R and System calls

Question

I have used R in the past to do very basic calls to the commmand line. The example can be found here.

This time around, I am looking to mimic this code which runs successfully from the command line in Windows:

> cd C:\Documents and Settings\BTIBERT\My Documents\My Dropbox\Eclipse\Projects\R\MLB\retrosheet\rawdata > bgame -y 2010 2010bos.eva >2010bos.txt 

This is the code I am trying to run inside of R. I have already set the working directory inside of R.

dir <- paste("cd", getwd(), sep=" ") system(dir) system("bgame -y 2010 2010bos.eva >2010bos.txt") 

I am sure this is user error, but what am I doing wrong? It appears to work initially, but returns the following error. I very well could be doing something wrong, but I believe I am using the same commands.

Expanded game descriptor, version 109(185) of 05/08/2008.   Type 'bgame -h' for help. Copyright (c) 2001 by DiamondWare. [Processing file 2010bos.eva.] >2010bos.txt: can't open. Warning message: running command 'bgame -y 2010 2010bos.eva >2010bos.txt' had status 2  

Any help you can provide will be appreciated.

Answer 1

You need to issue all commands in one system() call:

system(paste("cd",getwd() "&& bgame -y 2010 2010bos.eva >2010bos.txt",sep=" ")) 

You should already be in your working directory, so I'm not sure the cd getwd() is necessary. And you may need quotes around your path because it contains spaces. The error may be resolved by putting spaces around >.

If I were in your shoes, I would try this:

system("bgame -y 2010 2010bos.eva > 2010bos.txt") 

UPDATE:

And you should probably heed this advice in the "Differences between Unix and Windows" section of ?system that says you should use shell:

    • The most important difference is that on a Unix-alike       ‘system’ launches a shell which then runs ‘command’.  On       Windows the command is run directly - use ‘shell’ for an       interface which runs ‘command’ _via_ a shell (by default the       Windows shell ‘cmd.exe’, which has many differences from the       POSIX shell).        This means that it cannot be assumed that redirection or       piping will work in ‘system’ (redirection sometimes does, but       we have seen cases where it stopped working after a Windows       security patch), and ‘system2’ (or ‘shell’) must be used on       Windows.