how to read $body_bytes_sent nginx variable

Maxim Dounin mdounin at
Tue Nov 22 12:52:43 UTC 2016


On Tue, Nov 22, 2016 at 05:21:45AM -0500, Phani Sreenivasa Prasad wrote:

> Hi 
> I want to read the nginx the value of nginx variable $body_bytes_sent from
> my fastcgi application to check how many bytes nginx had sent to client? 
> I tried something below
> fastcgi_param BODY_BYTES_SENT $body_bytes_sent in my fastcgi_params
> and trying to read the fastcgi param value from the fastcgi application. But
> it always returns 0. 
> Please help me how to read nginx variables(apart from those defined default
> in fastcgi_params file) from my fastcgi app and when to read? I need to know
> when the value of $body_bytes_sent will get populated?

The $body_bytes_sent variable represents number of bytes sent to a 
client.  Obviously it is expected to be 0 before you've sent a 
response.  Effectively it is only available while logging a 

Maxim Dounin

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