Unix 向字符串添加重复的双引号

我有下面的单词列表：

1,"London","This is "London" which has, many streets","IST1"

我需要像这样双引号，这是第二次出现的搜索模式，并添加双引号，如前所述，csv输入文件，没有固定位置的“：

我试过sed的/*/\“&\“/g”，但没有成功

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上述解决方案需要额外的双引号。

假设您有上述固定格式，如果没有额外的引号，这将起作用

$ sed 's/"*"/\"\"/4' test.txt | sed 's/"*"/\"\"/5'

输出：

$ cat test.txt 
  1,"London","This is "London" which has, many streets","IST1"
  2,"India","This is "India" which has, many cultures","IST10"

$ sed 's/"*"/\"\"/4' test.txt | sed 's/"*"/\"\"/5' 
  1,"London","This is ""London"" which has, many streets","IST1"
  2,"India","This is ""India"" which has, many cultures","IST10"

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现在，如果您使用哪种技术没有限制，我建议您使用Pandas，因为这肯定是一个CSV文件，在Pandas中编辑它将变得相当容易，

假设您使用上述固定格式，如果没有额外的引号，这将起作用

$ sed 's/"*"/\"\"/4' test.txt | sed 's/"*"/\"\"/5'

输出：

$ cat test.txt 
  1,"London","This is "London" which has, many streets","IST1"
  2,"India","This is "India" which has, many cultures","IST10"

$ sed 's/"*"/\"\"/4' test.txt | sed 's/"*"/\"\"/5' 
  1,"London","This is ""London"" which has, many streets","IST1"
  2,"India","This is ""India"" which has, many cultures","IST10"

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现在，如果您使用哪种技术没有限制，我建议您使用Pandas，因为这绝对是一个CSV文件，在Pandas中编辑它将变得相当容易，

I；我刚刚提供了伦敦作为一个例子，它需要检查字符串中的任何值（如前所述）然后在特定列中添加双引号感谢Mukund，这不是固定格式，它需要搜索列中的双引号，然后再添加一个双引号，上面的答案是固定的，因此不满足要求；我刚才提供了London作为示例，它需要检查字符串中的任何值（如前所述）然后在特定列中添加双引号感谢Mukund，这不是固定格式，它需要在列中搜索双引号，然后再添加一个双引号，上面的答案是固定的，因此不足以满足要求