Re: essential vs. required vs. base
Justin Pryzby <justinpryzby@users.sourceforge.net> writes:
> Packages marked "Essential: yes" have to be operational before they are
> configured, and packages need not (and should not) depend on them, in
> the same was as they needn't and shouldn't to build-depend on
> build-essential packages such as gcc and make. Essential packages are
> also the only ones which can be relied on to be working in postrm:purge.
> The priority system exists to help define dependencies .. packages
> cannot depend on other packages with a lower priority. Policy indicates
> that "Priority: required" packages are thus marked because they are
> (mostly) needed by dpkg, which seems like a fine criteria.
> I'm including the context diff between essential packages and required
> ones. Since essential implies required, why isn't there simply another
> priority class, instead of a separate "Essential" field??
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. As a result, no libraries are essential since libraries
are removed when they're upgraded. They end up being essential in
practice because essential packages depend on them. That's most of the
delta.
mawk isn't essential because awk has alternatives and mawk is just the
default choice. Someone may want to install gawk and remove mawk, which
should continue to work. sysv-rc and initscripts similarly, as I recall,
have possible alternatives or at least might.
dselect probably shouldn't be required any more.
debconf implements a protocol, and another implementation of the same
protocol should be allowed. cdebconf is in progress, in fact.
That leaves the following as the only differences that I don't know the
story behind off-hand:
> +gcc-4.0-base
> +lsb-base
> +makedev
> +passwd
> +procps
--
Russ Allbery (rra@stanford.edu) <http://www.eyrie.org/~eagle/>
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