Format of the FDSE log file
By default, FDSE logs all searches to the file "searchdata/search.log.txt". In SQL logging mode, the same data fields are logged to a SQL table.
The log holds one record per visitor search. In the file, records are separated by newlines, and fields are separated by commas.
Each record looks like this:
$host ,$time,$human_time,$realm,$terms,$rank,$documents_found,$documents_searched,\n
$host is an IP address or fully-qualified domain name, pulled from $ENV{'REMOTE_HOST'}. It is the only field with a forced trailing space, which was added for compatibility with IP-resolution utilities.
$time is the number of seconds since 1970, as returned by time(). $human_time is a human-readable string, like '03/21/2001 18:27'.
$realm is the literal value of the 'Realm' form field, typically either 'All' or a named realm. In newer versions this many return 'include-by-name', in which case the exact realms which were included will not be known.
$terms is the literal value of the 'Terms' form field.
$rank is the starting position, 1 for default searches, 11 for "next page" hits, 21 for the next page, etc. Graphing the rank distribution shows how deeply visitors will explore multi-page search results.
$documents_found is the integer total number of search results for these search terms.
$documents_searched is the integer total number of documents searched (equal to the total number of documents in each realm that was searched).
Note: all newlines and commas are converted to spaces before being written to the log, and leading/trailing whitespace is stripped, and sequential whitespace is collapsed to a single space. Thus a literal search for ' what , ever ' will be logged as 'what ever'.
SQL Mode: when running with SQL logging, all above fields are saved to a SQL table instead of the 'search.logs.txt' file. To control the logging mode, go to "Admin Page" => "Data Storage" => "Select Log Storage Method".
Code
Searches are logged with the log_search subroutine in common.pl. Logs are viewed through the ui_ViewStats subroutine in common_admin.pl.
"Format of the FDSE log file"
http://www.xav.com/scripts/search/help/1083.html