.uucp

The name uucp was a pseudo-domain-style suffix used in the 1980s when identifying a hostname not connected directly to the Internet, but possibly reachable through other inter-network gateways. The suffix was appended to a UUCP bang path separated with a dot, e.g., host1!host2!host3.uucp. The suffix prevented messages from being routed via the Simple Mail Transfer Protocol (SMTP) in mail exchangers, and it indicated that the hostname preceding it was reachable by UUCP networking. It was not a top-level domain in the Domain Name System (DNS) root.

As UUCP hosts were not always uniquely named, and there was no official global table listing them, although the UUCP Mapping Project was an informal effort to create such a list, actual access to one (e.g., for routing e-mail to it) required the use of a full bang path, which did not follow domain-name-style syntax, unless the particular software being used had been programmed to recognize particular hostnames in a domain style and route to them.

UUCP

UUCP is an abbreviation of Unix-to-Unix Copy. The term generally refers to a suite of computer programs and protocols allowing remote execution of commands and transfer of files, email and netnews between computers.

A command named uucp is one of the programs in the suite; it provides a user interface for requesting file copy operations. The UUCP suite also includes uux (user interface for remote command execution), uucico (the communication program that performs the file transfers), uustat (reports statistics on recent activity), uuxqt (execute commands sent from remote machines), and uuname (reports the UUCP name of the local system). Some versions of the suite include uuencode/uudecode (convert 8-bit binary files to 7-bit text format and vice versa).

Although UUCP was originally developed on Unix in the 1970s and 1980s, and is most closely associated with Unix-like systems, UUCP implementations exist for several non-Unix-like operating systems, including Microsoft's MS-DOS, IBM's OS/2, Digital's VAX/VMS, Commodore's AmigaOS, classic Mac OS, and even CP/M.