Common Log Format

The Common Log Format is a standardised text file format used by web servers when generating log files. Because the format is standardised, the files may be analysed by a variety of analysis programs.

Each line in a file stored in the Common Log Format has the following syntax:

host ident authuser date request status bytes

Example

 127.0.0.1 - frank [10/Oct/2000:13:55:36 -0700] "GET /apache_pb.gif HTTP/1.0" 200 2326

A "-" in a field indicates missing data.

• 127.0.0.1 is the IP address of the client (remote host) which made the request to the server.
• - RFC 1413 identity of the client.
• frank is the userid of the person requesting the document.
• [10/Oct/2000:13:55:36 -0700] is the date, time, and time zone when the server finished processing the request, by default in strftime format %d/%b/%Y:%H:%M:%S %z
• "GET /apache_pb.gif HTTP/1.0" is the request line from the client. The method GET, /apache_pb.gif the resource requested, and HTTP/1.0 the HTTP protocol.
• 200 is the HTTP status code returned to the client. 2xx is a successful response, 3xx a redirection, 4xx a client error, and 5xx a server error.
• 2326 is the size of the object returned to the client, measured in bytes.

See also

• Extended Log Format
• Log management and intelligence
• Web log analysis software
• Web counter
• Data logging
• Syslog

References

• Common Logfile Format as described in the documentation of the World Wide Web consortia webserver (W3C httpd).
• Common Logfile Format as described in the documentation of the Apache webserver (2.2)
• Extended Logging Format - Draft from 1996