R help - Jan 2008 - a way to interrupt a stuck R session on OSX

Discovered by accident:
 
If your R session has become unresponsive to escape presses etcetera,
you can try this.
Open a terminal window, run the command
 
ps -ax | grep R.app
 
Note the process ID number in the first column.  Say it's 1234.
Then run
 
kill -4 1234
 
The key is that the signal you are sending to R.app is "4". 
 
The Console will now ask you how you want to exit.
This at a minimum gives you a chance to save any window content,
since it's a nicely threaded application.
Once (of 2 times) I could also cancel out of the dialog and resume the
session.
 
Roger Day 
University of Pittsburgh Departments of Biomedical Informatics and
Biostatistics 
University of Pittsburgh Cancer Institute 
University of Pittsburgh Molecular Medicine Institute
************************** 
Room 310, Suite 301 
Cancer Pavilion (CNPAV)
5150 Centre Ave. 
Pittsburgh, PA 15232 
e-mail:  day@upci.pitt.edu 
cell phone 412-609-3918
assistant:
    Lucy Cafeo:       (412) 623-2952
*************************** 
 

 
 

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On Jan 13, 2008 8:02 PM, Day, Roger S. <day at upci.pitt.edu>
wrote:
> Discovered by accident:
>
> If your R session has become unresponsive to escape presses etcetera,
> you can try this.
> Open a terminal window, run the command
>
> ps -ax | grep R.app
>
> Note the process ID number in the first column.  Say it's 1234.
> Then run
>
> kill -4 1234
>
> The key is that the signal you are sending to R.app is "4".
>
> The Console will now ask you how you want to exit.
> This at a minimum gives you a chance to save any window content,
> since it's a nicely threaded application.
> Once (of 2 times) I could also cancel out of the dialog and resume the
> session.
What signal is signal 4 on your OS (or more specifically, what signal
is it that R responds to in this manner)? If I understand correctly,
different OS's supporting kill(1) vary in the interpretation of
numerically specified signals, though I can only report this as
hearsay, and not provide specific examples. Nevertheless, folks in my
little circle tend to use kill -SIGTERM, kill -SIGQUIT, etc. rather
than numeric signal specifiers just in case kill(1) behaves
differently than they expect.

- Josh