임베디드 장치에서 스크립트를 실행할 때 변수가 바인딩되지 않습니까?

나는스크립트데스크탑에서 실행되면 정상적으로 작동합니다 curl -sL https://sentry.io/get-cli/ | bash.

curl임베디드 장치에서 위와 동일한 명령을 호출 하면 다음과 같은 결과가 나타납니다.

bash: line 22: !DOWNLOAD_URL_LOOKUP: unbound variable

왜 이런 일이 구형 임베디드 장치에서만 발생합니까?(Ubuntu 14.04, GNU bash, 버전 4.3.11(1)-릴리스(arm-unknown-linux-gnueabihf))

관련 스크립트:

#!/bin/bash
set -eu

SENTRY_DOWNLOAD_Darwin_x86_64="https://github.com/getsentry/sentry-cli/releases/download/1.26.0/sentry-cli-Darwin-x86_64"
SENTRY_DOWNLOAD_Linux_i686="https://github.com/getsentry/sentry-cli/releases/download/1.26.0/sentry-cli-Linux-i686"
SENTRY_DOWNLOAD_Linux_x86_64="https://github.com/getsentry/sentry-cli/releases/download/1.26.0/sentry-cli-Linux-x86_64"
SENTRY_DOWNLOAD_Windows_i686="https://github.com/getsentry/sentry-cli/releases/download/1.26.0/sentry-cli-Windows-i686.exe"
SENTRY_DOWNLOAD_Windows_x86_64="https://github.com/getsentry/sentry-cli/releases/download/1.26.0/sentry-cli-Windows-x86_64.exe"
VERSION="1.26.0"
PLATFORM=`uname -s`
ARCH=`uname -m`

# If the install directory is not set, set it to a default
if [ -z ${INSTALL_DIR+x} ]; then
  INSTALL_DIR=/usr/local/bin
fi
if [ -z ${INSTALL_PATH+x} ]; then
  INSTALL_PATH="${INSTALL_DIR}/sentry-cli"
fi

DOWNLOAD_URL_LOOKUP="SENTRY_DOWNLOAD_${PLATFORM}_${ARCH}"
DOWNLOAD_URL="${!DOWNLOAD_URL_LOOKUP}"

echo "This script will automatically install sentry-cli ${VERSION} for you."
echo "Installation path: ${INSTALL_PATH}"
if [ "x$(id -u)" == "x0" ]; then
  echo "Warning: this script is currently running as root. This is dangerous. "
  echo "         Instead run it as normal user. We will sudo as needed."
fi

if [ -f "$INSTALL_PATH" ]; then
  echo "error: sentry-cli is already installed."
  exit 1
fi

if [ x$DOWNLOAD_URL == x ]; then
  echo "error: your platform and architecture (${PLATFORM}-${ARCH}) is unsupported."
  exit 1
fi

if ! hash curl 2> /dev/null; then
  echo "error: you do not have 'curl' installed which is required for this script."
  exit 1
fi

TEMP_FILE=`mktemp "${TMPDIR:-/tmp}/.sentrycli.XXXXXXXX"`

cleanup() {
  rm -f "$TEMP_FILE"
}

trap cleanup EXIT
curl -SL --progress-bar "$DOWNLOAD_URL" > "$TEMP_FILE"
chmod 0755 "$TEMP_FILE"
if ! mv "$TEMP_FILE" "$INSTALL_PATH" 2> /dev/null; then
  sudo -k mv "$TEMP_FILE" "$INSTALL_PATH"
fi

echo 'Done!'