Using GitHub Actions to push changes

We can use GitHub Actions to push a new commit each time there is a new change detected.

I've recently had to do this to automate updating README.md with a listing of the repository files each time a new push has been detected. The GitHub workflow is found here.

Here are the learnings that may come useful to others:

Using bash to clear file content

cat /dev/null > README.md 

/dev/null is a pseudo file in Linux that has no output so we can override a file with this empty content.

Using bash to echo a string with new line

echo -e '# Today I Learned\n' > README.md 

-e is required to escape backslashes. This allows us to print new line (\n) when outputting to a file.

Using bash to read the first line of a file

head -n 1 $filename 

Using bash to remove characters from a string

echo '# Title' | sed 's/# //' 

sed is short for Stream EDitor and one of its common uses is pattern replacement. The above will remove # from the string (by replacing it with an empty string).

Using bash to append string to file

echo 'My string' >> README.md 

The >> operator is used to append to a file (or create the file if it does not exist).

Using GitHub Actions to push changes to a repository

actions/checkout is an offical GitHub Action that can checkout a repository. We can also use this to push changes back.

on: push jobs: update: runs-on: ubuntu-latest steps: - uses: actions/checkout@v2 - run: | # Clear README.md cat /dev/null > README.md # Add Title echo -e '# Today I Learned\n' > README.md # Loop through all TILs and add to README.md dir=./learnings for filename in "$dir"/* do title=$(head -n 1 $filename | sed 's/# //') echo "- [$title](https://github.com/petermekhaeil/til/blob/master/$filename)" >> README.md done # Push changes git config user.name github-actions git config user.email github-actions@github.com git add README.md git commit -m "Update README.md" git push 

Today I Learned
I share what I learn on Today I Learned.