Did you ever try to use log rotate facility in Linux with MySQL? There is no need to script one for this purpose, it is already installed. From MySQL spec file, it looks for logrotate.d folder:

    # Ensure that needed directories exists 
    install -d $RBR%{_sysconfdir}/{logrotate.d,init.d}

As well as there is dedicated mysql-log-rotate.sh script for installing logrotate script. The script path is: /mysql-5.6.24/support-files/mysql-log-rotate.sh Again from spec file:

    # Install logrotate and autostart 
    install -m 644 $MBD/release/support-files/mysql-log-rotate $RBR%{\_sysconfdir}/logrotate.d/mysql

After installing there will be mysql script in /etc/logrottate.d/.

   # The log file name and location can be set in
   # /etc/my.cnf by setting the "log-error" option
   # in either [mysqld] or [mysqld_safe] section as
   # follows: …