Re: essential vs. required vs. base
Justin Pryzby <justinpryzby@users.sourceforge.net> writes:
> On Wed, Nov 09, 2005 at 01:13:44PM -0800, Russ Allbery wrote:
>> Essential means that it's very difficult to remove the package and you
>> have to jump through extreme hoops to do so, and that removing it may
>> break the system.
> Yes, but how is that different from Priority: required?
Basically, there are times when you can, and want to, remove packages with
Priority: required. But you don't get to do that with essential ones.
>> As a result, no libraries are essential since libraries are removed
>> when they're upgraded.
> I noticed that; but aren't all packages removed when they're upgrade?
Sorry, I was being sloppy in my wording. The issue with libraries is that
the package name may change if the SONAME changes. Changing the package
name of a package that's essential is incredibly painful.
> My question isn't so much "why are some required packages not
> essential?", but "Why is there a special mechanism for 'essential'?".
> Why essential just another priority, for which dpkg has special tests?
Historical reasons, probably. The case it allows (an essential package
that's not required) doesn't sound useful. There *is* the potential issue
that the Priority is somewhat under the control of ftp-master rather than
the package maintainer due to the override file, but I don't know that
that separation of powers is actually being used to any real purpose in
this specific case.
--
Russ Allbery (rra@stanford.edu) <http://www.eyrie.org/~eagle/>
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