I'm running Ubuntu 18.04.5 LTS on a USB drive, and would like to update it to the latest version (also hoping this will solve the occasional freezing issues). I'm not very knowledgeable about how this running on a USB drive exactly works (someone else made it for me), so I wanted to get a confirmation about whether simply going through the normal update process would work (as if Ubuntu is installed on my laptop). With 'the normal update process' I mean downloading the update, maybe restarting if required, etc. Restarting for example wouldn't really work as usual I think, as I always have to manually boot Ubuntu up again.
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2It is not clear if you have a persistent live USB or full install in an USB. The answer will depend on that. See What would be the differences between a persistent USB live session and a instal? – user68186 Dec 30 '20 at 22:38
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1A live install should have an 'install ubuntu' icon on it when booted up, a full install will not have the install icon. Updates will be safe and easy, but will not remain with a live USB after reboot, only with a full install. – crip659 Dec 30 '20 at 22:42
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I don't think I've ever seen 'install ubuntu' on start up, and each time I start up ubuntu again it's the same as where I left it (as it would be when installed on a laptop/desktop). I assume I have the full install then? – Luuk Dec 30 '20 at 22:53
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1In another post I've also soon that for an installed version you should see '
@ – Luuk Dec 30 '20 at 23:00:~$' in the terminal, which is the case for me.
1 Answers
Update Ubuntu USB
An Ubuntu persistent USB saves all changes in a persistent file or partition, named "writable" or "casper-rw" and optional "home-rw".
Persistent files on FAT32 partitions are limited to 4GB, persistent partitions are limited only by disk size.
A full persistence file or partition will prevent a persistent USB from booting. An update or two will fill a 4GB file.
A full install stores data on an ext partition that does not limit size, a /home partition is optional.
Differences between Persistent installs and Full installs are shown here:
Running live usb on 2 different PC's
A Full install to USB is not much different than an install to Desktop or Laptop, updating is fine.
To confirm a Full install, look in the folder filesystem/cdrom, this is the root folder for a Live or Persistent drive. If there is nothing there, you have a Full install.

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