How to reference OS Environment Variales in nginx.conf

[caoxingk]

Hi there,

After set a variable by `set $name value`, i can reference it like
`$name`,
but when i export a OS Environment Variale by `env name_from_env`, like
http://wiki.nginx.org/CoreModule#env said,
and i am sure the name_from_env is valid which defined form nginx's
parent process.

But, my friends, how to reference it ? 
$name_from_env or ${name_from_env} or %name_from_env% didn't work what
i've tried before.

Thanks a lot.

Posted at Nginx Forum: http://forum.nginx.org/read.php?2,215269,215269#msg-215269