ultrix man page for utmp

utmp(5) 							File Formats Manual							   utmp(5)

Name
       utmp, wtmp - login records

Syntax
       #include <utmp.h>

Description
       The  file  records  information	about  who  is currently using the system.  The file is a sequence of entries with the following structure
       declared in the include file:
       struct utmp {
	       char    ut_line[8];	       /* tty name */
	       char    ut_name[8];	       /* user id */
	       char    ut_host[16];	       /* host name, if remote */
	       long    ut_time; 	       /* time on */
       };

       This structure gives the name of the special file associated with the user's terminal, the user's login name, and the time of the login	in
       the form of

       The  file  records  all	logins and logouts.  A null user name indicates a logout on the associated terminal.  A terminal referenced with a
       tilde (~) indicates that the system was rebooted at the indicated time.	The adjacent pair of entries with terminal names referenced  by  a
       vertical  bar  (|)  or  a right brace (}) indicate the system-maintained time just before and just after a command has changed the system's
       timeframe.

       The file is maintained by and Neither of these programs creates the file, so, if it is removed, record-keeping is turned off.  It is summa-
       rized by

Files
See Also
       last(1), lastcomm(1), login(1), who(1), ac(8), init(8)

																	   utmp(5)