url.exists: Check if URL exists

Description

This functions is analogous to file.exists and determines whether a request for a specific URL responds without error. We make the request but ask the server not to return the body. We just process the header.

Usage

url.exists(url, ..., .opts = list(...),
            curl = getCurlHandle(.opts = .opts),
             .header = FALSE)

Value

If .header is FALSE, this returns

TRUE or FALSE for each URL indicating whether the request was successful (had a status with a value in the 200 range).

If .header is TRUE, the header is returned for the request for each URL.

Arguments

url: a vector of one or more URLs whose existence we are to test
...: name = value pairs of Curl options.
.opts: a list of name = value pairs of Curl options.
curl: a Curl handle that the caller can specify if she wants to reuse an existing handle, e.g. with different options already specified or that has previously established a connection to the Web server
.header: a logical value that if TRUE causes the header information to be returned.

Author

Duncan Temple Lang

Details

This makes an HTTP request but with the nobody option set to FALSE so that we don't actually retrieve the contents of the URL.

References

HTTP specification

Examples

Run this code

 url.exists("https://www.omegahat.net/RCurl")
 try(url.exists("https://www.omegahat.net/RCurl-xxx"))

Run the code above in your browser using DataLab

Last chance! 50% off unlimited learning