Makefile QuickStart

Definition: A makefile is a file containing a set of directives used with the make build automation tool. (from Wikipedia)

Main Versions

• GNU make
• BSD make)
• Microsoft nmake

Makefile Grammars

Basic Format

# this is a comment
# in case target be ignored, add the following
# .PHONY: <target>

<target> : <prerequisites>
[tab] <commands>

# use '.RECIPEPREFIX = [operator]' to replace [tab]

• target:
  • filename(s), the one(s) to be constructed
  • name of a operation
  • phony target: If current dir has one file with the same name as the operation, this operation would be ignored. In case, add

    ```

    - **prerequisites**: Check if the files or operations exist
    - **commands**: Tell how, consists of line(s) of Shell instructions
    
    ### Learn from a example

Var

CXX = g++
OBJS = \
student.o \
one.o \
main.o
EXEC = run

$(var): fetch var

%.o: %.cpp %.h
@# This line won’t be printed
$(CXX) -c $< -o $@

$(EXEC): $(OBJS)
$(CXX) -o $@ $(OBJS)

clean:
rm -rf $(OBJS)
rm -rf $(EXEC)
```

• Every commands would be printed, plus ‘@’ prefix to avoid
• Wildcard: (*), (?), […], (%)
• Assignment: =, :=, ?=, +=
• Automatic Variables:
  • $@: indicate the target
  • $<: indicate the first prerequisite

More about if-statement, functions in Make 命令教程