TL;DR The variable MAKEOVERRIDES passes the variables defined in the make command line to sub-makes (even those make invoked indirectly). Emptying MAKEOVERRIDES can prevent sub-makes from picking up variables unexpected.

Tips about some special variables used in makefile: automatic variables, $@, $<, $^; wildcard placeholder % in targets and dependencies and $* in recipe; and .DEFAULT_GOAL.

The bash-completion package does not handle command make, while we can extend the completion support for make by adding bash configurations with keyword complete.