Have you ever fallen asleep to Netflix, and woken up to a fatal hard drive crash? I have. Computer hardware can fail, and it often picks less than ideal times to do so. That’s why I always keep a “digital Swiss army knife” around; a USB drive filled with what I need to fix most computer emergencies. For the last few years that has been a beaten up flash drive hidden away on my shelf, but with the ever declining prices for USB memory, I decided to make a new one.

A typical drive like this contains various tools you need to fix various computer issues. I tend to put Windows installation files, a live version of Linux, and various smaller tools on mine.

A live version of Linux means a Linux distro that has been readied for booting directly off the drive, allowing you to get into a fully working Linux OS on practically any machine, even if the hard drive of that machine has bit the dust. This is incredibly useful for many reasons. First off, it allows you to get the machine running, and access the hard drive of a computer where the drive is perhaps not broken, but you instead have software reasons for why it’s not booting. Many distros also come with a ton of useful tools bundled, like partitioning software, and I can’t even count the number of times I’ve booted into a live version of Ubuntu just to use Gparted. You also get a full OS this way, and it’s possible to make a live install “persistent,” meaning you assign some USB disk space where the OS can actually save changes when you use it, allowing anything you change while running it to persist from one boot to the next. This way you can use practically any computer and boot into your own customized OS. Finally, a live Linux install can be used to actually install that version of Linux natively on the computer. Linux is free, legal, and a great way to make old machines like new, as it generally requires less resources.

As for these other smaller tools, there are a lot of them out there. Things like a standalone version of Gparted, anti-virus and anti-malware software, disk utilities, and so on.

While I haven’t done this with my emergency drives in a while, it’s also possible to add so-called “portable apps” to a USB drive. These aren’t really for emergencies, but are instead programs you’re used to from your computer, in a format capable of running directly off the USB drive. This of it like a light version of running your own OS off the drive, and a way to for instance run your own version of Firefox off your drive when you’re using a public or borrowed computer. Portableapps.com is the place to go for this.

To make your own emergency tool, you need a USB drive. I bought a tiny SanDisk drive I’ve used before, the Cruzer Fit. It’s not the speediest of drives, which is an issue and something you should keep in mind when picking your drive, but the size of it means I can put it on my key chain and never notice it’s there.

As for capacity, that depends on how much you intend to put on there. I would recommend 16GB if you intend to put Windows installation files on it, or at least 8GB if you just want random tools or Linux distros. Technically you can get by with much less, but these days anything below 4GB isn’t really worth buying, just because drives have become so cheap.

I should also mention that it’s perfectly possible to store normal data on a emergency tool like this, so nothing is stopping you from going for a drive you can use for other things, or store the most important data you have on for backup purposes. A 64GB drive isn’t all that expensive these days, and can in many cases store the entire family photo library on it.

Now, on to actually getting all of this onto your drive. Pendrivelinux.com is a website that has been around for years, originally dedicated to running Linux off of USB drives. That’s technically still what it does, but things have become easier since I first discovered it. These days, all you need is the free tool YUMI for Windows, which is designed to allow you to create a custom multiboot drive. Multiboot drives include a tiny OS that starts when you boot from the drive, and it allows you to further select what you want to run from the drive. That way you can mix and match Windows installation files, Linux distros, and other tools all on the same drive.

The tool has a very simple wizard that guides you through what to do. Essentially, you select your drive, select what you want to put on it, and then select the location of the files needed. There’s an option to download the files needed for some of the options, something that’s most relevant for free tools. For putting Windows installation files on it, you simply point it to a .iso file of the Windows installation disc, essentially a single file that’s the equivalent of a physical disc (you can turn your installation disc into such a file in most disc burning utilities, like the free Img Burn).

The wizard truly is very easy to use, and it explains each step in the process. Adding more bootable options to the drive is as simple as running the wizard several times, and each time it will update the multiboot selector with the new options. It will handle everything else for you, so you can just sit back and relax. The list of supported tools and distros is long, and is also a great way to discover things you can put on the drive.

Once you have created your drive, you’re good to go. Booting from a USB drive various from computer to computer, but the most common way is to pay attention to the splash screen right when you boot, see which key to hit to bring up the boot menu, and then select your drive. Some computers are also set up to prioritize booting from a USB drive if a bootable drive is available, and this can be changed in the computer’s BIOS.

Booting the drive will present you with a very simple menu to select what you want to boot, and from there on out it depends on what you selected to boot. Other than the multiboot option, this is essentially the same as booting from a disc, or booting from a single-option drive. The multiboot feature is what makes this so useful, however, as it allows you to have a single drive that has all you need to handle any situation.

This little “trick” has been around for ages, but the combination of better creation tools (YUMI) and cheaper drives lately have turned this from being something computer geeks do to someone that anyone who ever uses a computer should do. It’s dirt cheap, takes you mere minutes to set up, and can be put in a form that disappears on your keychain. You might never need it, but one day you might face a laptop unwilling to boot, five minutes before you’re supposed to make an important presentation at work. Such a drive can have you up and running in Ubuntu in literally a minute, complete with a full OpenOffice suite. That’s not a bad idea to dedicated a cubic centimeter of keychain space for!