systemd is like the service manager for your Centos and other modern Linux distributions (including Debian/Mint/Ubuntu) allows you to enable services, stop them, restart them, check their status and even reboot your system.
The key commands or arguments you will use with systemctl are the following:
list-units [PATTERN...] List loaded units
Just type the following in the bash/terminal shell to enable the blue LED light on the Coolermaster CM Storm keyboard:
xset led 3
To make it automatic and permanent execute the following as root:
echo "xset led 3" >> /etc/rc.local
This is a fairly nice gaming keyboard which I bought because I type very quickly and the cheap standard keyboards simply can't keep up!........