Unix-to-Unix Copy (UUCP) started out as a package of programs that
transferred files over serial lines, scheduled those transfers, and
initiated execution of programs on remote sites. It has undergone major
changes since its first implementation in the late seventies, but it
is still rather spartan in the services it offers. Its main
application is still in Wide Area Networks, based on periodic dialup
telephone links.
UUCP was first developed by Bell Laboratories in 1977 for
communication between their Unix development sites. In mid-1978, this
network already connected over 80 sites. It was running email as an
application, as well as remote printing. However, the system's
central use was in distributing new software and bug fixes. Today, UUCP
is not confined solely to the Unix environment. There are free and
commercial ports available for a variety of platforms, including
AmigaOS, DOS, and Atari's TOS.
One of the main disadvantages of UUCP networks is that they operate in
batches. Rather than having a permanent connection established between
hosts, it uses temporary connections. A UUCP host machine might dial in to
another UUCP host only once a day, and then only for a short period of time.
While it is connected, it will transfer all of the news, email, and files that
have been queued, and then disconnect. It is this queuing that limits the
sorts of applications that UUCP can be applied to. In the case of email, a
user may prepare an email message and post it. The message will stay queued
on the UUCP host machine until it dials in to another UUCP host to transfer
the message. This is fine for network services such as email, but is no
use at all for services such as rlogin.
Despite these limitations, there are still many UUCP networks
operating all over the world, run mainly by hobbyists, which offer
private users network access at reasonable prices. The main reason for
the longtime popularity of UUCP was that it was very cheap compared to
having your computer directly connected to the Internet. To make your
computer a UUCP node, all you needed was a modem, a working UUCP
implementation, and another UUCP node that was willing to feed you
mail and news. Many people were prepared to provide UUCP feeds to
individuals because such connections didn't place much demand on their
existing network.
We cover the configuration of UUCP in a chapter of its own later in
the book, but we won't focus on it too heavily, as it's being replaced
rapidly with TCP/IP, now that cheap Internet access has become commonly
available in most parts of the world.
