sfeed_update: merge improvements

does not sort all entries by datetime descending anymore. Now only
new entries are appending in a datetime ascending order.

2 files changed, 14 insertions, 7 deletions

diff --git a/README b/README
index c949f56..fc97e34 100644
--- a/README
+++ b/README
@@ -74,6 +74,7 @@ Optional dependencies
 - make(1) (for Makefile).
 - POSIX sh(1),
   used by sfeed_update(1) and sfeed_opml_export(1).
+- awk(1), used by sfeed_update(1).
 - curl(1) binary: http://curl.haxx.se/ ,
   used by sfeed_update(1), can be replaced with any tool like wget(1),
   OpenBSD ftp(1).
diff --git a/sfeed_update b/sfeed_update
index cf384d1..e280d22 100755
--- a/sfeed_update
+++ b/sfeed_update
@@ -31,10 +31,14 @@ loadconfig() {
 # merge raw files.
 # merge(oldfile, newfile)
 merge() {
-	# unique sort by id, title, link.
-	# order by timestamp (desc).
-	(sort -t '	' -u -k6,6 -k2,2 -k3,3 "$1" "$2" 2>/dev/null) |
-	sort -t '	' -k1rn,1
+	# unique check by id, title, link.
+	# print only new entries in newfile.
+	# order new items by timestamp (asc).
+	(sed 's@^@O	@' "$1"
+	sed 's@^@N	@' "$2") | \
+		awk '!x[$7 "	" $3 "	" $4]++ && $1 == "N"' 2>/dev/null | \
+		cut -f 2- | \
+		sort -t '	' -k1n,1
 }
 
 # fetch a feed via HTTP/HTTPS etc.
@@ -88,10 +92,12 @@ feed() {
 		# if file exists, merge
 		if [ -e "${sfeedfile}" ]; then
 			merge "${sfeedfile}" "${tmpfeedfile}" > "${sfeedfilenew}"
-			# overwrite old file with updated file
-			mv "${sfeedfilenew}" "${sfeedfile}"
+
+			# append new entries to feed file.
+			cat "${sfeedfilenew}" >> "${sfeedfile}"
+			rm -f "${sfeedfilenew}"
 		else
-			merge "/dev/null" "${tmpfeedfile}" > "${sfeedfile}"
+			mv "${tmpfeedfile}" "${sfeedfile}"
 		fi
 	fi) &
 }