What do the makefile symbols $@ and $< mean

makefile

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?

Best 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:

  • $@ evaluates to all
  • $< evaluates to library.cpp
  • $^ evaluates to library.cpp main.cpp