はじめに
この記事を見ていて,
そういえば Codex をインストールしていなかったなと思いインストールしました.
備忘録です.
設定
インストール
$ brew install codex
サインイン
$ codex
_.=;++====,_
_+,/\||+|"==|;_^|*+_
,;/*;|*""` `"~!**+/^|,
/+/\|;,+_ `=*!||\
'/*|/^/||*\_ \^\||_
/|\\/ .,|\;\\ | \\|
=* | '*\|_"|, .*/|,
,-|,| ,-|"/\| ~_|=|
-"'| ;|*+~|*-~=++___++_~^";|
,\:\, ./*/;;| |*|__,!=.,;\`|\|`
'^| | "||+," "***"""**,///,/
'*~ \+ ` /^+^//
=^//*\, ,+;/",|'
=^+,_**^=;=;,:=*;`_+"
`*+*_:~____~;/^"
Welcome to Codex, OpenAI's command-line coding agent
Sign in with ChatGPT to use Codex as part of your paid plan
or connect an API key for usage-based billing
> 1. Sign in with ChatGPT
Usage included with Plus, Pro, and Team plans
2. Provide your own API key
Pay for what you use
Press Enter to continue
私は 1. Sign in with ChatGPT を選択しました.
サインインすると下記の表示に切り替わっていました.
$ codex
_,+_=+*++=+__
_=|+|\_,_==,|_|*|+_
,"+|',;*` "~:+|\;||,
/;|*;/` _;;\||;\
//|`/' ,/,,'*/*\|\
,\|"/` _***''/*'|~\|,
`||"| /:/. _|` "!|'*
~/| | |"|,_\, | */|
^"\ |+~;=====;=|_*|_"\_ | |~|
|\\_|"=" /`\ \|_\,~ \_|
/'| | `""""""" '`/;=|_/^/`
,||_|. ,/|\^/`
\ |,'/__ _.";*/+/
\=\+;*+\~==_++"-_+*`
"~!*=\~__+__**`
Welcome to Codex, OpenAI's command-line coding agent
✓ Signed in with your ChatGPT account
Before you start:
Decide how much autonomy you want to grant Codex
For more details see the Codex docs
Codex can make mistakes
Review the code it writes and commands it runs
Powered by your ChatGPT account
Uses your plan's rate limits and training data preferences
Press Enter to continue
$ codex
╭───────────────────────────────────────────╮
│ >_ OpenAI Codex (v0.42.0) │
│ │
│ model: gpt-5-codex /model to change │
│ directory: ~/... │
╰───────────────────────────────────────────╯
To get started, describe a task or try one of these commands:
/init - create an AGENTS.md file with instructions for Codex
/status - show current session configuration
/approvals - choose what Codex can do without approval
/model - choose what model and reasoning effort to use
▌ Improve documentation in @filename
⏎ send ⌃J newline ⌃T transcript ⌃C quit
モデル確認
/model で確認すると gpt-5-codex medium が選択されていました.
Select model and reasoning level
▌ Switch between OpenAI models for this and future Codex CLI session
▌
▌ 1. gpt-5-codex low
▌ > 2. gpt-5-codex medium (current)
▌ 3. gpt-5-codex high
▌ 4. gpt-5 minimal — fastest responses with limited reasoning; ideal for coding, instructions, or lightweight tasks
▌ 5. gpt-5 low — balances speed with some reasoning; useful for straightforward queries and short explanations
▌ 6. gpt-5 medium — default setting; provides a solid balance of reasoning depth and latency for general-purpose tasks
▌ 7. gpt-5 high — maximizes reasoning depth for complex or ambiguous problems
Press Enter to confirm or Esc to go back
最後に
Jetbrains の AI Chat と Junie,
Claude Code に追加して Codex という選択肢ができました.
CLI としては Claude Code と使い分けていきたいと思います.