% File src/library/base/man/capabilities.Rd
% Part of the R package, http://www.R-project.org
% Copyright 1995-2014 R Core Team
% Distributed under GPL 2 or later

\name{capabilities}
\alias{capabilities}
\title{Report Capabilities of this Build of R}
\description{
  Report on the optional features which have been compiled into this
  build of \R.
}
\usage{
capabilities(what = NULL)
}
\arguments{
  \item{what}{character vector or \code{NULL}, specifying
    required components.  \code{NULL} implies that all are required.}
}
#ifdef unix
\section{Note to OS X users}{
  Capabilities \code{"jpeg"}, \code{"png"} and \code{"tiff"} refer to
  the X11-based versions of these devices.  If
  \code{capabilities("aqua")} is true, then these devices with
  \code{type = "quartz"} will be available, and out-of-the-box will be the
  default type.  Thus for example the \code{\link{tiff}} device will be
  available if \code{capabilities("aqua") || capabilities("tiff")} if
  the defaults are unchanged.
}
#endif
\value{
  A named logical vector.  Current components are
    \item{jpeg}{is the \code{\link{jpeg}} function operational?}
    \item{png}{is the \code{\link{png}} function operational?}
    \item{tiff}{is the \code{\link{tiff}} function operational?}
    \item{tcltk}{is the \pkg{tcltk} package operational?
#ifdef unix
      Note that to make use of Tk you will almost always need to check
      that \code{"X11"} is also available.
#endif
    }
#ifdef unix
    \item{X11}{Are the \code{\link{X11}} graphics device and the
      X11-based data editor available?  This loads the X11 module if not
      already loaded, and checks that the default display can be
      contacted unless a \code{X11} device has already been used.}
    \item{aqua}{Are the \code{R.app} GUI components and the
      \code{\link{quartz}} function operational?  Only on some OS X
      builds.  Note that this is distinct from
      \code{.Platform$GUI == "AQUA"}, which is true when using the Mac
      \code{R.app} GUI console.}
#endif
#ifdef windows
    \item{X11}{always \code{FALSE} on Windows.}
    \item{aqua}{\code{FALSE} except on OS X.}
#endif
    \item{http/ftp}{Are \code{\link{url}} and the internal method for
      \code{\link{download.file}} available?}
    \item{sockets}{Are \code{\link{make.socket}} and related functions
      available?}
    \item{libxml}{is there support for integrating \code{libxml} with
      the \R event loop?}
    \item{fifo}{are FIFO \link{connections} supported?}
    \item{cledit}{is command-line editing available in the current \R
      session?  This is false in non-interactive sessions.
#ifdef unix
      It will be true for the command-line interface if \code{readline}
      support has been compiled in and \option{--no-readline} was
      \emph{not} used when \R was invoked.  (If \option{--interactive}
      was used, command-line editing will not actually be available.)
#endif
      }
    \item{iconv}{is internationalization conversion via
      \code{\link{iconv}} supported?  Always true in current \R.}
    \item{NLS}{is there Natural Language Support (for message translations)?}
    \item{profmem}{is there support for memory profiling?  See
      \code{\link{tracemem}}.}
    \item{cairo}{is there support the \code{\link{svg}},
      \code{\link{cairo_pdf}} and \code{\link{cairo_ps}} devices, and
      for \code{type = "cairo"} in the
#ifdef unix
      \code{\link{X11}},
#endif
      \code{\link{bmp}}, \code{\link{jpeg}}, \code{\link{png}},
      and \code{\link{tiff}} devices?}
}
\seealso{\code{\link{.Platform}}}

\examples{
capabilities()

if(!capabilities("http/ftp"))
   warning("internal download.file() is not available")

## See also the examples for 'connections'.
}
\keyword{utilities}