Only use specific directories.

[fx-xt]

Output of brew config

HOMEBREW_VERSION: 5.0.8-dirty
ORIGIN: https://github.com/Homebrew/brew
HEAD: b473452cf25e5f70522229d1472948584b74736b
Last commit: 2 days ago
Branch: stable
Core tap HEAD: e3e6518ae01098b4efa41a9ed6496363541c72d3
Core tap last commit: 63 minutes ago
Core tap JSON: 30 Dec 22:15 UTC
Core cask tap JSON: 30 Dec 22:15 UTC
HOMEBREW_PREFIX: /Applications/Ultramaker.app/Contents/.jmf/brew/homebrew
HOMEBREW_REPOSITORY: /Applications/Ultramaker.app/Contents/.jmf/brew/homebrew
HOMEBREW_CELLAR: /Applications/Ultramaker.app/Contents/.jmf/brew/homebrew/Cellar
HOMEBREW_CASK_OPTS: []
HOMEBREW_DOWNLOAD_CONCURRENCY: 20
HOMEBREW_FORBID_PACKAGES_FROM_PATHS: set
HOMEBREW_MAKE_JOBS: 10
Homebrew Ruby: 3.4.8 => /Applications/Ultramaker.app/Contents/.jmf/brew/homebrew/Library/Homebrew/vendor/portable-ruby/3.4.8/bin/ruby
CPU: deca-core 64-bit arm_donan
Clang: 17.0.0 build 1700
Git: 2.50.1 => /Library/Developer/CommandLineTools/usr/bin/git
Curl: 8.7.1 => /usr/bin/curl
macOS: 26.2-arm64
CLT: 26.2.0.0.1.1764812424
Xcode: N/A
Rosetta 2: false

Output of brew doctor

Please note that these warnings are just used to help the Homebrew maintainers
with debugging if you file an issue. If everything you use Homebrew for is
working fine: please don't worry or file an issue; just ignore this. Thanks!

Warning: Your Homebrew's prefix is not /opt/homebrew.

Most of Homebrew's bottles (binary packages) can only be used with the default prefix.
Consider uninstalling Homebrew and reinstalling into the default prefix.

This is a Tier 3 configuration:
  https://docs.brew.sh/Support-Tiers#tier-3
You can report Tier 3 unrelated issues to Homebrew/* repositories!
Read the above document before opening any issues or PRs.

Description of issue

I need to be able to compile things in a special directory. My machine is managed by my school and certain paths (like user paths) are blacklisted from running any applications. I have to have all of my binaries in a certain directory. When I install something (eg ffmpeg,) it uses /private/tmp/ which is blacklisted.

Heres the output of ~/Library/Logs/Homebrew/gettext/01.configure.log
01.configure.log

I don't have any way to use any other paths, so I need to build in a whitelisted path (one of these) "/Applications/", "/System/Library/", "/Library/", "/bin/", "/usr/bin/" (there are a few more but those are only system libraries.)

If this is the wrong fourm please redirect me to the correct one.

[p-linnane]

On modern macOS systems, directories like /System and /usr/bin are protected by the sealed system volume and are not writable, even as root. Homebrew cannot build or install software into these locations.

This setup involves multiple unsupported configurations, including using a non-standard Homebrew prefix inside an application bundle and blocking execution from temporary directories. Homebrew requires executing temporary build artifacts during compilation, so this environment is not supported.

[cho-m]

You could try setting HOMEBREW_TEMP environment variable, but no guarantee it works as it isn't a commonly used setting and your setup uses unsupported paths.

From https://docs.brew.sh/Manpage#environment,

Use this path as the temporary directory for building packages. Changing this may be needed if your system temporary directory and Homebrew prefix are on different volumes, as macOS has trouble moving symlinks across volumes when the target does not yet exist. This issue typically occurs when using FileVault or custom SSD configurations.

Default: macOS: /private/tmp, Linux: /var/tmp.

[fx-xt]

This works like a charm, thank you!