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% File src/library/base/man/interactive.Rd
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% Part of the R package, http://www.R-project.org
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% Copyright 1995-2009 R Core Team
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% Distributed under GPL 2 or later
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r |
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\name{interactive}
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murdoch |
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\alias{interactive}
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pd |
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\title{Is R Running Interactively?}
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maechler |
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\description{
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hornik |
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Return \code{TRUE} when \R is being used interactively and
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\code{FALSE} otherwise.
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}
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r |
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\usage{
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interactive()
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}
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\details{
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An interactive \R session is one in which it is assumed that there is
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a human operator to interact with, so for example \R can prompt for
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corrections to incorrect input or ask what to do next or if it is OK
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to move to the next plot.
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GUI consoles will arrange to start \R in an interactive session. When
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\R is run in a terminal (via \command{Rterm.exe} on Windows), it
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assumes that it is interactive if \file{stdin} is connected to a
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(pseudo-)terminal and not if \file{stdin} is redirected to a file or
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pipe. Command-line options \option{--interactive} (Unix) and
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\option{--ess} (Windows, \command{Rterm.exe}) override the default
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assumption.
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#ifdef unix
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(On a Unix-alike, whether the \code{readline} command-line editor is
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ripley |
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used is \strong{not} overridden by \option{--interactive}.)
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#endif
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Embedded uses of \R can set a session to be interactive or not.
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Internally, whether a session is interactive determines
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\itemize{
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\item how some errors are handled and reported, e.g. see
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maechler |
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\code{\link{stop}} and \code{\link{options}("showWarnCalls")}.
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\item whether one of \option{--save}, \option{--no-save} or
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\option{--vanilla} is required, and if \R ever asks whether to save the
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workspace.
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maechler |
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ripley |
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\item the choice of default graphics device launched when needed and
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maechler |
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by \code{\link{dev.new}}: see \code{\link{options}("device")}
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\item whether graphics devices ever ask for confirmation of a new
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page.
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}
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In addition, \R's own \R code makes use of \code{interactive()}: for
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example \code{\link{help}}, \code{\link{debugger}} and
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\code{\link{install.packages}} do.
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}
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\note{
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This is a \link{primitive} function.
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}
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r |
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\seealso{
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hornik |
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\code{\link{source}},
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\code{\link{.First}}
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r |
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}
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\examples{
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.First <- function() if(interactive()) x11()
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}
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maechler |
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\keyword{environment}
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\keyword{programming}
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