#!/usr/bin/perl # tailwtmp - watch for logins and logouts; # uses linux utmp structure, from utmp(5) $typedef = 's x2 i A12 A4 l A8 A16 l'; $sizeof = length pack($typedef, () ); use IO::File; open(WTMP, '/var/log/wtmp') or die "can't open /var/log/wtmp: $!"; seek(WTMP, 0, SEEK_END); for (;;) { while (read(WTMP, $buffer, $sizeof) == $sizeof) { ($type, $pid, $line, $id, $time, $user, $host, $addr) = unpack($typedef, $buffer); next unless $user && ord($user) && $time; printf "%1d %-8s %-12s %2s %-24s %-16s %5d %08x\n", $type,$user,$line,$id,scalar(localtime($time)), $host,$pid,$addr; } for ($size = -s WTMP; $size == -s WTMP; sleep 1) {} WTMP->clearerr(); }