[plug] updating packages (Debian) from later sources

[Craig Ringer]

> Now let's say I have perl installed, version 5.6.1.whatever from the
> Debian packages list.   For whatever reason I would like to update it to
> version 5.8.whatever from source.   I am confident that I can get the
> source, compile and install it.  Perl, I imagine to be a bit more
> central to OS health, being necessary for running perl scripts for
> example!

Apt uses perl extensively, as does dpkg. You'd probably be wise to leave 
the system perl in place and just install yours in /usr/local/perl.

> 1) should I remove the "old" perl package eg. using dpkg or the apt
> system, before I install my new perl?

_not_ reccomended; see above.

> 3) if for some reason I wanted to subsequently retreat back to the Debian
> perl package how would I uninstall the new version? Simply delete the
> directory(ies?) where the new perl resides?

update-alternatives --config perl
rm -rf /usr/local/perl

that should work.

> 4) do I need to "inform" the apt system about the changes so that if in
> the future an official Debian updated perl package becomes available, I
> can avoid its automatic "update" via the usual apt-get update;apt-get
> upgrade route?

The only way I'm aware of of doing that is packing your own perl version 
as a debian package. Now, if it was all _DOCUMENTED_ it probably 
wouldn't be a problem but IMHO debian packaging is so badly 
under-documented now that it'd be easier to build an RPM and convert it 
using alien!

> 5) if I install the new perl under, for instance, perl5.8, then I suppose
> I can point to it via etc/alternatives?

Should work.

-- 
Craig Ringer
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