Access input file names in system hooks?

Is there a way to access the input filename for system hooks? I’m trying to run sort --output $file $file on a set of simple Yaml files containing only key-value pairs.

repos:
  - repo: local
    hooks:
      - id: sort-simple-yaml
        name: Sort simple YAML files
        entry: sort --output $file $file
        language: system
        files: .+\.yml

Related: https://github.com/pre-commit/pre-commit/issues/522

I tried sort-simple-yaml but couldn’t get it to sort even when setting files explicitly.

repos:
  - repo: https://github.com/pre-commit/pre-commit-hooks
    rev: v2.3.0
    hooks:
      - id: sort-simple-yaml
        files: ^.*\.yml$ # nothing happens

[janosh]

Cool, didn’t know about the file-contents-sorter hook. Will use that then.

Just to confirm, there’s no documented way to access the file name in an entry field?

[asottile]

just tried it, seems to work fine to me?

$ pre-commit run --all-files
file contents sorter.....................................................Failed
- hook id: file-contents-sorter
- exit code: 1
- files were modified by this hook

Sorting test.yml