Introduction

Kernel is the word we use to refer to the Linux program itself. The kernel controls access to the hardware and other system resources. The kernel is the single most important program on a system, and thus, access to it is, of necessity, highly restricted. The programs described in this section provide the means of interactive access to the kernel.

One of the nice things about Linux is that the source code for the kernel is included in the distribution, specifically in the directory /usr/src/linux. If you don't like something, change it.

Some parts of the kernel can be compiled separately and linked as needed. These programs are known as modules. The linking process depends on the kernel's internal data structure for resolving variable and function names, known as the symbol table, being exported for outside use.

The module names generally make sense. If you're trying to figure out what module is associated with, say, the reverse address resolution protocol, try typing:

modprobe -l | grep rarp

The commands covered in this section include

`depmod`	Create a module dependency list.
`modprobe`	Load or list loadable modules.
`insmod`	Install a module.
`kerneld`	Run kernel program in user space.
`ksyms`	Display kernel symbols.
`lsmod`	List installed modules.
`bdflush`	Flush dirty buffers to disk.
`rmmod`	Remove specified module.