Every Web servers maintain some sort of system that stores information about which pages, images, and files are requested, who requests them, and how many bytes are transferred etc in a file called log file. With log file analysis tools, it’s possible to get a good idea about your visitors such as were they are coming from, how often they return, and how they navigate through your site, which pages are most visited etc.

These log files are used by administrator for effectively managing web server, getting feedback about performance of servers etc.

You can open and read log files in any text editor; for more user-friendly view you can use some stand-alone software or browser-based viewer which will give you more precise data in form of charts/graphs/tables.

The format of the common log file line has the following fields separated by a space:

Remotehost rfc931 authuser [date] “request” status bytes

151.99.190.27 - - [09/Jan/2007:13:06:51] “GET /~bacusHTTP/1.0″ 301 13276

For the above example:

remotrhost : 151.99.190.27
authuser : -
frc931 : -
[date] : [09/Jan/200713:06:51 -0600]
” request ” : ” GET /~bacuslab HTTP/1.0″
status: 301
bytes : 13276

Understanding log fields :

remotehost : Remote hostname or IP address number if DNS hostname is not available.

rfc931 : The remote login name of the user. (If not available a minus sign is typically placed in the field)

authuser :The username as which the user has authenticated himself. (If not available a minus sign is typically placed in the field)

[date] : Date and time of the request.

“request” : The request line exactly as it came from the client. (i.e., the file name, and the method used to retrieve it [typically GET])

status : The HTTP response code returned to the client. Indicates whether or not the file was successfully retrieved, and if not, what error message was returned.

bytes : The number of bytes transferred.