[R] Named pipe connections and stdout

[Peter Dalgaard BSA]

Mark Myatt <mark at myatt.demon.co.uk> writes:

> All,
> 
> I am trying to use a named pipe to steer R from an external application.
> Following the examples in RNEWS 1:1, I have created a simple listener:
> 
>         zz <- fifo("TESTFIFO", "r")
>         repeat
>   
>          {
>          a <- readLines(zz)
>          if(length(a) != 0)
>            {
>            e <- try(eval(parse(text = a)))
>            if (inherits(e, "try-error"))
>              {
>              # error handling code here
>              cat("Error", "\n")
>       
>              }
>            }
>         }
> 
> 
> 
> I tested this by steering R from a simple console (e.g. using something
> like:
> 
>         echo "<r-command> > TESTFIFO
> 
> This works OK but where has stdout gone?

With eval() in a loop, wouldn't you need a print(e)? 

-- 
   O__  ---- Peter Dalgaard             Blegdamsvej 3  
  c/ /'_ --- Dept. of Biostatistics     2200 Cph. N   
 (*) \(*) -- University of Copenhagen   Denmark      Ph: (+45) 35327918
~~~~~~~~~~ - (p.dalgaard at biostat.ku.dk)             FAX: (+45) 35327907
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