[Rd] suppressing stderr output from system() calls

[Prof Brian Ripley]

See ?system2 to answer your subject line.

But you seem confused about external programs and R's own stdout() 
connection.  Have you read the R News article on connections?

On Wed, 5 Oct 2011, Mark Cowley wrote:

> Dear list,
> I'm trying to suppress/redirect/squash the output from commands like install.packages, or download.file. The problem is that none of: sink(..., type="message"), sink(..., type="output"), capture.output, suppressMessages are quite doing the trick. Output gets written to the stderr stream, despite any combination of the above suppression commands.
> According to ?sink:
> Messages sent to ?stderr()? (including those from ?message?, ?warning? and ?stop?) can be diverted by ?sink(type = "message")? (see below).
>
> I'm pretty sure it's the system(), or .Internal() calls which are the culprit, which currently write the majority (all?) of their output to the stderr stream.
>
> Simple example:
> con <- file("stderr.txt", "w")
> sink(con, type="message")
> system("ls")
> sink(NULL, type="message")
> close(con)
> # instead of the output going to stderr.txt, it gets printed to the console.
>
> # no good either
> capture.output(system("ls"))
> character(0)
>
> This is an issue, since i'm writing GenePattern modules to run R code, and if anything is written to stderr, then the job gets hit with a 'job failed' status, when all that might have happened is an R package got installed, or a file got downloaded via FTP.
>
> Any ideas? Can system() and .Internal() output be redirected to stdout?
>
> cheers,
> Mark
>
>
> sessionInfo()
> R version 2.13.1 (2011-07-08)
> Platform: x86_64-apple-darwin9.8.0/x86_64 (64-bit)
>
> locale:
> [1] en_AU.UTF-8/en_AU.UTF-8/C/C/en_AU.UTF-8/en_AU.UTF-8
>
> attached base packages:
> [1] stats     graphics  grDevices utils     datasets  methods   base
>>
>
>
>
> -----------------------------------------------------
> Mark Cowley, PhD
>
> Pancreatic Cancer Program | Peter Wills Bioinformatics Centre
> Garvan Institute of Medical Research, Sydney, Australia
> -----------------------------------------------------
>
>
> 	[[alternative HTML version deleted]]
>
>

-- 
Brian D. Ripley,                  ripley at stats.ox.ac.uk
Professor of Applied Statistics,  http://www.stats.ox.ac.uk/~ripley/
University of Oxford,             Tel:  +44 1865 272861 (self)
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