I prefer to cp/truncate instead of deleting. That way you do not have to worry about restarting the service that has the file open for logdumping. on commandline it looks like this:

rm logfile.5
mv logfile.4 logfile.5
mv logfile.3 logfile.4
mv logfile.2 logfile.3
mv logfile.1 logfile.2
cp logfile logfile.1
cat /dev/null > logfile
[download]

its about the same thing in perl except you use File::Copy's copy and move and open OUTFILE, ">logfile"; close OUTFILE; to truncate