[R] help with function "system" and MS-DOS command TYPE

[Prof Brian Ripley]

On Wed, 31 Jan 2007, Vladimir Eremeev wrote:

> Chen, Xiao wrote:
>>
>> Greetings -
>>
>> I have a quick question that I hope someone will have a quick answer. I
>> have tried to use the R function "system" with the MS-DOS command "type"
>> to display the full content of a text file. But it always returns with a
>> message saying the text file is not found. I could accomplish the same
>> task with the "cat" command which is one of the unix-like commands that
>> I have installed on my windows machine. But I would like to know how it
>> would work with the "type" command.
>>
>> Here is what I have tried:
>>
>>> zz<-file("d:/work/test/test.txt", "w")
>>> cat("this is a test\n", file=zz)
>>> close(zz)
>>> system("cat test.txt", show.output.on.console=T)
>> this is a test
>>> system("type test.txt", show.output.on.console=T)
>> test.txt not found
>>
>
> type is an internal command, rather than an executable file
>
> use
> system("cmd /c type test.txt", show.output.on.console=T)
> or
> system("command /c type test.txt", show.output.on.console=T)

or use the user-friendly version shell(), as it says on the help page for 
system() (together with a portable version of the above).

Please can people who answer questions do their homework as the posting 
guide requests, and point to the definitive documentation.  The archives 
of these lists are a public resource, and often searched to pick up
pieces of misinformation.

-- 
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)
1 South Parks Road,                     +44 1865 272866 (PA)
Oxford OX1 3TG, UK                Fax:  +44 1865 272595