The R Project SVN R

% File src/library/utils/man/make.socket.Rd
% Part of the R package, https://www.R-project.org
% Copyright 1995-2015 R Core Team
% Distributed under GPL 2 or later

\name{make.socket}
\alias{make.socket}
\alias{print.socket}
\title{Create a Socket Connection}
\usage{
make.socket(host = "localhost", port, fail = TRUE, server = FALSE)
}
\arguments{
  \item{host}{name of remote host}
  \item{port}{port to connect to/listen on}
  \item{fail}{failure to connect is an error?}
  \item{server}{a server socket?}
}
\description{
  With \code{server = FALSE} attempts to open a client socket to the
  specified port and host.  With \code{server = TRUE} the \R process
  listens on the specified port for a connection and then returns a
  server socket.  It is a good idea to use \code{\link{on.exit}} to
  ensure that a socket is closed, as you only get 64 of them.
}
\value{
  An object of class \code{"socket"}, a list with components:
  \item{socket}{socket number.  This is for internal use.  On a
    Unix-alike it is a file descriptor.}
  \item{port}{port number of the connection.}
  \item{host}{name of remote computer.}
}
\author{Thomas Lumley}
\references{
  Adapted from Luke Tierney's code for \code{XLISP-Stat}, in turn
  based on code from Robbins and Robbins \dQuote{Practical UNIX Programming}.
}
\section{Warning}{
  I don't know if the connecting host name returned
  when \code{server = TRUE} can be trusted.  I suspect not.
}

\seealso{
  \code{\link{close.socket}}, \code{\link{read.socket}}.

  Compiling in support for sockets was optional prior to \R 3.3.0: see
  \code{\link{capabilities}("sockets")} to see if it is available.
}

\examples{
daytime <- function(host = "localhost"){
    a <- make.socket(host, 13)
    on.exit(close.socket(a))
    read.socket(a)
}
## Official time (UTC) from US Naval Observatory
\dontrun{daytime("tick.usno.navy.mil")}
}
\keyword{misc}