[R] quotes within quotes

[janet rosenbaum]

How does one put quotes within quotes, if it's possible?  
I've tried replacing one set of the quotes by single quotes.

If it's not possible, is there any way to do the following?

 > cmd <- "read.dta"
 > opt <- "convert.factors=FALSE"
 > data.file <- " file="/full/path/name.dta" "
 > eval(call(cmd,data.file,opt))

Prior to adding this option, I had been using match.fun to get the 
function call corresponding to cmd and then evaluating it, but match.fun 
doesn't seem to help here.

Thanks,

Janet