I would like to have my USB stick always ready as an emergency Live Ubuntu, but use it - in the meanwhile - as a FAT storage media for file exchange between different computers (Win, Linux, Mac).

Is it possible (using Ubuntu 16.04 or newer) and how?

further details

I have the feeling that, up to some versions ago, a USB stick created with Startup Disk Creator used to be readable and writable while not in use as a bootable drive.

However, a bootable drive that I've recently created with Startup Disk Creator on Ubuntu 16.04 doesn't seem to mount as a writable partition.

Indeed, it refuses mount -o remount,rw, chown to my user, and even reformatting of the free space (it reports a disagreement in the block size specification), which however – if I'm not mistaken – wouldn't be a proper solution as Windows doesn't read partitions other than the first.


You can try creating a ext4 partition and a fat partition on the same usb stick and make sure you only dd the iso to the ext4 partition

It might not like that if it tries to expand the fs or create a virtual swap

I have a 16gb usb and it runs my ubuntu usb for Installs and emergencies but I can easily save files to the system and I can retrieve files saved to the usb on my windows or Mac but unless you install software or use a vm instance of linux on Mac and windows you may have issues saving files on the usb if you only keep 1 partition

On my Mac I have a ubuntu install iso that I dd'd onto a seperate partition and it works just fine but my Mac doesn't see the seperate partition on the harddrive but does see any usb isos when plugged in

I'd start w a two partition usb and only dd the ubuntu iso onto the first and make sure it's ext4 - give it enough space to run and expand the fs so I'd do at least 10gb for ubuntu and whatever leftover for fat

Also be careful about which partition table you use and need as linux doesn't like older Macs gpt table and you'd have to use gparted to mount and do anything w it

Try and use mbr but depending how old your system is that your using and if you require secure boot vs legacy boot vs uefi boot, that may not be an option

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