This is a Pandoc Lua filter that replaces absolute links with links relative to the URL of the document. See test/in/main.md for example input and test/expected/main.md for what the output looks like.
The document metadata must contain a url attribute which indicates where the document itself is intended to reside. For example, if you put this metadata block at the top of a markdown document:
---
url: https://example.com/stuff/boring
---
...the filter would rewrite any link to https://example.com/stuff/awesome to be ../awesome.
To run the filter, download the pandoc-link-relativizer-filter.lua file and use --lua-filter path/to/pandoc-link-relativizer-filter.lua when when invoking pandoc.
Some test pandoc markdown files are in test/in and the corresponding outputs are in test/expected.
There is a script that will run pandoc on all the test files and diff the outputs against the expected outputs. To ensure you're using the intended version of pandoc, I suggest running them in Docker. If you have Docker installed and are on Mac/Linux, just run ./test/docker-test.sh to build the image and run the tests.
See the LICENSE file.