How do you set CFLAGS in makefile?
If you look further down in your makefile, you should see that $(CFLAGS) is probably used like: $(CC) $(CFLAGS) some-more-arguments… The -D option set pre-processor variables, so in your case, all code that is in the specified “#ifdef / #endif” blocks will be compiled.
Does order matter in a Makefile?
The order of rules is not significant, except for determining the default goal: the target for make to consider, if you do not otherwise specify one. The default goal is the target of the first rule in the first makefile. If the first rule has multiple targets, only the first target is taken as the default.
What is the character in a Makefile that separates the target and the dependencies?
TAB character
Dependencies are separated by spaces. Each rule has zero or more actions, commands to run to build the target using the dependencies. Actions are indented using the TAB character, not 8 spaces.
How to override a variable in the Makefile?
If a variable has been set with a command argument (see Overriding Variables), then ordinary assignments in the makefile are ignored. If you want to set the variable in the makefile even though it was set with a command argument, you can use an override directive, which is a line that looks like this: override variable = value
Is it OK to have two Makefiles for the same recipe?
Sometimes it is useful to have a makefile that is mostly just like another makefile. You can often use the ‘ include ’ directive to include one in the other, and add more targets or variable definitions. However, it is invalid for two makefiles to give different recipes for the same target.
What happens if you say make bar in makefile?
If you say ‘ make bar ’, make will find no way to make bar in GNUmakefile, so it will use the recipe from the pattern rule: ‘ make -f Makefile bar ’. If Makefile provides a rule for updating bar, make will apply the rule. And likewise for any other target that GNUmakefile does not say how to make.
When to use an override directive in make?
If a variable has been set with a command argument (see Overriding Variables ), then ordinary assignments in the makefile are ignored. If you want to set the variable in the makefile even though it was set with a command argument, you can use an override directive, which is a line that looks like this: