rcp stands for the Unix 'remote copy' command. It is a command on the Unix operating systems that is used to remotely copy—to copy one or more files from one computer system to another. It typically uses the TCP/IP protocol and the .rhosts file for authentication, but has been implemented to alternatively support Kerberos.

As described in the rlogin

Rlogin

rlogin is a software utility for Unix-like computer operating systems that allows users to log in on another host via a network, communicating via TCP port 513.It was first distributed as part of the 4.2BSD release....

 article, rcp is not secure for network use, because it sends unencrypted information over the network, among other things. It has largely been replaced by the ssh

Secure Shell

Secure Shell is a network protocol for secure data communication, remote shell services or command execution and other secure network services between two networked computers that it connects via a secure channel over an insecure network: a server and a client...

-based utility scp

Secure copy

Secure Copy or SCP is a means of securely transferring computer files between a local and a remote host or between two remote hosts. It is based on the Secure Shell protocol....

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