NAME
utmp, wtmp, btmp — user login record format
SYNOPSIS
#include <sys/types.h>
#include <utmp.h>
DESCRIPTION
These files, which hold user and accounting information
for such commands as
last,
who,
write,
and
login
(see
last(1),
who(1),
write(1),
and
login(1)),
have the following structure as defined by
<utmp.h>:
#define UTMP_FILE "/etc/utmp"
#define WTMP_FILE "/var/adm/wtmp"
#define BTMP_FILE "/var/adm/btmp"
#define ut_name ut_user
struct utmp {
char ut_user[8]; /* User login name */
char ut_id[4]; /* /etc/inittab id(usually line#)*/
char ut_line[12] /* device name (console, lnxx) */
pid_t ut_pid; /* process id */
short ut_type; /* type of entry */
struct exit_status
short e_termination; /* Process termination status*/
short e_exit; /* Process exit status*/
} ut_exit; /* The exit status of a process*/
/* marked as DEAD_PROCESS.*/
unsigned short ut_reserved1; /* Reserved for future use*/
time_t ut_time; /* time entry was made*/
char ut_host[16]; /* host name,if remote*/
unsigned long ut_addr; /* host Internet addr, if remote*/
};
/* Definitions for ut_type */
#define EMPTY 0
#define RUN_LVL 1
#define BOOT_TIME 2
#define OLD_TIME 3
#define NEW_TIME 4
#define INIT_PROCESS 5 /* Process spawned by "init" */
#define LOGIN_PROCESS 6 /* getty process awaiting login */
#define USER_PROCESS 7 /* A user process */
#define DEAD_PROCESS 8
#define ACCOUNTING 9
#define UTMAXTYPE ACCOUNTING /* Max. legal value of ut_type */
/* Special strings or formats used in the "ut_line" field */
/* when accounting for something other than a process */
/* No string for the ut_line field can be more than */
/* 11 chars + a NULL in length */
#define RUNLVL_MSG "run-level %c"
#define BOOT_MSG "system boot"
#define OTIME_MSG "old time"
#define NTIME_MSG "new time"
File
utmp
contains a record of all users logged onto the system.
File
btmp
contains bad login entries for each invalid logon attempt.
File
wtmp
contains a record of all logins and logouts.
Note that
wtmp
and
btmp
tend to grow without bound, and should be checked regularly.
Information that is no longer useful
should be removed periodically to prevent it from becoming too large.
Also note that
wtmp
and
btmp
are not created by the programs that maintain them.
Thus, if these files are removed, record-keeping is turned off.
FILES
/etc/utmp
/var/adm/wtmp
/var/adm/btmp
AUTHOR
utmp,
wtmp,
and
btmp
were developed by HP
and
the University of California, Berkeley.
STANDARDS CONFORMANCE
<utmp.h>: XPG2
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