Fix link #717


	# Check links on the 2nd day of the month.
	# 2nd as the first letter of this repo is the 2nd letter in the alphabet.
	on:
	push:
	pull_request:
	schedule:
	- cron: "0 0 2 * *"

	name: check-links

	jobs:
	check-links:
	runs-on: ubuntu-latest
	env:
	GITHUB_PAT: ${{ secrets.GITHUB_TOKEN }}
	steps:
	- uses: actions/checkout@v2

	- name: Remove folders that are allowed broken links
	run: \|
	rm -rf docs/sep23
	rm docs/extra/rpackages_copy.md

	# The link checker will only work if mlc_config.json is a valid JSON
	- name: Validate JSON
	uses: docker://orrosenblatt/validate-json-action:latest
	env:
	INPUT_SCHEMA: .github/workflows/valid_json_schema.json
	INPUT_JSONS: mlc_config.json

	# These are status code that cannot be ignored.
	#
	# If there is a valid external link that fails,
	# add it to mlc_config.json
	- name: External links must be checked, do not allow '0' in the 'aliveStatusCodes' of mlc_config.json
	run: if [[ $(grep --regexp "[^0-9]0[^0-9]" mlc_config.json \| wc --lines) == "1" ]]; then echo "FOUND"; exit 42; fi

	- name: Internal links must checked, do not allow '400' in the 'aliveStatusCodes' of mlc_config.json
	run: if [[ $(grep --regexp "[^0-9]400[^0-9]" mlc_config.json \| wc --lines) == "1" ]]; then echo "FOUND"; exit 42; fi

	- uses: gaurav-nelson/github-action-markdown-link-check@v1
	with:
	config-file: 'mlc_config.json'
	use-quiet-mode: 'yes'
	use-verbose-mode: 'no'

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