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split_string_assign_multiple_variables.md

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很多时候，需要将一行字符分割成多个变量，例如处理文本

这里需要注意，默认分割符是空格，如果是不同分割符，则需要设置 IFS

IFS="," read -r v_space v_email v_name v_sn <<< ",[email protected],不一样的烟火,123456"

然后我们就可以随便使用变量了

echo $v_name

显示输出

不一样的烟火

json和多变量案例

我在结合上述方法，采用循环方式根据 app 名字访问API来获得应用的配置(json)。

例如，单条命令

app=ABC
AK=XXXXXXXX

curl -s --location --request GET "http://api.example.com/getAppInfo.json?appName=$app" --header "apiauth-token: $AK" | jq

可以获得某个应用的信息如下

{
  "app": {
    ...
    "owner": {
      ...
      "email": "[email protected]",
      "nickName": "dogfood",
      "staffNo": "123",
      ...
    },
...

则我通过jq多变量读取：

curl -s --location --request GET "http://api.example.com/getAppInfo.json?appName=$app" --header "apiauth-token: $AK" | jq -r '.app.owner | .email + "," + .nickName + "," + .staffNo'

可以输出

[email protected],dogfood,123
  • 然后我们可以通过多变量赋值直接读取到3个变量，方便后续shell处理
IFS="," read -r owner_email owner_nickName onwer_staffNo <<< $(curl -s --location --request GET "http://api.example.com/getAppInfo.json?appName=$app" --header "apiauth-token: $AK" | jq -r '.app.owner | .email + "," + .nickName + "," + .staffNo')

不过，上述采用 $() 来把执行结果转换为字符串变量然后通过 <<< 输入给左边3个变量的方法，如果使用了循环，则只能在高版本bash上正常工作(例如bash 4.4.19):

for app in `cat $APP_LIST`; do
  IFS="," read -r owner_email owner_nickName onwer_staffNo <<< $(curl -s --location --request GET "http://api.example.com/getAppInfo.json?appName=$app" --header "apiauth-token: $AK" | jq -r '.app.owner | .email + "," + .nickName + "," + .staffNo')

  echo "owner_nickName: $owner_email"
  echo "owner_email: $owner_nickName"
  echo "onwer_staffNo: $onwer_staffNo"
done

则在 macOS的bash 3.2.57上执行结果是错误的

owner_email: [email protected] dogfood 123
owner_nickName:
onwer_staffNo: 
...

但是，如果运行环境是高版本 bash 4.4.19 (linux)，则完全正常

owner_email: [email protected]
owner_nickName: dogfood
onwer_staffNo: 123
...

为了兼容低版本bash，脚本需要修订成 <<< 右边直接使用字符串变量 "$string" :

for app in `cat $APP_LIST`; do
  AppInfo=`curl -s --location --request GET "http://api.example.com/getAppInfo.json?appName=$app" --header "apiauth-token: $AK" | jq -r '.app.owner | .email + "," + .nickName + "," + .staffNo'`
  IFS="," read -r owner_email owner_nickName onwer_staffNo <<< "$AppInfo"
done

则通用能够正常工作输出正确结果

参考