Linux Fundamentals

Configuring a Linux System

In Windows, the Registry is an all in one database that contains the system configuration. You cannot simply run an application by copying the files to a given location. The application must first register itself with the system to function, and this registration information is stored in the registry. Linux is based entirely on files, and the simple presence or absence of files means a great deal. Linux uses a method of operation known as Late Binding. What this means is that applications generally do not require that things be present until they are needed. When an application runs, and needs configuration information, it simply looks in a preconfigured place for a preconfigured file, and if the file is there, and contains the information required, the application runs. If the file is not then the application does not run.

All configuration of a Linux system is manipulation of text files, either directly or indirectly. Many current distributions have collections of utilities that provide a graphical front end to file modification commands. Many installation programs run wizard like scripts that prompt you for information that is simply fed into file modification commands.

A simple example of this is the file /etc/fstab. This text file stands for “file systems at boot” and contains a list of the file systems that are stored on the computer and which directory then can be accessed from. When a change is made to the disk configuration this file needs to be updated. There are two ways this can be accomplished. First of all you can run a graphical disk administration utility that will modify your file systems and then write all changes to the appropriate places, or secondly, you can make command prompt based modifications, and manually edit the fstab file. Either way accomplishes exactly the same thing

Another example of this is the configuration of XWindows, your GUI. When the setup wizard prompts you for information on your monitor, video adapter and desired screen settings. All this information is saved to a text file that is read when XWindows is booted and from there your GUI is displayed. A simple edit in this file can adjust the display of XWindows. For those of you that are more familiar with Windows, you can compare the general setup of Linux to a system based on .INI files.