[R] How to import specific column(s) using "read.table"?

[F Duan]

Dear R people,

I have a very big tab-delim txt file with header and I only want to import 
several columns into R. I checked the options for "read.table" and only 
found "nrows" which lets you specify the maximum number of rows to read in. 
Although I can use some text editors (e.g., wordpad) to edit the txt file first 
before running R, I feel it’s not very convenient. The reason for me to do this 
is that if I import the whole file into R, it will eat up too much of my 
system’s memory. Even after I remove it later, I still can’t release the memory.

Anyone has any suggestions?

Thank you very much,

Frank