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Jo 67930321fb Align shell prek-only docs note

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Configuration

prek reads one configuration file per project. You only need to choose one format:

prek.toml (TOML) — recommended for new users
.pre-commit-config.yaml (YAML) — best if you already use pre-commit or rely on tool/editor support

Both formats are first-class and will be supported long-term. They describe the same configuration model: you list repositories under repos, then enable and configure hooks from those repositories.

=== "prek.toml"

```toml
[[repos]]
repo = "https://github.com/pre-commit/pre-commit-hooks"
hooks = [{ id = "trailing-whitespace" }]
```

=== ".pre-commit-config.yaml"

```yaml
repos:
  - repo: https://github.com/pre-commit/pre-commit-hooks
    hooks:
      - id: trailing-whitespace
```

Pre-commit compatibility

prek is fully compatible with pre-commit YAML configs, so your existing .pre-commit-config.yaml files work unchanged.

If you use prek.toml, there’s nothing to worry about from a pre-commit perspective: upstream pre-commit does not read TOML.

If you use the same .pre-commit-config.yaml with both tools, keep in mind:

prek supports several extensions beyond upstream pre-commit.
Upstream pre-commit may warn about unknown keys or error out on unsupported features.
To stay maximally portable, avoid the extensions listed below (or keep separate configs).

Notable differences (when using YAML):

Workspace mode is a prek feature that can discover multiple projects; upstream pre-commit is single-project.
files / exclude can be written as glob mappings in prek (in addition to regex), which is not supported by upstream pre-commit.
repo: builtin adds fast built-in hooks in prek.
Upstream pre-commit uses minimum_pre_commit_version, while prek uses minimum_prek_version and intentionally ignores minimum_pre_commit_version.

Prek-only extensions

These entries are implemented by prek and are not part of the documented upstream pre-commit configuration surface. They work in both YAML and TOML, but they only matter for compatibility if you share a YAML config with upstream pre-commit.

Top-level:
- minimum_prek_version
- orphan
Repo type:
- repo: builtin
Hook-level:

Configuration file

Location (discovery)

By default, prek looks for a configuration file starting from your current working directory and moving upward. It stops when it finds a config file, or when it hits the git repository boundary.

If you run without --config, prek then enables workspace mode:

The first config found while traversing upward becomes the workspace root.
From that root, prek searches for additional config files in subdirectories (nested projects).

Workspace discovery respects .gitignore, and also supports .prekignore for excluding directories from discovery. For the full behavior and examples, see Workspace Mode.

!!! tip

After updating `.prekignore`, run with `--refresh` to force a fresh project discovery so the changes are picked up.

If you pass --config / -c, workspace discovery is disabled and only that single config file is used.

File name

prek recognizes the following configuration filenames:

prek.toml (TOML)
.pre-commit-config.yaml (YAML, preferred for pre-commit compatibility)
.pre-commit-config.yml (YAML, alternate)

In workspace mode, each project uses one of these filenames in its own directory.

!!! note "One format per repo"

We recommend using a **single format** across the whole repository to avoid confusion.

If multiple configuration files exist in the same directory, `prek` uses only one and ignores the rest.
The precedence order is:

1. `prek.toml`
2. `.pre-commit-config.yaml`
3. `.pre-commit-config.yml`

File format

Both prek.toml and .pre-commit-config.yaml map to the same configuration model (repositories under repos, then hooks under each repo).

This section focuses on format-specific authoring notes and examples.

TOML (`prek.toml`)

Practical notes:

Structure is explicit and less indentation-sensitive.
Inline tables are common for hooks (e.g. { id = "ruff" }).

TOML supports both inline tables and array-of-tables, so you can choose between a compact or expanded hook style.

Inline tables (best for small/simple hook configs):

[[repos]]
repo = "https://github.com/pre-commit/pre-commit-hooks"
rev = "v6.0.0"
hooks = [
  { id = "end-of-file-fixer", args = ["--fix"] },
]

Array-of-tables (more readable for larger hook configs):

[[repos]]
repo = "https://github.com/pre-commit/pre-commit-hooks"
rev = "v6.0.0"

[[repos.hooks]]
id = "trailing-whitespace"

[[repos.hooks]]
id = "check-json"

Example:

=== "prek.toml"

```toml
default_language_version.python = "3.12"

[[repos]]
repo = "local"
hooks = [
  {
    id = "ruff",
    name = "ruff",
    language = "system",
    entry = "python3 -m ruff check",
    files = "\\.py$",
  },
]
```

The previous example uses multiline inline tables, a feature that was introduced in TOML 1.1, not all parsers have support for it yet. You may want to use the longer form if your editor/IDE complains about it.

=== "prek.toml"

```toml
default_language_version.python = "3.12"

[[repos]]
repo = "local"

[[repos.hooks]]
id = "ruff"
name = "ruff"
language = "system"
entry = "python3 -m ruff check"
files = "\\.py$"
```

YAML (`.pre-commit-config.yaml` / `.yml`)

Practical notes:

Regular expressions are provided as YAML strings. If your regex contains backslashes, quote it (e.g. files: '\\.rs$').
YAML anchors/aliases and merge keys are supported, so you can de-duplicate repeated blocks.

Example:

=== ".pre-commit-config.yaml"

```yaml
default_language_version:
  python: "3.12"

repos:
  - repo: local
    hooks:
      - id: ruff
        name: ruff
        language: system
        entry: python3 -m ruff check
        files: "\\.py$"
```

Choosing a format

prek.toml

Clearer structure and less error-prone syntax.
Recommended for new users or new projects.

.pre-commit-config.yaml

Long-established in the ecosystem with broad tool/editor support.
Fully compatible with upstream pre-commit.

Recommendation

If you already use .pre-commit-config.yaml, keep it.
If you want a cleaner, more robust authoring experience, prefer prek.toml.

!!! tip

If you want to switch, you can use [`prek util yaml-to-toml`](cli.md#prek-util-yaml-to-toml) to convert YAML configs to `prek.toml`.
YAML comments are not preserved during conversion.

Scope (per-project)

Each configuration file (prek.toml, .pre-commit-config.yaml, or .pre-commit-config.yml) is scoped to the project directory it lives in.

In workspace mode, prek treats every discovered configuration file as a distinct project:

A project’s config only controls hook selection and filtering (for example files / exclude) for that project.
A project may contain nested subprojects (subdirectories with their own config). Those subprojects run using their own configs.

Practical implication: filters in the parent project do not “turn off” a subproject.

Example layout (monorepo with a nested project):

foo/.pre-commit-config.yaml (project foo)
foo/bar/.pre-commit-config.yaml (project foo/bar, nested subproject)

If project foo config contains an exclude that matches bar/**, then hooks for project foo will not run on files under foo/bar:

=== "prek.toml"

```toml
# foo/prek.toml
exclude = { glob = "bar/**" }
```

=== ".pre-commit-config.yaml"

```yaml
# foo/.pre-commit-config.yaml
exclude:
  glob: "bar/**"
```

But if foo/bar is itself a project (has its own config), files under foo/bar are still eligible for hooks when running in the context of project foo/bar.

!!! note "Excluding a nested project"

If `foo/bar/.pre-commit-config.yaml` exists but you *don’t* want it to be recognized as a project in workspace mode, exclude it from discovery using [`.prekignore`](workspace.md#discovery).

Like `.gitignore`, `.prekignore` files can be placed anywhere in the workspace and apply to their directory and all subdirectories.

!!! tip

After updating `.prekignore`, run with `--refresh` to force a fresh project discovery so the changes are picked up.

Validation

Use prek validate-config to validate one or more config files.

If you want IDE completion / validation, prek provides a JSON Schema at https://prek.j178.dev/docs/prek.schema.json.

And the schema is also submitted to the JSON Schema Store, so some editors may pick it up automatically.

That schema tracks what prek accepts today, but prek also intentionally tolerates unknown keys for forward compatibility.

Configuration reference

This section documents the configuration keys that prek understands.

Top-level keys

`repos` (required)

A list of hook repositories.

Each entry is one of:

a remote repository (typically a git URL)
repo: local for hooks defined directly in your repository
repo: meta for built-in meta hooks
repo: builtin for prek's built-in fast hooks

See Repo entries.

`files`

Global include regex applied before hook-level filtering.

Type: regex string (default, pre-commit compatible) or a prek-only glob pattern mapping
Default: no global include filter

This is usually used to narrow down the universe of files in large repositories.

!!! note "What path is matched? (workspace + nested projects)"

`files` (and `exclude`) are matched against the file path **relative to the project root** — i.e. the directory containing the configuration file.

- For the root project, this is the workspace root.
- For a nested project, this is the nested project directory.

Example (workspace mode):

- Root project config: `./.pre-commit-config.yaml`
- Nested project config: `./nested/.pre-commit-config.yaml`

For a file at `nested/excluded_by_project`:

- Root project sees the path as `nested/excluded_by_project`
- Nested project sees the path as `excluded_by_project`

This matters most for anchored patterns like `^...$`.

!!! tip "Regex matching"

When `files` / `exclude` are regex strings, they are matched with *search* semantics (the pattern can match anywhere in the path).
Use `^` to anchor at the beginning and `$` at the end.

`prek` uses the Rust [`fancy-regex`](https://github.com/fancy-regex/fancy-regex) engine.
Most typical patterns are portable to upstream `pre-commit`, but very advanced regex features may differ from Python’s `re`.

!!! note "prek-only globs"

In addition to regex strings, `prek` supports glob patterns via:

- `files: { glob: "..." }` (single glob)
- `files: { glob: ["...", "..."] }` (glob list)

This is a `prek` extension. Upstream `pre-commit` expects regex strings here.

For more information on the glob syntax, refer to the [globset documentation](https://docs.rs/globset/latest/globset/#syntax).

Examples:

=== "prek.toml"

```toml
# Regex (portable to pre-commit)
files = "\\.rs$"

# Glob (prek-only)
files = { glob = "src/**/*.rs" }

# Glob list (prek-only; matches if any glob matches)
files = { glob = ["src/**/*.rs", "crates/**/src/**/*.rs"] }
```

=== ".pre-commit-config.yaml"

```yaml
# Regex (portable to pre-commit)
files: "\\.rs$"

# Glob (prek-only)
files:
  glob: "src/**/*.rs"

# Glob list (prek-only; matches if any glob matches)
files:
  glob:
    - "src/**/*.rs"
    - "crates/**/src/**/*.rs"
```

`exclude`

Global exclude regex applied before hook-level filtering.

Type: regex string (default, pre-commit compatible) or a prek-only glob pattern mapping
Default: no global exclude filter

exclude is useful for generated folders, vendored code, or build outputs.

!!! note "What path is matched?"

Same as [`files`](#top-level-files): the pattern is evaluated against the file path **relative to the project root** (the directory containing the config).

!!! note "prek-only globs"

Like `files`, `exclude` supports `glob` (single glob or glob list) as a `prek` extension.
For glob syntax details, see the [globset documentation](https://docs.rs/globset/latest/globset/#syntax).

Examples:

=== "prek.toml"

```toml
# Regex (portable to pre-commit)
exclude = "^target/"

# Glob (prek-only)
exclude = { glob = "target/**" }

# Glob list (prek-only)
exclude = { glob = ["target/**", "dist/**"] }
```

=== ".pre-commit-config.yaml"

```yaml
# Regex (portable to pre-commit)
exclude: "^target/"

# Glob (prek-only)
exclude:
  glob: "target/**"

# Glob list (prek-only)
exclude:
  glob:
    - "target/**"
    - "dist/**"
```

Verbose regex example (useful for long allow/deny lists):

=== "prek.toml"

```toml
# `(?x)` enables "verbose" regex mode (whitespace and newlines are ignored).
exclude = """(?x)^(
  docs/|
  vendor/|
  target/
)"""
```

=== ".pre-commit-config.yaml"

```yaml
# `(?x)` enables "verbose" regex mode (whitespace and newlines are ignored).
exclude: |
  (?x)^(
    docs/|
    vendor/|
    target/
  )
```

`fail_fast`

Stop the run after the first failing hook.

Type: boolean
Default: false

This is a global default; individual hooks can also set fail_fast.

`default_language_version`

Map a language name to the default language_version used by hooks of that language.

Type: map
Default: none (hooks fall back to language_version: default)

Example:

=== "prek.toml"

```toml
default_language_version.python = "3.12"
default_language_version.node = "20"
```

=== ".pre-commit-config.yaml"

```yaml
default_language_version:
  python: "3.12"
  node: "20"
```

prek treats language_version as a version request (often a semver-like selector) and may install toolchains automatically. See Difference from pre-commit.

`default_stages`

Default stages used when a hook does not specify its own.

Type: list of stage names
Default: all stages

Allowed values:

manual
commit-msg
post-checkout
post-commit
post-merge
post-rewrite
pre-commit
pre-merge-commit
pre-push
pre-rebase
prepare-commit-msg

`default_install_hook_types`

Default Git shim name(s) installed by prek install when you don’t pass --hook-type.

Type: list of --hook-type values
Default: [pre-commit]

This controls which Git shims are installed (for example pre-commit vs pre-push). It is separate from a hook’s stages, which controls when a particular hook is eligible to run.

Allowed values:

pre-commit
pre-push
commit-msg
prepare-commit-msg
post-checkout
post-commit
post-merge
post-rewrite
pre-merge-commit
pre-rebase

`minimum_prek_version`

!!! note "prek-only"

This key is a `prek` extension. Upstream `pre-commit` uses `minimum_pre_commit_version`, which `prek` intentionally ignores.

Require a minimum prek version for this config.

Type: string (version)
Default: unset

If the installed prek is older than the configured minimum, prek exits with an error.

Example:

=== "prek.toml"

```toml
minimum_prek_version = "0.2.0"
```

=== ".pre-commit-config.yaml"

```yaml
minimum_prek_version: "0.2.0"
```

`orphan`

!!! note "prek-only"

`orphan` is a `prek` workspace-mode feature and is not recognized by upstream `pre-commit`.

Workspace-mode setting to isolate a nested project from parent configs.

Type: boolean
Default: false

When orphan: true, files under this project directory are handled only by this project’s config and are not “seen” by parent projects.

Example:

=== "prek.toml"

```toml
orphan = true

[[repos]]
repo = "https://github.com/astral-sh/ruff-pre-commit"
rev = "v0.8.4"
hooks = [{ id = "ruff" }]
```

=== ".pre-commit-config.yaml"

```yaml
orphan: true
repos:
  - repo: https://github.com/astral-sh/ruff-pre-commit
    rev: v0.8.4
    hooks:
      - id: ruff
```

See Workspace Mode - File Processing Behavior for details.

Repo entries

Each item under repos: is a mapping that always contains a repo: key.

Remote repository

Use this for hooks distributed in a separate repository.

Required keys:

repo: repository location (commonly an https git URL)
rev: version to use (tag, branch, or commit SHA)
hooks: list of hook selections

Remote hook definitions live inside the hook repository itself in the .pre-commit-hooks.yaml manifest (at the repo root). Your config only selects hooks by id and optionally overrides options. See Authoring Hooks if you maintain a hook repository.

`repo`

Where to fetch hooks from.

In most configs this is a git URL. prek also recognizes special values documented separately: local, meta, and builtin.

`rev`

The revision to use for the remote repository.

Use a tag or commit SHA for repeatable results. If you use a moving target (like a branch name), runs may change over time.

`hooks`

The list of hooks to enable from that repository.

Each item must at least specify id. You can also add hook-level options (filters, args, stages, etc.) to customize behavior.

Example:

=== "prek.toml"

```toml
[[repos]]
repo = "https://github.com/astral-sh/ruff-pre-commit"
rev = "v0.8.4"
hooks = [{ id = "ruff", args = ["--fix"] }]
```

=== ".pre-commit-config.yaml"

```yaml
repos:
  - repo: https://github.com/astral-sh/ruff-pre-commit
    rev: v0.8.4
    hooks:
      - id: ruff
        args: [--fix]
```

Notes:

For reproducibility, prefer immutable pins (tags or commit SHAs).
prek auto-update can help update rev values.

`repo: local`

Define hooks inline inside your repository.

Keys:

repo: must be local
hooks: list of local hook definitions (see Local hook definition)

Example:

=== "prek.toml"

```toml
[[repos]]
repo = "local"
hooks = [
  {
    id = "cargo-fmt",
    name = "cargo fmt",
    language = "system",
    entry = "cargo fmt",
    files = "\\.rs$",
  },
]
```

=== ".pre-commit-config.yaml"

```yaml
repos:
  - repo: local
    hooks:
      - id: cargo-fmt
        name: cargo fmt
        language: system
        entry: cargo fmt
        files: "\\.rs$"
```

`repo: meta`

Use pre-commit-style meta hooks that validate and debug your configuration.

prek supports the following meta hook ids:

check-hooks-apply
check-useless-excludes
identity

Restrictions:

id is required.
entry is not allowed.
language (if set) must be system.

You may still configure normal hook options such as files, exclude, stages, etc.

Example:

=== "prek.toml"

```toml
[[repos]]
repo = "meta"
hooks = [{ id = "check-useless-excludes" }]
```

=== ".pre-commit-config.yaml"

```yaml
repos:
  - repo: meta
    hooks:
      - id: check-useless-excludes
```

`repo: builtin`

!!! note "prek-only"

`repo: builtin` is specific to `prek` and is not compatible with upstream `pre-commit`.

Use prek’s built-in fast hooks (offline, zero setup).

Restrictions:

id is required.
entry is not allowed.
language (if set) must be system.

Example:

=== "prek.toml"

```toml
[[repos]]
repo = "builtin"
hooks = [
  { id = "trailing-whitespace" },
  { id = "check-yaml" },
]
```

=== ".pre-commit-config.yaml"

```yaml
repos:
  - repo: builtin
    hooks:
      - id: trailing-whitespace
      - id: check-yaml
```

For the list of available built-in hooks and the “automatic fast path” behavior, see Built-in Fast Hooks.

Hook entries

Hook items under repos[*].hooks have slightly different shapes depending on the repo type.

Remote hook selection

For a remote repo, the hook entry must include:

id (required): selects the hook from the repository

All other hook keys are optional overrides (for example args, files, exclude, stages, …).

!!! note "Advanced overrides"

`prek` also supports overriding `name`, `entry`, and `language` for remote hooks.
This can be useful for experimentation, but it may reduce portability to the original `pre-commit`.

Local hook definition

For repo: local, the hook entry is a full definition and must include:

id (required): stable identifier used by prek run <id> and selectors
name (required): label shown in output
entry (required): command to execute
language (required): how prek sets up and runs the hook

Builtin/meta hook selection

For repo: builtin and repo: meta, the hook entry must include id. You can optionally provide name and normal hook options (filters, stages, etc), but not entry.

Common hook options

These keys can appear on hooks (remote/local/builtin/meta), subject to the restrictions above.

`id`

The stable identifier of the hook.

For remote hooks, this must match a hook id defined by the remote repository.
For local hooks, you choose it.

id is also used for CLI selection (for example prek run <id> and PREK_SKIP).

!!! note "Hook ids containing :"

If your hook id contains `:` (for example `id: lint:ruff`), `prek run lint:ruff`
will not select that hook. `prek` interprets `lint:ruff` as the selector
`<project-path>:<hook-id>`, with project `lint` and hook `ruff`.
To select the hook id `lint:ruff`, add a leading `:` and run
`prek run :lint:ruff`.

`name`

Human-friendly label shown in output.

Required for repo: local hooks.
Optional as an override for remote/meta/builtin hooks.

`entry`

The command line to execute for the hook.

Required for repo: local hooks.
Optional override for remote hooks.
Not allowed for repo: meta and repo: builtin.

If pass_filenames: true, prek appends matching filenames to this command when running.

`shell`

!!! note "prek-only"

`shell` is a `prek` extension and may not be recognized by upstream `pre-commit`.

Run entry through a predefined shell adapter.

Type: one of sh, bash, pwsh, powershell, cmd
Default: null (run entry directly without a shell)

When shell is omitted, prek preserves the default no-shell behavior: it parses entry into argv, invokes the command directly, and appends args and matching filenames as process arguments.

When shell is set, entry is treated as source for that shell. prek writes the source to a temporary script file, runs it with the selected shell adapter, and passes hook args followed by matching filenames as script arguments.

`shell`	Adapter command	Script arguments
`bash`	`bash --noprofile --norc -eo pipefail <script>`	`"$@"`
`sh`	`sh -e <script>`	`"$@"`
`pwsh`	`pwsh -NoProfile -NonInteractive -File <script>`	`$args`
`powershell`	`powershell -NoProfile -NonInteractive -File <script>`	`$args`
`cmd`	`cmd /D /E:ON /V:OFF /S /C CALL <script>`	`%*`

=== "prek.toml"

```toml
[[repos]]
repo = "local"
hooks = [
  {
    id = "test-all",
    name = "test-all",
    language = "system",
    entry = """
    uv run --python=3.10 --isolated pytest
    uv run --python=3.11 --isolated pytest
    """,
    shell = "bash",
    pass_filenames = false,
  },
]
```

=== ".pre-commit-config.yaml"

```yaml
repos:
  - repo: local
    hooks:
      - id: test-all
        name: test-all
        language: system
        entry: |
          uv run --python=3.10 --isolated pytest
          uv run --python=3.11 --isolated pytest
        shell: bash
        pass_filenames: false
```

??? note "Unsupported languages"

`shell` is rejected for language backends that do not run `entry` through
the shell-aware entry resolver, and for `repo: meta` and `repo: builtin`
hooks.

| Language | Why `shell` is unsupported |
| -- | -- |
| `docker`, `docker_image` | `entry` participates in container image or entrypoint selection instead of direct host process execution. |
| `fail` | `entry` is the failure message body. |
| `julia`, `rust` | `entry` participates in install/runtime package resolution and is split before execution. |
| `pygrep` | `entry` is the regex pattern. |
| `conda`, `coursier`, `dart`, `perl`, `r` | The language backend is not implemented yet. |

`language`

How prek should run the hook (and whether it should create a managed environment).

Required for repo: local hooks.
Optional override for remote hooks.
Not allowed (except as system) for repo: meta and repo: builtin.

Common values include system, python, node, rust, golang, ruby, and docker.

See Language Support for per-language behavior, supported values, and language_version details.

!!! note "Language name aliases"

For compatibility with upstream `pre-commit`, the following legacy language names are also accepted:

- `unsupported` is treated as `system`
- `unsupported_script` is treated as `script`

`alias`

An alternate identifier for selecting the hook from the CLI.

If set, you can run the hook via either prek run <id> or prek run <alias>.

`args`

Extra arguments appended to the hook’s entry.

Type: list of strings

Example:

=== "prek.toml"

```toml
hooks = [{ id = "ruff", args = ["--fix"] }]
```

=== ".pre-commit-config.yaml"

```yaml
hooks:
  - id: ruff
    args: [--fix]
```

`env`

!!! note "prek-only"

`env` is a `prek` extension and may not be recognized by upstream `pre-commit`.

Extra runtime environment variables for the hook process.

Type: map of string to string

Values override the existing process environment (including variables such as PATH). They are applied when the hook runs, not when prek installs or prepares the hook environment.

For remote hooks, env may also be set by the hook author in .pre-commit-hooks.yaml. Values from the project configuration are merged with manifest values and override duplicate keys.

For docker / docker_image hooks, these variables are passed into the container rather than being applied to the container runtime command.

Example:

=== "prek.toml"

```toml
[[repos]]
repo = "local"
hooks = [
  {
    id = "cargo-doc",
    name = "cargo doc",
    language = "system",
    entry = "cargo doc --all-features --workspace --no-deps",
    env = { RUSTDOCFLAGS = "-Dwarnings" },
    pass_filenames = false,
  },
]
```

=== ".pre-commit-config.yaml"

```yaml
repos:
  - repo: local
    hooks:
      - id: cargo-doc
        name: cargo doc
        language: system
        entry: cargo doc --all-features --workspace --no-deps
        env:
          RUSTDOCFLAGS: -Dwarnings
        pass_filenames: false
```

`files` / `exclude`

Filters applied to candidate filenames.

files selects which files are eligible for the hook.
exclude removes files matched by files.

If you use both global and hook-level filters, the effective behavior is “global filter first, then hook filter”.

By default (and for compatibility with upstream pre-commit), these are regex strings. As a prek extension, you can also specify globs using glob or a glob list.

See Top-level files and Top-level exclude for syntax notes and examples.

`types` / `types_or` / `exclude_types`

File-type filters based on identify tags.

!!! tip

Use [`prek util identify <path>`](cli.md#prek-util-identify) to see how prek tags a file when you’re troubleshooting `types` filters.

Compared to regex-only filtering (files / exclude), tag-based filtering is often easier and more robust:

tags can match by file extension and by shebang (for extensionless scripts)
you can easily exclude things like symlinks or binary files

Common tags include:

file, text, binary, symlink, executable
language-ish tags such as python, rust, javascript, yaml, toml, ...
types: all listed tags must match (logical AND)
types_or: at least one listed tag must match (logical OR)
exclude_types: tags that disqualify a file

How these combine:

files / exclude, types, and types_or are combined with AND.
Tags within types are combined with AND.
Tags within types_or are combined with OR.

Defaults:

types: [file] (matches all files)
types_or: []
exclude_types: []

These filters are applied in addition to regex filtering.

Examples:

=== "prek.toml"

```toml
[[repos]]
repo = "local"
hooks = [
  # AND: must be under `src/` AND have the `python` tag
  {
    id = "lint-py",
    name = "Lint (py)",
    language = "system",
    entry = "python -m ruff check",
    files = "^src/",
    types = ["python"],
    exclude_types = ["symlink"]
  },

  # OR: match any of the listed tags under `web/`
  {
    id = "lint-web",
    name = "Lint (web)",
    language = "system",
    entry = "npm run lint",
    files = "^web/",
    types_or = ["javascript", "jsx", "ts", "tsx"]
  },
]
```

=== ".pre-commit-config.yaml"

```yaml
repos:
  - repo: local
    hooks:
      - id: lint-py
        name: Lint (py)
        language: system
        entry: python -m ruff check
        files: ^src/
        types: [python]
        exclude_types: [symlink]

      - id: lint-web
        name: Lint (web)
        language: system
        entry: npm run lint
        files: ^web/
        types_or: [javascript, jsx, ts, tsx]
```

If you need to match a path pattern that doesn’t align with a hook’s default types (common when reusing an existing hook in a nonstandard way), override it back to “all files” and use files:

=== "prek.toml"

```toml
[[repos]]
repo = "meta"
hooks = [
  {
    id = "check-hooks-apply",
    types = ["file"],
    files = "\\.(yaml|yml|myext)$"
  },
]
```

=== ".pre-commit-config.yaml"

```yaml
repos:
  - repo: meta
    hooks:
      - id: check-hooks-apply
        types: [file]
        files: \.(yaml|yml|myext)$
```

`always_run`

Run the hook even when no files match.

Type: boolean
Default: false

This is commonly used for hooks that check repository-wide state (for example, running a test suite) rather than operating on specific files.

`pass_filenames`

Controls whether prek appends the matching filenames to the command line.

Type: boolean or positive integer
Default: true which passes all matching filenames

Set pass_filenames: false for hooks that don’t accept file arguments (or that discover files themselves).

Set pass_filenames: n (a positive integer) to limit each invocation to at most n filenames. When there are more matching files than n, prek splits them across multiple invocations. Those invocations may run concurrently unless require_serial: true is set. This is useful for tools that can only process a limited number of files at once.

Prek will automatically limit the number of filenames to ensure command lines don’t exceed the OS limit, even when pass_filenames: true.

!!! note "prek-only"

`pass_filenames: n` with a positive integer is a `prek` extension. Upstream `pre-commit` only accepts a boolean value.

`stages`

Declare which stages a hook is eligible to run in.

Type: list of stage names
Default: all stages

Allowed values:

manual
commit-msg
post-checkout
post-commit
post-merge
post-rewrite
pre-commit
pre-merge-commit
pre-push
pre-rebase
prepare-commit-msg

When you run prek run --hook-stage <stage>, only hooks configured for that stage are considered.

`require_serial`

Force a hook to run without parallel invocations (one in-flight process for that hook at a time).

Type: boolean
Default: false

This is useful for tools that use global caches/locks or otherwise can’t handle concurrent execution.

`priority`

!!! note "prek-only"

`priority` controls `prek`'s scheduler and does not exist in upstream `pre-commit`.

Each hook can set an explicit priority (a non-negative integer) that controls when it runs and with which hooks it may execute in parallel.

Scope:

priority is evaluated within a single configuration file and is compared across all hooks in that file, even if they appear under different repos: entries.
priority does not coordinate across different config files. In workspace mode, each project’s config file is scheduled independently.

Hooks run in ascending priority order: lower priority values run earlier. Hooks that share the same priority value run concurrently, subject to the global concurrency limit.

When priority is omitted, prek assigns an implicit value based on hook order to preserve sequential behavior.

Example:

=== "prek.toml"

```toml
[[repos]]
repo = "local"
hooks = [
  {
    id = "format",
    name = "Format",
    language = "system",
    entry = "python3 -m ruff format",
    always_run = true,
    priority = 0,
  },
  {
    id = "lint",
    name = "Lint",
    language = "system",
    entry = "python3 -m ruff check",
    always_run = true,
    priority = 10,
  },
  {
    id = "tests",
    name = "Tests",
    language = "system",
    entry = "just test",
    always_run = true,
    priority = 20,
  },
]
```

=== ".pre-commit-config.yaml"

```yaml
repos:
  - repo: local
    hooks:
      - id: format
        name: Format
        language: system
        entry: python3 -m ruff format
        always_run: true
        priority: 0

      - id: lint
        name: Lint
        language: system
        entry: python3 -m ruff check
        always_run: true
        priority: 10

      - id: tests
        name: Tests
        language: system
        entry: just test
        always_run: true
        priority: 20
```

!!! danger "Parallel hooks modifying files"

If two hooks run in the same priority group and both mutate the same files (or depend on shared state), results are undefined.
Use separate priorities to avoid overlap.

!!! note "Hooks modifying files without a non-zero exit code"

If a hook modifies files without emitting a non-zero exit code (e.g. `ruff format`), the priority group as a whole will fail.
It is not possible for prek to attribute the failure to a specific hook in the group which modified files.
Use separate priorities for clearer failure attribution.

!!! note "require_serial is different"

`require_serial: true` prevents concurrent invocations of the *same hook*.
It does not prevent other hooks from running alongside it; use a unique `priority` if you need exclusivity.

`fail_fast`

Hook-level fail-fast behavior.

Type: boolean
Default: false

If true, a failure in this hook stops the run immediately.

`verbose`

Print hook output even when the hook succeeds.

Type: boolean
Default: false

`log_file`

Write hook output to a file when the hook fails (and also when verbose: true).

Type: string path

`description`

Free-form description shown in listings / metadata.

Type: string

`language_version`

Choose the language/toolchain version request for this hook.

Type: string
Default: default

If not set, prek may use default_language_version for the hook’s language.

!!! note "prek-only"

`language_version` is treated as a **version request**, not a single pinned value. For languages that use semver requests, you can specify ranges (for example `^1.2`, `>=1.5, <2.0`).

Special values:

- `default`: use the language’s default resolution logic.
- `system`: require a system-installed toolchain (no downloads).

Language-specific behavior:

- Python: passed to the Python resolver (for example `python3`, `python3.12`, or a specific interpreter name). May trigger toolchain download.
- Node: passed to the Node resolver (for example `20`, `18.19.0`). May trigger toolchain download.
- Go: uses Go version strings such as `1.22.1` (downloaded if missing).
- Rust: supports rustup toolchains such as `stable`, `beta`, `nightly`, or versioned toolchains.
- Other languages: parsed as a semver request and matched against the installed toolchain version.

Examples:

=== "prek.toml"

    ```toml
    hooks = [
      { id = "ruff", language = "python", language_version = "3.12" },
      { id = "eslint", language = "node", language_version = "20" },
      { id = "cargo-fmt", language = "rust", language_version = "stable" },
      { id = "my-tool", language = "system", language_version = "system" },
    ]
    ```

=== ".pre-commit-config.yaml"

    ```yaml
    hooks:
      - id: ruff
        language: python
        language_version: "3.12"

      - id: eslint
        language: node
        language_version: "20"

      - id: cargo-fmt
        language: rust
        language_version: stable

      - id: my-tool
        language: system
        language_version: system
    ```

`additional_dependencies`

Extra dependencies for hooks that run inside a managed environment (for example Python or Node hooks).

Type: list of strings

If you set this for a language that doesn’t support dependency installation, prek fails with a configuration error.

`minimum_prek_version`

!!! note "prek-only"

This is a `prek`-specific requirement gate. Upstream `pre-commit` does not have a hook-level minimum version key.

Require a minimum prek version for this specific hook.

Type: string (version)
Default: unset

Environment variables

prek supports the following environment variables:

PREK_HOME — Override the prek data directory (caches, toolchains, hook envs). If beginning with ~, it is expanded to the user’s home directory. Defaults to ~/.cache/prek on macOS and Linux, and %LOCALAPPDATA%\prek on Windows.
PREK_COLOR — Control colored output: auto (default), always, or never.
PREK_QUIET — Control quiet output mode. Set to 1 for quiet mode (equivalent to -q, only shows failed hooks), or 2 for silent mode (equivalent to -qq, no output to stdout).
PREK_SKIP — Comma-separated list of hook IDs to skip (e.g. black,ruff). See Skipping Projects or Hooks for details.
PREK_ALLOW_NO_CONFIG — Allow running without a configuration file (useful for ad‑hoc runs).
PREK_NO_CONCURRENCY — Disable parallelism for installs and runs (If set, force concurrency to 1).
PREK_MAX_CONCURRENCY — Set the maximum number of concurrent hooks (minimum 1). Defaults to the number of CPU cores when unset. Ignored when PREK_NO_CONCURRENCY is set. If you encounter "Too many open files" errors, lowering this value or raising the file descriptor limit with ulimit -n can help.
PREK_NO_FAST_PATH — Disable Rust-native built-in hooks; always use the original hook implementation. See Built-in Fast Hooks for details.
PREK_UV_SOURCE — Control how uv (Python package installer) is installed. Options:
- github (download from GitHub releases)
- pypi (install from PyPI)
- tuna (use Tsinghua University mirror)
- aliyun (use Alibaba Cloud mirror)
- tencent (use Tencent Cloud mirror)
- pip (install via pip)
- a custom PyPI mirror URL
If not set, prek automatically selects the best available source.
PREK_NATIVE_TLS — Use the system trusted store instead of the bundled webpki-roots crate.
PREK_CONTAINER_RUNTIME — Specify the container runtime to use for container-based hooks (e.g., docker, docker_image). Options:
- auto (default, auto-detect available runtime)
- docker
- podman
- container (Apple's Container runtime on macOS, see container)
PREK_LOG_TRUNCATE_LIMIT — Control the truncation limit for command lines shown in trace logs (Executing ...). Defaults to 120 characters of arguments; set a larger value to reduce truncation.
PREK_RUBY_MIRROR — Override the Ruby installer base URL used for downloaded Ruby toolchains (for example, when using mirrors or air-gapped CI environments). See Ruby language support for details.

Compatibility fallbacks:

PRE_COMMIT_ALLOW_NO_CONFIG — Fallback for PREK_ALLOW_NO_CONFIG.
PRE_COMMIT_NO_CONCURRENCY — Fallback for PREK_NO_CONCURRENCY.
SKIP — Fallback for PREK_SKIP.

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Configuration

Pre-commit compatibility

Prek-only extensions

Configuration file

Location (discovery)

File name

File format

TOML (prek.toml)

YAML (.pre-commit-config.yaml / .yml)

Choosing a format

Scope (per-project)

Validation

Configuration reference

Top-level keys

repos (required)

files

exclude

fail_fast

default_language_version

default_stages

default_install_hook_types

minimum_prek_version

orphan

Repo entries

Remote repository

repo

rev

hooks

repo: local

repo: meta

repo: builtin

Hook entries

Remote hook selection

Local hook definition

Builtin/meta hook selection

Common hook options

id

name

entry

shell

language

alias

args

env

files / exclude

types / types_or / exclude_types

always_run

pass_filenames

stages

require_serial

priority

fail_fast

verbose

log_file

description

language_version

additional_dependencies

minimum_prek_version

Environment variables

42 KiB

Raw Permalink Blame History

TOML (`prek.toml`)

YAML (`.pre-commit-config.yaml` / `.yml`)

`repos` (required)

`files`

`exclude`

`fail_fast`

`default_language_version`

`default_stages`

`default_install_hook_types`

`minimum_prek_version`

`orphan`

`repo`

`rev`

`hooks`

`repo: local`

`repo: meta`

`repo: builtin`

`id`

`name`

`entry`

`shell`

`language`

`alias`

`args`

`env`

`files` / `exclude`

`types` / `types_or` / `exclude_types`

`always_run`

`pass_filenames`

`stages`

`require_serial`

`priority`

`fail_fast`

`verbose`

`log_file`

`description`

`language_version`

`additional_dependencies`

`minimum_prek_version`