Don't process unmodified files.

TODO

@@ -1,5 +1,4 @@
 ============
 *** TODO ***
 ============
- - File date comparison to avoid unnecessary processing
  - Manner to loop through files in directory

sssg.sh

@@ -65,7 +65,6 @@ function parse {
 
 function generate {
 	# create directories
-	rm -rf _site
 	for i in $(find . -type d -not -path "./_templates" \
 		-not -path "./_site" -not -path "./_templates/*" \
 		-not -path "./_site/*")
@@ -81,6 +80,8 @@ function generate {
 		"./_site/*")
 	do
 		file_path=${i:2}
+		if [ "$file_path" -nt "_site/$file_path" ]
+		then
 			if [ ${file_path: -4} == ".htm" ] ||
 				[ ${file_path: -4} == ".HTM" ] ||
 				[ ${file_path: -5} == ".html" ] ||
@@ -94,6 +95,7 @@ function generate {
 				cp $file_path _site/$file_path
 				echo "OK"
 			fi
+		fi
 	done
 }