[alex@rand alex]$ perl -de 1

Loading DB routines from perl5db.pl version 1.19
Editor support available.

Enter h or `h h' for help, or `man perldebug' for more help.

main::(-e:1):   1
  DB<1> @file1=qw/dave bob rich jim/;

  DB<2> @file2=qw/dave rich/;

  DB<3> foreach(@file1){$list{$_}=1;}

  DB<4> foreach(@file2){delete $list{$_};}

  DB<5> print "Remaining elements " . join("; ",keys %list) . "\n";
Remaining elements jim; bob

  DB<6>