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Check if a File Exists at a URL

Source: R/fileExistURL.R
fileExistURL.Rd

Performs an HTTP request to determine whether a resource exists at a given URL. Uses a HEAD request by default and falls back to GET if necessary.

Usage

fileExistURL(url, timeout = 5)

Arguments

url

character string. The full URL to check.

timeout

numeric. Timeout in seconds for the HTTP request. Default is 5.

Value

logical value indicating whether the resource exists (TRUE) or not (FALSE).

The returned value has additional attributes:

  • status: HTTP status code returned by the server (e.g. 200, 404).

  • error: error message (if a request error occurred).

Details

The function first sends an HTTP HEAD request to minimize data transfer. If the server responds with a status indicating that HEAD itself is not supported (403, 405, 501), a GET request is attempted as a fallback. A plain 404 is taken at face value, so that non-existing files do not trigger a second request.

If the request fails (e.g., due to network issues or invalid URLs), the function returns FALSE and stores the error message as an attribute.

See also

Other file.path: buildPath(), findDownload(), isFilePath(), isURL(), splitPath()

Examples

if (FALSE) { # \dontrun{
fileExistURL("https://www.example.com/data.csv")

res <- fileExistURL("https://invalid-url.test/file.csv")
attr(res, "status")
attr(res, "error")
} # }