fw_getenv
str = fw_getenv(envname);
yamontty = fw_getenv("yamontty");
mode_var = fw_getenv(mode_var_name);
var = fw_getenv(var_names[i]);
extern char *fw_getenv(char *name);
char *rng_seed_hex = fw_getenv("rngseed");
var = fw_getenv(var_names[i]);
s = fw_getenv("modetty0");