# tac /var/log/biglog |  perl -ne 'print; exit 0 if (($DateCurrent -$Date) > 300 );'

##</code><code>##

# tail -3 biglog
78.49.150.102 - - [01/Nov/2011:00:53:01 +0600] "GET /mem.png HTTP/1.1" 200 51883 "http://net.com/" "Opera/9.80 (Windows NT 6.1; U; ru) Presto/2.9.168 Version/11.52"
78.49.150.102 - - [01/Nov/2011:00:53:01 +0600] "GET /cpu.png HTTP/1.1" 200 42875 "http://net.com/" "Opera/9.80 (Windows NT 6.1; U; ru) Presto/2.9.168 Version/11.52"
78.49.150.102 - - [01/Nov/2011:00:53:01 +0600] "GET /traf.png HTTP/1.1" 200 48121 "http://net.com/" "Opera/9.80 (Windows NT 6.1; U; ru) Presto/2.9.168 Version/11.52"