Nice tutorial, tried it on my centos.

It works, however, there are a few inconsistencies I noticed.

-w key doesn’t necessarily write changes to /etc/sysctl.conf, in my case it didn’t.

Then, if I append some lines to /etc/sysctl.conf through vim and reboot the system, these changes are still applied. This means, the method with manual editing configs in /etc/sysctl.conf isn’t temporary, but rather permanent change.