Use consistent patterns for environment variable handling in shell scripts. Always provide sensible defaults using the `${VAR:-default}` syntax, validate required variables early with clear error messages, and preserve the ability to override configuration values. For variables with defaults: ```bash strategies=${STRATEGIES:=fast,hi_res,ocr_only} RUN_SCRIPT=${RUN_SCRIPT:-unstructured-ingest} PYTHONPATH=${PYTHONPATH:-.} ``` For required variables, validate early and provide helpful error messages: ```bash if [ -z "$VECTARA_OAUTH_CLIENT_ID" ]; then echo "Skipping VECTARA ingest test because VECTARA_OAUTH_CLIENT_ID env var is not set." exit 0 fi ``` Document configurable environment variables in script comments or usage instructions to make them discoverable for users who aren't familiar with shell scripting. This approach allows scripts to work out-of-the-box with reasonable defaults while remaining flexible for different environments and use cases.