The "cgi" command:

Usage: fossil ?cgi? SCRIPT

The SCRIPT argument is the name of a file that is the CGI script
that is being run.  The command name, "cgi", may be omitted if
the GATEWAY_INTERFACE environment variable is set to "CGI" (which
should always be the case for CGI scripts run by a webserver.)  The
SCRIPT file should look something like this:

     #!/usr/bin/fossil
     repository: /home/somebody/project.db

The second line defines the name of the repository.  After locating
the repository, fossil will generate a webpage on stdout based on
the values of standard CGI environment variables.

See also: http, server, winsrv