Fix % format comma separator and empty positions.json parse error

update.sh

@@ -0,0 +1,19 @@
+#!/usr/bin/env bash
+# Copies updated source files to /opt/crypto-trader after a git pull.
+# Usage: sudo bash update.sh
+set -euo pipefail
+
+INSTALL_DIR="/opt/crypto-trader"
+SCRIPT_DIR="$(cd "$(dirname "${BASH_SOURCE[0]}")" && pwd)"
+
+if [ "$(id -u)" -ne 0 ]; then
+  echo "ERROR: Run with sudo: sudo bash update.sh"
+  exit 1
+fi
+
+for item in *.py *.txt systemd; do
+  [ -e "$SCRIPT_DIR/$item" ] && cp -r "$SCRIPT_DIR/$item" "$INSTALL_DIR/"
+done
+
+chown -R crypto-trader:crypto-trader "$INSTALL_DIR"
+echo "Updated. Run a test: sudo -u crypto-trader $INSTALL_DIR/venv/bin/python $INSTALL_DIR/bot.py"