A bootable USB can help you try an operating system or carry a deliberately configured workspace. Decide what must survive a restart before you build it. For a first trial, use a current official live image on a computer you own or are authorized to administer, with a separate place to save anything important.
Choose what the USB is meant to do
On a narrow screen, swipe the table or focus it and use the arrow keys.
| Arrangement | What survives a restart | Best starting question |
|---|---|---|
| Ordinary live session | Treat session changes as temporary; explicitly export files you need. | Am I only evaluating the interface and hardware? |
| Live session with persistence | Configured files or changes are saved in a persistent area. | Exactly which paths and settings are retained? |
| Installation medium | The USB launches an installer; installation writes to a selected destination. | Which drive will receive the installed system? |
| Full installation on an external drive | The external drive holds a normal installed system and its updates. | How are boot files, updates and host compatibility managed? |
The walkthrough below stops at a live preview. A persistent system or full external installation needs its own supported procedure and recovery plan. The Debian Live manual’s persistence section illustrates why: persistence requires deliberate storage configuration and boot settings, and encryption is a separate configuration. Follow instructions for your chosen distribution and release.
Prepare the host, download and target
Record the computer model, processor architecture, firmware boot mode and existing disk-encryption recovery information. Follow workplace policy on managed computers. Use the computer maker’s boot-menu instructions; a one-time USB selection avoids an unnecessary permanent boot-order change. Keep backups of the host and the USB’s contents before starting.
Download from the operating-system publisher. Ubuntu’s verification procedure authenticates the signed checksum list and compares the ISO against its SHA-256 entry. Use files for the same release and exact ISO filename, check the signing-key fingerprint as instructed, and keep the result. A checksum from an unrelated download page provides weaker evidence of provenance.
Before writing, identify the disposable target by its model, capacity and connection. Remove other removable drives when practical. Recheck the selection immediately before approving erasure. If the writer’s device list is ambiguous, stop and resolve it; a drive letter alone is a fragile identifier.
A supported starting path: Ubuntu Desktop live preview
Canonical’s Try Ubuntu Desktop tutorial currently uses Ubuntu Desktop 26.04 LTS and recommends a USB drive of at least 8 GB. This example is for a compatible x86-64 PC using the amd64 image; other architectures and Apple Silicon require their own supported instructions.
- On Windows, use Rufus from its official site, select the intended USB device and the downloaded ISO, and follow Canonical’s writing options. Writing the image erases that USB.
- Boot the PC using its documented USB boot-menu entry. Follow the initial language and keyboard prompts, then select Try Ubuntu. Leave installation for a separate decision.
- Test the display, keyboard, pointing device, network and the applications you actually need. The preview uses open-source drivers; hardware requiring proprietary drivers may behave differently after installation.
- Export wanted files to a chosen separate destination and verify them. Restart from the system menu, remove the USB when prompted, and confirm that the normal system starts.
For Ubuntu or macOS as the writing computer, use the corresponding tab in Canonical’s tutorial. Creating media on one architecture and booting it on another are separate compatibility questions.
If the USB fails to start
Record whether the USB is missing from the boot menu, the firmware rejects it, or the operating system starts and then stalls. Those observations lead to different checks: target writing and port detection, image/firmware trust, or hardware/driver support. Confirm the exact image architecture and computer instructions before recreating media.
Ubuntu supports a signed Secure Boot chain, described in Canonical’s UEFI Secure Boot documentation. Firmware trust and signed components matter, so retain the computer’s existing security settings while checking current publisher guidance. A boot failure is insufficient reason to disable Secure Boot or enroll unfamiliar keys. A managed device may need its administrator.
Test persistence and define a trust boundary
Keep a second copy of wanted files outside the workspace. Record the release, image checksum, writing tool, host model, boot result, persistence locations and last successful restart test. Revisit the image and updates before relying on an older USB for travel or recovery.
A live environment can access local disks if you mount and modify them, and network services can retain activity. Use a trusted host and ordinary account-security practices. Portability is a workflow convenience, not a promise of immunity from malware or absence of traces.