stdout == 'Terminal' or 'File' {was 'bad interaction ...'}
First, on an R console, stdout() is normally neither a `normal file' nor a `user terminal'. Let alone under an embedded R ... or use under ESS (where for you, Martin, it is neither). On vanilla R under Unix-alikes (and Rterm but not otherwise) what stdout is is a function of the C runtime system. It's up to the C system if it tells you what stdout has been redirected to, and if it can tell you whether it is a terminal, or a pty (as used under some versions of Emacs) or a file or a socket .... The information is at best unreliable. interactive() is as good a test as we have, and I think if a better test is required in the interactive case, the user should be asked.
On Wed, 12 May 2004, Martin Maechler wrote:
"MartinS" == Martin Schlather <schlather@cu.lu>
on Wed, 12 May 2004 09:15:17 +0100 writes:
MartinS> Dear Ben,
MartinS> I do not know how to solve the general problem that
MartinS> backspaces cause within Sweave, but which are
MartinS> needed to implement running counters.
aha! now I understand more what you are talking about.
This is a more interesting problem, in general: It's not quite a
matter of if(interactive()) that Ben tried, but really you want
to find out if the stdout() connection you are using is a normal file
(where you don't need or want a running counter) or a
user terminal where Martin Schlather applied the 1^H2^H... ('1' Backspace
'2' Backspace ..) trick.
Any ideas what can be done here, using our current connection
tools -- or is there the need for something new?
Interesting topic!
Martin M?chler
PS. I know that strictly speaking the subject question is
non-sense, since, at least on Unix-alikes, a console is a
special file as well, and stdout is always a file.
Brian D. Ripley, ripley@stats.ox.ac.uk Professor of Applied Statistics, http://www.stats.ox.ac.uk/~ripley/ University of Oxford, Tel: +44 1865 272861 (self) 1 South Parks Road, +44 1865 272866 (PA) Oxford OX1 3TG, UK Fax: +44 1865 272595