如何用jq从其他文本文件读取内容更新JSON文件？

初始需求 #

我有多个文本文件，每个文件内包含一个标题，示例创建命令如下：

echo 'title: hello' > 1.txt
echo 'title: world' > 2.txt
echo 'title: good' > 3.txt

同时存在一个Shell脚本生成的JSON文件abc.json，内容如下：

{
  "": [
    {
      "title": "",
      "file": "1"
    },
    {
      "title": "",
      "file": "2"
    },
    {
      "title": "",
      "file": "3"
    }
  ]
}

需要将abc.json中的title值替换为对应文本文件中的标题，更新后效果如下：

{
  "": [
    {
      "title": "hello",
      "file": "1"
    },
    {
      "title": "world",
      "file": "2"
    },
    {
      "title": "good",
      "file": "3"
    }
  ]
}

所有文本文件与JSON文件位于同一目录：

➜  tmp.uFtH6hMC ls
1.txt    2.txt    3.txt    abc.json

更新后的详细需求 #

之前的需求描述有遗漏，补充以下关键细节：

• 文本文件名可能包含空格，当前目录结构如下：

➜  $ gfind . -maxdepth 1 -type f -printf '%P
'
The text file contain one title line and more content.txt
The title identifier in the text file is fixed.txt
The filename of text file may contain space.txt
abc.json

• 文本文件中存在一行标题行（可位于文件任意位置），格式为## <title-value>，其中##是固定的标题标识符，与标题值之间用单个空格分隔，需要提取该行的标题值填入abc.json的title字段。示例文件内容：
  • The text file contain one title line and more content.txt：

  ## hello world
  some more content below...
  ...
  

  • The title identifier in the text file is fixed.txt：

  ## How are you?
  some more content below...
  ...
  

  • The filename of text file may contain space.txt：

  some pre-content...
  ...
  
  ## I'm fine, thank you.
  
  some more content below...
  ...
  

• 更新前abc.json内容：

{
  "": [
    {
      "title": "",
      "file": "The filename of text file may contain space"
    },
    {
      "title": "",
      "file": "The text file contain one title line and more content"
    },
    {
      "title": "",
      "file": "The title identifier in the text file is fixed"
    }
  ]
}

• 更新后abc.json预期效果：

{
  "": [
    {
      "title": "I'm fine, thank you.",
      "file": "The filename of text file may contain space"
    },
    {
      "title": "hello world",
      "file": "The text file contain one title line and more content"
    },
    {
      "title": "How are you?",
      "file": "The title identifier in the text file is fixed"
    }
  ]
}

内容的提问来源于stack exchange，提问作者hustnzj