#define trace2_cmd_list_config() trace2_cmd_list_config_fl(__FILE__, __LINE__)
+/*
+ * Emit one or more 'def_param' events for "important" environment variables.
+ *
+ * Use the TR2_SYSENV_ENV_VARS setting to register a comma-separated list of
+ * environment variables considered important. For example:
+ * git config --system trace2.envVars 'GIT_HTTP_USER_AGENT,GIT_CONFIG'
+ * or:
+ * GIT_TRACE2_ENV_VARS="GIT_HTTP_USER_AGENT,GIT_CONFIG"
+ */
+void trace2_cmd_list_env_vars_fl(const char *file, int line);
+
+#define trace2_cmd_list_env_vars() trace2_cmd_list_env_vars_fl(__FILE__, __LINE__)
+
/*
* Emit a "def_param" event for the given config key/value pair IF
* we consider the key to be "important".