Users regularly need just a fraction of the functionality provided by larger applications, such as word processors, for their daily work. To avoid inactive program components unnecessarily hogging RAM – and OpenOffice has over 200MB of this stuff – developers tend to offload them into special files. In Linux, these dynamic libraries are identifiable by their .so suffix. When a user triggers a specific action, the program locates the matching library, loads it into RAM, and runs the requested function. This strategy keeps the applications lean, and to update, you simply install a newer version of the library.

A modular approach like this offers another advantage: Programs can share libraries. An application that gives users a graphical interface can either draw the menus, buttons, and lists itself, or it can rely instead on the Gtk+ or Qt libraries installed in any major distribution. Relying on libraries is very popular because it saves both programming and memory resources.

The drawback to the modular approach becomes obvious when you want to install a new version of the program. First you need to resolve the dependencies on various libraries. This can be very trying for fans of multimedia applications: The software typically relies on numerous libraries, some of which can be fairly exotic – if you have ever tried to install the Kdenlive video editing program, you will know what I mean. As Listing 1 shows, even simple system tools like ls rely on multiple libraries. Fortunately, the package manager typically resolves dependencies quickly and reliably.

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