capabilities(what = NULL)NULL, specifying
    required components.  NULL implies that all are required.jpeg function operational?png function operational?tiff function operational?"X11" is also available.
  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 X11 device has already been used.aquaIs the quartz function operational?
    Only on some OS X builds, including CRAN binary
    distributions of R.Note that this is distinct from .Platform$GUI == "AQUA",
    which is true only when using the Mac R.app GUI console.
 windows
  X11always FALSE on Windows.
  aquaFALSE except on OS X.
  url and the internal method for
    download.file available?make.socket and related functions
    available?libxml with
    the R event loop?readline
    support has been compiled in and --no-readline was
    not used when R was invoked.  (If --interactive
    was used, command-line editing will not actually be available.)
  iconv supported?  Always true in current R.tracemem.svg,
    cairo_pdf and cairo_ps devices, and
    for type = "cairo" in the
 unix
    X11,
    bmp, jpeg, png,
    and tiff devices?icuSetCollate: it is never
    used for a C locale.C long double
    type which is longer than double?  Some platforms do not
    have such a type, and on others its use can be suppressed by the
    configure option --disable-long-double.Although not guaranteed, it is a reasonable assumption that if
    present long doubles will have at least as much range and accuracy
    as the ISO/IEC 60559 80-bit extended precision format.
  libcurl available in this build?  Used by
    function curlGetHeaders and optionally by
    download.file and url..Platformcapabilities()
if(!capabilities("http/ftp"))
   warning("internal download.file() method is not available")
## See also the examples for 'connections'.
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