Install

Check Requirements first — the macOS floor is 15 (Sequoia).

Homebrew (recommended)

1. Tap and install:

   brew tap rexenv/tap
   brew trust rexenv/tap
   brew install --cask rexenv

2. Launch it:

   open -a rexenv

`brew trust` is required, not optional

Current Homebrew refuses to install a cask from a tap it has not been told to trust. Skip that line and the install stops with a refusal that reads like a broken package.

Two things this path gives you that the disk image does not:

• No Gatekeeper step. The cask’s postflight removes the quarantine attribute, so the app opens on a normal double-click the first time.
• rex on your PATH automatically, linked into Homebrew’s bin. No Settings toggle needed.

Disk image

1. Download rexenv_<version>_universal.dmg from the releases page.

2. Verify it against the published checksum:

   shasum -a 256 rexenv_*_universal.dmg

   Compare the output with the .dmg.sha256 file next to the download.

3. Open the disk image, drag rexenv into Applications, eject.

4. Right-click (or Control-click) rexenv in Applications → Open → Open again in the dialog. Once only.

Why the right-click

rexenv is ad-hoc code-signed and not yet notarized by Apple, so Gatekeeper refuses a plain double-click the first time with “rexenv can’t be opened” or “unidentified developer”. The ad-hoc signature is what lets Apple Silicon run the app at all.

If you double-clicked first and got blocked, System Settings → Privacy & Security → scroll down → Open Anyway does the same thing. After once, rexenv opens normally forever.

The Homebrew path avoids this entirely. It is the better install for that reason alone.

What happens on first launch

rexenv asks for permission three times — an admin password, a Keychain prompt, and an admin password again. They are expected, they all stay on your machine, and First run explains exactly what each one writes.

Updating

With Homebrew:

brew update && brew upgrade --cask rexenv

With the disk image: quit rexenv and drag the new copy over the old one in Applications.

Either way your sites, settings and downloaded components are kept — they live in ~/Library/Application Support/dev.rexenv.rexenv/, not inside the app.

Uninstalling

Do not just drag the app to the Bin. rexenv installs privileged, system-level things that deleting the app cannot remove. Uninstall has the one in-app step that undoes them.