用户parkydr给出了更好的答案:

User parkydr gave the better answer:

您无法从stdin创建tar文件. tar中的每个文件都有一个包含文件长度的标头，因此tar在写标头之前必须知道有多少数据. – parkydr

You can't create a tar file from stdin. Each file in the tar has a header including the length of the file, so tar has to know how much data there is before writing the header. – parkydr