How to determine if you have an internet connection in R

Question

Sometimes I need to download data from the internet. On occasions this has failed either because the website is down or because my computer has lost its internet connection.

Question: Is there some function in R which will return TRUE/FALSE as to whether I am connected to the internet?

What operating system? In Windows I think you'd have to run ipconfig from a shell, and on Linux it would be ifconfig. You'd then have to parse the output and test. — Spacedman, Feb 22 '11 at 10:15
The ability to download data from a remote machine depends on so many factors which are outside of the control of your code, and whose state may change at any time. The only 100% certain way to know if you can download the file is to attempt to download it, and succeed. Even if you can start a transfer, it doesn't guarantee that the net connection won't go down part way through, so you need to write code to cope with this situation anyway. So just write that code, and ditch trying to detect beforehand whether you'll succeed. — Damien_The_Unbeliever, Feb 22 '11 at 10:24
A more elegant method is testing dns via `utils::nsl` (unix only) or `curl::nslookup` (cross-platform). — Jeroen Ooms, Jan 23 '16 at 23:12

Jeroen Ooms · Answer 1 · 2019-10-14T12:43:11.617

35

The curl package has a function has_internet which tests by performing a nslookup:

curl::has_internet
## function(){
##    !is.null(nslookup("google.com", error = FALSE))
## }

Testing DNS is faster and may be more reliable than retrieving a URL because the latter might fail for unrelated reasons (e.g. firewall, server down, etc).

edited Oct 14 '19 at 12:43

answered Jan 23 '16 at 23:10

Jeroen Ooms

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score 29 · Answer 2 · edited Feb 22 '11 at 23:37

29

A dirty work around would be using RCurl::getURL function.

if (is.character(getURL("www.google.com"))) {
    out <- TRUE
} else {
    out <- FALSE
}

edited Feb 22 '11 at 23:37

aL3xa

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answered Feb 22 '11 at 10:16

Roman Luštrik

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Could be shortened to: `out <- is.character(getURL("www.google.com"))` – G. Grothendieck Feb 22 '11 at 11:41
Thank you for improving my ragged solution. – Roman Luštrik Feb 22 '11 at 13:06
2

actually when no network getURL issues an error, you should use `out <-try(is.character(getURL("www.google.com"))) == TRUE` – cmbarbu Jul 24 '15 at 13:54
2

See my answer below for a more elegant solution in the `curl` package. – Jeroen Ooms Jan 23 '16 at 23:10
Another alternative: `out<-RCurl::url.exists("https://www.google.com")` This is TRUE only if internet available – mattador Sep 09 '21 at 16:02

score 20 · Accepted Answer · answered Feb 22 '11 at 12:18

20

Here is an attempt at parsing the output from ipconfig/ifconfig, as suggested by Spacedman.

havingIP <- function() {
  if (.Platform$OS.type == "windows") {
    ipmessage <- system("ipconfig", intern = TRUE)
  } else {
    ipmessage <- system("ifconfig", intern = TRUE)
  }
  validIP <- "((25[0-5]|2[0-4][0-9]|[01]?[0-9][0-9]?)[.]){3}(25[0-5]|2[0-4][0-9]|[01]?[0-9][0-9]?)"
  any(grep(validIP, ipmessage))
}

With a simple TRUE/FALSE output

> havingIP()
[1] TRUE

answered Feb 22 '11 at 12:18

eyjo

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I don't suppose i[pf]config return a useful return value if the interface isn't up? It's not mentioned in the ifconfig man page, and I don't want to take my box's network down to test because I'm logging on remotely and I'd probably kill my connection :) – Spacedman Feb 22 '11 at 18:24
If the return value from the system is not containing a valid IP the function returns FALSE. Thus, f.e.x. now home using Linux I get FALSE due to the fact that I need to be root to use ifconfig. I get "sh: ifconfig: not found" is echoed to the R terminal before the FALSE return value. – eyjo Feb 22 '11 at 18:56
2

At least on my computer (Mint based on linux 3.13) , this can return TRUE when no internet connection. – cmbarbu Jul 24 '15 at 14:02
2

This does not check if you have an active internet connection. It checks if you have a valid IP Address. I just turned off my wifi and this still returns TRUE. – Jonathan Hill Sep 14 '17 at 01:02
AFAI understand this correctly, ifconfig returns useful information (a character string) regardless of connection (Being on a macbook osx 10.14) – Janhoo Aug 30 '19 at 11:28

Tony Breyal · Answer 4 · 2011-02-28T09:51:17.963

11

Just another one to add to the pot, inspired by @romans answer, this works only on Windows I'd assume, not sure about other platforms:

canPingSite <- function(test.site) {
    !as.logical(system(paste("ping", test.site)))
}

Which we test as follows:

> t1 <- canPingSite("www.yahoo.com")
[...]

> t2 <- canPingSite(";lkjsdflakjdlfhasdfhsad;fs;adjfsdlk")
[...]

> t1; t2
[1] TRUE
[1] FALSE

edited Feb 28 '11 at 09:51

answered Feb 22 '11 at 13:25

Tony Breyal

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I got two downvotes for this, but I can't work out why? I don't care about reputation points (they are meaningless to me), but I would like to understand what's bad about this solution. My reasoning for the downvotes would be because this solution will only work on windows, which I guess is sort of fair enough :) – Tony Breyal Feb 28 '11 at 09:50
1

Like this one, on Linux just adapt to: `canPingSite <- function(test.site) { !as.logical(system(paste("ping -c 1", test.site))) }` – cmbarbu Jul 24 '15 at 14:00
I'd suggest adding `ping -n 1` because we don't need to do the standard 4 pings. I'm not patient enough to wait for 4 separate responses ;) – Jonathan Hill Sep 14 '17 at 01:07

score 7 · Answer 5 · edited Aug 21 '19 at 10:17

7

Do it with just two lines of code:

install.packages('pingr')
pingr::is_online()

edited Aug 21 '19 at 10:17

BroVic

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answered Jul 27 '17 at 10:26

TPArrow

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As it is, you don't need line 2. – BroVic Aug 21 '19 at 08:29
1

You're welcome. The `::` operator takes care of that. – BroVic Aug 21 '19 at 09:34
Cheers. I knew it escaped you :) – BroVic Aug 21 '19 at 10:07

score 7 · Answer 6 · answered Jun 18 '20 at 22:23

All these answers use packages or code outside of base R. Here's how to do it with just base R:

# IANA's test website
is_online <- function(site="http://example.com/") {
  tryCatch({
    readLines(site,n=1)
    TRUE
  },
  warning = function(w) invokeRestart("muffleWarning"),
  error = function(e) FALSE)
}

Eric · Answer 7 · 2015-07-07T14:51:16.443

Bioconductor's Biobase package has a function for testing internet connection.

Biobase::testBioCConnection()

Below is a heavily modified version of this function for testing ability to read lines from a URL.

can_internet <- function(url = "http://www.google.com") {

    # test the http capabilities of the current R build
    if (!capabilities(what = "http/ftp")) return(FALSE)

    # test connection by trying to read first line of url
    test <- try(suppressWarnings(readLines(url, n = 1)), silent = TRUE)

    # return FALSE if test inherits 'try-error' class
    !inherits(test, "try-error")
}

can_internet()

score 1 · Answer 8 · 2013-06-09T21:40:07.047

As the function above from eyjo

havingIP <- function() {
 if (.Platform$OS.type == "windows") {
   ipmessage <- system("ipconfig", intern = TRUE)
 } else {
   ipmessage <- system("ifconfig", intern = TRUE)
 }
 validIP <- "((25[0-5]|2[0-4][0-9]|[01]?[0-9][0-9]?)[.]){3}(25[0-5]|2[0-4][0-9]|[01]?[0-9][0-9]?)"
 any(grep(validIP, ipmessage))
}

also returns true for localhost ip "127.0.0.1" it needs to be removed to prevent false positives. For example as shown below:

 havingIP <- function() {
 if (.Platform$OS.type == "windows") {
   ipmessage <- system("ipconfig", intern = TRUE)
 } else {
   ipmessage <- system("ifconfig", intern = TRUE)
 }
 validIP <- "((25[0-5]|2[0-4][0-9]|[01]?[0-9][0-9]?)[.]){3}(25[0-5]|2[0-4][0-9]|[01]?[0-9][0-9]?)"
 any(grep(validIP, ipmessage[-grep("127.0.0.1", ipmessage)]))
}

But even better would be a solution that prevents localhosts by modifying the regex of validIP.

This last does not work for me; now it says FALSE even when I do have internet. — Doctorambient, Mar 03 '19 at 21:23

score 0 · Answer 9 · answered Sep 19 '19 at 16:05

0

This is a version of eyjo's answer which sacrifices accuracy for speed.

IPavailable <- function() {
  cmd <- switch(.Platform$OS.type, "windows" = "ipconfig", "ifconfig")
  any(grep("(\\d+(\\.|$)){4}", system(cmd, intern = TRUE)))
}

answered Sep 19 '19 at 16:05

Agriculturist

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How to determine if you have an internet connection in R

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