Share Home between 2 releases

[Liam Proven]

On Thu, 11 Nov 2021 at 10:29, Ralf Mardorf via ubuntu-users
<ubuntu-users at lists.ubuntu.com> wrote:
>
> When doing this, a user should know what s/he is doing.

OK. I see lots of contradiction of my blanket statement. OK. Fair.

But what Ralf said here is the most important observation by far, I think.

It _is_ possible to do this.

When I said "you can't", I meant my answer 2 ways:

[1] It is not possible to do this simply, cleanly, for example by
clicking a couple of buttons in the install program. It *is* possible
to share a /home partition this way, and it's a simple easy thing to
do.

This means several things:
• if something is easy to do in the installer, it's probably safe and
straightforward and OK to do.
• if something is really hard to do in the installer, it's probably
nonstandard or unsafe or unwise or risky.

[2] If something is complicated or hard to do, and not the normal
standard way of doing things, then there is a good chance that it's
not a wise choice unless you are an expert. If you're an expert, like
say Ralf here who does some wildly nonstandard stuff, then you can
just do it and you probably don't need to ask.

So when you asked if it was possible, and I said "no", I was not
simply saying "that is impossible".

What I was really saying was:
• that's a bad idea
• so you probably shouldn't do that
• so, if you *really* need to do that, then the best way is to go back
several steps and reconsider how your computer is configured
• if you need to ask, you shouldn't try to do it, as the risks of it
going wrong and damaging your installations (plural) is extremely high
• you *did* need to ask, so my advice to you is that *you* can't do
this and shouldn't try to.

For instance, using a filesystem with subvolumes, it is entirely
possible to install multiple different Linux distros into a single
partition. That is a thing that some people do, and it works for them,
and I'm sure they have their reasons although those reasons make no
sense to me.

But by the same token, it's also completely correct to say that you
can't install more than 1 Linux distro into the same partition and
have them run side-by-side. The fact that an expert *can* do it does
not alter the fact that using the normal tools and methods, a
non-expert can't.

If you want to share a /home directory tree between distros or
installs, the right way to do it is to have it in its own partition.
Then, so long as you use different usernames, it is easy, safe,
straightforward and reliable. I've been doing it for over 20 years.

Sure, you _could_ make one user's home directory a partition as Colin
said. I don't recommend it, to me it sounds weird and nonstandard, and
strange stuff will happen if you add more users, stuff that's hard to
explain and that even a Linux expert may well be puzzled by. So:
don't.

Similarly, yes, you could come up with some ugly hack to let 1 distro
mount a home directory inside another distro's root partition. But
again: me it sounds weird and nonstandard, and strange stuff will
happen if you add more users, stuff that's hard to explain and that
even a Linux expert may well be puzzled by. So: don't.

So, despite multiple people disagreeing with me, I stand by my statement:

You can't do this. Don't even try. You will regret it.

-- 
Liam Proven ~ Profile: https://about.me/liamproven
Email: lproven at cix.co.uk ~ gMail/gTalk/FB: lproven at gmail.com
Twitter/LinkedIn: lproven ~ Skype: liamproven
UK: (+44) 7939-087884 ~ Czech [+ WhatsApp/Telegram/Signal]: (+420) 702-829-053