Questions "make"

1. What is the meaning of the following makefile variables: $@, $<, $^, CFLAGS, LDFLAGS, LDLIBS.
   Hint: GNU make manual: automatic variables, implicit variables, implicit rules.

2. What will the following makefile print (after running command make) and why,

   CFLAGS = -Wall -Ofast -std=c1x
   C = F
   all:
   	echo CFLAGS
   	echo $CFLAGS
   	echo $(C)FLAGS
   	echo $(CFLAGS)
   

3. Suppose you have your whole C-program in one file main.c. Which of the following makefiles will compile and link the program into the executable file main?

   1. all: main
      

   2. main: main.c
      

   3. main: main.o
      

   4. all: main
      main: main.o
      main.o: main.c
      

   5. all: main
      main.o: main.c
      main: main.o
      

   6. main.o: main.c
      all: main
      main: main.o
      

   7. main: main.c
      	cc main.c -o main
      

   8. main: main.c
      	$(CC) $(CFLAGS) $(LDFLAGS) $^ $(LDLIBS) -o $@
      

   9. all: main
      main: main.o
      	cc main.o -o main
      main.o: main.c
      	cc -c main.c -o main.o
      

   Remember that the tabulator-sign before the command may not be copy-pasted correctly.