USER_CMD_T
USER_CMD_T *list; /* head of list */
USER_CMD_T *tail; /* points at last element of list */
USER_CMD_T *cur_cmd; /* NULL, or currently executing command */
USER_CMD_T *next;
USER_CMD_T *ucmd;
USER_CMD_T *ucmd;
n = S_DROUND(sizeof (USER_CMD_T));