Jerry:
On 2024-11-26 12:03, list_email--- via macports-users wrote:
As a first step in re-installing MacPorts (long story), I ran
$ sudo port -fp uninstall installed
...Before uninstalling, the Finder indicated that /opt/local contained 21 GB.
After, /opt/local was nearly empty, as expected. I completed the steps
indicated to complete the uninstallation.
I happened to check the “Used” quantity, as indicated by Finder on Get Info on
my boot volume (which contained /opt/local) before uninstalling, and again
after uninstalling. I expected to see this quantity reduced by 21 GB. But there
was no change!
Why was the “Used” number unchanged after deleting 21 GB?
I am not an expert and don't have a definitive answer. But my first
guess is: the APFS file system, and snapshots. If something made a
snapshot of the file system contents before you deleted everything in
/opt/local, then maybe those file system contents are still present and
occupying space in the snapshot. Time Machine is one system which can
create snapshots; there are probably others. And, you should ask
yourself the question, what exactly is Finder's formula for its "Used"
quantity?
Howard Oakley's excellent Eclectic Light Company blog has a steady
stream of interesting details on the behaviour of Macs and macOS. The
post, "Explainer: Disk free space" from 2021-12-04
<https://eclecticlight.co/2021/12/04/explainer-disk-free-space/> may
answer your question. There might be more insight in the blog posts
tagged with "free space" <https://eclecticlight.co/tag/free-space/>.
TL;DR: File systems aren't as simple as they used to be.
I hope this is helpful,
--Jim DeLaHunt
