How to Install FSL 6.0.7.23 on Apple Silicon Mac? 2026

The installer finishes, but you are not sure whether FSL commands or FSLeyes actually work on your Mac.

This week: use the official macOS guide and its recommended getfsl.sh route, then verify the shell, GUI, and a permitted project copy separately. FSL 6.0.7.23 is listed in the official release history as published on July 28, 2026 (FSL release history); a completed installation is not proof that your MRI workflow has passed acceptance.

For graduate students and PhD candidates working mainly on Linux or Windows, this guide walks through installing and checking FSL on macOS.
For research software support staff, it separates installation paths, command-line checks, and graphical checks.
If you do not have a local Mac, it also helps you judge whether a remote macOS environment can support your project review.

Before installation: confirm the machine and the project

FSL’s documentation lists recent macOS versions on both Intel and Apple Silicon as supported platforms, and recommends getfsl.sh for new users (official FSL macOS installation guide). Treat that as a platform-level starting point, not a promise that every tool, dependency, plugin, or lab pipeline has been tested on your specific system.

Start by checking the architecture and defining what “working” means for your project:

• Record the Mac architecture. Use the system information available on the Mac and note whether it reports Apple Silicon or Intel. Keep the result with your lab’s environment notes.
• List the FSL tools your workflow needs. A project that uses only command-line utilities has different acceptance needs from one that depends on FSLeyes or another GUI.
• Check the project’s dependencies. Note any scripts, external packages, shell configuration, or lab-specific setup that the analysis expects. Do not assume the FSL installer configures those items for you.
• Choose a permitted test input. Make a copy of a non-sensitive image or another sample your institution allows you to use. Do not use identifiable or restricted participant data as an installation test unless your approval and data-handling process explicitly allow it.
• Write down a baseline. Record the existing FSL path, relevant shell settings, and the commands your project currently expects. This makes it easier to distinguish a new installation problem from an older configuration.

FSL 6.0.7.23 is a specific release, so confirm that version against the official release history rather than relying on a copied installer command or an old lab note. If the current installation page or release information has changed since your notes were written, follow the official page that applies now.

Prepare a clean installation path

Before running the installer, review the destination and the state of your shell. This is where a technically successful install can still leave you with a confusing setup: an old FSL directory may remain on the command path, a shell startup file may point somewhere unexpected, or a filesystem may not support a link or permission behavior needed by the installation.

Read the official macOS instructions from beginning to end before executing commands. Confirm the installation location they recommend, the current network requirements, and any terminal prerequisites. The FSL configuration guidance is also useful when you need to understand how configuration and environment settings affect a working installation.

Take these precautions before changing anything:

• Save a copy of any shell configuration file you plan to edit.
• Note whether FSLDIR or related FSL settings already exist in your current shell.
• Avoid installing over an existing FSL directory until you know whether another project uses it.
• Use a filesystem and path consistent with the official guidance; do not assume every mounted volume or network share behaves like a local installation volume.
• Keep enough terminal history or a saved transcript to review any warnings and errors after the installer exits.

If the machine already has an FSL installation, pause before running a second setup. First determine which project uses the existing path and whether changing shell configuration would redirect its commands.

Install with the official getfsl.sh route

For a new installation, FSL recommends getfsl.sh in its macOS guide. Use the current instructions from that page rather than a command copied from a forum, a colleague’s notes, or an older setup document. This matters because installer locations and supported procedures can change; the authoritative reference for the current route is the FSL macOS installation page.

Follow this sequence:

• Open the official guide and confirm that its platform guidance applies to the Mac you are preparing.
• Read the complete installation procedure, including the destination and shell configuration steps.
• Run the command exactly as shown in the current official guide. Do not add options or change the destination unless the documentation or your administrator instructs you to.
• Watch the terminal output for warnings, failed downloads, permission errors, or skipped components. A process ending without an obvious error is useful evidence, but it is not a complete validation result.
• Save the output or copy relevant messages into your lab record. Include the date you performed the installation and the FSL version you intended to install.
• Complete the configuration steps described by FSL, then open a new terminal session before testing.

Avoid treating the script as an opaque “one-click” operation. If installation stops unexpectedly, do not repeatedly rerun it into the same directory without checking what was created and what failed. Preserve the output first, compare the error with the current documentation, and resolve the specific issue before another attempt.

First shell session: check FSL configuration

After installation, start a fresh Terminal session. This tests whether the configuration is loaded when you begin ordinary work, rather than only in the shell that ran the installer.

Check the configured directory:

echo "$FSLDIR"

The output should point to the installation directory you expected. If it is blank or points elsewhere, do not immediately edit multiple startup files. Review the official FSL configuration instructions, identify which shell initialization file your terminal uses, and check whether an older FSL configuration is taking precedence.

Then check whether required tools are discoverable:

command -v fslmaths
command -v imcp

FSL’s installation verification guide describes the official verification approach, while the FSL utilities reference explains tools such as fslmaths and imcp. If a command is not found, distinguish a missing configuration from a missing component before reinstalling. Compare the command path, FSLDIR, and the installer output.

A command being discoverable is only a basic shell check. It does not establish that the command can read your project’s files, that your input format is suitable, or that an analysis produces scientifically acceptable output.

GUI checks: distinguish FSLeyes from the command line

FSLeyes is a separate acceptance gate. It is possible for command-line tools to be available while the graphical application fails to launch, and a GUI window opening does not prove that a project’s image data display correctly.

Use the official FSLeyes documentation alongside the FSL installation verification guidance. Follow the documented launch method, preferably from Terminal during initial diagnosis, so you can retain any messages printed when the application starts.

Check the layers separately:

• Launch: Does FSLeyes start, or does the terminal return an error?
• Load: Can you open a permitted sample image without an error?
• Display: Does the image render in a way that makes sense for the file you selected?
• Repeat: Can you close and reopen the application without relying on a one-off terminal state?

If FSLeyes does not open, record the exact error and whether the command-line checks passed. Review the official configuration and FSLeyes guidance before changing shell files or reinstalling. Avoid concluding that the whole FSL installation is unusable based on a GUI error alone; the fault may be limited to application launch or display.

Compare the environment choices

Choose the next step based on what you need to validate, not on whether installation appears convenient. The ratings below are qualitative fit assessments, not performance measurements.

If you need to compare remote options, begin with the VPSMAC environment overview and check the current details on the available Mac environment page. Do not infer a particular macOS version, access method, or research-data approval from a general service description. Confirm those points before planning a test.

Project acceptance: test a copy before relying on the setup

Once the shell and GUI checks are complete, test a representative copy of the project. Match the test to the task you actually need to perform. A simple command can establish that a tool runs, but it cannot establish that a full analysis is reproducible or methodologically sound.

Use this acceptance sequence:

• Select an approved copy. Check the lab’s data policy before moving any files to a local or remote machine. If approval is unclear, use a non-sensitive sample or ask the responsible administrator.
• Run the intended tool on a representative input. Include the file format and processing path your project expects, not just an unrelated demonstration file.
• Check reads and writes. Confirm that the command can access its input and create output in the intended location. Verify that the output is present and can be opened by the next step in your workflow.
• Compare with the project baseline. Review expected files, logs, and any established quality checks. A difference should trigger investigation; it should not be dismissed as an installation detail.
• Have the responsible researcher review the result. Software launch and file creation do not replace method-specific review or the lab’s scientific acceptance process.
• Record the environment. Keep the FSL version, architecture, installation path, relevant configuration, test input description, and observed outcome with the project notes.

This final step is where you decide whether the environment is ready for your study. If a command works but the project output differs from the established baseline, investigate dependencies and workflow assumptions before processing study data. If the command line passes but the GUI does not, decide whether the project actually requires FSLeyes or whether a separate approved environment is needed for visual inspection.

Frequently asked questions

How do I install FSL on an Apple Silicon Mac?

Start with the current FSL macOS installation guide and use its recommended getfsl.sh route for a new installation. Check the supported-platform wording and the current command on that page before running it. Keep the terminal output, then reopen your shell and confirm the configured FSL directory and required commands before testing a research project.

How can I tell whether getfsl.sh finished installing FSL correctly?

Do not rely on the script reaching its final line. Open a fresh terminal, inspect FSLDIR, and check whether required commands such as fslmaths and imcp resolve. Then run a harmless test on a copy of a permitted image. These checks establish basic command availability, not that every FSL tool or your study pipeline has passed validation.

What should I check if FSLeyes will not open on my Mac?

First separate a shell setup problem from a graphical launch problem. Confirm FSLDIR and the relevant command paths, then launch FSLeyes from Terminal and save the full error output. Check the official FSLeyes guidance and your macOS configuration before changing environment files. A failed GUI launch does not by itself prove that FSL command-line tools are unusable.

Can I validate an FSL project without owning a Mac?

A remote macOS environment can be a candidate for checking tools that need macOS, but suitability depends on your project dependencies, access to the required files, and your institution’s data rules. Use a non-sensitive project copy unless approved otherwise. Confirm the environment’s current system details and remote access method before you transfer data or treat results as accepted.

Choose the next environment from the acceptance result

Use the official installation route first, then make your decision from the evidence: shell commands available, FSLeyes checked if needed, and a representative project copy reviewed. If you already have an approved local Mac, continuing there may be the simplest option. If your lab’s Linux or Windows workflow meets the project requirements and no macOS-specific validation is needed, there may be no reason to add another environment.

A shared lab machine can be hard to schedule, may not match your target macOS setup, and can make ownership of shell changes or project files unclear. A personal Mac avoids some access coordination but requires you to supply and maintain the hardware. If the missing piece is temporary access to macOS for FSL verification, consider VPSMAC only after checking the current environment details and confirming that your institution permits the intended data handling. Start with a non-sensitive project copy, review the available options through the VPSMAC environment page, and keep the research team responsible for the final workflow approval.