\Header{library.dynam}{Loading Shared Libraries}
\alias{.dynLibs}{library.dynam}
\methalias{library.dynam.unload}{library.dynam}
\keyword{data}{library.dynam}
\begin{Description}\relax
Load the specified file of compiled code if it has not been loaded
already, or unloads it.
\end{Description}
\begin{Usage}
\begin{verbatim}
library.dynam(chname, package = .packages(), lib.loc = NULL,
              verbose = getOption("verbose"),
              file.ext = .Platform$dynlib.ext, ...)
library.dynam.unload(chname, libpath,
              verbose = getOption("verbose"),
              file.ext = .Platform$dynlib.ext)
.dynLibs(new)
\end{verbatim}
\end{Usage}
\begin{Arguments}
\begin{ldescription}
\item[\code{chname}] a character string naming a shared library to load.
\item[\code{package}] a character vector with the names of packages to search
through.
\item[\code{lib.loc}] a character vector describing the location of \R{}
library trees to search through, or \code{NULL}.  The default value
of \code{NULL} corresponds to all libraries currently known.
\item[\code{libpath}] the path to the loaded package whose shared library is
to be unloaded.
\item[\code{verbose}] a logical value indicating whether an announcement
is printed on the console before loading the shared library.  The
default value is taken from the verbose entry in the system
options.
\item[\code{file.ext}] the extension to append to the file name to specify
the library to be loaded. This defaults to the appropriate value
for the operating system.
\item[\code{...}] additional arguments needed by some libraries that
are passed to the call to \code{\Link{dyn.load}} to control
how the library is loaded.
\item[\code{new}] a character vector of packages which have loaded shared
libraries.
\end{ldescription}
\end{Arguments}
\begin{Details}\relax
\code{library.dynam} is designed to be used inside a package rather
than at the command line, and should really only be used inside
\code{\Link{.First.lib}} on \code{\Link{.onLoad}}.  The
system-specific extension for shared libraries
(e.g., \file{.so} or \file{.sl} on Unix systems)
should not be added.

\code{library.dynam.unload} is designed for use in \code{\Link{.Last.lib}} or
\code{\Link{.onUnload}}.

\code{.dynLibs} is used for getting or setting the packages that have
loaded shared libraries (using \code{library.dynam}).  Versions of \R{}
prior to 1.6.0 used an internal global variable \code{.Dyn.libs} for
storing this information: this variable is now defunct.
\end{Details}
\begin{Value}
\code{library.dynam} returns a character vector with the names of
packages which have used it in the current \R{} session to load shared
libraries.  This vector is returned as \code{\Link{invisible}}, unless
the \code{chname} argument is missing.

\code{library.dynam.unload} returns the updated character vector, invisibly.
\end{Value}
\begin{References}\relax
Becker, R. A., Chambers, J. M. and Wilks, A. R. (1988)
\emph{The New S Language}.
Wadsworth \& Brooks/Cole.
\end{References}
\begin{SeeAlso}\relax
\code{\Link{.First.lib}}, \code{\Link{library}},
\code{\Link{dyn.load}}, \code{\Link{.packages}},
\code{\Link{.libPaths}}

\code{\Link{SHLIB}} for how to create suitable shared libraries.
\end{SeeAlso}
\begin{Examples}
\begin{ExampleCode}
library.dynam() # which packages have been "dynamically loaded"
\end{ExampleCode}
\end{Examples}

