What Is OpenAI Codex CLI and How Do You Use It?

OpenAI Codex CLI is OpenAI's terminal-based coding agent: you run it from your shell, describe a task in natural language, and it reads your repository, proposes edits, and (with your approval) applies them. It fits developers who already work in a terminal and want an agent that operates directly on a local checkout rather than in a browser tab or a separate IDE panel. The release history tracked on Havoptic shows it shipping as a Rust binary under version tags like rust-v0.160.0 and rust-v0.159.3, which is the naming you'll see when you check what you have installed.

How the CLI differs from the Codex web and IDE experience

The three surfaces share a model and a general "describe the task, get code" loop, but they differ in where your code lives and who holds the context:

The practical consequence: the CLI is the surface where "review the diff, then approve or reject" is the central interaction. If your workflow is already git add -p and reading patches before committing, the CLI's approval model will feel familiar.

Installing and authenticating

Installation and sign-in details change between releases, so treat the steps below as the shape of the process and confirm exact commands against the current release notes for your version.

1. Install the binary. Codex CLI ships as a Rust binary. Depending on your platform you'll install it through a package manager or a direct download; the release tags (rust-v0.160.0, rust-v0.159.3) identify which build you're getting.
2. Authenticate. You sign in with an OpenAI account or configure an API key. Recent releases added optional reminders to complete account security setup for local sessions — that's a nudge, not a requirement, and you can decline it.
3. Verify the install. Run the version command and confirm the tag matches what you intended to install. This matters because the changelog is organized by version, so knowing your version tells you which features you actually have.

A note on access: the source material here doesn't state pricing or whether sign-in is required for every mode, so don't assume the CLI is free or that it runs without an account. Check OpenAI's own documentation for the current terms.

The core workflow: prompt, review, approve

The loop is short and worth internalizing:

• Prompt. Describe the change in the terminal — a bug to fix, a function to add, a refactor to perform.
• Let it read. The agent inspects the relevant files in your working directory to build context.
• Review the diff. It proposes edits as a diff. This is the checkpoint where you decide.
• Approve or reject. Accepted changes are written to disk; rejected ones aren't. Nothing lands in your repo without that step.

Two recent changes make this loop smoother. rust-v0.160.0 added easier browsing of task history and the ability to paste text directly in fullscreen terminal mode, plus a stability overhaul that fixed message delays. If you've been annoyed by laggy output or by not being able to paste into a fullscreen session, that release is the one that addresses it.

Everyday commands and configuration

The exact flag set moves between versions, so the durable advice is to learn the categories of control and check --help for the current spelling:

• Session and history controls — resume or browse prior tasks. Task-history browsing improved in rust-v0.160.0.
• Approval and permission settings — decide how much the agent can do without asking. This is the setting that most changes your day-to-day experience: tighter approval means more interruptions but more control.
• Terminal behavior — fullscreen mode, paste handling, and output rendering. Fullscreen paste support arrived in rust-v0.160.0.
• Account and security — the optional security-setup reminders added in rust-v0.159.3 live here.

If you're configuring for the first time, start with the approval setting. It determines whether the tool feels like a cautious pair programmer or an autonomous editor, and it's the choice you'll revisit most.

Checking your version and tracking releases

Because features are gated by version, tracking releases is part of using the tool well rather than an afterthought.

• Check what you have. Run the version command in your terminal and note the tag.
• Track what's new. Havoptic maintains a timeline of AI coding tool releases, updated daily via automated pipelines, with OpenAI Codex CLI listed among its tracked tools. Its last-updated stamp is October 3, 2026, and its recent entries include rust-v0.160.0 (October 1, 2026) and rust-v0.159.3 (September 30, 2026). That's a reasonable single place to watch Codex CLI alongside Claude Code, Cursor, Gemini CLI, and the other tools it tracks.
• Read the entry for your gap. If you're several versions behind, scan the entries between your version and the latest for anything that changes your workflow — stability fixes and paste/history improvements are the kind of thing you'd otherwise never notice.

One caveat on the timeline: it's an automated aggregation, so for anything security-relevant or breaking, confirm against OpenAI's official changelog before you act.

Where it fits among the other CLI agents

Codex CLI isn't alone in this category. Havoptic tracks Claude Code, Gemini CLI, Kiro CLI, GitHub Copilot CLI, Antigravity CLI, and others on the same timeline. The differentiators that matter for choosing between them are which model and account you already have, how the approval model works, and which one integrates with the editor or CI you use. If you're already in OpenAI's ecosystem, Codex CLI is the natural terminal entry point; if you're standardized on another provider, the equivalent CLI from that provider will usually be less friction. The release cadence across all of them is fast enough that a tool's current feature set is a weak reason to commit — pick on ecosystem fit, and let the changelogs handle the rest.