Environment variables

The following environment variables configure Biome and its npm package.

BIOME_DISTRIBUTION

Overrides the installation source detected by biome upgrade.

The following installation sources are supported:

• npm: Treats Biome as installed through an npm-compatible package manager. You must update Biome using that package manager.
• homebrew: Updates Biome by running brew upgrade biome.
• standalone: Updates the standalone Biome binary directly.

Use this when biome upgrade cannot correctly detect how Biome was installed, such as a Homebrew installation under a custom prefix.

BIOME_DISTRIBUTION=homebrew biome upgrade

BIOME_LOG_FILE

Writes internal CLI logs from commands such as check, lint, format, and ci to the specified file.

Use this to save detailed CLI logs while investigating unexpected behavior.

BIOME_LOG_FILE=biome-debug.log BIOME_LOG_LEVEL=debug biome check .

BIOME_LOG_PATH

Directory where the Biome daemon stores its log files.

Use this to keep daemon logs in a project-specific directory while troubleshooting an editor integration.

BIOME_LOG_PATH="$PWD/.biome-logs" biome start

BIOME_LOG_PREFIX_NAME

Prefix added to daemon log file names. Defaults to server.log.

Use this to distinguish logs from different projects that share a log directory.

BIOME_LOG_PREFIX_NAME=my-project.log biome start

BIOME_LOG_LEVEL

Controls internal logging for commands such as check, lint, format, and ci. Defaults to none.

The following logging levels are supported:

• none: Disables internal logging.
• tracing: Shows the most detailed logs, including span timing.
• debug: Shows detailed information useful for debugging.
• info: Shows general information about Biome’s operation.
• warn: Shows warnings and errors.
• error: Shows only errors.

Use this to inspect Biome’s internal CLI activity while checking a project.

BIOME_LOG_LEVEL=debug biome check .

BIOME_LOG_KIND

Controls the internal log format for commands such as check, lint, format, and ci. Defaults to pretty.

The following log formats are supported:

• pretty: Displays human-readable, multiline logs with terminal styling.
• compact: Displays logs in a condensed, human-readable format.
• json: Displays machine-readable JSON logs.

Use this to collect machine-readable internal logs in CI. Set BIOME_LOG_LEVEL to enable logging.

BIOME_LOG_LEVEL=info BIOME_LOG_KIND=json biome ci .

BIOME_CONFIG_PATH

Path to a Biome configuration file or directory.

Use this to apply a shared configuration stored outside the current directory.

BIOME_CONFIG_PATH="$HOME/.config/biome/biome.json" biome check .

BIOME_THREADS

Number of worker threads used by biome ci. Defaults to automatic selection.

Use this to limit CPU and memory usage in a constrained CI runner.

BIOME_THREADS=2 biome ci .

BIOME_WATCHER_KIND

Selects the file watcher used by the Biome daemon. Defaults to recommended.

The following file-watching strategies are supported:

• recommended: Uses the strategy recommended by the operating system.
• polling: Periodically checks for changes. This can be slower but may work better on mounted or network filesystems.
• none: Disables file watching. The daemon and editor integrations will not detect file changes.

Use polling when native file notifications are unreliable, such as on a network drive or mounted filesystem.

BIOME_WATCHER_KIND=polling biome start

BIOME_WATCHER_POLLING_INTERVAL

Polling interval, in milliseconds, used by the Biome daemon when BIOME_WATCHER_KIND is set to polling. Defaults to 2000 milliseconds (two seconds).

Use this to adjust how quickly the polling watcher detects changes.

BIOME_WATCHER_KIND=polling BIOME_WATCHER_POLLING_INTERVAL=1000 biome start

BIOME_BINARY

Overrides the Biome binary used by the @biomejs/biome npm package. If this variable is not set, the package automatically selects the correct binary for your platform.

Use this to run a system-installed or locally built binary through the @biomejs/biome package.

BIOME_BINARY=/usr/local/bin/biome npx @biomejs/biome check .

RUST_BACKTRACE

Captures a backtrace if Biome panics, which can help identify where the panic occurred.

Use this when reporting a Biome panic to include a stack trace that can help locate the problem.

RUST_BACKTRACE=1 biome check .

Note

RUST_BACKTRACE is a Rust environment variable, not a Biome-specific option. Biome supports it because it is built with Rust and uses Rust’s backtrace support when reporting a panic.