Works great. Fixed minor bug in your first open and added code to test to see if the file has been rotated. I think this will work well. Much better than my original idea of comparing the first line of the files. I simply test to see if the old end of file seek is larger than the new end of file seek.

thanks much for the assist

{
        # get end of log file
        open(LOG, "<$LOG") or die "Can't read $LOG: $!";
        seek(LOG, 0, 2);  # jump to the EOF
        $new_seek = tell(LOG);
        close LOG;
        # get last known position of EOF
        if (open(SEEK, "<$OutputDir/$NAME/last_seek")) {
                $seek = <SEEK>;
                chomp $seek;
                close SEEK;
        }
        else { # no EOF recorded, find it
                # warn "Failed to read seek: $!\nCreating\n";
                &write_seek($new_seek);
                exit;
        }
        if ($seek > $new_seek) { # New Log File
                $seek = 0;
        }               
        open(LOG, "<$LOG") or die "Can't read $log: $!";
        seek(LOG, $seek, 0); # jump to the last EOF
        while (<LOG>) {
                $id = (split / /)[2];
                $login_id{$id}++;
        }
        $seek = tell(LOG);
        &write_seek($seek);
        close LOG;
        @Result = keys %login_id;
        print "USERS=$#Result\n";
}

sub write_seek {
        my $seek = shift;
        open(SEEK, ">$OutputDir/$NAME/last_seek") or die "Can't write 
+to seek: $!";
        print SEEK $seek;
        close SEEK;
}
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