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Install the Agent

The agent is the program you talk to. It does the typing for you — including installing everything on the pages that follow. So this is the one page where you paste a couple of commands yourself. After it, you only paste prompts.

The English pages use OpenAI Codex CLI; the Chinese pages use DeepSeek Harness — different tools, the same way of working.

You need a terminal for this page

On Windows that is PowerShell, on macOS Terminal, on Linux whatever your system calls its terminal. Paste the line, press Enter. That is the whole skill.

1. Install it​

Pick the tab for your computer. Each line downloads a ready-made program and needs nothing installed beforehand — by design: the things it would otherwise need are the things it is about to install for you.

curl -fsSL https://chatgpt.com/codex/install.sh | sh

Homebrew users get the same result with:

brew install --cask codex

Check it arrived:

codex --version

What you should see: a version number.

"command not found" right after a successful install

The terminal was opened before the install finished, so it has stale information. Close it, open a new one, and run the check again. This is not a failed install.

2. Log in​

codex login
codex doctor

What you should see: codex doctor prints a short report — where its settings file is, what it is allowed to do, and whether it can reach the internet. All three have to look right. If something later goes wrong, run codex doctor again before blaming anything you said.

3. Work in the right folder​

The folder you start the agent in is the only folder it can change, and where it looks for a project's instruction files. You do not have a project yet, so start in the folder your project is about to be created inside — not the project itself.

mkdir ~/projects
codex -C ~/projects

Joining an existing project? Start inside it instead:

codex -C ~/projects/admin-platform

What you should see: ask the agent to run pwd. The folder it prints must be the one you meant. Getting this wrong surfaces much later as an agent that reports success while nothing appears where you expected — it built it somewhere else.

Two settings keep the agent inside that folder instead of asking about every click or quietly changing files elsewhere. Create a file called .codex/config.toml inside that folder, containing exactly this — or simply ask the agent to create it (the folder is one it may write to):

approval_policy = "on-request"
sandbox_mode    = "workspace-write"

[sandbox_workspace_write]
network_access = true
LineWhat goes wrong without it
approval_policy = "on-request"it can create a project in the wrong folder and you will not notice
sandbox_mode = "workspace-write"it can change files outside your project
network_access = trueinstalls fail, and the error looks like the internet is broken rather than a setting

Check it took effect:

codex doctor

What you should see: the settings file it names is the one you just created in that folder — not one in your home folder.

Never use --yolo

You will find this option suggested online. It switches off both safety rules at once. If the agent asks too many questions, ask it for something smaller — do not remove the guard rails.

Next​

Install the skill — after that, setting up the rest of your computer becomes a sentence instead of a command list.