3.7 How Makefiles Are Remade
Sometimes makefiles can be remade from other files, such as RCS or SCCS
files. If a makefile can be remade from other files, you probably want
make to get an up-to-date version of the makefile to read in.
To this end, after reading in all makefiles, make will consider each as a goal target and
attempt to update it. If a makefile has a rule which says how to update it (found either
in that very makefile or in another one) or if an implicit rule applies to it (see Chapter 10
[Using Implicit Rules], page 101), it will be updated if necessary.
After all makefiles have been checked, if any have actually been
changed, make starts with a clean slate and reads all the makefiles over
again. (It will also attempt to update each of them over again, but
normally this will not change them again, since they are already up to
date.)
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I have copied some lines from the manual GNU make and have some questions. What are RCS and SCCS files? Where are they?
make will consider each Makefile as a goal target? What makefiles is it talking about? the makefiles that have been included?
Would you please clarify it by an example?