openssh unix dev - Mar 2021 - "ssh-keygen -R hostname" errors out with non-existent known_hosts

On Tue, 23 Mar 2021, Nico Kadel-Garcia wrote:
> On Tue, Mar 23, 2021 at 7:01 PM Damien Miller <djm at mindrot.org>
wrote:
> >
> > On Tue, 23 Mar 2021, Nico Kadel-Garcia wrote:
> >
> > > I've just run into what I consider a bug: If
~/.ssh/known_hosts does
> > > not exist, and the account owner runs the command or their script
> > > includes the command "ssh-keygen -R {hostname}", it
reports an error
> > > rather than reporting "oh, yes, the file was empty and
therefore your
> > > attempt to delete the hostname was unnecessary".
> > >
> > > If I want to delete a hostkey entry, and there is none to be
found,
> > > shouldn't that be considered a successful operation?
> >
> > I think the condition of known_hosts being absent is worth
communicating.
> > Maybe a different exit value for that case?
> 
> Exit 0, please. An absent known_hosts file doesn't contain the entry
> the "ssh-keygen -R hostname" entry is expected to remove, and the
> result should be considered a success for the command.
I certainly don't agree.

"grep foo /nonexistent" or "sed -i s/foo/bar /nonexistent"
don't return
status 0 either for exactly the same reason.

-d

On Wed, 24 Mar 2021, Damien Miller wrote:
> > Exit 0, please. An absent known_hosts file doesn't contain the
entry
> > the "ssh-keygen -R hostname" entry is expected to remove,
and the
> > result should be considered a success for the command.
Agreed.
> "grep foo /nonexistent" or "sed -i s/foo/bar
/nonexistent" don't return
> status 0 either for exactly the same reason.
This is more of a ,g/entry/d than a /entry/d in ed(1) parlance.

It?s a convenience command to remove an entry from the list of
known hosts, whether it exists or not or the file doesn?t even
exist; it should only fail when the job can?t be done (e.g. the
file is write-protected).

Think of it as 'rm -f known_hosts/entry' which won?t fail if
known_hosts/ doesn?t exist.

bye,
//mirabilos
-- 
?MyISAM tables -will- get corrupted eventually. This is a fact of life. ?
?mysql is about as much database as ms access? ? ?MSSQL at least descends
from a database? ?it's a rebranded SyBase? ?MySQL however was born from a
flatfile and went downhill from there? ? ?at least jetDB doesn?t claim to
be a database?	(#nosec)    ??? Please let MySQL and MariaDB finally die!