MacPorts and /opt/local on Catalina and Big Sur read only volumes

[Bjarne D Mathiesen]

Tabitha McNerney wrote:
> Hi all,
> 
> I haven't installed a fresh MacPorts system in quite some time but will
> soon be doing so on a few Macs one running Catalina and the other Big
> Sur. Starting with Catalina, the root volume / is read-only so how do
> the MacPorts package installers set things up such that /opt/local can
> remain the default path to MacPorts for both read and write
> functionality on Catalina and Big Sur? 

/opt is one of the directories Apple defines at the / level as part of
the Data Volume

> Do the MacPorts package
> installers make use of Apple's new bi-directional firmlinks capability
> defined in /etc/synthetic.conf as also described on this page?
> 
> https://derflounder.wordpress.com/2020/01/18/creating-root-level-directories-and-symbolic-links-on-macos-catalina/

No. That's not necessary as /opt transparently exists and is writable.

> 
> Thank you.
> 
> -TM

In depth explanations are here :
https://arstechnica.com/gadgets/2019/10/macos-10-15-catalina-the-ars-technica-review/11/#h1
https://arstechnica.com/gadgets/2020/11/macos-11-0-big-sur-the-ars-technica-review/11/#h1

So, If you go to /System/Volumes/Data in Terminal & do 'ls -l' you'll
see the opt directory.

-- 
Bjarne D Mathiesen
Korsør ; Danmark ; Europa
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