Gemini CLI: what it is and what still works

What Gemini CLI is, and what changed in June

Gemini CLI is an open-source (Apache 2.0) agent that runs in your terminal, reads your repository, edits files, runs shell commands, and calls tools over MCP. It is the same shape as Claude Code and the Codex CLI: a REPL you launch in a project directory, plus a non-interactive mode for scripts.

The complication is that Google reorganised its developer tooling at I/O on 19 May 2026 and consolidated everything under the Antigravity brand. On 18 June 2026, Gemini CLI stopped serving requests for individual accounts: free tier, Google AI Pro, and Google AI Ultra. The project itself was not deleted, archived, or abandoned. Only that authentication rail was switched off.

That table is the single most important thing on this page. Everything below assumes you are on a rail that still resolves.

Install it

npm install -g @google/gemini-cli

# macOS and Linux, via Homebrew
brew install gemini-cli

# macOS, via MacPorts
sudo port install gemini-cli

# no install at all
npx @google/gemini-cli

gemini --version

Homebrew lags npm by a meaningful margin. When this guide was checked in August 2026 the npm package was on 0.54.4 and the Homebrew formula was on 0.46.0. If a flag in this guide is missing from your build, check gemini --version before assuming the documentation is wrong.

There are three release channels. Stable ships weekly on Tuesdays and is what you get by default. Preview ships weekly and is unvetted. Nightly ships daily from main.

npm install -g @google/gemini-cli@latest    # stable, the default
npm install -g @google/gemini-cli@preview
npm install -g @google/gemini-cli@nightly

Authentication that still resolves

Two rails are available to an individual developer in August 2026: a Gemini API key from AI Studio, or Vertex AI through a Google Cloud project. Both bill separately from any Google AI subscription you hold.

export GEMINI_API_KEY="YOUR_KEY"

# make it stick
echo 'export GEMINI_API_KEY="YOUR_KEY"' >> ~/.zshrc

$env:GEMINI_API_KEY="YOUR_KEY"

cd ~/code/your-project
gemini

Vertex AI instead

Vertex AI is the route when you want higher limits, an organisation-owned billing account, or Express Mode's 90-day no-billing window. It needs two variables set regardless of which credential type you use.

export GOOGLE_CLOUD_PROJECT="your-project-id"
export GOOGLE_CLOUD_LOCATION="us-central1"

# then one of:
gcloud auth application-default login   # ADC
# or a service account JSON key, or a Google Cloud API key

Gemini CLI commands

There are three layers: the shell command and its flags, subcommands like gemini mcp, and slash commands inside the REPL. The flags are where the behaviour actually lives.

Slash commands inside the session

How to use it on a real repository

The default install answers questions well and edits files badly, because it knows nothing about your project. Three files close most of that gap.

# Project

TypeScript monorepo, pnpm workspaces, Postgres via Prisma.

## Commands
- Test one package: `pnpm --filter @app/api test` (NOT `pnpm test`, that is 9 minutes)
- Typecheck: `pnpm -r typecheck`
- Regenerate the client after a schema change: `pnpm prisma generate`

## Conventions
- Every route handler returns a typed Result, never throws across a boundary.
- packages/generated is generated. Never hand-edit it.

## Do not
- Do not add dependencies without asking.
- Do not touch prisma/migrations unless the task is a migration.

printf 'dist/\ncoverage/\n*.snap\ntestdata/large/\n' > .geminiignore

gemini --approval-mode plan       # read and propose, no edits
gemini --approval-mode auto_edit  # edit files freely, ask for shell commands
gemini --approval-mode yolo       # approve everything, for throwaway containers

Non-interactive runs

The -p flag is what makes Gemini CLI scriptable, and -o json is what makes it parseable.

gemini -p "summarize the changes in the last 5 commits"

# structured output for a pipeline
gemini -p "list every TODO in src/ as JSON" -o json | jq

# stdin as context
git diff --staged | gemini -p "write a commit message for this diff"

Antigravity CLI is the successor

Google's replacement for individual developers is the Antigravity CLI: a Go binary called agy, sharing an agent core with the Antigravity 2 desktop app. It installs from a script rather than npm, and it is faster to start because it is a single compiled binary rather than a Node process.

curl -fsSL https://antigravity.google/cli/install.sh | bash
agy

When it breaks

If you are moving off it entirely, remove the package and then decide what to do with ~/.gemini, because that directory is now shared with Antigravity CLI.

Questions people ask

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