UPDWTMP
NAME SYNOPSIS DESCRIPTION AVAILABILITY FILES SEE ALSO
updwtmp, logwtmp - append an entry to the wtmp file
#include wtmp_file, const struct utmp *ut); void logwtmp(const char *line, const char *name, const char *host);
updwtmp() appends the utmp structure ut to the wtmp file.
logwtmp() constructs an utmp structure using line, name, host, current time and current process id. Then it calls updwtmp() to append the structure to the utmp file.
Both functions are available under glibc2, but not under libc5. However, logwtmp occurs in the old libbsd.
/var/log/wtmp
database of past user logins
One page links to logwtmp(3):