[R] It is possible to use a Shell command inside a R script?

[Dirk Eddelbuettel]

On Fri, Aug 24, 2007 at 10:57:46AM -0400, Duncan Murdoch wrote:
> On 8/24/2007 10:33 AM, Dirk Eddelbuettel wrote:
>> On Fri, Aug 24, 2007 at 08:32:00AM -0400, Duncan Murdoch wrote:
>>> On 8/24/2007 6:58 AM, Ronaldo Reis Junior wrote:
>>> > Hi,
>>> > > It is possible to use a shell command inside a R script?
>>> > > I'm write a R script and I like to put somes shell commands inside to 
>>> R. > Somethink like: convert fig01.png fig01.xpm or sed ..., etc.
>>> The details and available functions depend on the platform, but you want 
>>> to look at ?system, ?shell, and/or ?shell.exec.  (These all exist in 
>>> Windows; on Unix-alikes, you probably won't have the latter two.)
>> Don't forget pipes. R's ability to consistently work on connections that 
>> may be local
>> files, remotes files, program output, ... is a true treasure (and
>> thanks and credits to, I believe, Brian Ripley to make it so).
>> Eg you can do this   OD <- read.table(pipe("links -dump 
>> http://cran.r-project.org/src/contrib/ | awk '/tar.gz/ {print $3, $4}'"), 
>> header=FALSE, col.names=c("file", "date"))
>> to get files and dates of files on CRAN.   As I recall, this also works on 
>> that other operating system, provided
>> you do all the legwork of installing other tools, setting PATHs etc
>> to provide what works out of the box on the supposedly unfriendlier OS.
>
> The pipe command you list doesn't work in Windows.  I'd guess this is 
> because the pipe syntax "|" within the command is unsupported:  it tries to 
> execute "links", with the rest of the line passed as arguments.  But I 
> haven't traced through to check on this.

Hm, wishful thinking must have gotten the better of me then. Sorry for
spreading misinformation about the capabilities of that other OS.

Dirk

-- 
Three out of two people have difficulties with fractions.