I am mostly ignorant about Ubuntu and Linux.
Here is my sequence of thoughts:

I would like to have a "fast boot" PC (boot < 100,150 secs) and lightly customized to my needs to be able to do my banking ops and manage my passwords.

For security reason, I need to run a --most of the time read only-- OS, (preferably) open source. The only read-only enforcement mechanism that I trust is a hardware switch (not quite safe, I know. I have to trust the builder). I would put the OS on an external usb drive.

At this point, my question is preliminary: Today, is there a easy way (for some one who has worked in IT in the past) to install a custom (custom not once for all) Linux OS on an external drive with a read only switch? What would it allow or, on the contrary, what would it not be able to do?

Custom not-once-for-all because I want to be able to take advantage of new features or new packages or security patches, to be able to install them r/w and then to use them read-only.

Thanks for your help and ideas. LB

PS I have made some research but I haven't seen any real answer. And answers might change over time. Question close to this one: xubuntu custom read only image


You can install Ubuntu into an external drive (like you would install it into an internal drive). But when an installed system is running, it 'wants to' write to its root partition and that will not work if you make the drive read-only with a hardware switch.

Boot Ubuntu from external drive.

Maybe it is possible to work around this problem, if you use the boot option toram, which puts some of the disk activities into RAM. It is worth trying.

But I think the best alternative is to use an Ubuntu live drive made by cloning from the iso file to the target drive (USB pendrive or memory card). It has an ISO 9660 file system which is read-only by design, so there is no risk, that it will be modified. All disk activities will be run in RAM.

You can clone with the Startup Disk Creator in Ubuntu 16.04 LTS and newer versions, and with Disks alias gnome-disks and with mkusb.

  • 1
    +1 for the toram suggestion. The Ubuntu live suggestions does not allow for updating the system (as far as I understand) and is therefore no real solution as doing online banking with an outdated browser is no good idea even when using a read only system. – Bruni Sep 19 '17 at 12:16

Your Answer

By clicking “Post Your Answer”, you agree to our terms of service, privacy policy and cookie policy

Not the answer you're looking for? Browse other questions tagged or ask your own question.