Add Makefile

Makefile

@@ -0,0 +1,48 @@
+SCRIPT_NAME := alpine-make-vm-image
+
+DESTDIR := /
+PREFIX := /usr/local
+
+SED := sed
+SHA1SUM := sha1sum
+
+ifeq ($(shell uname -s),Darwin)
+	SED := gsed
+	SHA1SUM := shasum -a 1
+endif
+
+#: Update version in the script and README.adoc to $VERSION.
+bump-version:
+	test -n "$(VERSION)"  # $$VERSION
+	$(SED) -E -i "s/^(readonly VERSION)=.*/\1='$(VERSION)'/" $(SCRIPT_NAME)
+	$(SED) -E -i "s/^(:version:).*/\1 $(VERSION)/" README.adoc
+
+#: Update variable :script-sha1: in README.adoc with SHA1 checksum of the script.
+readme-update-checksum:
+	$(SED) -E -i \
+		-e "s/^(:script-sha1:).*/\1 $(shell $(SHA1SUM) $(SCRIPT_NAME) | cut -d ' ' -f 1)/" \
+		README.adoc
+
+#: Bump version to $VERSION, create release commit and tag.
+release: .check-git-clean | bump-version readme-update-checksum
+	test -n "$(VERSION)"  # $$VERSION
+	git add .
+	git commit -m "Release version $(VERSION)"
+	git tag -s v$(VERSION) -m v$(VERSION)
+
+#: Install script into $DESTDIR.
+install:
+	mkdir -p $(DESTDIR)$(PREFIX)/bin
+	install -m 755 $(SCRIPT_NAME) $(DESTDIR)$(PREFIX)/bin/$(SCRIPT_NAME)
+
+#: Print list of targets.
+help:
+	@printf '%s\n\n' 'List of targets:'
+	@$(SED) -En '/^#:.*/{ N; s/^#: (.*)\n([A-Za-z0-9_-]+).*/\2 \1/p }' $(MAKEFILE_LIST) \
+		| while read label desc; do printf '%-30s %s\n' "$$label" "$$desc"; done
+
+.check-git-clean:
+	@test -z "$(shell git status --porcelain)" \
+		|| { echo 'You have uncommitted changes!' >&2; exit 1; }
+
+.PHONY: bump-version readme-update-checksum release help .check-git-clean