What is the fd_install file?
During the install, the installer needs to determine which FTP path, Perl path and CGI extension will work on your server. It uploads several files named fd_install.cgi or fd_install.pl and then makes web requests for them to see if they execute properly as CGI scripts. During this "path discovery" process, the server may return 404 Not Found errors as the installer tries to negotiate which FTP path maps to the web path.
Once the script finishes with Step 5, Verify Install Information, it will move on to Step 6, Install and Test. Between these steps it will leave a larger fd_install.cgi script on the server which is used to report on the progress of the install. If you abandon the install after Step 5, or if the install fails to complete after Step 5, then the fd_install file may be permanently left on your server. You can safely delete this file. Its output includes server path information, Perl version, and the output of file existence checks for all script files.
"What is the fd_install file?" http://www.xav.com/scripts/installer/3054.html