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

[Duncan Murdoch]

On 8/24/2007 11:14 AM, Dirk Eddelbuettel wrote:
> 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.

Actually, the OS is fine, it's R that's not.  I'll fix it for 2.6.0.

Duncan Murdoch