Use printf rather than echo for portability

example/Makefile

@@ -15,6 +15,6 @@ example.pdf: example.tex meta.tex
 
 meta.tex: Makefile .FORCE
 	rm -f $@
-	echo '% GENERATED FILE -- edit this in the Makefile' >>$@
-	/bin/echo '\\newcommand{\\vcsRevision}{$(GITVERSION)$(GITDIRTY)}' >>$@
-	/bin/echo '\\newcommand{\\vcsDate}{$(GITDATE)}' >>$@
+	printf "%s\n" "% GENERATED FILE -- edit this in the Makefile" >>$@
+	printf "%s\n" "\newcommand{\vcsRevision}{$(GITVERSION)$(GITDIRTY)}" >>$@
+	printf "%s\n" "\newcommand{\vcsDate}{$(GITDATE)}" >>$@