Definition
Unix-to-Unix Copy (UUCP) is a suite of legacy protocols and software tools for transferring files and emails between computers. While it was initially developed for Unix in the 1970s, other operating systems, like classic macOS, DOS, and OS/2/, later adapted it.
However, modern systems have replaced UUCP with the TCP/IP protocols. Nonetheless, some UUCP principles, such as configuration files and batch processing, have significantly impacted the development of modern networking technologies.
How UUCP Works
Before transmitting any file, the involved systems must define the UUCP ‘Systems’ file and configure the access permissions in the ‘Permissions’ file.
Then, the sending system uses the Unix-to-Unix Input/Output (UUCICO) daemon to create a dial-up connection to the receiving system and share information about the files to be transferred.
After that, the UUX command (which facilitates running commands on the remote system) starts the file transfer. Batch processing enables the UUCP to transfer multiple files in a single session. The daemon closes the connection once the transfer is complete, and the system resumes an idle state.