shell scripting

Special Macros

Before issuing any command in a target rule set there are certain special macros predefined.

• $@ is the name of the file to be made.
• $? is the names of the changed dependents
• $< the name of the related file that caused the action.
• $* the prefix shared by target and dependent files.

for example, we could use a rule

hello: main.cpp hello.cpp factorial.cpp         $(CC) $(CFLAGS) $? $(LDFLAGS) -o $@ alternatively: hello: main.cpp hello.cpp factorial.cpp         $(CC) $(CFLAGS) $@.cpp $(LDFLAGS) -o $@

In this example $@ represents hello and $? or $@.cpp will pickup all the changed source files.