How do I "move" a user from one disk to another

[unclemiltie]

I just gave my son an older iMac that I've upgraded to run Monterey. the SSD in it is not big enough for all of his stuff from his even older Mac Mini so I put his old hard drive into a USB enclosure and was going to put his data files on that.

What I'd like to do is have the iMac automatically mount that external USB when it boots and then change his account such that the external HDD is his default for everything. (desktop, downloads, etc)

can that be done?

 

[FreakinEurekan]

It can. But that’s grad-school level scripting.

Id suggest just plug in a USB SSD and install on that, pretend the internal storage doesn’t even exist.

 

[gilby101]

What I'd like to do is have the iMac automatically mount that external USB when it boots and then change his account such that the external HDD is his default for everything. (desktop, downloads, etc)

I suggest that is a recipe for disaster (even if possible). With a second admin account you can move the whole of his stuff to the external disk - but again I don't recommend this for lack of consistent reliability.

Much better to leave his Library, Documents, Desktop, Downloads as they are. Then create folders on the external to hold his documents, etc. To make it easy to use, you can create symlinks or aliases so that these external folders appear in the home folder.

Requires a bit of discipline to not leave stuff in the home folder longer than necessary.

That avoids issues like a) external being disconnected and blocking login, b) apps which use ~/Documents, etc. may fail if that is not internal, c) similarly the other folders.

If you wanted to especially kind you would buy an external SSD for data and repurpose the HDD for backup.

Or just do as @FreakinEurekan suggests.

 

[unclemiltie]

I kind of like that idea, just put links in those folders so that he can easily find the stuff on the external disk but keep the main of his login on the internal drive.

The biggest challenge is that he's into music production and has ~300GB sittng on his desktop. I've tried to convince him that he needs to move those just to keep himself sane but I'm a stupid old man and he knows everything.

 

[Fishrrman]

Tell us what year the iMac was made.
Tell us what kind of drive is inside and what size it is.