This is an adaptation of... um... I think recipe 8.6 in Cookbook, "Picking a random line from a file", though I may have seen it elsewhere. (Corrections? Credit?)

#!/usr/bin/perl
open ( FH,'data' ) or die ( "data: $!\n" );
while( <FH> ) {
  if ( eof ( FH ) ) {
    print $.
  }
}
[download]

What I like about this is that you aren't storing anything in memory - so this should wade through a 2GB file (as mentioned fearfully later in this thread) fairly quickly.

blyman setenv EXINIT 'set noai ts=2'