LogRotate

vi /etc/logrotate.d/name_of_file

/var/log/some_dir/somelog.log {
su root root
missingok
notifempty
compress
size 5M
daily
create 0600 root root
}

su - run a root user
missingok - do not output error if logfile is missing
notifempty - donot rotate log file if it is empty
compress - Old versions of log files are compressed with gzip(1) by default
size - Log file is rotated only if it grow bigger than 20k
daily - ensures daily rotation
create - creates a new log file wit permissions 600 where owner and group is root user

logrotate -f /etc/logrotate.conf

Once it's all done no need to do anything else, log rotate already runs in /etc/cron.daily/logrotate