Configuration

The configuration file (lun.toml by default) is written in TOML.

Top-level fields

• careful (boolean, default: false): Include tool version in cache keys for more conservative caching.
• cache_size (integer, optional): Maximum cache size in bytes. Defaults to 1.25 MiB.
• cores (integer, optional): Number of parallel jobs to run. If not specified, uses the number of CPU cores.
• mtime (boolean, default: true): Use file modification times (see Caching).
• ninja (boolean, default: false): Enable or disable Ninja build file generation.
• no_default_ignores (boolean, default: false): Disable default ignore patterns for image files (JPG, JPEG, PNG, SVG).
• refs (array of strings, default: []): Git refs to compare against when determining which files to check.
• ignore (array of strings, default: []): Glob pattern(s) matching files that all tools should ignore. These patterns are combined with the default ignore patterns unless no_default_ignores is set.
• linter (array of tables): Array of linter configurations, see below.
• formatter (array of tables): Array of formatter configurations, see below.

Warning configuration

• allow (array of strings, default: []): Warning names to allow (suppress).
• warn (array of strings, default: []): Warning names to warn about (print but continue).
• deny (array of strings, default: []): Warning names to deny (print and exit with failure).

[[linter]]

Each linter is defined in a [[linter]] table array.

• name (string, optional): Display name for the linter. If not specified, uses the command.

• cmd (string, required): Command to run for the linter.

• files (array of strings, required): Glob pattern(s) matching files that this linter should process.

• ignore (array of strings, default: []): Glob pattern(s) matching files that this linter should ignore.

• args (string, default: "many"): How file paths are passed as command-line arguments:

  • "none": No files passed on command line (tool discovers files itself)
  • "one": One file per invocation
  • "many": Multiple files per invocation (for parallelism)
  • "all": All matching files must be passed in a single invocation

• include_unchanged (boolean, default: false): Whether to include unchanged files (files that haven’t been modified since the last successful run). Set to true for tools that need to see all relevant files, not just changed ones.

• configs (array of strings, default: []): Paths to configuration files that affect linter behavior. Changes to these files invalidate the cache.

• cd (string, optional): Working directory for the linter.

• fix (string, optional): Command to run to automatically fix issues (see --fix). If not specified, uses cmd.

[[formatter]]

Each formatter is defined in a [[formatter]] table array.

• name (string, optional): Display name for the formatter. If not specified, uses the command.

• cmd (string, required): Command to run for the formatter.

• files (array of strings, required): Glob pattern(s) matching files that this formatter should process.

• ignore (array of strings, default: []): Glob pattern(s) matching files that this formatter should ignore.

• args (string, default: "many"): How file paths are passed as command-line arguments:

  • "none": No files passed on command line (tool discovers files itself)
  • "one": One file per invocation
  • "many": Multiple files per invocation (for parallelism)
  • "all": All matching files must be passed in a single invocation

• include_unchanged (boolean, default: false): Whether to include unchanged files (files that haven’t been modified since the last successful run). Set to true for tools that need to see all relevant files, not just changed ones.

• configs (array of strings, default: []): Paths to configuration files that affect formatter behavior. Changes to these files invalidate the cache.

• cd (string, optional): Working directory for the formatter.

• check (string, optional): Command to run in check-only mode (no modifications). If not specified, uses cmd.

[[tool]]

The [[tool]] table array provides a shorthand for configuring known tools. Instead of specifying all fields manually, you can reference a tool by name and optionally override specific fields.

[[tool]]
name = "cargo clippy"

This is equivalent to writing out the full [[linter]] configuration for cargo clippy with all its default settings.

You can override specific fields while keeping the defaults for everything else:

[[tool]]
name = "cargo clippy"
ignore = ["generated/*.rs"]
configs = ["Cargo.toml", "clippy.toml"]

Available fields (all optional except name):

• name (string, required): Name of the known tool (e.g., "cargo clippy", "ruff check", "cargo fmt").
• cmd (string, optional): Override the command to run.
• files (array of strings, optional): Override the file patterns.
• ignore (array of strings, optional): Override the ignore patterns.
• args (string, optional): Override how file paths are passed ("none", "one", "many", or "all").
• include_unchanged (boolean, optional): Override whether to include unchanged files.
• configs (array of strings, optional): Override the configuration file paths.
• cd (string, optional): Override the working directory.
• fix (string, optional): Override the fix command (for linters).
• check (string, optional): Override the check command (for formatters).

Known tools

The following tools are recognized by name:

Linters:

• bash -n
• cargo clippy
• cargo test
• hlint
• jq null
• make -n
• mdlynx
• mypy
• ruff check
• shellcheck
• tagref
• ttlint
• ty
• typos
• zizmor

Formatters:

• cargo fmt
• ruff format
• taplo