Re: [PLUG] Using diff

[Walt Mankowski via plug <plug@lists.phillylinux.org>]

I didn't know about the -u option to uniq. Nice!

I think the reason I tend to do them in Perl or Python is that it's
usually part of a bigger process and I want to do some sort of
post-processing on the list. The pattern of reading the first file
into a dictionary, then checking the contents of the second file
against the dictionary, is useful for all sorts of things.

On Thu, May 27, 2021 at 08:53:08PM -0400, Martin Dellwo via plug wrote:
> If you know one list contains the other entirely, and neither has its own repetitions, ‘sort first second | uniq -u’ oughta work just fine. 
> 
> Martin Dellwo
> martin.dellwo@gmail.com
> 
> > On May 27, 2021, at 8:29 PM, Walt Mankowski via plug <plug@lists.phillylinux.org> wrote:
> > 
> > I usually end up doing this in Perl or Python. The diff solution is
> > nice. If you're interested, I've attached a little Perl script I just
> > whipped up. It has the advantage of not requiring the lists to be
> > sorted.
> > 
> > Then I wrote a Python version, too. :)
> > 
> > Walt
> > 
> >> On Thu, May 27, 2021 at 07:36:05PM -0400, Michael Lazin via plug wrote:
> >> Awesome, thanks!   Comm got the job done in a pinch but I am going to try
> >> diff tomorrow morning.  Thanks again for your help.
> >> 
> >> Sincerely,
> >> 
> >> Michael Lazin
> >> 
> >>> On Thu, May 27, 2021, 6:01 PM Carlos M. Fernández <aremmes@gmail.com> wrote:
> >>> 
> >>> This has worked for me before:
> >>> 
> >>> diff -Nau first second | grep '^+'
> >>> 
> >>> This assumes that first and second are sorted.
> >>> 
> >>> On Thu, May 27, 2021, 17:37 Michael Lazin via plug <
> >>> plug@lists.phillylinux.org> wrote:
> >>> 
> >>>> I used the sort command to make two lists.  One list has everything on
> >>>> the first list and more.  They are already alphabetically sorted.  I want
> >>>> to know what is on the second list that is not on the first list.  I am
> >>>> trying to use diff but perhaps there is a better way.   I tried awk and an
> >>>> ugly egrep and now I am giving up and asking for help.  Thanks for your
> >>>> time.
> >>>> 
> >>>> Sincerely,
> >>>> 
> >>>> Michael Lazin
> >>>> 
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> > 
> > <not_in_first.pl>
> > <not_in_first.py>
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