Log rotation: store first 500 lines of print3d and firmware logs separately to prevent them from being rotated.

src/script/logrotate-wifibox.conf

@@ -9,5 +9,28 @@ create
 	size 1000k
 	missingok
 	olddir /tmp/wifibox-rotated
-	copytruncate 
+
+	# as alternative to copytruncate (which *might* miss lines) we could implement
+	# SIGUSR1 in print3d and firmware to reopen their logs
+	copytruncate  # 'create' is ignored with copytruncate, as the file stays in place
+
+	prerotate
+		FIRST_N_LINES=500
+		PRINT3D_LOGHEAD_FILE=print3d-loghead
+		WIFIBOX_LOGHEAD_FILE=wifibox-loghead
+		ROTATED_FILES_PATH=/tmp/wifibox-rotated
+
+		#Note: by looking at creation date of the print3d socket and comparing against that
+		#      of print3d-loghead we could detect a server restart (e.g. due to reconnected printer)
+
+		echo "$1" | grep -q "print3d-.*\.log"
+		if [ $? -eq 0 -a ! -f "$ROTATED_FILES_PATH/$PRINT3D_LOGHEAD_FILE" ]; then
+			head -q -n$FIRST_N_LINES "$1" > "$ROTATED_FILES_PATH/$PRINT3D_LOGHEAD_FILE"
+		fi
+
+		echo "$1" | grep -q "wifibox.log"
+		if [ $? -eq 0 -a ! -f "$ROTATED_FILES_PATH/$WIFIBOX_LOGHEAD_FILE" ]; then
+			head -q -n$FIRST_N_LINES "$1" > "$ROTATED_FILES_PATH/$WIFIBOX_LOGHEAD_FILE"
+		fi
+	endscript
 }