Makefile: use make variables for filenames

Makefile

@@ -1,9 +1,14 @@
 PLUGINS = df cpu if_ if_err_ load memory processes swap netstat uptime interrupts irqstats ntpdate plugindir_
+CONFIGURATION_FILE ?= munin-node.conf
+TARGET_FILE ?= munin-node
+VERSION ?= $(shell cat VERSION)
+DIST_DIR = releases
+TGZ_FILE ?= $(DIST_DIR)/muninlite-$(VERSION).tar.gz
 
 
-munin-node: plugins/* munin-node.conf
-	@export VERSION=$$(cat VERSION); \
-	export CONF=$$(grep -v '^#' munin-node.conf); \
+$(TARGET_FILE): plugins/* $(CONFIGURATION_FILE)
+	@export VERSION="$(VERSION)"; \
+	export CONF=$$(grep -v '^#' "$(CONFIGURATION_FILE)"); \
 	export "PLUGINS=$(PLUGINS)"; \
 	echo "Making munin-node for muninlite version $$VERSION"; \
 	export PLSTR=""; \
@@ -17,30 +22,32 @@ munin-node: plugins/* munin-node.conf
 	    s/\@\@CONF\@\@/$$ENV{"CONF"}/; \
 	    s/\@\@PLUGINS\@\@/$$ENV{"PLUGINS"}/; \
 	    s/\@\@PLSTR\@\@/$$ENV{"PLSTR"}/;' \
-	  munin-node.in > munin-node
-	@chmod +x munin-node
+	  munin-node.in >"$(TARGET_FILE)"
+	@chmod +x "$(TARGET_FILE)"
 
-all: munin-node
+all: $(TARGET_FILE)
 
 clean-node:
-	@echo "Removing munin-node"
-	@rm -f munin-node
+	@echo "Removing $(TARGET_FILE)"
+	@rm -f "$(TARGET_FILE)"
 
 clean-tgz:
 	@echo "Removing old releases"
-	@rm -rf releases
+	@rm -rf "$(DIST_DIR)"
 
 clean: clean-node
 
 clean-all: clean-node clean-tgz
 
-tgz: clean-node
-	@VERSION=$$(cat VERSION); \
- 	echo "Building release/muninlite-$$VERSION.tar.gz"; \
-	mkdir -p releases; \
-	cp -ra . releases/muninlite-$$VERSION 2>/dev/null || true; \
-	cd releases; \
-	rm -rf muninlite-$$VERSION/releases; \
+tgz: $(TGZ_FILE)
+
+$(TGZ_FILE):
+	@VERSION="$(VERSION)"; \
+	echo "Building "$(DIST_DIR)"/muninlite-$$VERSION.tar.gz"; \
+	mkdir -p "$(DIST_DIR)"; \
+	cp -ra . "$(DIST_DIR)"/muninlite-$$VERSION 2>/dev/null || true; \
+	cd "$(DIST_DIR)"; \
+	rm -rf muninlite-$$VERSION/"$(DIST_DIR)"; \
 	rm -rf muninlite-$$VERSION/.svn; \
 	tar zcvf muninlite-$$VERSION.tar.gz muninlite-$$VERSION >/dev/null; \
 	rm -rf  muninlite-$$VERSION;