Apache access log format| Log Format of Apache

LogFormat “%h %l %u %t \”%r\” %>s %b \”%{Referer}i\” \”%{User-agent}i\”" combined
  • %h is the remote host (ie the client IP)
  • %l is the identity of the user determined by identd (not usually used since not reliable)
  • %u is the user name determined by HTTP authentication
  • %t is the time the server finished processing the request.
  • %r is the request line from the client. (“GET / HTTP/1.0″)
  • %>s is the status code sent from the server to the client (200, 404 etc.)
  • %b is the size of the response to the client (in bytes)
  • Referer is the page that linked to this URL.
  • User-agent is the browser identification string.
Reference:
http://httpd.apache.org/docs/2.2/logs.html