With macOS High Sierra a new file system is available: APFS.
This file system supports clone operations for files: No data duplication on storage.
cp command has a flag (-c) that enables cloning in Terminal (shell).
But I didn't find a way to identify theses cloned files after.
Somebody knows how to identify cloned files with a shell command, or a flag in a existent command, like ls?
After 3 years and 2 months... I received a lot of points because of this question here on stackoverflow.
So yesterday I decided to revisit this topic :).
Using fcntl and F_LOG2PHYS is possible to check if files are using same physical blocks or not.
So I made an utility using this idea and put it on github (https://github.com/dyorgio/apfs-clone-checker).
It is only the first release guys, but I hope that the community can improve it.
Now maybe a good tool to remove duplicated files using clone APFS feature can be born. >:)
The command you have used, is not a feature of APFS-Filesystem. The CP -c command calls a function named "clonefile" which is part of bsd since 2015 (s. Man-Page)
http://www.manpagez.com/man/2/clonefile/
So if you clone a file for example, you can change attributes from Original and the Clone can have diffrent Attributs.
I think, the Feature, you are searching for is build in per Copy and Write. You can see the different, if you make a clone with Time Machine.
A have not found a commando per Terminal today, to show this differences, but the clonefile command therefore is not the right function.
The only Known-Way today to Show changed Attributes in Clones is Apple Time Machine Backup Solution.
It`s a Snapshot Solution. Something about this, in this Apple Dev Support-Case:
I think this is meant to be an internal proprietary feature of APFS that you are not supposed to be playing with. It strikes me as a relatively useless feature. If you want to have two files that are the same and use standard APIs, try either hard or soft links, or else Apple aliases.
