message: script install_db4.sh added check for patch command
diff: #!/bin/sh
  -# Copyright (c) 2017-2019 The Bitcoin Core developers
  +# Copyright (c) 2017-2021 The Bitcoin Core developers
  # Distributed under the MIT software license, see the accompanying
  # file COPYING or http://www.opensource.org/licenses/mit-license.php.
  @@ -62,6 +62,12 @@ http_get() {
  sha256_check "${3}" "${2}"
  }
  +# Ensure the commands we use exist on the system
  +if ! check_exists patch; then
  + echo "Command-line tool 'patch' not found. Install patch and try again."
  + exit 1
  +fi
  +
  mkdir -p "${BDB_PREFIX}"
  http_get "${BDB_URL}" "${BDB_VERSION}.tar.gz" "${BDB_HASH}"
  tar -xzvf ${BDB_VERSION}.tar.gz -C "$BDB_PREFIX"
  