Query regarding set([])?

[David Robinow]

On Fri, Jul 10, 2009 at 8:52 AM, vox<vox2000 at gmail.com> wrote:
> I am looking for a script that compares file1 and file2, for each line
> in file1, check if line is present in file2. If the line from file1 is
> not present in file2, print that line/write it to file3, because I
> have to know what lines to add to file2.
  Just copy file1 to file2.
(I'm pretty sure that's not what you want, but in explaining why it
should become clearer what you're trying to do.)