struct utmp {
short ut_type; type of login
pid_t ut_pid; pid of login process
char ut_line[UT_LINESIZE]; device name of tty - "/dev/"
char ut_id[4]; init id or abbrev. ttyname
char ut_user[UT_NAMESIZE]; user name
char ut_host[UT_HOSTSIZE]; hostname for remote login
struct exit_status ut_exit; The exit status of a process
marked as DEAD_PROCESS.
ong ut_session; session ID, used for windowing
struct timeval ut_tv; time entry was made.
int32_t ut_addr_v6[4]; IP address of remote host.
char pad[20]; Reserved for future use.
};