[R] capturing output from Win 98 shell

[Uwe Ligges]

Simon Fear wrote:
> Uwe, you suggest
> 
> 
>>So you almost got it, just read ?shell carefully enough:
>>
>>  filenames <- shell("dir D:\\tmp\\*.sasb7dat /b", intern = TRUE)
>>
> 
> 
> Unfortunately, this does not work and is why I wrote to Rhelp (OK I used
> system instead of shell, but I tried shell first); here filenames is
> assigned
> character(0) even though the dir output is not empty.

(sure about "intern = TRUE" ?)

Hmmm. It works on WinNT, and I cannot check a DOS based OS like Win98, 
because we don't have any of those DOS based operating systems in our 
department.


> Believe me I did read ?shell many times before I wrote: but I am
> reporting
> that shell does not do what ?shell says it should.
> 
> 
>>or even better in this case:
>>
>>  filenames <- list.files("d:/tmp", pattern = "sasb7dat")
>>
> 
> 
> THANK YOU! I'm always forgetting about file.* and friends. Platform
> independent too.
> 
> Still leaves me asking the bigger question though: how do I capture DOS
> command output in general?

Or, to come back to Peter's suggestion, the help file ?system tells us:

"... (To use DOS internal commands use 
paste(Sys.getenv("COMSPEC"),"/c",cmd).)..."

[Peter, we don't need to be experts to read this on Windows -- even with 
that heatwave in Dortmund ... ;-)]

So we get:

  filenames <- system(paste(Sys.getenv("COMSPEC"), "/c", "dir /b"), 
intern = TRUE)

but that's the same way shell() works, so I woudn't expect this to work 
when shell() doesn't...

Uwe Ligges


> 
> Simon Fear
> Senior Statistician
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