typedef u_short comp_t /*3-bit base 8 exponent; 13bit fraction */
struct acct
{
char ac_flag; /* flag*/
char ac_stat; /* termination status */
uid_t ac_uid ; /* real user ID */
uid_t ac_gid ; /* real group ID*/
dev_t ac_tty ; /* controlling terminal */
time_t ac_btime; /* starting calendar time */
comp_t ac_utime; /* user cpu time */