env_getenv
if ((ev = env_getenv(name)) != NULL) {
if (overwrite || (env_getenv(name) == NULL))
if ((ev = env_getenv(name)) == NULL) {
if ((ev = env_getenv(name)) != NULL) {
extern struct env_var *env_getenv(const char *name);
struct env_var *ev = env_getenv(name);
env_discard(env_getenv(name));