Re: /var on tmpfs

["Jeremy C. Reed" <reed%reedmedia.net@localhost>]

On Thu, 15 Nov 2018, Don NetBSD wrote:

> I've a box with a DoM.  I'd like to mount / as ro and create a
> tmpfs for /var (and /tmp).  I don't think anything else NEEDS to
> be rw (the infrequent changes to /etc can be made by unlocking /
> to make those changes).
> 
> I imagine I can just make a tarball of a skeletal /var and
> unpack this over /var, once mounted?
> 
> Is there a preexisting mechanism for this sort of thing?
> Or, do I roll my own?

Have a look at the /etc/mtree/ specifications. Many /var/ entries in 
there.  You could use it to create your own spec file for your required 
files and directories with correct ownership and permissions and then 
run mtree to generate them.

Or (looking at my notes from 2002), I used a /var.copy directory 
pre-populated as needed and after the /var was mounted and "cp -R -p 
/var.copy/* /var" into it.