perl -i~ -pe ' s/(.*) ([0-9]{1,3}\.[0-9]{1,3}\.[0-9]{1,3}\.[0-9]{1,3})$/$2 $1/;' 2001-01-02.log

##</code><code>##

234.234.234.234.asd.f2.35.346t.sdfg.aws.5332.6t.sdf.as4.23.4234 12.12.153.43