我继承了一个shell脚本，它包含以下代码

while IFS='=' read -r key value
do
  # echo "key ${key}"
  if [[ ${key} =~ ^# ]]; then
    # echo "comment line ${key},  skipping....."
    continue
  fi
  eval ${key}=\${value}
  echo "key: ${key}, value: ${value}"
done <kafka-parameters.txt

其中kafka-parameters.txt文件包含如下条目

#Schema Registry
DEV_SR_URLS=http://sr1-dev:8081, http://sr2-dev:8081
QA_SR_URLS=http://sr1-qa:8081, http://sr2-qa:8081
STAGE_SR_URLS=http://sr1-qa:8081, http://sr2-qa:8081
PROD_SR_URLS=http://sr1:8081, http://sr2:8081
#
#Bootstrap Servers
DEV_BOOTSTRAP_SERVERS=broker1-dev:9092,broker2-dev:9092,broker3-dev:9092
QA_BOOTSTRAP_SERVERS=broker1-qa:9092,broker2-qa:9092,broker3-qa:9092
STAGE_BOOTSTRAP_SERVERS=broker1-qa:9092,broker2-qa:9092,broker3-qa:9092
PROD_BOOTSTRAP_SERVERS=broker1:9092,broker2:9092,broker3:9092
#

在上面的代码片段中，${value}前面的“\”的用途是什么？
根据我的理解，eval ${key}=${value}创建了一个名为${key}的变量，并将值${value}赋给它，eval使该赋值在循环后可用。
是否正确？仍不明白${value}的用途
或者两者之间有什么区别

eval ${key}=\${value}

and

eval ${key}=${value}