download.file              package:base              R Documentation

Download File from the Internet

Description:

     This function can be used to download a file from the Internet.

Usage:

     download.file(url, destfile, method, quiet = FALSE, mode="w",
                   cacheOK = TRUE)

Arguments:

     url: A character string naming the URL of a resource to be
          downloaded.

destfile: A character string with the name where the downloaded file is
          saved.  Tilde-expansion is performed.

  method: Method to be used for downloading files.  Currently download
          methods `"internal"', `"wget"' and `"lynx"' are available. 
          The default is to choose the first of these which
          `"internal"'. The method can also be set through the option
          `"download.file.method"': see `options()'.

   quiet: If `TRUE', suppress status messages (if any).

    mode: character.  The mode with which to write the file. Useful
          values are `"w"', `"wb"' (binary), `"a"' (append) and `"ab"'.
           Only used for the `"internal"' method.

 cacheOK: logical. Is a server-side cached value acceptable?
          Implemented for the `"internal"' and `"wget"' methods.

Details:

     The function `download.file' can be used to download a single file
     as described by `url' from the internet and store it in
     `destfile'. The `url' must start with a scheme such as
     `"http://"', `"ftp://"' or `"file://"'.

     `cacheOK = FALSE' is useful for `"http://"' URLs, and will attempt
     to get a copy directly from the site rather than from an
     intermediate cache.  (Not all platforms support it.) It is used by
     `CRAN.packages'.

     The remaining details apply to method `"internal"' only.

     The timeout for many parts of the transder can be set by the
     option `timeout' which defaults to 60 seconds.

     The level of detail provided during transfer can be set by the
     `quiet' argument and the `internet.info' option.  The details
     depend on the platform and scheme, but setting `internet.info' to
     0 gives all available details, including all server responses.
     Using 2 (the default) gives only serious messages, and 3 or more
     suppresses all messages.

     Proxies can be specified via environment variables. Setting
     `"no_proxy"' stops any proxy being tried. Otherwise the setting of
     `"http_proxy"' or `"ftp_proxy"' (or failing that, the all
     upper-case version) is consulted and if non-empty used as a proxy
     site.  For FTP transfers, the username and password on the proxy
     can be specified by `"ftp_proxy_user"' and `"ftp_proxy_password"'.

     Method `"wget"' can be used with proxy firewalls which require
     user/password authentication if proper values are stored in the
     configuration file for `wget'.

Note:

     Methods `"wget"' and `"lynx"' are for historical compatibility.
     They will block all other activity on the R process.

     For methods `"wget"' and `"lynx"' a system call is made to the
     tool given by `method', and the respective program must be
     installed on your system and be in the search path for
     executables.

See Also:

     `options' to set the `timeout' and `internet.info' options.

     `url' for a finer-grained way to read data from URLs.

     `url.show', `CRAN.packages', `download.packages' for applications

