makefile

What do the makefile symbols $@ and $< mean?

CC=g++
CFLAGS=-c -Wall
LDFLAGS=
SOURCES=main.cpp hello.cpp factorial.cpp
OBJECTS=$(SOURCES:.cpp=.o)
EXECUTABLE=hello

all: $(SOURCES) $(EXECUTABLE)

$(EXECUTABLE): $(OBJECTS)
    $(CC) $(LDFLAGS) $(OBJECTS) -o $@

.cpp.o:
    $(CC) $(CFLAGS) $< -o $@

What do the $@ and $< do exactly?

Solution

  • $@ is the name of the target being generated, and $< the first prerequisite (usually a source file). You can find a list of all these special variables in the GNU Make manual.

    For example, consider the following declaration:

    all: library.cpp main.cpp

    In this case: