codex/docs/install.md

Installing & building

System requirements

Requirement	Details
Operating systems	macOS 12+, Ubuntu 20.04+/Debian 10+, or Windows 11 via WSL2
Git (optional, recommended)	2.23+ for built-in PR helpers
RAM	4-GB minimum (8-GB recommended)

DotSlash

The GitHub Release also contains a DotSlash file for the Codex CLI named codex. Using a DotSlash file makes it possible to make a lightweight commit to source control to ensure all contributors use the same version of an executable, regardless of what platform they use for development.

Build from source

# Clone the repository and navigate to the root of the Cargo workspace.
git clone https://github.com/openai/codex.git
cd codex/codex-rs

# Install the Rust toolchain, if necessary.
curl --proto '=https' --tlsv1.2 -sSf https://sh.rustup.rs | sh -s -- -y
source "$HOME/.cargo/env"
rustup component add rustfmt
rustup component add clippy
# Install helper tools used by the workspace justfile:
cargo install just
# Optional: install nextest for the `just test` helper
cargo install cargo-nextest

# Build Codex.
cargo build

# Launch the TUI with a sample prompt.
cargo run --bin codex -- "explain this codebase to me"

# After making changes, use the root justfile helpers (they default to codex-rs):
just fmt
just fix -p <crate-you-touched>

# Run the relevant tests (project-specific is fastest), for example:
cargo test -p codex-tui
# If you have cargo-nextest installed, `just test` runs the test suite via nextest:
just test
# If you specifically want the full `--all-features` matrix, use:
cargo test --all-features

Tracing / verbose logging

Codex is written in Rust, so it honors the RUST_LOG environment variable to configure its logging behavior.

The TUI defaults to RUST_LOG=codex_core=info,codex_tui=info,codex_rmcp_client=info and log messages are written to ~/.codex/log/codex-tui.log, so you can leave the following running in a separate terminal to monitor log messages as they are written:

tail -F ~/.codex/log/codex-tui.log

By comparison, the non-interactive mode (codex exec) defaults to RUST_LOG=error, but messages are printed inline, so there is no need to monitor a separate file.

See the Rust documentation on RUST_LOG for more information on the configuration options.