I guess this would depend on network access. If your clients are behind an extensive firewall then maybe you can leave all updates off and just deploy your update.

I'd consider making this distro real install (and make it minimal) and let it auto update all distro related software. Set your program to update from your server. That would send your updates and let the distro update.

With persistence, the app will be wherever you put it initially. If you put it in /home/user it will be there on reboot and if you put it elsewhere (say /usr/bin) it will be there on reboot.

No, it wouldn't as it would be wherever you initally place it. As pointed out above, if you are using dpkg or a software manager or are downloading on a LAN, you would need an internet connection. You should be able to set this and have it available on reboot also.

The link below gives a description of casper-rw and how it works. The official Ubuntu documentation on it is at the 2nd link.

https://www.howtogeek.com/howto/1491...b-flash-drive/

https://help.ubuntu.com/community/LiveCD/Persistence

I'm not sure if USB with persistence can help with system upgrades. You should look at AntiX and various Puppy Linuxes, how they do it (both designed to be run from USB stick).
A full USB install miight also be possible, but one should make sure that the installer does not create hardware-dependent setups.

I'd agree with that at least as far as Ubuntu is concerned. Not sure about others. I've never had any success with an Ubuntu persistent usb even making a change to an fstab file although it is pretty simple to download/install software or to remove it. The OP indicates that what he is using is a 'custom' cloning app. Written or modified by himself? Obtained from Ubuntu repositories and modified? Does it have dependencies? If it was a script that needed to be modified regularly, that would be simple enough on a persistent usb. If whatever software this is has a lot of dependencies I would expect this would seriously complicate things. Without answers to these questions it is not really possible to say whether a persistent usb suggested would work

The app is written in Pascal and uses code borrowed from the old Redo app. I'm investigating the use of a modified wget function to install the updated app instead of needing to use persistence. The iso already has network manager so connectivity isn't a problem.

Larry

Live plus persistence can only update a few items. Anything like kernel can't be updated.

From your point of view you simply need to maintain the program like any out of software manager program does.