add rsync usage example

README.md

@@ -32,4 +32,36 @@ RUST_LOG=warn flarumdown -s '/path/to/flarum.sqlite' \
                          -r http://hc3fycfadz7fkapp62fqi6llioe46fvis6wuswfobl5ghc2u7snq.b32.i2p \
                          -r http://w6vtcpbir5vvokwdqqbqlrdtnzwyfc4iyqn6owxuyjeppszuydutqwqd.onion
 ```
-* optionally, delegate `-u` to `rsync` by using `crontab -e`
+
+### rsync
+
+Optionally, delegate `-u` to `rsync` by using `crontab -e`:
+
+``` bash
+#!/bin/bash
+
+mkdir -p /var/www/flarum/public/flarumdown/dump/assets/files
+
+readonly RSYNC_FILTER_P="*-thumb.webp"
+readonly RSYNC_TARGET_D="/var/www/flarum/public/flarumdown/dump/assets"
+find "$RSYNC_TARGET_D" -name "$RSYNC_FILTER_P" -type f -delete # rsync has --filter, cleanup matches manually
+/usr/bin/rsync -av --delete --filter="-p $RSYNC_FILTER_P" \
+		/var/www/flarum/public/assets/files \
+		$RSYNC_TARGET_D
+
+RUST_LOG=warn /usr/local/bin/flarumdown -s /var/www/flarum/flarum.sqlite \
+					-t /var/www/flarum/public/flarumdown/dump \
+					-i index \
+					-r http://[202:68d0:f0d5:b88d:1d1a:555e:2f6b:3148] \
+					-r http://[505:6847:c778:61a1:5c6d:e802:d291:8191] \
+					-r http://hc3fycfadz7fkapp62fqi6llioe46fvis6wuswfobl5ghc2u7snq.b32.i2p \
+					-r http://w6vtcpbir5vvokwdqqbqlrdtnzwyfc4iyqn6owxuyjeppszuydutqwqd.onion
+
+readonly TARGET_DIR=/var/www/flarum/public/flarumdown/dump
+cd "$TARGET_DIR"
+if [ "$(pwd)" != "$TARGET_DIR" ]; then
+	echo "Unexpected path!"
+	exit 1
+fi
+zip -FS -r -9 /var/www/flarum/public/flarumdown/dump.zip .
+```