In a Jekyll site one excludes files like this:
exclude:
- "*.json"
- "Gemfile*"
- "*.txt"
- vendor
- README.md
- somefile.html
So to create the production build I run: $ JEKYLL_ENV=production bundle exec jekyll build
How can I exclude the somefile.html file only when I run the production ENV?
Perhaps you could try using a specific config file for production and one for development. In the production you could exclude the files using exclude as described here.
Then run:
jekyll build --trace --config _config.yml,_config_dev.yml
or
jekyll build --trace --config _config.yml,_config_prod.yml
In the _config.yml you'd set generic settings, and in the config with the environment suffix you'd set a environment specific configuration.
The trace flag is optional, it will help setting it up since it will show occuring errors.
optional: -t, --trace Show the full backtrace when an error occurs