Compiling a custom kernel has its advantages and disadvantages. However, new Linux user/admin find it difficult to compile Linux kernel. Compiling kernel needs to understand few things and then type a couple of commands. This step by step howto covers compiling Linux kernel version 4.20 under an Ubuntu or Debian Linux. The following instructions successfully tested on an RHEL 7/CentOS 7 (and clones), Debian Linux, Ubuntu Linux and Fedora Linux 28. However, instructions remain the same for any other Linux distribution.