Question

As I very new to bash shell script, I could not understand the Makefile that I am using for compiling some program.

Could you explain the meaning of ‘$@’ and ‘$<‘ in the following source code? Thank you in advance.

CC=g++
CFLAGS=-c -Wall -I /usr/local/include/boost-1_37/ -g
LDFLAGS=-L /usr/local/lib
SOURCES=cluster.cpp test.cpp
OBJECTS=$(SOURCES:.cpp=.o)
EXECUTABLE=k-means

all: $(SOURCES) $(EXECUTABLE)


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

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

clean:
    rm -fr *.o *~ $(EXECUTABLE)

Answer 1

See Automatic Variables in GNU make manual:

$@

The file name of the target of the rule. If the target is an archive member, then $@ is the name of the archive file. In a
pattern rule that has multiple targets (see Introduction to Pattern
Rules), $@ is the name of whichever target caused the rule’s recipe
to be run.

$<

The name of the first prerequisite. If the target got its recipe from an implicit rule, this will be the first prerequisite added by the implicit rule (see Implicit Rules).