Fallback Environment Variable Bash

fallback_env.sh

#!/usr/bin/env bash

fallback_env() {
    local TARGET_VARIABLE="$1"
    local FALLBACK_VALUE="$2"
    local CURRENT_VALUE=$(env | grep "^${TARGET_VARIABLE}=" | awk -F '=' '{print $2}')

    if [[ -z "$CURRENT_VALUE" ]]; then
        build_message "${TARGET_VARIABLE} is not set and will defaulting to ${FALLBACK_VALUE}"
        eval "export ${TARGET_VARIABLE}=${FALLBACK_VALUE}"
    fi
}