIX)
        rm -f *.o *.kmo core
else
   ifeq ($(OS), SunOS)
        rm -f *.o *.M core
   else
        rm -f *.o core
   endif
endif

clobber: clean
        rm -f chi

A Makefile for the HDF programs:

HDF_LIB        = /afs/ovpit.indiana.edu/@sys/HDF/lib
HDF_MODULES    = /afs/ovpit.indiana.edu/@sys/HDF/modules
OS             = $(shell uname -s)
F90            = f90
RM             = /bin/rm

ifeq ($(OS), IRIX)
   F90_OPTS    = -n32 -g
   LIBS        = -lmfhdf -ldf -ljpeg -lz -lm
   F90_MODULES = -I$(HDF_MODULES)
else
   ifeq ($(OS), SunOS)
      F90_OPTS    = -g
      LIBS        = -lmfhdf -lnsl -ldf -ljpeg -lz -lm
      F90_MODULES = -M$(HDF_MODULES)
   else
      F90_OPTS    = -g
      LIBS        = -lmfhdf -ldf -ljpeg -lz -lm
      F90_MODULES = -I$(HDF_MODULES)
   endif
endif

hdf-1: hdf-1.o
        $(F90) $(F90_OPTS) -o $@ $< -L$(HDF_LIB) $(LIBS)

hdf-1.o: hdf-1.f90
        $(F90) $(F90_OPTS) -c $(F90_MODULES) $<

hdf-2: hdf-2.o
        $(F90) $(F90_OPTS) -o $@ $< -L$(HDF_LIB) $(LIBS)

hdf-2.o: hdf-2.f90
        $(F90) $(F90_OPTS) -c $(F90_MODULES) $<

...

hdf-8: hdf-8.o
        $(F90) $(F90_OPTS) -o $@ $< -L$(HDF_LIB) $(LIBS)

hdf-8.o: hdf-8.f90
        $(F90) $(F90_OPTS) -c $(F90_MODULES) $<

clean:
        $(RM) -f *.o core

clobber: clean
        $(RM) -f hdf-1 hdf-2 hdf-3 hdf-4 hdf-5 hdf-6 hdf-7 hdf-8

Defining make rules for repetitive patterns: 

• The command that converts a .f90 file into a .o file looks the same for all .f90 files in this Makefile:

  $(F90) $(F90_OPTS) -c $(F90_MODULES) $<
  

• We can define a general rule, which can be applied to all .f90 files as a default:

  %.o: %.f90
          $(F90) $(F90_OPTS) -c $(F90_MODULES) $<
  

• Once the rule is defined we can just leave the dependencies on our Makefile:

  hdf-1.o: hdf-1.f90
  hdf-2.o: hdf-2.f90
  hdf-3.o: hdf-3.f90
  hdf-4.o: hdf-4.f90
  hdf-5.o: hdf-5.f90
  hdf-6.o: hdf-6.f90
  hdf-7.o: hdf-7.f90
  hdf-8.o: hdf-8.f90
  

• Can we also automate the loading step the same way? Here's how to do that:

  %: %.o
          $(F90) $(F90_OPTS) -o $@ $< -L$(HDF_LIB) $(LIBS)
  

• After this rule has been defined, leave only the dependencies as before:

  hdf-1: hdf-1.o
  hdf-2: hdf-2.o
  hdf-3: hdf-3.o
  hdf-4: hdf-4.o
  hdf-5: hdf-5.o
  hdf-6: hdf-6.o
  hdf-7: hdf-7.o
  hdf-8: hdf-8.o
  

• If the directory that contains the Makefile contains only the .f90 files (and none of, say, hdf-1.c files), you can remove the dependencies too, and just replace all of them with the following:

  HDF_EXAMPLES   = hdf-1 hdf-2 hdf-3 hdf-4 hdf-5 hdf-6 hdf-7 hdf-8
  ...
  all: $(HDF_EXAMPLES)
  

• The following Makefile will work both on the Ships Cluster and on the Burrow Sun Cluster in Lindley Hall (LH004)
• When invoked it will make programs hdf-1 through hdf-8 and will remove all intermediary files, hdf-1.o through hdf-8.o. This is not equivalent to doing make clean though. GNU make does the last step out of its own initiative.

HDF_LIB        = /afs/ovpit.indiana.edu/@sys/HDF/lib
HDF_MODULES    = /afs/ovpit.indiana.edu/@sys/HDF/modules
OS             = $(shell uname -s)
F90            = f90
RM             = /bin/rm
HDF_EXAMPLES   = hdf-1 hdf-2 hdf-3 hdf-4 hdf-5 hdf-6 hdf-7 hdf-8

ifeq ($(OS), IRIX)
   F90_OPTS    = -n32 -g
   LIBS        = -lmfhdf -ldf -ljpeg -lz -lm
   F90_MODULES = -I$(HDF_MODULES)
else
   ifeq ($(OS), SunOS)
      F90_OPTS    = -g
      LIBS        = -lmfhdf -lnsl -ldf -ljpeg -lz -lm
      F90_MODULES = -M$(HDF_MODULES)
   else
      F90_OPTS    = -g
      LIBS        = -lmfhdf -ldf -ljpeg -lz -lm
      F90_MODULES = -I$(HDF_MODULES)
   endif
endif

%.o: %.f90
        $(F90) $(F90_OPTS) -c $(F90_MODULES) $<

%: %.o
        $(F90) $(F90_OPTS) -o $@ $< -L$(HDF_LIB) $(LIBS)

all: $(HDF_EXAMPLES)

clean:
        $(RM) -f *.o core

clobber: clean
        $(RM) -f $(HDF_EXAMPLES)