I have already blogged about installing Linux on an external USB stick or drive (better if it’s an SSD) to make such an installation portable on any computer. In that old blog post, I was using VirtualBox to do the actual installation. I was relying on VirtualBox because when I had tried to install Linux directly to an external USB drive after booting with another USB with a live image I ended up breaking my current computer’s grub configuration: if I tried to boot my computer without the newly created USB installation I couldn’t select any OS to boot. At that time, I did not investigate further, because the VirtualBox solution was working like a charm for me.

However, the USB with Linux installed through VirtualBox could be used only when booting from a computer with “Legacy boot” enabled, that is, it could not be booted if UEFI was the only choice in that computer. Even in that case, it wasn’t a problem for me: it was enough to enable Legacy Boot in the computer’s BIOS. Unfortunately, when I tried to boot such a Linux USB in my new LG GRAM 16, I realized that this LG GRAM provides no way to specify Legacy boot! Then, I found this interesting post from “It’s FOSS” that both explains the problem with UEFI I had previously experienced (that is, the fact I couldn’t boot my computer at all because the GRUB configuration was broken) and a way to circumvent the problem. I suggest you go and read that post!

In this post, I’d like to summarize my experience applying the suggested workaround and also report that you might still get into trouble in some circumstances, but fixing things will be easy.

Just like suggested in https://itsfoss.com/intsall-ubuntu-on-usb/, before you start experimenting with the procedure of this tutorial, read it entirely.

The scenario

First of all, let’s summarize what I want to do. I want to install Linux on a portable external USB SSD. I don’t want a live distribution: a live distribution only allows you a small testing experience, it’s not easily maintainable and upgradable, it’s harder to keep your data in there. On the contrary, installing Linux on a USB drive will give you the full experience (and if the USB drive is fast it’s almost like using Linux on a standard computer; that’s surely the case for an external SSD, which are quite cheap nowadays).

In the previous post, I described how to create such an installation from VirtualBox. As I said, such a USB drive can only be booted with Legacy mode (I still have to investigate if you can get a UEFI bootable USB drive by installing it through VirtualBox There’s also a more recent post where I achieve the same goal, a UEFI bootable USB drive, by using VirtualBox).

Now I want to install Linux on a USB drive performing a real installation: I’m going to boot my computer with a USB stick with a Linux Live distribution, then I’m going to attach a USB external SSD drive, where I’m going to perform the actual installation. Thus, I’m NOT going to install Linux on the very computer, but on the USB external drive.

I’m going to perform this experiment:

• I’m going to use a Dell XPS 13 where I already have (in multi-boot, UEFI), Windows, Ubuntu, Kubuntu, and Manjaro GNOME
• I’m going to install Manjaro KDE (I have already created a LIVE USB stick) into an external USB SanDisk SSD

The USB stick with the Live distribution is a SanDisk as well (just to let you know, in case you see SanDisk in the screenshots; I’ll try to make it clear when I’m talking about the Live USB stick and the USB SSD).

I know that I’ve said that I cannot boot with Legacy boot from the LG GRAM, while I can from the Dell XPS, but to make the experiment more interesting I decided to install Linux on the external USB drive using the Dell so that I can then test it both from the Dell and from the new LG GRAM.

The problem

That’s already well explained in the blog post https://itsfoss.com/intsall-ubuntu-on-usb/. I’ll briefly summarize it here: a system can only have one active ESP partition at a time. Even though you choose the USB as the destination for the bootloader while installing Linux, the EFI file for the new distribution (remember, installed on an external drive) will be put in the existing ESP partition (belonging to the computer you’re using just for performing the installation in the external drive). Thus, the computer you used for installing Linux on the external drive will not boot if you don’t have the Linux external USB drive plugged in.

I might add that the fact that the Linux installer lets you use another device for the boot loader, while it will silently use an existing ESP partition might be seen as a bug. Indeed, I read about that in many places. However, it looks like all the Linux installers share this behavior, so we’ll have to live with that, and use a workaround.

The solution

The solution (workaround) for the problem above, as described in https://itsfoss.com/intsall-ubuntu-on-usb/ is simple and clever: you fool the installer by removing the ESP flag from the ESP partition (of the current computer’s SSD) before installing Linux on the external USB drive. Of course, it is crucial to put the ESP back after installation, before rebooting (as instructed at the end of the installation procedure). The removal and addition of the ESP flag can be done after booting into the live system with a partition manager program, which is usually part of the live installation media.

As I anticipated, you might still get into little trouble. I’ll talk about that at the end of the post. However, fear not, the trouble is not as bad as breaking the whole booting procedure of your computer 😉

My experience

So I booted with the Live USB stick with Manjaro KDE. Remember, the Live USB must have been created appropriately with UEFI support, or everything from now on will not work at all. Remember that I’m booting the Live USB from the Dell XPS, where the Legacy boot is enabled. So I have to make sure to boot the Live USB with UEFI, NOT with Legacy:

Being KDE, the partition manager available in the Live system is the one of KDE. I prefer Gparted instead, so it’s just a matter of installing that in the live system, using the package manager. Since I’m using Manjaro in this example, I just run

For Ubuntu, it will be a command based on apt (if it’s not already there) and for Fedora, you’ll have to use dnf (again, unless it’s already installed).

Then, I launch GParted; in my system, you can see the complex configuration of the internal SSD of my computer (/dev/nvme0n1)You can see a few reserved partitions for recovering the Windows installation (the one that came with this computer), 3 ext4 partitions for the 3 Linux OSes mentioned above, 1 ext4 partition that is mounted in all the 3 installed Linuxes, the Windows installation and, the one we’re interested in, the first one, with label ESP. You can see its flags boot and esp. We have to remove those flags before starting the installation. Right-click on that partition, choose “manage flags” and unselect one of the two flags boot or esp: the other one will be automatically unselected and a new flag mfsdata will be selected, but that’s not important.

Let’s close GParted, and let’s run the Manjaro installer. This part is not documented because I’m assuming you’re already familiar with the installation procedure of the Linux distribution you want to install in the external USB drive. The important part is when you have to partition the target drive. Of course, it is crucial to select the right one (the external USB drive where you want to install Linux), NOT the SSD of your computer or you’ll be in real trouble, as you can imagine 😉

In my example, I selected /dev/sdb, because /dev/sda is the Live USB stick (as seen above, the internal SSD is /dev/nvme0n1). Then it’s up to you to partition the target drive appropriately. In this example, I decide to let the Manjaro installer erase that entire disk, specifying to create a SWAP partition with hibernate. Depending on the installer you might choose something else. I chose this strategy because this way, the installer will also create the ESP partition for the boot manager on the target drive automatically, with the right flags. If you want to partition that manually, again, depending on the installer, you might have to create the ESP partition manually. (you can see an example of such a manual partition in the mentioned article https://itsfoss.com/intsall-ubuntu-on-usb/.)Remember that you still have a chance to review such changes before starting the actual modifications on the file system

When the installation finishes, you see the message to reboot into the newly installed system… DON’T DO THAT YET. Remember: you have to reset the esp and boot flag of the ESP partition of the internal drive of the computer: simply use GParted again and follow a procedure similar to the one performed at the beginning.

Since you’re still in GParted, you might also want to verify that also the external drive where you’ve just installed Linux looks correct, for example in my case

Now, it’s finally time to reboot and see what happens…

Small Trouble

First of all, I wanted to make sure that I could still boot the operating systems on my Dell XPS computers, so I made sure I booted with all the USB drives unplugged. Everything seemed to work but… wait… the main UEFI loader on my computer was the Manjaro GNOME one, which was automatically configured to boot also the Ubuntu OSes, simply relying on the os-prober, which is usually part of most Linux installations (apart from PopOS, from what I know). However, there was no trace of the old Manjaro UEFI loader: the Ubuntu UEFI loader showed up. You know that you can have several UEFI loaders on the same machine, and you can also reorder them from the BIOS. Also getting into the BIOS, the Manjaro UEFI was gone! The problem, in this case, is that Ubuntu doesn’t seem to be able to boot a Manjaro distribution (I still don’t know why). The Manjaro installation was still there but I could not boot it!

But wait… I still have the brand new installation on the external USB drive! I booted with that and that one shows both the new Manjaro KDE (the first one of course in the menu) and the entry for booting the Manjaro GNOME of my computer. Indeed the os-prober kicked in also during the installation on the external hard drive: it detected also the OSes installed on my computer (that’s expected). You can see that in the photo (note the reference to the /dev/nvme0n1 partition):

Great! I could boot into the computer’s Manjaro GNOME, using the boot loader of the external drive. Once there, I disconnected the external drive and reinstalled the GRUB UEFI of Manjaro GNOME into my computer. It’s just a matter of running sudo grub-install (no need to specify anything else: the existing installed OS already knows where to install GRUB) and then sudo update-grub:

Rebooted and everything went back to normal on my computer!

all’s well that ends well! 😉

Why did that happen anyway? To be honest, I’m not completely sure… what I noted before when I installed Ubuntu and then Kubuntu on this computer was that since the GRUB configurations of both systems use “Ubuntu” as the label, the Kubuntu installation, which was done after the Ubuntu installation, replaced the UEFI entry of the former; that had never been a problem because I can boot Ubuntu from Kubuntu, and vice-versa in case. Maybe that happened also in my experiment since I had a “Manjaro” (GNOME) UEFI entry on my computer and I installed on the external hard drive another “Manjaro” (KDE) distribution: both use the same “Manjaro” label. That shouldn’t have happened because the ESP partition should not have been detected from the installer, but maybe that was a wrong assumption (after all, os-prober can still detect existing OS installations).

This situation is NOT described in https://itsfoss.com/intsall-ubuntu-on-usb/ and indeed in that article the experiment was slightly different: the author installs on the external hard drive an “Ubuntu” distribution, while the computer already had a “Debian” distribution, so the labels were different.

Anyway, even in case of problems like the one experienced, it was pretty easy to fix things!

Hope you find this tutorial useful for experimenting with installing Linux on portable USB hard drives, or even USB sticks, provided they are fast ones 😉

Concluding Remarks

Please keep in mind that the created Linux installation on the USB external drive is effectively portable: you can use it on several computers and laptops. However, some drivers for some specific computer configurations might not be installed in the Linux installation of the external USB. Also, other configurations like screen resolutions and scaling might really depend on the computer you’re booting and might have to be adjusted each time you test the external USB drive in a different computer.