First version

In this version, you use posix-egrep to pass a regular expression to the action to exclude or include file lines counts.
In next releases it will be simplified.
To install action copy the workflow code into a .github/workflows/main.yml file in your repository

on: [push]

jobs:
  lines_counter_job:
    runs-on: ubuntu-latest
    name: A job to count lines of code and generate badge
    steps:
      - uses: actions/checkout@v4
      - id: counting
        uses: ./                   # write the action name instead
        with:
          include-files: '.*\.sh'  # default value - include all files
          exclude-files: ''        # default value - exclude no files

See README.md for more regex examples.
The badge will be generated in image-data branche of your repository. For this you need to configure Setting the permissions of the GITHUB_TOKEN for your repository.