Improve makefile and add dockerignore.

.dockerignore

@@ -0,0 +1,6 @@
+.gitignore
+build-docker
+Makefile
+README.md
+start
+start.tmpl

Makefile

@@ -1,8 +1,9 @@
+PREFIX := /usr/local
 START_SCRIPT := start
 START_SCRIPT_SRC := start.tmpl
-INSTALLATION_NAME := openvpn-aria2
+INSTALLATION_NAME := docker-aria2
 DOCKERFILE := Dockerfile
-TAG = openvpn-aria2
+TAG = docker-aria2
 
 build: build-docker $(START_SCRIPT)
 
@@ -15,10 +16,15 @@ $(START_SCRIPT): $(START_SCRIPT_SRC)
 	sed -e "s/{TAG}/$(TAG)/g" -e "s/{INSTALLATION_NAME}/$(INSTALLATION_NAME)/g" $< > $@
 	chmod +x $@
 
+shellcheck: $(START_SCRIPT)
+	shellcheck $<
+
+check: shellcheck
+
 clean:
 	$(RM) build-docker $(START_SCRIPT)
 
 install: build
-	install -D --mode=755 $(START_SCRIPT) /usr/local/bin/$(INSTALLATION_NAME)
+	install -D --mode=755 $(START_SCRIPT) $(PREFIX)/bin/$(INSTALLATION_NAME)
 
-.PHONY: clean
+.PHONY: shellcheck check clean