http://www.reddit.com/r/perl/comments/1jt5fe/wtmp_script_help/

gistfile1.pl

#!/usr/bin/env perl
use strict;
use warnings;

my @files = ('/var/log/wtmp', '/var/log/wtmp.1');
my %TIMES;

foreach my $file (@files) {
    parse($file);
}

foreach (sort keys %TIMES) {
    next if $_ eq "reboot";
    print "$_ $TIMES{$_}\n";
}

sub parse {
    my $f = shift;
    return if ! -r $f;
    open my $fh, "last -f $f |";
    while (<$fh>) {
        if (my ($name,$days,$hours,$mins) = /^(\w+).+\((?:(\d+)\+)?(\d+):(\d+)/) {
            $days = 0 if !$days;
            $TIMES{$name} += 1440 * $days + 60 * $hours + $mins;
        }
    }
    close($fh);
}