what about comm? or am I missing something. Of course if file1 needs transforming use perl or whatever filter

# comm -12 <(sort file1) <(sort file2) > dups.out

the 'cmd <(cmd1 ...) ...' notation if not supported by your shell means the two-step process 'cmd ... > temp1; cmd1 temp1' cmd1 being a "filter".

or in other "words" ;)

% stephan@armen (/home/stephan) %
% cat dat1 
3     110582 SFCA            4158675309               041414041421
3     060784 NYNY            2125552368               190159204657
3     121906 RANC            9195551234               123401123620

% stephan@armen (/home/stephan) %
% cat dat2
3     110582 SFCB            2258675309               041414041421
3     110582 SFCA            4158675309               041414041421

% stephan@armen (/home/stephan) %
% sort dat1 > dat1.sorted         

% stephan@armen (/home/stephan) %
% sort dat2 > dat2.sorted

% stephan@armen (/home/stephan) %
% comm -12 dat1.sorted dat2.sorted
3     110582 SFCA            4158675309               041414041421
[download]

hth --stephan, just another unix hacker,