Some operating systems have replaced the old Unix inetd daemon with
xinetd, which has a similar mission but with a very different
configuration file format.
The typical configuration file is either /etc/xinetd.conf or a subfile
in the /etc/xinetd.d directory. You need a configuration something
like this for Fossil:
service http
{
  port = 80
  socket_type = stream
  wait = no
  user = root
  server = /usr/bin/fossil
  server_args = http /home/fossil/repos/
}
This example configures Fossil to serve multiple repositories under the
/home/fossil/repos/ directory.
Beyond this, see the general commentary in our article on the inetd
method as they also apply to service via xinetd.