The shrinking role of ETXTBSY

That isn't strictly true, at least with respect to GNU make. There are a number of built-in patterns. For example, in a directory containing only a source file "test.c" (and no makefile) if you run "make 'libtest.a(test.o)'" the GNU make will invoke the following commands automatically:

cc -c -o test.o test.c
ar rv libtest.a test.o
rm test.o

So without being told it knows at least how to compile .c files into .o files, add .o files to a static library, and remove the temporary .o files afterward. There is also at least one built-in implicit rule (%.out: %) which involves copying files: if you run "make test.c.out" it will invoke "cp test.c test.c.out". And if you have a file "script.sh" and run "make script" it will copy "script.sh" to "script"—using cat(1) and redirection rather than cp(1)—and then mark the resulting file as executable.

Besides the built-in rules, GNU make also removes any intermediate files generated when multiple implicit rules are chained to build a target: <https://www.gnu.org/software/make/manual/html_node/Chaine...>.

You can list all the built-in rules available on your system with "make -f /dev/null -p". There is also a partial list in the manual: <https://www.gnu.org/software/make/manual/html_node/Catalo...>.