docs: migrate Docker instructions to relative bind mount

[MikeMcC399]

• supersedes docs: migrate Docker instructions to relative bind mount #374

Issue

The README > Run using Docker command example

docker run -v ${PWD}:/tmp:ro --rm -i ghcr.io/tcort/markdown-link-check:stable /tmp/README.md

uses PWD (Print Working Directory). The syntax ${PWD} can now be replaced by a simpler one using relative paths.

Relative paths

The Docker documentation for docker container run (with alias docker run) describes the option Mount volume (-v) using relative paths:

As of Docker Engine version 23, you can use relative paths on the host.

docker run -v ./content:/content -w /content -i -t ubuntu pwd

• Docker Engine 23.0.0 was released on Feb 1, 2023. The current version is
• Docker Engine 28.0.1 released on Feb 26, 2025.

Change

Use the relative path . syntax instead of ${PWD}:

docker run -v .:/tmp:ro --rm -i ghcr.io/tcort/markdown-link-check:stable /tmp/README.md

Verification

For example, under Ubuntu 24.04.2 LTS

git clone https://github.com/tcort/markdown-link-check
cd markdown-link-check
docker run -v .:/tmp:ro --rm -i ghcr.io/tcort/markdown-link-check:stable /tmp/README.md

Confirm that markdown-link-check runs successfully.

Logs

$ docker run -v .:/tmp:ro --rm -i ghcr.io/tcort/markdown-link-check:stable /tmp/README.md
Unable to find image 'ghcr.io/tcort/markdown-link-check:stable' locally
stable: Pulling from tcort/markdown-link-check
43c4264eed91: Pull complete
453ca8c35a67: Pull complete
7a291b8a7b57: Pull complete
15929fe50b42: Pull complete
c70efbd48e66: Pull complete
4f4fb700ef54: Pull complete
0e06fe306355: Pull complete
b28c781acdb5: Pull complete
5e49cffc8ea6: Pull complete
68f40888b8a2: Pull complete
Digest: sha256:b812aa72676ed310c045d2c89d56abc1f88dd06e68edbea982799a7ff01c8569
Status: Downloaded newer image for ghcr.io/tcort/markdown-link-check:stable

FILE: /tmp/README.md
  [✓] https://www.npmjs.com/package/isemail
  [✓] https://github.com/gaurav-nelson/github-action-markdown-link-check
  [✓] https://pre-commit.com
  [✓] https://megalinter.io/latest/
  [✓] https://megalinter.io/latest/descriptors/markdown_markdown_link_check/
  [✓] https://www.npmjs.com/package/ms
  [✓] https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/String/replace#specifying_a_string_as_the_replacement
  [✓] https://github.com/tcort/markdown-link-check/blob/master/LICENSE.md
  [✓] https://github.com/tcort/markdown-link-check/actions/workflows/ci.yml/badge.svg

  9 links checked.

[BaseMax]

Dear Mike,

Thank you for your contribution. I see that your merge request is still in draft. Once it is ready for review, please let us know.

Many thanks.