@ Indicates the output is suppressed
$ @ Target file set
$ ^ All dependent files set
$ <First dependent file
$? Is newer than the target file dependencies list
$% * Some target mode and before
$ + -Dependent file set, but without removing duplicate rows
$% When the target is a library file, rules target member name
-rm minus sign indicates ignore rm execution error
.PHONY: clean when clean statement is false target, to avoid the presence of a file named clean the command can not be executed
Bank # print head is not subject to [Tab] forward, print Bank