download.packages("[パッケージ名]", destdir="/download/dir", type="source")
で、ダウンロードできる。

http://d.hatena.ne.jp/t_ume_tky/20120725/1343189052
に記載されているのを発見。

??download.package

download.packages {utils}	R Documentation
Download Packages from CRAN-like Repositories

Description

These functions can be used to automatically compare the version numbers of installed packages with the newest available version on the repositories and update outdated packages on the fly.

Usage

download.packages(pkgs, destdir, available = NULL,
                  repos = getOption("repos"),
                  contriburl = contrib.url(repos, type),
                  method, type = getOption("pkgType"), ...)
Arguments

pkgs	
character vector of the names of packages whose latest available versions should be downloaded from the repositories.

destdir	
directory where downloaded packages are to be stored.

available	
an object as returned by available.packages listing packages available at the repositories, or NULL which makes an internal call to available.packages.

repos	
character vector, the base URL(s) of the repositories to use, i.e., the URL of the CRAN master such as "https://cran.r-project.org" or its Statlib mirror, "http://lib.stat.cmu.edu/R/CRAN".

contriburl	
URL(s) of the contrib sections of the repositories. Use this argument only if your repository mirror is incomplete, e.g., because you burned only the ‘contrib’ section on a CD. Overrides argument repos.

method	
Download method, see download.file.

type	
character string, indicate which type of packages: see install.packages and ‘Details’.

...	
additional arguments to be passed to download.file and available.packages.

Details

download.packages takes a list of package names and a destination directory, downloads the newest versions and saves them in destdir. If the list of available packages is not given as argument, it is obtained from repositories. If a repository is local, i.e. the URL starts with "file:", then the packages are not downloaded but used directly. Both "file:" and "file:///" are allowed as prefixes to a file path. Use the latter only for URLs: see url for their interpretation. (Other forms of file:// URLs are not supported.)

For download.packages, type = "both" looks at source packages only.

Value

A two-column matrix of names and destination file names of those packages successfully downloaded. If packages are not available or there is a problem with the download, suitable warnings are given.

See Also

available.packages, contrib.url.

The main use is by install.packages.

See download.file for how to handle proxies and other options to monitor file transfers.

The ‘R Installation and Administration’ manual for how to set up a repository.

[Package utils version 3.5.1 Index]