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Expand system variables Unix style
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README.md

expandvars

Expand system variables Unix style

PyPI version CircleCI codecov

Inspiration

This module is inspired by GNU bash's variable expansion features. It can be used as an alternative to Python's os.path.expandvars function.

A good use case is reading config files with the flexibility of reading values from environment variables using advanced features like returning a default value if some variable is not defined. For example:

[default]
my_secret_access_code = "${ACCESS_CODE:-default_access_code}"

NOTE: Although it copies most of the common behaviours, it doesn't follow it strictly. For example, it doesn't work with arrays.

Usage

from expandvars import expandvars

print(expandvars("$PATH:$HOME/bin:${SOME_UNDEFINED_PATH:-/default/path}"))
# /bin:/sbin:/usr/bin:/usr/sbin:/home/you/bin:/default/path

Examples

For now, refer to the test cases to see how it behaves.

Contributing

To contribute, setup environment following way:

# Clone repo
git clone https://github.com/sayanarijit/expandvars && cd expandvars

# Create virtualenv
virtualenv .venv && source .venv/bin/activate

# Install library in edit mode along with other handy dev tools
pip install -r dev-requirements.txt
  • Follow general git guidelines.
  • Keep it simple. Use black to format code.
  • Test your changes locally by running pytest.
  • If you are familiar with tox, you may want to use it for testing in different python versions.
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