How to remove subset from a file efficiently?

[Christopher Weimann]

On 01/12/2006-09:04AM, fynali wrote:
> 
>   - PSP0000320.dat (quite a large list of mobile numbers),
>   - CBR0000319.dat (a subset of the above, a list of barred bumbers)
> 

fgrep -x -v -f CBR0000319.dat PSP0000320.dat > PSP-CBR.dat