my $whole_event_string = '1.2.3.4 - Unauth [09/Oct/2003: 10:12:06 -0700] "GET / HTTP/1.1" 200 1979';

my ($srcip) = $whole_event_string =~ /^(\d+\.\d+\.\d+\.\d+)/;

die 'I read perlintro  ', $srcip;
__END__
I read perlintro  1.2.3.4 at - line 6.