如何在不覆盖任何数据的情况下在文件开头添加新行？

I am trying to figure out how to write a new line of text at the beginning of a file (a header). I know I can open the file, or seek to the beginning of a file, but if I write with that, it will overwrite what's there. Do I have to write a new file and then write the other data to it line by line, or is there a better way?I am trying to figure out how to write a new li