Ctrl-C with R.exe and Rterm.exe in R v1.9.0

-----Original Message-----
From: r-devel-bounces@stat.math.ethz.ch 
[mailto:r-devel-bounces@stat.math.ethz.ch] On Behalf Of Duncan

Sent: den 6 maj 2004 16:16
To: Henrik Bengtsson
Cc: r-devel@stat.math.ethz.ch
Subject: Re: [Rd] Ctrl-C with R.exe and Rterm.exe in R v1.9.0


On Wed, 5 May 2004 12:57:29 +0200, "Henrik Bengtsson" 
<hb@maths.lth.se> wrote :

Ctrl-C works as expected. Exiting R and you're back at a "clean" 
prompt. Now, try the same thing with R.exe (from a restarted

C:\Program Files\R>rw1090\bin\R.exe --vanilla --quiet

^C
^C
1+1

[1] 2

Sys.sleep(100)

^C
C:\Program Files\R>

Strange things happen. R seems still to be running but has 

at the same 

time returned(?) the control back to the Command prompt.

Yes, that is indeed strange behaviour.  

Ctrl-C definitely presents problems.  For instance, on my 
WinXP system running R from a Cygwin prompt, a Ctrl-C during 
the Sys.sleep kills Rterm, whereas under the Windows cmd.exe 
prompt it works properly as it did for you.

I can guess at an explanation for what you saw, but I don't 
know how to fix it:

- R (as opposed to Rterm) is a small .exe program that does a 
little argument parsing, then runs Rterm.  It looks as though 
the Ctrl-C is going to R, and killing that process, but 
leaving the child process Rterm running.  But since both 
Rterm and cmd.exe are reading and writing to standard file 
handles, you get the messed up prompts.

I've just tried doing what the Windows documentation says 
should work (adding this line before Rterm is called:

SetConsoleCtrlHandler(NULL, TRUE);  /* Ignore Ctrl-C; Rterm 
will handle them */

but this didn't fix the problems, it just made them different 
(i.e. Ctrl-C stopped working completely).  Rterm *does* set a 
Ctrl-C handler, but it just isn't being called, as far as I can

A simple workaround is to run Rterm or Rgui rather than R.  
If anyone knows a real fix, please let me know.

Duncan Murdoch