How to create a bootable USB drive from the command line on any system

  • A bootable USB drive allows you to boot and install or repair operating systems without needing a working hard drive or DVD drive.
  • In Windows you can prepare the USB drive with Diskpart, bootsect and xcopy or use tools like Media Creation Tool or Rufus.
  • In Linux, simply identify the drive and copy the ISO using dd, after unmounting the device and carefully checking the destination.
  • Properly configuring the BIOS or UEFI and knowing the typical errors when booting from USB is key to making the process reliable.
Joaquin Romero

15 minutes

Bootable USB

When the computer decides not to start and gets stuck on a black screen, a Bootable USB It's often a lifesaver. It doesn't matter if the computer has Windows, Linux, or is completely empty: if you properly prepare a bootable USB drive, you can install or repair the operating system without needing a DVD drive or any unusual tools.

If you're also comfortable using the terminal or command prompt, you can create that bootable USB drive. Commands only, no additional programs requiredThis works on both Windows and Linux. And yes, you can also create a bootable USB drive with Windows using only your Ubuntu computer or any other Linux distribution—very useful when your Windows PC has given up the ghost.

What is a bootable USB and what is it for?

A bootable USB drive is simply a USB memory stick prepared so that the computer can boot directly from it without depending on the operating system installed on the hard drive. When connected and configured in the BIOS/UEFI as the first boot device, the computer loads the files from the USB drive and not those from the internal hard drive.

To achieve this, the memory must contain a valid ISO image (from the operating system, rescue tool, etc.), a compatible file system (usually FAT32 or NTFS), and a prepared boot sector. Simply copying files is not enough: the partition must be marked as active and the appropriate boot code written.

This type of USB is essential when you need install, reinstall or repair An operating system on a computer that doesn't have an OS, won't boot, or is experiencing serious errors, such as the infamous black screen or Windows failing to load. It's also very useful for:

  • Repair a damaged hard drive or with problematic sectors through specific utilities.
  • Reinstall Windows or Linux from scratch even if the current system does not load.
  • Upgrade the system to a more recent version without relying on DVDs.
  • Install other operating systems (for example, testing Linux distributions in live mode).
  • Recover data booting from an alternative system when the main one is broken.
  • Diagnose critical errors when you only see a black screen or looped restarts.

There is also the concept of multiboot: using a single memory to save multiple ISO images and boot the system you want at any given time. This is usually done with advanced tools, but the basic principle remains the same: a USB drive prepared to be a bootable device.

Cloning and restoring disks and USBs with Rufus Ventoy BalenaEtcher
Related article:
Cloning and restoring disks and USBs with Rufus / Ventoy / BalenaEtcher

Basic requirements for creating a bootable USB

Before you start typing commands like there's no tomorrow, you need to be clear on a few requirements to avoid surprises and don't load the wrong disk. Are these:

  • An USB flash drive with sufficient space (4 GB minimum for most Linux distros, 8 GB or more for Windows).
  • La ISO image of the operating system or the tool you are going to use (Windows, Ubuntu, Arch, etc.).
  • Access to a terminal on Linux or CMD/PowerShell on Windows with administrator permissions.
  • In some cases, a alternative functional equipment (for example, your Linux PC when your Windows PC has died).

An ISO image is an exact copy of a physical medium (such as an installation DVD) stored as a file. When you copy it correctly to a USB drive and mark it as bootable, that USB drive behaves as if it were the original system DVD.

It's always best if the USB drive is at least USB 3.0 and connect it to a USB 3.0 port on your computer if one is available. It's not mandatory, but installation and file copying will be significantly faster.

Create a bootable USB drive from Windows using commands (Diskpart + CMD)

In Windows you have a console tool called diskpart It allows you to manage disks and partitions from the command line. Thanks to it, you can prepare a USB drive to be bootable without the need for external programs.

With diskpart you can list disks, create partitions, format drivesAssign drive letters and mark partitions as active. Just what you need before copying the Windows installer files or any other ISO. If you encounter problems formatting, you can consult guides for Fix USB formatting errors.

Prepare the USB drive with Diskpart

To use diskpart in Windows 10 or 11, the first thing to do is open the command prompt as administratorType it into the search bar (cmd), right-click, and select "Run as administrator." Then:

  1. Write diskpart and press Enter to launch the utility.
  2. In the diskpart console, use list disk to see all connected disks.
  3. Identify your USB drive by its size (for example, “Disk 1”, “Disk 5”, etc.). Pay close attention to this, because choosing the wrong one here means erase an entire hard drive.
  4. Select the USB drive with select diskX (replace X with the correct number).
  5. Thoroughly clean the unit with cleanThis erases all partitions on the USB drive.
  6. Create a primary partition with create partition primary.
  7. Select the newly created partition with Select Partition 1.
  8. Mark it as active with active so that it can be started.
  9. Format the partition. You can use format fs = ntfs quick o format fs = fat32 quick Depending on your needs. FAT32 is more compatible with UEFI, NTFS is common for large Windows installers.
  10. Assign a drive letter with assign.
  11. Exit diskpart with exit.

With those steps, you now have a USB drive with an active and formatted partition, ready to receive the installation files. From there, all that's left is... copy the contents of the ISO or from the DVD to the USB drive and adjust the boot sector if necessary.

Create a bootable USB drive using bootsect and xcopy

In many cases, simply copying all the files from the ISO to the USB drive is enough to make it work, but if you're working with older Windows systems or need to ensure the boot code is correct, you can use the command bootsect.

A fairly typical way to do this is as follows, assuming that:

  • The drive with the DVD or ISO mounted is, for example, the I:
  • The USB drive you prepared is the G:

From the Windows command prompt (with administrator privileges):

  1. Switch to the mounted DVD or ISO drive by typing I: and pressing Enter.
  2. Go to the boot folder with Cd boot until you are in I:\boot>.
  3. Write bootsect /nt60 g: to write the NT6 compatible boot code (Vista, 7, 8, 10, 11) to drive G:.
  4. Close that command window.
  5. Open the command prompt again, and to copy all the installation files to the USB drive you can use xcopy i:\*.* /S /E /F g:

the modifier /S copy subdirectories, /E includes the gaps and /F It displays the full file names while they are being copied. After that copy, the USB drive looks like this: bootable installation medium of Windows. If you need tools for recover or repair the startThese types of kits can be very helpful after copying the files.

PowerShell option for Windows 10 and 11 users

If you prefer PowerShell to the old CMD, you can also perform the process from there using more modern commands. The approach is the same: Identify the disk, create a partition, format it, and mark it as active. and copy files. The end result is identical: a bootable USB drive without relying on external programs.

Create a bootable USB drive in Windows for any system (example with Arch Linux)

Bootable USB

You can use these commands not only for Windows. If you have an ISO of a Linux distribution (for example, Arch Linux), you can prepare a... memory listed as bootable and then copy the ISO or its contents.

Basic diskpart setup would be very similar to what we've already seen, with the difference that many Linux distributions work very well with FAT32 and they don't need Windows-style bootsect.

  1. Open CMD as administrator.
  2. Run diskpart and then list disk to locate your USB drive.
  3. Select the correct disk with select diskX (replace X with your USB number).
  4. Clear memory with clean.
  5. Create primary partition with create partition primary.
  6. Activate it with active.
  7. Format in FAT32 with format fs = fat32 (This format causes fewer problems with many UEFIs).
  8. Assign letter with assign and go out with exit.

You can then copy the contents of the ISO to the root of the USB drive in several ways. One commonly used method in classic examples is xcopy D:*.* /s /e /f B:Assuming the mounted ISO is on D: and the USB drive on B:. Another option, when you don't have a physical drive, is to mount the ISO with a program like Daemon Tools or simply Unzip it with 7-Zip directly into memory.

Some distributions, such as certain versions of Arch Linux, may require that the memory have a concrete volume label (drive name) for the boot to work 100%. In that case, you would only have to rename the drive in the explorer (right click > Rename) and give it the identifier that the distro expects, for example “ARCH_2015.05” or another similar one mentioned in the ISO.

Create a bootable USB drive in Linux using only the terminal

If your Windows PC won't boot and you only have a Linux machine (Ubuntu, Fedora, etc.), you're not out of luck. Linux provides everything you need to... Create a bootable USB drive using only commands, including installing Windows from an official ISO.

The star tool for this is the command ddHowever, it's advisable to prepare the device beforehand, disassemble it, and, if desired, format it to a compatible file system (for example, FAT32 with mkfs.vfat).

Identify the USB drive with lsblk

First, plug the USB drive into your Linux computer and open a terminal. Then run lsblk to list block devices:

lsblk

You'll see something like this, with disks, partitions, and mount points:

NAME MAJ:MIN RM SIZE RO TYPE MOUNTPOINT sda 8:0 0 465.8G 0 disk ├─sda1 8:1 0 200M 0 part /boot/efi ├─sda2 8:2 0 1G 0 part /boot └─sda3 8:3 0 464.6G 0 part ├─... ... sdb 8:16 1 14.4G 0 disk

In this example, the USB drive is / Dev / sdbIn your case it could be /dev/sdc, /dev/sdd, etc. Make absolutely sure which one it is, because dd does not forgive mistakesIf you aim at the main hard drive, you'll take it down.

Remove and format the USB drive (optional but recommended)

Before accessing the device, it's important that it doesn't have any mounted partitions. If lsblk shows mount points at /dev/sdb1, /dev/sdb2, etc., unmount those partitions.

umount /dev/sdb*

If you get a "not mounted" error, it simply means the drive is already free. Afterward, if you want to clean the drive and format it as FAT32, you can use mkfs.vfat with superuser permissions:

sudo mkfs.vfat -F 32 /dev/sdb -I

Parameter -F32 FAT32 strength and -I This indicates that the entire device will be formatted. Keep in mind that this will erase all content of the memory.

Copy the ISO to the USB drive using dd

Once the device has been located and disassembled, the key moment arrives: use dd To copy the ISO directly to the USB drive. The general method would be:

sudo dd if=/path/to/the-image.iso of=/dev/sdb bs=4M status=progress conv=fsync

Where if (input file) is the ISO of Windows, Linux or whatever you want, and of (output file) is the full USB device. The parameter bs = 4M Adjust the block size to speed up the process a little. status=progress shows the progress and conv=fsync Ensure that the buffer is properly emptied upon completion.

Depending on the size of the ISO file and the speed of your USB port, the process will take anywhere from a few seconds to several minutes. When dd finishes, you'll see a summary of the number of bytes transferred. At that point, you can proceed. safely remove the memory and test it on the equipment you want to install or repair.

Create a bootable USB drive in Windows using official and third-party tools

Although the most "geeky" and flexible approach is to use the command line, many people prefer something more visual. Windows offers a good collection of programs that allow you to create a bootable pendrive with just a few clicks, for Windows, Linux and other systems.

Burn an ISO to USB
Related article:
How to burn ISO to USB in a simple way

Media Creation Tool: Microsoft's official option

If your goal is to prepare a USB drive with Windows 10 or Windows 11The official Microsoft tool is the Media Creation Tool. This utility can be downloaded from the Microsoft website and is responsible for:

  • Download the official ISO of Windows in the edition and architecture of your choice.
  • format the flash drive (minimum 8 GB) and prepare it as a boot drive.
  • Copy all necessary files without you having to worry about commands.

The typical workflow is: download them from the Windows software downloads page, run the program, accept the terms, choose the language, edition, and architecture (32/64 bits) or leave the recommended options, and then choose whether you want create USB directly or generate an ISO file to burn it to a DVD later.

In USB mode, select the corresponding drive (be careful not to choose the hard drive), let it work, and after a while you'll have a USB ready to install or reinstall Windows on any PC, as long as you have a valid license.

Popular programs for creating bootable USB drives

Besides the official tool, there are plenty of well-known utilities that make life easier when you want to avoid using the terminal. Some of the most popular are:

  • RufusProbably the most popular. It allows you to create bootable USB drives for Windows, GNU/Linux distributions, and other systems. It's lightweight, free, and very flexible: it supports MBR and GPT partition schemes, FAT32 and NTFS formats, and automatically configures the most suitable options based on the ISO.
  • Universal USB InstallerDesigned primarily for Linux, but also compatible with other image systems. Simply choose your distribution, select the ISO and the USB drive, and the tool will handle the rest. It offers quick drive formatting before burning.
  • UNetbootinA true classic in the Linux world. It allows you to automatically download many distributions (Ubuntu, Debian, Fedora, openSUSE, etc.) or use an ISO you already have. It works on Windows, Linux, and macOS.
  • Whale EtcherIt's very user-friendly, even for less experienced users. It's open source and cross-platform. It works in three steps: choose an image, choose a destination, and click "Flash." It includes safeguards to prevent accidental deletion of hard drives.

In addition, there are more advanced options geared towards professional or multiboot environments, such as Yumi, RMPrepUSB, UltraISO, Acronis True Image, Ultimate Boot CD o AOMEI BackupperThese add cloning, backup, repair, diagnostic, and USB preparation functions, allowing you to create drives with multiple operating systems on the same drive. For those seeking complete solutions, there are also alternatives to Hiren's Boot which integrate many of these utilities.

How to boot a PC from a USB drive

Once you have your USB drive ready, the next step is to tell your computer to boot from it instead of the internal hard drive. Depending on your motherboard or laptop model, this is done in slightly different ways, but the logic is the same: Configure the boot order in BIOS/UEFI or invoke the boot menu.

The typical sequence is as follows:

  1. With the PC turned off, connect the Bootable USB to a free port.
  2. Turn on the computer and, as soon as you see the manufacturer's logo, repeatedly press the appropriate key to enter the BIOS/UEFI or boot menu. It is usually Esc, Del, F1, F2, F10, F11 or F12.
  3. If you enter the BIOS/UEFI, look for a section called “Boot”, “Boot Order” or similar, and set the option to Removable devices / USB as the first boot device.
  4. Save the changes and restart. If everything is okay, the PC will boot from the USB drive and the installer or live system will start.

In Windows 10 and 11, if the system is still working, you can also force access to advanced boot options from the Start menu itself: hold down the key Shift While clicking on “Restart” and, from the advanced options, enter UEFI and change the boot order.

Common problems when booting from a USB drive and how to deal with them

No matter how carefully you do everything, there can always be situations where the PC refuses to boot from the USB drive on the first try. Some of the most common errors and their usual causes are:

  • The USB drive is not detected as a boot deviceThis could be due to the USB drive being damaged, the partitioning/formatting scheme not being compatible with the device's firmware, or the creation process not being done correctly.
  • The memory does not appear in the BIOS/UEFIOften, this is because the boot order is set to boot directly from the internal hard drive. It can also happen if the USB port isn't working properly or if the older firmware doesn't support booting from USB in certain modes.
  • The USB drive does not appear in the boot menu.If you use a very old USB drive (USB 1.0/2.0, which are not very compatible) or one with a strange format, the system may "ignore" the device as a boot candidate.
  • The device freezes on the startup screen or goes black.This is usually due to a corrupted ISO, a bad copy (e.g., dd interrupted before finishing), or UEFI/Legacy settings that do not match the image mode.
  • The drive never boots, but other USB drives do.In this case, it's quite likely that that memory is... physically damaged or corruptedThe quick fix is ​​usually to change the USB drive and repeat the process.

When something goes wrong, the wisest course of action is to review the steps: check the ISO (ideally downloading it again from the official source), verify that the USB drive has been formatted with the correct boot scheme (MBR for BIOS/Legacy, GPT for UEFI in many cases), and ensure that there are no Secure Boot restrictions in the BIOS/UEFI settings that might be blocking the device. If the problems originate from the ports, a guide from [unclear - possibly "USB drive troubleshooter"] might be helpful. USB port diagnostics.

Having a well-prepared bootable USB drive, whether created from Windows with diskpart and CMD, from Linux with dd, or using tools like Rufus and Media Creation Tool, gives you enormous freedom to install, reinstall, repair or diagnose any operating system Without relying on DVD drives or the current system booting; by mastering these command-line methods and knowing the graphical alternatives, you'll always have a "plan B" ready to rescue your PC when the dreaded black screen appears or you want to build a system from scratch on any computer. Share this tutorial so other users can learn about the topic.