Makefile of a project you can find a
.PHONY element followed by a label and then the same label used as a target for the Makefile.
.PHONY: build build: go build
.PHONY is actually itself a target for the
make commandand and it denotes labels that do not represent files of the project. What does it mean?
In the general case, assuming that there are no files called build in the project, when not using the
.PHONY target, like so
build: go build
make build command is invoked it will execute the specified command (in this case
go build). However, if there was a file named build, the
make build would be bound by the presence of this file and executed only if that file was updated.
.PHONY target overrides this last behaviour and let's the
make build execute no matter of the presence of a file named build.
For a more in-depth overview head to the
make command reference.