Web hosting resellers - 414 CHAPTER 29 INSTALLING SOFTWARE Formats of
414 CHAPTER 29 INSTALLING SOFTWARE Formats of Linux Installation Files If you visit the web site of a particular Linux application, you may find that the application is available to download in a number of different formats. The program will almost certainly be available as source code the original listing that the developer created. It might also be available as a binary, or as a package file. Note Linux isn t the only operating system for which open-source programs are created and used. There are open-source projects for both Windows and Apple Macintosh, many of which are hosted at the http:// sourceforge.net web site. Many other less widely used operating systems also rely on open-source software to a greater or lesser extent. Here are the formats by which Linux software is normally distributed: Source code: Programmers write their software in various programming languages, such as C and C++, and the code that results is known as source code. To make source code usable, it must be compiled into a binary file. Because the cornerstone of the Linux philosophy is the sharing of source code, you ll almost always find the source code of a program available at the developer s web site. You can then download and compile this on your own system (or, if you re so inclined, study the source code to further your understanding). Although compiling source code isn t very hard to do, it s more convenient to download either a binary version of the program or a package. Binary files: You might find ready-made binary files are available at the developer s web site. In other words, the programmer has, as a service to users of the program, compiled the source code so that it s ready for use as soon as it s downloaded. Sometimes, binary files come with scripts to help you install them. However, in most cases, you simply place the files in a convenient location on your hard disk, and then run them from there. Note In both the case of source code and binary files, the files usually come in a tarball, which is a single archive file containing other files. A tarball isn t by definition compressed, but usually the bzip2or gzip tool is used to shrink the file to ease transportation across the Internet. Self-installing binaries: Some larger programs are made available as self-installing binary files. This comes very close to the way Windows works because, when the file is executed, a GUI-based wizard takes you through installation. If you download OpenOffice.org from the official web site (www.openoffice.org), for example, you ll end up with a single 80MB+ file, which you then simply run from the command line to install the program. Package files: In many cases, you ll find that a package file of the program is available. In this case, someone has compiled the software files and put them altogether in a single, easily transportable file. Ubuntu package files end with .deb file extensions, but other Linux distributions use other package formats, such as RPM (Red Hat Package Manager). The software that oversees packages is called a package manager.