codex: command not found after installing

What you see

The install step looked fine, but the shell answers:

codex: command not found

or, on Windows:

'codex' is not recognized as an internal or external command,
operable program or batch file.

The shell is saying it searched the directories listed in PATH and did not find an executable named codex. It says nothing at all about whether Codex is installed.

What it usually means

There are three distinct situations, and they need different fixes:

1. Nothing was installed. An installer can exit “successfully” while a download step failed, or you may have installed a different package.
2. It is installed, but not where this shell looks. This is the most common case. The binary exists; its directory is not on PATH for the shell you are using. A GUI terminal and a shell started from an IDE often inherit different environments.
3. You are in a different environment than the one you installed into. This is the classic WSL case: you installed inside Windows and are running a Linux shell, or the reverse. The two do not share installed programs.

Quick checks

1. Which shell and which system am I actually in? In WSL this matters more than anything else. If you installed with the Windows PowerShell installer, the command belongs in Windows terminals, not in a WSL shell.
2. Does it work in a brand-new terminal? Open a fresh one. A PATH change made by an installer only reaches terminals started afterwards.
3. Does it work when called by absolute path? If you can run the binary from the directory it was installed to, the install is fine and this is purely a PATH problem.
4. Which install method did you actually use? Re-read the command you ran. The documented methods install to different places:
   • macOS / Linux standalone: curl -fsSL https://chatgpt.com/codex/install.sh | sh
   • Windows standalone: powershell -ExecutionPolicy ByPass -c "irm https://chatgpt.com/codex/install.ps1 | iex"
   • npm: npm install -g @openai/codex
   • Homebrew: brew install --cask codex

Fixes, by branch

If a fresh terminal still cannot find it

• Confirm the install command you used is one of the documented methods above, exactly as written. A typo in the URL or package name is easy to miss.
• Re-run it and read the output rather than watching for an exit code. Installers that fall back between download sources can print a warning that is easy to skim past. The standalone installers download from releases.openai.com by default and fall back to GitHub Releases.
• Prefer one install method and remove the others. Mixing a Homebrew install with an npm install in the same account is a reliable way to end up with two copies and confusing PATH results.

If it works by absolute path but not by name

The directory holding the binary needs to be on PATH for the shell that is failing.

• Find where your install method puts executables, then add that directory to the PATH used by your shell’s startup file.
• For an npm global install, npm prefix -g prints the prefix directory whose bin (macOS/Linux) or root (Windows) holds global executables. Use that to locate what to add.
• On Windows, a PATH change made in one place may not apply to a shell launched from another context. Set it in the environment the terminal actually inherits, then start a new terminal.

If you are in WSL

• Decide which side should run Codex. Running it inside the Linux distribution is the cleaner choice if your project lives there.
• Install inside that distribution, using the macOS/Linux standalone installer, and verify the first run offers a sign-in choice.
• Do not try to add a Windows executable to a Linux PATH. It is possible with interop, but it is a support burden you do not need.

What not to do

• Do not run the installer with sudo to “make it findable”. That installs for a different user and usually moves the problem rather than solving it.
• Do not paste installer output containing tokens or account identifiers into a public issue.
• Do not add broad directories such as your home directory to PATH to make one command resolve. That is how unrelated executables start shadowing system ones.

How to tell it worked

Running codex starts the client and offers a sign-in path, rather than returning a not-found error. In the documented first-run flow you are offered a choice including Sign in with ChatGPT. Reaching that prompt means the install and the PATH are both fine.

If it is still failing

If the command resolves and the client starts but the sign-in step fails, that is a different problem with a different set of causes. If it starts and then prints configuration warnings, look at the MCP startup path instead.

Known limits of this guidance

• Evidence level: documentary. The install methods are quoted from the official README as read on the review date; installer behaviour can change between releases.
• The PATH troubleshooting here is standard operating-system practice, not a claim taken from OpenAI documentation. It is presented as a method, not as an official instruction.
• Windows-specific PATH editing differs between shells and system versions, so no single procedure is prescribed here.
• This guide does not cover package-manager-specific failures, such as a proxy blocking npm.