.TH UTMP 5 .SH NAMEutmp, wtmp \- login records.SH SYNOPSIS.B #include <utmp.h>.SH DESCRIPTIONThe.I utmpfile allows one to discover information about who is currentlyusing UNIX.The file is a sequence of entries with the followingstructure declared in the include file:.RS.PP.nf.so /usr/include/utmp.h.fi.RE.PPThis structure gives the name of the special fileassociated with the user's terminal, the user's login name,and the time of the login in the form of.IR time (2)..PPThe.I wtmpfile records all logins and logouts.Its format is exactly like.I utmpexcept thata null user name indicates a logout on the associatedterminal.Furthermore, the terminal name `~' indicates that thesystem was rebooted at the indicated time;the adjacent pair of entries with terminal names`\^|\^' and `}' indicate the system-maintained timejust before and just after a.I datecommand has changed the system's idea of the time..PP.I Wtmpis maintained by.IR login (1)and.IR init (8).Neither of these programs creates the file,so if it is removed record-keeping is turned off.It is summarized by.IR ac (1)..SH FILES/etc/utmp.br/usr/adm/wtmp.SH "SEE ALSO"login(1), init(8), who(1), ac(1)