bug#50097: gzip: add "--keep" option to keep original files unchanged

[Paul Eggert]

On 8/20/21 5:20 AM, Krzysztof Żelechowski wrote:
> > gzip -k b && gzip -cd b.gz >b
> >
> > which would trash the hard-linked file as well.
> That would replace the content of the file b with the content of the file b.
> How bad can that be? ;-)

It could be a problem as-is if some other file reads 'a' in the middle 
of the process. And the problem would be more serious in other examples, 
such as:

echo hello >a
ln a b
gzip -k b && gzip -cd b.gz >>b

This would trash 'a' if gzip -k succeeded. (Same with 'ln -s'.)

> > > Of course one can use -f to go ahead and compress anyway.
>
> That would silently replace an existing target, which is bad.

Sure. The only question here is what things "gzip -k" should be able to 
do, without the things being considered "bad".

Perhaps if you gave us the surrounding context; that might help explain 
why it would be useful to change the behavior of gzip -k on links. Bug 
report 50097 seems to start up in the middle of a conversation that I'm 
not privy to.