From dace604129418ff0ea8a91b6f16cd82b7c1c1450 Mon Sep 17 00:00:00 2001
From: Chris Berkhout <chrisberkhout@gmail.com>
Date: Mon, 4 Apr 2022 15:52:43 +0200
Subject: [PATCH] Note about fetching new prices only.

---
 README.md | 11 +++++++++++
 1 file changed, 11 insertions(+)

diff --git a/README.md b/README.md
index 05f6492..ca74284 100644
--- a/README.md
+++ b/README.md
@@ -152,6 +152,17 @@ P 2021/01/07 € $1.5836
 P 2021/01/08 € $1.5758
 ```
 
+### Fetch new prices only
+
+You can update an existing file without refetching the prices you already have.
+First find the date of the last price, then fetch from there, drop the header
+line if present and append the rest to the existing file.
+
+```
+last=$(tail -1 prices-eur-usd.csv | cut -d, -f1)
+pricehist fetch ecb EUR/USD -sx $last -o csv | sed 1d >> prices-eur-usd.csv
+```
+
 ### Load prices into GnuCash
 
 You can generate SQL for a GnuCash database and apply it immediately with one