wtmp(5) [mojave man page]

UTMP(5) 						      BSD File Formats Manual							   UTMP(5)

NAME

     utmp, wtmp, lastlog -- login records (DEPRECATED)

SYNOPSIS

     #include <utmp.h>

DESCRIPTION

     The interfaces in file <utmp.h> are all DEPRECATED and are only provided for compatibility with previous releases of Mac OS X.  See
     pututxline(3) and utmpx(5) for the supported interfaces.

     <utmp.h> declares the structures used to record information about current users in the file utmp, logins and logouts in the file wtmp, and
     last logins in the file lastlog.  The time stamps of date changes, shutdowns and reboots are also logged in the wtmp file.

     These files can grow rapidly on busy systems, daily or weekly rotation is recommended.  If any of these files do not exist, it is not cre-
     ated.  These files must be created manually and are normally maintained in either the script /etc/daily or the script /etc/weekly.  (See
     cron(8).)

	   #define _PATH_UTMP	   "/var/run/utmp"
	   #define _PATH_WTMP	   "/var/log/wtmp"
	   #define _PATH_LASTLOG   "/var/log/lastlog"

	   #define UT_NAMESIZE	   8
	   #define UT_LINESIZE	   8
	   #define UT_HOSTSIZE	   16

	   struct lastlog {
		   time_t  ll_time;
		   char    ll_line[UT_LINESIZE];
		   char    ll_host[UT_HOSTSIZE];
	   };

	   struct utmp {
		   char    ut_line[UT_LINESIZE];
		   char    ut_name[UT_NAMESIZE];
		   char    ut_host[UT_HOSTSIZE];
		   time_t  ut_time;
	   };

     Each time a user logs in, the login program looks up the user's UID in the file lastlog. If it is found, the timestamp of the last time the
     user logged in, the terminal line and the hostname are written to the standard output. (Providing the login is not quiet, see login(1).)  The
     login program then records the new login time in the file lastlog.

     After the new lastlog record is written , the file utmp is opened and the utmp record for the user inserted.  This record remains there until
     the user logs out at which time it is deleted.  The utmp file is used by the programs rwho(1), users(1), w(1), and who(1).

     Next, the login program opens the file wtmp, and appends the user's utmp record.  The same utmp record, with an updated time stamp is later
     appended to the file when the user logs out. (See launchd(8).)  The wtmp file is used by the programs last(1) and ac(8).

     In the event of a date change, a shutdown or reboot, the following items are logged in the wtmp file.

     reboot
     shutdown	 A system reboot or shutdown has been initiated.  The character '~' is placed in the field ut_line, and reboot or shutdown in the
		 field ut_name.  (See shutdown(8) and reboot(8).)

     date	 The system time has been manually or automatically updated.  (See date(1).)  The command name date is recorded in the field
		 ut_name.  In the field ut_line, the character '|' indicates the time prior to the change, and the character '{' indicates the new
		 time.

FILES

     (These files no longer exist in 10.5 or later.)

     /var/run/utmp     The utmp file.
     /var/log/wtmp     The wtmp file.
     /var/log/lastlog  The lastlog file.

SEE ALSO

     last(1), login(1), who(1), ac(8), launchd(8)

HISTORY

     A utmp and wtmp file format appeared in Version 6 AT&T UNIX.  The lastlog file format appeared in 3.0BSD.

4th Berkeley Distribution					  March 17, 1994					 4th Berkeley Distribution

Check Out this Related Man Page

LOGIN(3)						     Linux Programmer's Manual							  LOGIN(3)

NAME

       login, logout - write utmp and wtmp entries

SYNOPSIS

       #include <utmp.h>

       void login(const struct utmp *ut);

       int logout(const char *ut_line);

       Link with -lutil.

DESCRIPTION

       The utmp file records who is currently using the system.  The wtmp file records all logins and logouts.	See utmp(5).

       The function login() takes the supplied struct utmp, ut, and writes it to both the utmp and the wtmp file.

       The function logout() clears the entry in the utmp file again.

   GNU details
       More  precisely,  login() takes the argument ut struct, fills the field ut->ut_type (if there is such a field) with the value USER_PROCESS,
       and fills the field ut->ut_pid (if there is such a field) with the process ID of the calling process.  Then it  tries  to  fill	the  field
       ut->ut_line.   It takes the first of stdin, stdout, stderr that is a terminal, and stores the corresponding pathname minus a possible lead-
       ing /dev/ into this field, and then writes the struct to the utmp file.	On the other hand, if no terminal name was found,  this  field	is
       filled with "???"  and the struct is not written to the utmp file.  After this, the struct is written to the wtmp file.

       The  logout()  function	searches the utmp file for an entry matching the ut_line argument.  If a record is found, it is updated by zeroing
       out the ut_name and ut_host fields, updating the ut_tv timestamp field and setting ut_type (if there is such a field) to DEAD_PROCESS.

RETURN VALUE

       The logout() function returns 1 if the entry was successfully written to the database, or 0 if an error occurred.

FILES

       /var/run/utmp
	      user accounting database, configured through _PATH_UTMP in <paths.h>

       /var/log/wtmp
	      user accounting log file, configured through _PATH_WTMP in <paths.h>

CONFORMING TO

       Not in POSIX.1-2001.  Present on the BSDs.

NOTES

       Note that the member ut_user of struct utmp is called ut_name in BSD.  Therefore, ut_name is defined as an alias for ut_user in <utmp.h>.

SEE ALSO

       getutent(3), utmp(5)

COLOPHON

       This page is part of release 3.53 of the Linux man-pages project.  A description of the project, and information about reporting bugs,  can
       be found at http://www.kernel.org/doc/man-pages/.

GNU
								    2004-05-06								  LOGIN(3)

Linux and UNIX Man Pages

wtmp(5) [mojave man page]

Check Out this Related Man Page