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
  Hypertext Transfer Protocol
  The Hypertext Transfer Protocol is a networking protocol for distributed, collaborative, hypermedia information systems. HTTP is the foundation of data communication for the World Wide Web....
  
  .
• 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 byte
  Byte
  The byte is a unit of digital information in computing and telecommunications that most commonly consists of eight bits. Historically, a byte was the number of bits used to encode a single character of text in a computer and for this reason it is the basic addressable element in many computer...
  
  s.

See also

• Extended Log Format
  Extended Log Format
  Extended Log Format is a standardised text file format, like Common Log Format , that is used by web servers when generating log files, but ELF files provide more information and flexibility.- Example : #Version: 1.0 #Date: 12-Jan-1996 00:00:00...
  
  
• Log management and intelligence
  Log management and intelligence
  Log management comprises an approach to dealing with large volumes of computer-generated log messages...
  
  
• Web log analysis software
  Web log analysis software
  Web log analysis software is a simple kind of Web analytics software that parses a log file from a web server, and based on the values contained in the log file, derives indicators about who, when, and how a web server is visited...
  
  
• Web counter
  Web counter
  A web counter or hit counter is a computer software program that indicates the number of visitors, or hits, a particular webpage has received...
  
  
• Data logging
• Syslog
  Syslog
  Syslog is a standard for computer data logging. It allows separation of the software that generates messages from the system that stores them and the software that reports and analyzes them...