There was a time when changes to the Linux kernel came out on a daily basis, and the hardest part about building a Linux kernel was knowing how to stop. These days, the production kernel tree is much more stable, but there are still significant kernel updates released on a regular basis.
One way to take advantage of these updates is to download and install the kernel update packages made available in conjunction with the Linux distribution you are using. The advantage of this method is that the changes are merged into the actual distribution's kernel source code—in other words, the source code as modified by the distribution's creators—a process that can be daunting and difficult for anyone else.
However, you may still decide to build your own custom kernel, probably beginning from a standard source-code package. If you decide to go this route, be sure that you understand any changes that may be required to support distribution-specific features that you may be using.
The following commands illustrate the basic procedure for building a Linux kernel (the conservative way, not the kernel hacker's way). By way of illustration, they apply patches to bring the source code package to the current revision level before building the kernel.
The first steps are to save the old kernel and unpack the kernel source code, if necessary:
cp /boot/vmlinuz /boot/vmlinuz.saveSave current kernel. #
cd /usr/srcChange to source code area. #
bzip2 -dc linux-2.4.x
.tar.bz2 | tar xvf -Unpack starting ...