Transform a file with dynamic size.

[Irelia]

We want to transform a file which is being written to. 

In other words,we want to send one request to NGINX server to download a
file which is being written to. And we want to get the complete file
finally. We read http/1.1 and knew that the "Transfer-Encoding: chunked "
should be used. 

But we don't know how to let NGINX know the file is not completed and use "
Transfer-encoding: Chunked". 

Please suggest us some ways .

Posted at Nginx Forum: https://forum.nginx.org/read.php?2,283332,283332#msg-283332