\Header{zip.file.extract}{Extract File from a Zip Archive}
\keyword{file}{zip.file.extract}
\begin{Description}\relax
This will extract the file named \code{file} from the zip archive,
if possible, and write it in a temporary location.
\end{Description}
\begin{Usage}
\begin{verbatim}
zip.file.extract(file, zipname = "R.zip")
\end{verbatim}
\end{Usage}
\begin{Arguments}
\begin{ldescription}
\item[\code{file}] A file name.
\item[\code{zipname}] The file name of a \code{zip} archive, including the
\code{".zip"} extension if required.
\end{ldescription}
\end{Arguments}
\begin{Details}\relax
The method used is selected by \code{options(unzip=)}. All platforms
support an \code{"internal"} unzip: this is the default under Windows
and the fall-back under Unix if no \code{unzip} program was found
during configuration and \env{R\_UNZIPCMD} is not set.

The file will be extracted if it is in the archive and any required
\code{unzip} utility is available.  It will probably be extracted to
the directory given by \code{tempdir}, overwriting an existing file of
that name.
\end{Details}
\begin{Value}
The name of the original or extracted file.  Success is indicated by
returning a different name.
\end{Value}
\begin{Note}\relax
The \code{"internal"} method is very simple, and will not set file dates.
\end{Note}

