Follow GNU coding standards

Makefile

@@ -21,43 +21,46 @@
 # OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
 # SOFTWARE.
 #
-ifneq ($(PREFIX),)
-prefix ?= $(PREFIX)
-endif
-ifneq ($(DESTDIR),)
-prefix ?= /usr
-endif
-ifneq ($(shell id -u),0)
+ifneq ($(if $(DESTDIR),0,$(shell id -u)),0)
+# If the current user is not root and DESTDIR is not set, install to user home
 prefix ?= $(HOME)/.local
 else
 prefix ?= /usr/local
 endif
-
-bindir ?= bin
-mandir ?= share/man/man1
+exec_prefix ?= $(prefix)
+bindir ?= $(exec_prefix)/bin
+mandir ?= $(prefix)/share/man
+man1dir ?= $(mandir)/man1
 
 help:
 	@echo
-	@echo "* Run 'make install' to install the script to $(prefix)/$(bindir)"
+	@echo "* Run 'make install' to install the script to $(bindir)"
 	@echo "* Run 'make uninstall' to uninstall the script again."
 	@echo "* You can pick a different install prefix than $(prefix) with"
 	@echo "  make prefix=/other/prefix install"
 	@echo
 
-install: $(DESTDIR)$(prefix)/$(bindir)/git-archive-all $(DESTDIR)$(prefix)/$(mandir)/git-archive-all.1.gz
+all:
+
+clean:
+
+install: $(DESTDIR)$(bindir)/git-archive-all $(DESTDIR)$(man1dir)/git-archive-all.1.gz
 
 uninstall:
-	rm $(DESTDIR)$(prefix)/$(bindir)/git-archive-all
-	rm -f $(DESTDIR)$(prefix)/$(mandir)/git-archive-all.1.gz
+	rm $(DESTDIR)$(bindir)/git-archive-all
+	rm -f $(DESTDIR)$(man1dir)/git-archive-all.1*
+
+check:
+	./test.bats
 
-$(DESTDIR)$(prefix)/$(bindir)/git-archive-all: git-archive-all $(DESTDIR)$(prefix)/$(bindir)
-	install -m755 $< $(DESTDIR)$(prefix)/$(bindir)
+$(DESTDIR)$(bindir)/git-archive-all: git-archive-all $(DESTDIR)$(bindir)
+	install -m755 $< $(DESTDIR)$(bindir)
 
-$(DESTDIR)$(prefix)/$(mandir)/git-archive-all.1.gz: git-archive-all $(DESTDIR)$(prefix)/$(mandir)
+$(DESTDIR)$(man1dir)/git-archive-all.1.gz: git-archive-all $(DESTDIR)$(man1dir)
 	pod2man -r "" -c "Git Manual" $< > $(basename $@) && gzip -9fn $(basename $@)
 
-$(DESTDIR)$(prefix)/$(bindir) $(DESTDIR)$(prefix)/$(mandir):
+$(DESTDIR)$(bindir) $(DESTDIR)$(man1dir):
 	mkdir -p $@
 
-.PHONY: install uninstall
+.PHONY: all check clean help install uninstall