4.4BSD/usr/share/man/cat5/utmp.0

UTMP(5)                     BSD Programmer's Manual                    UTMP(5)

NNAAMMEE
     uuttmmpp, wwttmmpp, llaassttlloogg - login records

SSYYNNOOPPSSIISS
     ##iinncclluuddee <<uuttmmpp..hh>>

DDEESSCCRRIIPPTTIIOONN
     The file <_u_t_m_p_._h> declares the structures used to record information
     about current users in the file uuttmmpp, logins and logouts in the file
     wwttmmpp, and last logins in the file llaassttlloogg. The time stamps of date
     changes, shutdowns and reboots are also logged in the wwttmmpp 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 created.
     These files must be created manually and are normally maintained in ei-
     ther the script _/_e_t_c_/_d_a_i_l_y or the script _/_e_t_c_/_w_e_e_k_l_y. (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];
                   long    ut_time;
           };

     Each time a user logs in, the login program looks up the user's UID in
     the file llaassttlloogg.. 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 _q_u_i_e_t, see login(1).)  The login pro-
     gram then records the new login time in the file llaassttlloogg.

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

     Next, the login program opens the file wwttmmpp, and appends the user's _u_t_m_p
     record.  The same _u_t_m_p record, with an updated time stamp is later ap-
     pended to the file when the user logs out. (See init(8).)  The wwttmmpp 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 wwttmmpp file.

     reboot
     shutdown    A system reboot or shutdown has been initiated.  The charac-
                 ter `~' is placed in the field _u_t___l_i_n_e, and reboot or
                 shutdown in the field _u_t___n_a_m_e. (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 _u_t___n_a_m_e. In the field _u_t___l_i_n_e, the character `{' indi-
                 cates the time prior to the change, and the character `|' in-
                 dicates the new time.

FFIILLEESS
     /var/run/utmp     The uuttmmpp ffiillee..
     /var/log/wtmp     The wwttmmpp ffiillee..
     /var/log/lastlog  The llaassttlloogg ffiillee..

SSEEEE AALLSSOO
     last(1),  login(1),  who(1),  ac(8),  init(8)

HHIISSTTOORRYY
     A uuttmmpp and wwttmmpp file format appeared in Version 6 AT&T UNIX.  The llaassttlloogg
     file format appeared in 3.0BSD.

4th Berkeley Distribution        June 5, 1993                                2