should be it

external/duckdb/tools/sqlite3_api_wrapper/shell_extension.cpp

@@ -0,0 +1,45 @@
+#include "shell_extension.hpp"
+#include "duckdb/main/extension/extension_loader.hpp"
+#include "duckdb/common/vector_operations/unary_executor.hpp"
+#include "duckdb/main/config.hpp"
+#include <stdio.h>
+#include <stdlib.h>
+
+namespace duckdb {
+
+static void GetEnvFunction(DataChunk &args, ExpressionState &state, Vector &result) {
+	UnaryExecutor::Execute<string_t, string_t>(args.data[0], result, args.size(), [&](string_t input) {
+		string env_name = input.GetString();
+		auto env_value = getenv(env_name.c_str());
+		if (!env_value) {
+			return StringVector::AddString(result, string());
+		}
+		return StringVector::AddString(result, env_value);
+	});
+}
+
+static unique_ptr<FunctionData> GetEnvBind(ClientContext &context, ScalarFunction &bound_function,
+                                           vector<unique_ptr<Expression>> &arguments) {
+	auto &config = DBConfig::GetConfig(context);
+	if (!config.options.enable_external_access) {
+		throw PermissionException("getenv is disabled through configuration");
+	}
+	return nullptr;
+}
+
+void ShellExtension::Load(ExtensionLoader &loader) {
+
+	loader.SetDescription("Adds CLI-specific support and functionalities");
+	loader.RegisterFunction(
+	    ScalarFunction("getenv", {LogicalType::VARCHAR}, LogicalType::VARCHAR, GetEnvFunction, GetEnvBind));
+}
+
+std::string ShellExtension::Name() {
+	return "shell";
+}
+
+std::string ShellExtension::Version() const {
+	return DefaultVersion();
+}
+
+} // namespace duckdb