junky gist to make two binaries

Makefile

# compiler
# clang rocks, try it sometime
# clang, gcc, cc, etc.
CC = gcc

# these are C++ flags
# -std=c++11 -ggdb `pkg-config --cflags opencv`
CFLAGS = 

# other includes you want in the command to compile
INCLUDES = 

# linker flags
LFLAGS = 

# i use things like boost here
# -lboost_system -lboost_filesystem `pkg-config --libs opencv`
LIBS =   

#I recommend renaming everything to something
# besides first and second

# every .c file you need for the binaries
FIRST_SRCS = fileone.c filetwo.c
SECOND_SRCS = filethree.c filefour.c

# the object names
FIRST_OBJS = $(FIRST_SRCS:.c=.o)
SECOND_OBJS = $(SECOND_SRCS:.c=.o)

FIRST = outputbinaryname
SECOND = otheroutputbinary

# default make command since first target
all: $(FIRST) $(SECOND)
	@echo  Success

$(FIRST): $(FIRST_OBJS) 
	$(CC) $(CFLAGS) $(INCLUDES) -o $(SECOND) $(FIRST_OBJS) $(LFLAGS) $(LIBS)

$(SECOND): $(SECOND_OBJS) 
	$(CC) $(CFLAGS) $(INCLUDES) -o $(FIRST) $(SECOND_OBJS) $(LFLAGS) $(LIBS)

.c.o:
	$(CC) $(CFLAGS) $(INCLUDES) -c $<  -o $@ 

clean:
	$(RM) *.o *~ $(FIRST) $(SECOND)