Upgrade problem

[Colin Watson]

On Sun, May 19, 2019 at 04:43:50PM +0100, Colin Law wrote:
> I know that Ralf suggests there is a difference between apt
> full-upgrade and apt-get dist-upgrade but I don't think any
> differences are of great importance (if there actually are any).

There aren't really, no.  "apt-get dist-upgrade" and "apt full-upgrade"
run precisely identical upgrade resolution code.  The only differences
are some tiny details of tool initialisation.  As far as I know, the new
name was introduced simply because "dist-upgrade" was a rather
misleading name: while it was especially useful for upgrading between
major versions of the distribution, it was also useful at many other
times, and users were often confused by this.  So it is indeed better to
recommend "apt full-upgrade", but only because the name is better for
teaching purposes.

The real logic difference is between "apt-get upgrade" and "apt
upgrade".  Neither of those commands will remove packages that are
currently installed.  However, the former will never install new
packages, while the latter will install new packages if needed to
satisfy dependencies.  Since even very straightforward upgrades often
need to introduce new dependencies (for example, a change in a library's
SONAME, where old and new versions of the library can coexist on the
system), "apt-get upgrade" was something that looked safe but was often
too restrictive to be useful, while "apt upgrade" retains the safety
catch of not removing existing packages but is much more useful in
practice.

-- 
Colin Watson                                       [cjwatson at ubuntu.com]