utmp(4)

NAME

utmp, wtmp − utmp and wtmp entry formats

SYNOPSIS

#include <sys/types.h>
#include <utmp.h>

DESCRIPTION

These files, which hold user and accounting information for such commands as who(1), write(1), and login(1), are an array of utmp structures with the following members:

#defineut_nameut_user
     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. ∗/
     time_t   ut_time; /∗ time entry was made ∗/
     char     ut_host[16];/∗ host name, if remote ∗/
The definitions for ut_type are:
EMPTY
RUN_LVL
BOOT_TIME
OLD_TIME
NEW_TIME
INIT_PROCESS/∗ Process spawned by "init" ∗/
LOGIN_PROCESS/∗ A "getty" process waiting for login ∗/
USER_PROCESS/∗ A user process ∗/
DEAD_PROCESS
ACCOUNTING

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 + NULL in length

#defineRUNLVL_MSG      "run−level %c"
#defineBOOT_MSG        "system boot"
#defineOTIME_MSG       "old time"
#defineNTIME_MSG       "new time"

NOTES

The structure documented above is the AT&T SYSV.2 version of utmp with one additional field, ut_host, borrowed from 4.2BSD. The ut_host field, as it is not compatible with several standards, should not be used. The 4.2BSD version of utmp is a subset of the one above.

The most significant difference between the 4.2BSD and SYSV.2 structures is the ut_type field. A 4.2BSD system distinguishes among the different types of records (login, logout, reboot, change of system time, etc.) in the wtmp file with values in ut_name. A SYSV.2 system uses ut_type for that purpose.

Record	4.2BSD	SYSV.2
	ut_name	ut_type


logout	null	DEAD_PROCESS
reboot	’~’	BOOT_TIME
old date	’\|’	OLD_TIME
new date	’}’	NEW_TIME

FILES

/usr/include/utmp.h
/etc/utmp
/etc/wtmp

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