[R-SIG-Mac] Blank help window

Marc Schwartz m@rc_@chw@rtz @ending from me@com
Fri Oct 19 01:08:12 CEST 2018

Ok, I think that Peter and Duncan are on to the key issue here.

I have been trying to figure out what the difference is between displaying HTML help in R.app versus in the terminal and we now know.

If running R in R.app, where .Platform$GUI == "AQUA", the key line in the HTML browser display process is:

  x <- gsub(" <>", "http://localhost <http://localhost/>", x, fixed = TRUE)

where the IP address in the help file URL ('x') is changed to localhost. That does not happen when running R from the terminal and the IP address is used.

In other words, a url something like:


gets regex'd to:


Typically there is an entry in /etc/hosts that maps to localhost. If that entry is not present, then the OS does not know how to map the domain 'localhost' to a physical IP address, much like a DNS server could not map an internet domain name to a physical server IP address.

Ben, if you are not sure about how to look at /etc/hosts per Peter's message below, you can use:

  cat /etc/hosts | grep localhost

in a terminal and see what it returns.


> On Oct 18, 2018, at 6:29 PM, peter dalgaard <pdalgd using gmail.com> wrote:
> Cannot _find_ localhost?? Can you do this (in a Terminal window) ?
> Peter-Dalgaards-MacBook-Air:STAT pd$ ping localhost
> PING localhost ( 56 data bytes
> Request timeout for icmp_seq 0
> Request timeout for icmp_seq 1
> ^C
> --- localhost ping statistics ---
> 3 packets transmitted, 0 packets received, 100.0% packet loss
> If not, what is in the first couple of lines in /etc/hosts?
> -pd
>> On 19 Oct 2018, at 00:09 , Ben Tupper <btupper using bigelow.org> wrote:
>> Just a little followup.  Switching the default browser from Firefox to Safari yields a similar message in the browser after...
>> Browse[2]> browseURL(x)
>> 'Safari can't open the page "localhost:29682/library/utils/html/help.html"
>> because Safari can't find the server "localhost".'
> -- 
> Peter Dalgaard, Professor,
> Center for Statistics, Copenhagen Business School
> Solbjerg Plads 3, 2000 Frederiksberg, Denmark
> Phone: (+45)38153501
> Office: A 4.23
> Email: pd.mes using cbs.dk  Priv: PDalgd using gmail.com
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