Net web server - CHAPTER 16 Taking Control of
CHAPTER 16 Taking Control of the System By now, you should be starting to realize that the shell offers an enormous amount of power when it comes to administering your PC. The BASH shell commands give you quick and efficient control over most aspects of your Linux setup. However, the shell truly excels in one area: controlling the processes on your system. Controlling processes is essential for administration of your system. You can tidy up crashed programs, for example, or even alter the priority of a program so that it runs with a little more consideration for other programs. Unlike with Windows, this degree of control is not considered out of bounds. This is just one more example of how Linux provides complete access to its inner workings and puts you in control. Without further ado, let s take a look at what can be done. Viewing Processes A process is something that exists entirely behind the scenes. When the user runs a program, one or many processes might be started, but they re usually invisible unless the user specifically chooses to manipulate them. You might say that programs exist in the world of the user, but processes belong in the world of the system. Processes can be started not only by the user, but also by the system itself to undertake tasks such as system maintenance, or even to provide basic functionality, such as the GUI system. Many processes are started when the computer boots up, and then they sit in the background, waiting until they re needed (such as programs that send mail). Other processes are designed to work periodically to accomplish certain tasks, such as ensuring system files are up- to-date. You can see what processes are currently running on your computer by running the top program. Running top is simply a matter of typing the command at the shell prompt. As you can see in Figure 16-1, top provides very comprehensive information and can be a bit overwhelming at first sight. However, the main area of interest is the list of processes (which top refers to as tasks).