The transfer of files among systems is the most common application of the Basic Networking Utilities (BNU). BNU uses four commands, uucp, uusend, uuto, and uupick, to exchange files between local and remote systems.
The uucp command is the primary BNU-data transfer utility. The uusend command is the Berkeley Software Distribution (BSD) transfer command incorporated into BNU. The uuto and uupick commands are specialized send and receive commands working with the uucp command.
The BNU commands, uuencode and uudecode, assist file transferring. These commands encode and decode binary files transmitted through the BNU mail facility.
The uucp command and options exchange files within your local system, between your local and a remote system, and between remote systems. The uucp options can, for example, create directories to hold files on the receiving end or mail messages on the success or failure of file transfers.
Use the uusend command specifically to send files to a remote system that is not directly linked to the sending system but is accessible through a chain of BNU connections. Though equipped with fewer options than the uucp command, uusend is included among the BNU utilities to satisfy the preferences of BSD UNIX-to-UNIX Copy Program (UUCP) users.
The uuto command sends files from one system to another. It is part of the uucp command and simplifies the file exchange process for senders and receivers. The uuto command sends files to a specific user and deposits them directly into the user's personal directory under that system's BNU public directory. It notifies the recipient that a file has arrived. The recipient uses the uupick command to handle the new file.
The uupick command receives and manipulates files sent with the uuto command. It has file-handling options that allow the recipient to, for example, find sent files, move files to a specified directory, execute commands, or delete files.
For a demonstration of how the uuto and uupick commands can be applied, see How to Use the uuto and uupick Commands to Exchange Files.
The uuencode and uudecode commands work in tandem to prepare files for transmission by modem. The uuencode command transforms binary files into ASCII files. These files can be sent by the mail facility to a remote system.
With the uudecode command, the receiving user converts ASCII-encoded files back to binary format.