Re: [PLUG] Perl one-liner to remove duplicates without changing file order

[JP Vossen <jp@jpsdomain.org>]

> Date: Mon, 22 Oct 2012 17:15:00 -0400
> From: Frank Szczerba<frank@szczerba.net>
>
> I'm way behind on emails, so apologies if someone else has already
mentioned it, but the -i doesn't work because you are printing your
output in an END block. If you give perl -i multiple files to process,
it will edit each one in place separately, but the END block doesn't run
until after all files have been processed.
> You can make this work with -i by doing:
>
> $ perl -i -ne '$line{$_} = $.; if (eof) { for (sort{$line{$a}<=>$line{$b}} keys %line) {print} }'

That's awesome!  I knew there had to be a pure-Perl way to do it, but I 
wasn't seeing it.


> If you really are processing multiple files, you probably also want
> to  clear %line in between files:
>
> $ perl -i -ne '$line{$_} = $.; if (eof) { for (sort{$line{$a}<=>$line{$b}} keys %line) {print} %line = () }'

I wasn't, but probably better safe than sorry!  I tested and the first 
form *does* mangle your input files.  Or rather, it keeps appending to 
them, as may be obvious since the hash is never cleared between files.

Thanks!
JP
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