[Techtalk] finding added lines in a file

[Bonnie King]

grep can take a list of patterns separated by newlines.

grep -F "$(cat A.txt B.txt |sort |uniq -u)" B.txt

You'll get the added lines back in the order they appear in B.txt.




On Thu, Aug 15, 2013 at 6:59 PM, Miriam English <mim at miriam-english.org>wrote:

> Hi folks,
>
> Forgive my thickness. I've read (or attempted to read) the manual pages
> for diff, cmp, and comp and still can't work out how to list just the lines
> added to file B when comparing two files, A and B. Perhaps I can blame
> having just getting out of hospital after a bout with a mystery high fever,
> but I do remember having difficulty trying to work this out before too.
>
> Anybody know the secret?
>
>  - compare two files, A and B
>  - just print the additional lines of file B
>
> It should be easy, right? I'm completely stumped.
>
> I have used the two-step
>  cat A.txt B.txt | sort | uniq -u >C.txt
>  cat C.txt B.txt | sort | uniq -d
> but this uses a temporary file (C.txt) and upsets the order of the lines
> in the original (B.txt) when it sorts them.
>
> Cheers,
>
>         - Miriam
> --
> If you don't have any failures then you're not trying hard enough.
>  - Dr. Charles Elachi, director of NASA's Jet Propulsion Laboratory
> -----
> Website: http://miriam-english.org
> Blogs:   http://miriam-e.dreamwidth.org
>          http://miriam-e.livejournal.**com<http://miriam-e.livejournal.com>
>
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-- 
Bonnie King