how to separate robot access log and human access log

[meteor8488]

thanks for your reply.

I know that I can use if to enable conditional logging.
But what I want to do is 

if $spiderbot=0, then log to location_access.log
if $spiderbot=1, then log to spider_access.log.

And I don't want the same logs write to different files.
How can I do that?

thanks

Posted at Nginx Forum: http://forum.nginx.org/read.php?2,258417,258656#msg-258656