-DEB_VERSION := $(shell LC_ALL=C dpkg-parsechangelog | grep ^Version: | sed 's/^Version: *//')
-DATE := $(shell date +"%Y-%m-%d")
-
-.PHONY: version.ent
-version.ent:
+DEB_VERSION := $(shell LC_ALL=C dpkg-parsechangelog | grep '^Version: ' | sed 's/^Version: *//')
+# pretty-print the date
+DATE := $(shell date --date="`dpkg-parsechangelog | grep '^Date: ' | sed 's/^Date: *//'`" '+%d %B, %Y')
+
+# source depends -- check if these packages are installed
+SRC_DEPENDS := debiandoc-sgml lout psutils
+
+.PHONY: source-depends
+source-depends:
+ @set -e ;\
+ for dep in $(SRC_DEPENDS); do \
+ echo "checking if package \`$$dep' is installed..." ;\
+ dpkg --get-selections | grep "$$dep\W\+install" || \
+ exit 1 ;\
+ done
+ @echo "all source-depends seem to be installed, good"
+
+build: developers-reference.sgml