Re: [R] Capturing output from external executables, in windows

From: Duncan Murdoch <murdoch_at_stats.uwo.ca>
Date: Wed 24 Jan 2007 - 14:13:51 GMT

On 1/24/2007 8:22 AM, Darren Obbard wrote:
> Hi,
>
> Any help on the following would be much appreciated
>
> I wish to capture the output (currently going to console) from an
> external executable.
>
> The executable is successfully run using
>
> system("program -switch ")
>
> and the output printed to the DOS console.
>
> How do I capture this output? I have tried redirecting the output to a
> text file, and then reading this in
>
> system("program -switch > textfile.txt")
> data<-scan("textfile.txt")
>
> But this does not seem to work (the textfile.txt is not written).

The redirection character ">" is normally handled by the shell. The system() function is low level, so it will pass it directly to your program.  >
It
> does however work if I invoke the console to be permanent
>
> system("cmd /K program -switch > textfile.txt")
> data<-scan("textfile.txt")
>
> Unfortunately, this leaves me with an open console window I have to
> close manually.

Use the /C option instead of /K; it executes and then terminates. Or use the "intern" or "show.output.on.console" arg to system().

Duncan Murdoch

>
> Is there a way of doing this (under windows) using system( ) or some
> other command? It appears that pipe( ) may do it, but I cannot
> understand the documentation.
>
> An example of the appropriate syntax would be an enormous help.
>
> Thanks in advance,
>
> Darren
>
> Darren.Obbard@ed.ac.uk
>



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