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R is a programming language for statistical computing and data visualization. It has been adopted in the fields of data mining, bioinformatics, and data analysis. [8] The core R language is augmented by a large number of extension packages, containing reusable code, documentation, and sample data. R software is open-source and free software.
Declarative programming stands in contrast to imperative programming via imperative programming languages, where control flow is specified by serial orders (imperatives). (Pure) functional and logic-based programming languages are also declarative, and constitute the major subcategories of the declarative category.
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- Protocol
- Commands
- Security
- Further Reading
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The original Berkeley package that provides rlogin also features rcp (remote-copy, allowing files to be copied over the network) and rsh(remote-shell, allowing commands to be run on a remote machine without the user logging into it). As an example, the protocol is as follows: The server would check that the user should have access. If so, it return...
rlogin
rlogin enables a user to log in on another server via computer network, using TCP network port513. rlogin is also the name of the application layer protocol used by the software, part of the TCP/IP protocol suite. Authenticated users can act as if they were physically present at the computer. RFC 1282, in which it was defined, states: "The rlogin facility provides a remote-echoed, locally flow-controlled virtual terminal with proper flushing of output." rlogin communicates with a daemon, rlog...
rsh
rsh opens a shell on a remote computer without a login procedure. Once connected, the user can execute commands on the remote computer through the shell's command-line interface. rsh passes input and output through the standard streams, and it sends standard output to the user's console. Over the network, standard input and standard out flow through TCP port 514, while Standard Error flows through a different TCP port, which the rsh daemon (rshd) opens.
rexec
Like rsh, rexec enables the user to run shell commands on a remote computer. However, unlike the rsh server, the rexec server (rexecd) requires login: it authenticates users by reading the username and password (unencrypted) from the network socket. rexecuses TCP port 512.
Those r-commands which involve user authentication (rcp, rexec, rlogin, and rsh) share several serious security vulnerabilities: 1. All information, including passwords, is transmitted unencrypted (making it vulnerable to interception). 2. The .rlogin (or .rhosts) file is easy to misuse. They are designed to allow logins without a password, but the...
Noordergraaf, Alex (2003) [2002]. "Remote Access Services (rsh, rlogin, and rcp)". Enterprise Security: Solaris Operating Environment, Security Journal, Solaris OE v2.51, 2.6, 7, and 8. Prentice Ha...Poniatowski, Marty (2000). UNIX User's Handbook (1st ed.). Prentice Hall. pp. 475–77. ISBN 978-0-13-027019-1. OCLC 43561861.Rogers, Lawrence R. (November 1998). "rlogin(1): The Untold Story" (PDF). Archived from the original (PDF)on 2001-12-17.RFC 1282, BSD Rlogin (1991)rlogin(1) – Linux User Commands Manualrlogin(1): remote login – Darwin and macOS General Commands Manualrlogin(1): remote login – Solaris 11.4 User Commands Reference Manualv. t. e. The analytical engine was a proposed digital mechanical general-purpose computer designed by English mathematician and computer pioneer Charles Babbage. [2] [3] It was first described in 1837 as the successor to Babbage's difference engine, which was a design for a simpler mechanical calculator. [4] The analytical engine incorporated ...
In certain theories of syntax, an R-expression (short for referring expression) is a category in the three-way classification of noun phrases in binding theory, the other two being anaphors and pronominals. According to principle C of binding theory, R-expressions must be free.
In computer science, imperative programming is a programming paradigm of software that uses statements that change a program's state. In much the same way that the imperative mood in natural languages expresses commands, an imperative program consists of commands for the computer to perform.
Rattle GUI is a free and open source software ( GNU GPL v2) package providing a graphical user interface (GUI) for data mining using the R statistical programming language. Rattle is used in a variety of situations.
