multi-line-replacer 1.0.0b1

A CLI utility for replacing multi-line strings in files. Supports textual replacements with wildcard matching indentation-aware replacements.

Multi-Line Replacer (mlr)

Copyright 2025 Caleb Evans
Released under the MIT license

Multi-Line Replacer is a CLI utility for replacing multi-line hunks of strings across one or more files. Matching is mostly textual, but wildcard matching is supported, and replacements are indentation-aware.

Usage

The workflow takes one or more files on which to run replacements, and then a series of "replacement rule" files with the -r flag:

mlr .github/workflows/*.yml -r example-rules/uv-gha.md

Each replacement rule must be a Markdown file with one or more pairs of GFM fenced code blocks (see documentation). Every odd code block represents the target text to replace, and every even code block represents the textual replacement. All other Markdown formatting is ignored, so feel free to add headings, explainer text, or anything else!

This rule replaces flake8 with ruff in a Github Actions linting workflow.

## flake8

```yml
- name: Run flake8
  run: flake8 MATCH_UNTIL_END_OF_LINE
```

## ruff

```yml
- name: Run ruff
  run: |
    uv run ruff check .
    uv run ruff format --check .
```

The language specifier at the start of each code fence is ignored by the utility. Still, it is highly recommended to specify so that syntax highlighting is enabled in your editor (for a better authoring experience).

Wildcard Matching

There are two special wildcard variables:

• MATCH_UNTIL_END_OF_LINE ([^\n]*)
• MATCH_ALL_BETWEEN ([^\n]*?)

These variables can be used anywhere in a rule (no word boundaries required).

More Examples

To better understand the expected rules format and what's allowed, please see the example-rules directory.