Berkeley r-commands

The Berkeley r-commands are a suite of computer programs designed to enable users of one Unix system to log in or issue commands to another Unix computer via TCP/IP computer network. The r-commands were developed in 1982 by the Computer Systems Research Group (CSRG) at the University of California, Berkeley, based on an early implementation of TCP/IP (the protocol stack of the Internet).

The CSRG incorporated the r-commands into their Unix operating system, the Berkeley Software Distribution (BSD). The r-commands premiered in BSD v4.1. Among the programs in the suite are: rcp (remote copy), rexec (remote execution), rlogin (remote login), rsh (remote shell), rstat, ruptime, and rwho (remote who).

The r-commands were a significant innovation, and became de facto standards for Unix operating systems. With wider public adoption of the Internet, their inherent security vulnerabilities became a problem, and beginning with the development of Secure Shell protocols and applications in 1995, its adoption entirely supplanted the deployment and use of r-commands (and Telnet) on networked systems.