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% File src/library/utils/man/make.socket.Rd
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% Part of the R package, https://www.R-project.org
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% Copyright 1995-2015 R Core Team
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% Distributed under GPL 2 or later
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\name{make.socket}
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\alias{make.socket}
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\alias{print.socket}
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\title{Create a Socket Connection}
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\usage{
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make.socket(host = "localhost", port, fail = TRUE, server = FALSE)
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}
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\arguments{
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  \item{host}{name of remote host}
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  \item{port}{port to connect to/listen on}
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  \item{fail}{failure to connect is an error?}
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  \item{server}{a server socket?}
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}
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\description{
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  With \code{server = FALSE} attempts to open a client socket to the
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  specified port and host.  With \code{server = TRUE} the \R process
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  listens on the specified port for a connection and then returns a
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  server socket.  It is a good idea to use \code{\link{on.exit}} to
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  ensure that a socket is closed, as you only get 64 of them.
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}
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\value{
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  An object of class \code{"socket"}, a list with components:
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  \item{socket}{socket number.  This is for internal use.  On a
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    Unix-alike it is a file descriptor.}
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  \item{port}{port number of the connection.}
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  \item{host}{name of remote computer.}
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}
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\author{Thomas Lumley}
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\references{
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  Adapted from Luke Tierney's code for \code{XLISP-Stat}, in turn
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  based on code from Robbins and Robbins \dQuote{Practical UNIX Programming}.
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}
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\section{Warning}{
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  I don't know if the connecting host name returned
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  when \code{server = TRUE} can be trusted.  I suspect not.
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}
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\seealso{
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  \code{\link{close.socket}}, \code{\link{read.socket}}.
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  Compiling in support for sockets was optional prior to \R 3.3.0: see
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  \code{\link{capabilities}("sockets")} to see if it is available.
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}
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\examples{
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daytime <- function(host = "localhost"){
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    a <- make.socket(host, 13)
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    on.exit(close.socket(a))
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    read.socket(a)
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}
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## Official time (UTC) from US Naval Observatory
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\dontrun{daytime("tick.usno.navy.mil")}
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}
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\keyword{misc}