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OpenAI Codex CLI in Depth
Codex is OpenAI's agentic coding tool for the terminal — the same category of tool as
Claude Code. This deep dive covers the whole surface: installing and signing in, driving it
interactively versus headless in CI with codex exec, resuming sessions, the
slash commands, the approval and sandbox model that decides what it may touch, the
AGENTS.md project file, ~/.codex/config.toml, MCP, and the cloud.
Every command here is copy-pasteable, and a mapping table translates what you already know
from Claude Code into Codex.