Tools and Development Environment (make & cvs)
From Wiki**3
The following examples describe how to use the make and cvs tools. This very short guide is not intended as a replacement for the corresponding manuals.
Make
Make is a utility for building and maintaining programs. In a more general definition, it can be described as a dependency management tool (in the sense that is controls how targets are updated when dependencies change).
Make is especially useful for managing large programs, in which multiple, often not obvious, dependencies occur.
Below, the most usual features are covered (other features, such as conditionals and cycles are not, since they are not of special interest in most cases).
Rules
The general syntax of a rule is as follows (target is supposed to be "built" by the commands 1 though N):
target: dependency1 dependency2 ... dependencyN
command1
command2
...
commandN
There are two types of rules: implicit, which make uses for derived building targets from derived (calculated) dependencies; and explicit, in which both targets and dependencies are specified.
The following is an example of an implicit rule for obtaining a compiled (.o) file from a C++ (.cpp) source, by simple compilation. Variable CXXFLAGS is used to specify compilation flags and CXX is the compiler's name (g++ by default).
CXXFLAGS=-ggdb -O3
%.o: %.cpp
$(CXX) $(CXXFLAGS) -c $*.c -o $*.o
In this rule, % represents a pattern (the same pattern appears in commands section represented by the $* pseudo-variable).
The same rule could be written thus (here $< represents the first dependency, and $@ the target to be built by the rule):
%.o: %.cpp
$(CXX) $(CXXFLAGS) -c $< -o $@
Additional dependencies cannot be specified in the above rule, but, since make accumulates the dependencies for a given target, additional dependencies may be specified by compatible rules. These additional rules do not need a section with commands (the commands in the implicit rule will be used). Nevertheless, if there are commands in both an implicit and an explicit rule, the explicit's are used.
A comparable explicit rule would be:
program.o: program.cpp somelib.h anotherlib.h
$(CXX) $(CXXFLAGS) -c $< -o $@