[R] readline() and Rterm in Windows

[Duncan Murdoch]

Mikkel Grum wrote:
> I've tried your proposal in a number of ways, and
> there must be something I'm not understanding. If I
> run your script (using source() in RGui, or ctrl-R
> from the R Editor, I get:

It requires a command line console, i.e. it will only work in Rterm, not 
Rgui.  I was assuming you'd run it using the style of your batch file 
down below, but without changing the paths.

Duncan Murdoch
> 
> 
>>conout <- file('CONOUT$','w')
> 
> Error in file("CONOUT$", "w") : unable to open
> connection
> In addition: Warning message:
> cannot open file 'CONOUT$', reason 'Permission denied'
> 
> 
> 
> so I added the path as in:
> 
> conout <- file('C:\\R\\R-2.2.0\\CONOUT$','w')
> conin <- file('C:\\R\\R-2.2.0\\CONIN$', 'r')
> cat('Please enter an ID:', file=conout)
> flush(conout)
> id <- readLines(conin, 1)
> print(id)
> 
> 
> Using RGui and ctrl-R from the R Editor, I get
> 
> 
>>conout <- file('C:\\R\\R-2.2.0\\CONOUT$','w')
>>conin <- file('C:\\R\\R-2.2.0\\CONIN$', 'r')
> 
> Error in file("C:\\R\\R-2.2.0\\CONIN$", "r") : 
>         unable to open connection
> In addition: Warning message:
> cannot open file 'C:\R\R-2.2.0\CONIN$', reason 'No
> such file or directory' 
> 
>>cat('Please enter an ID:', file=conout)
>>flush(conout)
>>id <- readLines(conin, 1)
> 
> Error in readLines(conin, 1) : object "conin" not
> found
> 
> and with
> 
>>source("foo.R")
> 
> Error in file("C:\\R\\R-2.2.0\\CONIN$", "r") : 
>         unable to open connection
> In addition: Warning message:
> cannot open file 'C:\R\R-2.2.0\CONIN$', reason 'No
> such file or directory' 
> 
> 
> When I create a batch file with the following command
> :
> C:\R\R-2.2.0\bin\Rterm.exe --vanilla
> <C:\R\R-2.2.0\foo.R> C:\R\R-2.2.0\foo.out
> 
> and double click on the batch file, the out file gives
> me:
> 
> R : Copyright 2005, The R Foundation for Statistical
> Computing
> Version 2.2.0  (2005-10-06 r35749)
> ISBN 3-900051-07-0
> . . .
> Type 'q()' to quit R.
> 
> 
>>conout <- file('C:\\R\\R-2.2.0\\CONOUT$','w')
>>conin <- file('C:\\R\\R-2.2.0\\CONIN$', 'r')
> 
> 
> and nothing else. In none of the situations do I get
> prompted for input. What am I doing hopelessly wrong?
> 
> Mikkel
> 
> --- Duncan Murdoch <murdoch at stats.uwo.ca> wrote:
> 
> 
>>Mikkel Grum wrote:
>>
>>>Duncan and Prof, thanks for your comments and
>>>apologies for not being more specific. I'm not
>>
>>getting
>>
>>>the same results you get from the steps you
>>
>>propose.
>>
>>>If I write a script foo.R with two lines
>>>
>>>	id <- readline("Please enter an ID: ")
>>>	id
>>>
>>>and then use source("foo.R") (either at the Rterm
>>>prompt, or in RGui) it is true that get prompted,
>>
>>but
>>
>>>the second line does not visibly run, i.e. I get
>>>
>>>
>>>>source("id.r")
>>>
>>>Please enter an ID: 5
>>>
>>>
>>>and if I then type id, I get
>>>
>>>
>>>>id
>>>
>>>[1] "id"
>>>
>>>If I cut and paste the two lines in RGui (in one
>>
>>go),
>>
>>>I get
>>>
>>>
>>>>id <- readline("Please enter an ID: ")
>>>
>>>Please enter an ID: id
>>>
>>>
>>>What I really want is a batch file on the desktop
>>
>>with
>>
>>>the following commands:
>>>
>>>   c:\r\R-2.2.0\bin\Rterm.exe --no-save
>>
>>--no-restore
>>
>>><script.R> script.out 2>&1
>>>   c:\texmf\miktex\bin\latex
>>>\nonstopmode\input{blue.tex}
>>>
>>>
>>>and script.R reads something like:
>>>
>>>   id <- readline("Please enter an ID: ")
>>>   id
>>>   Sweave("blue.Rnw")
>>>
>>>I said that script.R didn't run, which was an
>>>incorrect description. It runs without prompting
>>
>>for
>>
>>>the ID, and gives error messages all through
>>
>>because
>>
>>>blue.Rnw needs the id.
>>>
>>>This is a very simplified version of what I'm
>>
>>doing,
>>
>>>but if I use only the first line of the batch file
>>
>>and
>>
>>>the first two lines of the script and could get
>>
>>that
>>
>>>to work, I could figure out the rest.
>>
>>It won't work so simply.  You're redirecting stdin,
>>so user input would 
>>be taken from there; you're redirecting stdout and
>>stderr, so the prompt 
>>won't be visible to the user.
>>
>>You need to open new handles to the console.  The
>>code below will do it 
>>in Windows; the syntax to specify the console in
>>Unix-alikes will be 
>>different (but I don't know what it is).
>>
>>conout <- file('CONOUT$','w')
>>conin <- file('CONIN$', 'r')
>>cat('Please enter an ID:', file=conout)
>>flush(conout)
>>id <- readLines(conin, 1)
>>print(id)
>>
>>Duncan Murdoch
>>
> 
> 
> 
> 
> 	
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