Obtaining Red Hat Linux Applications

Investigating your desktop

More and more high-quality desktop applications are being packaged with Red Hat Linux, mostly as part of the GNOME or KDE desktop environments. In other words, to start finding some excellent office applications, games, multimedia players, and communications tools, you don't have to look any further than the red hat menu button on your desktop.

So before you start hunting around the Internet for the software you need, see if you can use something already installed with Red Hat Linux. The chapters that follow this one describe how to use publishing tools, play games, work with multimedia, and communicate over the Internet — all with programs that are either on the CDs that come with this book or are easily attainable. Appendix B contains a list of the software packages that are included with the complete version of Red Hat Linux that is packaged with this book.

Finding applications on the Internet

If you don't already know the names of applications you want to use, there are a lot of places to look for Linux applications on the Internet. If you do know what you want, your best bet might be to head for a software repository that has packages build specifically for Red Hat Linux and Fedora.

Here are a few Web sites that you can browse for software that runs in Linux:

• Freshmeat (www.freshmeat.net) — This site maintains a massive index of Linux software. You can do keyword searches for software projects or browse for software by category.

• SourceForge (www.sourceforge.net) — This site hosts thousands of open source software projects. You can download software and documentation from those projects from the SourceForge site.

• Tucows Linux site (linux.tucows.com) — Both free and commercial software for Linux is available from the Tucows Linux Web site. This site also features news articles on Linux and a listing of software downloads from the site by category.

When you purchase a commercial application, you usually get the application on CD. Installation is often simplified, and hard copy documentation is provided. Of course, when you download software, you get immediate gratification — when you purchase it, you have to wait for the package to arrive in the mail.

You can visit FTP sites containing RPM packages if you already have some idea of what you are looking for. You can start by reading the README and INDEX files for a particular software product to get your bearings. When you find the software you want, simply click the link to begin downloading the software to your computer. Here are a few sites that are particularly good for finding RPM packages:

• Rpmfind (www.rpmfind.net) — Open source software that is already packaged up in Red Hat Package Management (RPM) format is available from this site. Do a keyword search from this Web site, then download the appropriate RPM from the search results.

• FreshRPMs (www.freshrpms.net) — Another site with a good selection of high-quality RPMs.

• Red Hat FTP Mirrors (www.redhat.com/mirrors.html) — Go to this page for a listing of FTP sites containing Red Hat software that you can download. Most of these sites also have a variety of freeware and shareware applications that are usable with Linux.

Often, you can't just download a single software package to get the software in that package to work. Many packages depend on other packages. For example, software packages for playing audio and video typically rely on other software packages for decoding different kinds of content. To deal with this issue, Red Hat Linux (Fedora Core) has included the yum package.

Downloading and installing applications with yum

The Yellow dog Updater, Modified (yum) software package lets you install and update selected software packages in RPM format from software repositories on the Web. Once you know the software package that you want, yum is probably the best way to download and install that package.

The yum package is included on the Fedora Core CDs that come with this book. To use yum to install RPM software packages, follow these basic steps:

1. Determine the software package you want. Many popular add-on packages for Red Hat Linux are already built for specific versions Red Hat Linux (Red Hat 8, 9, Fedora, and so on) and stored in software repositories on the Internet. Lists of repositories are available from the Yum Web site at http://linux.duke.edu/projects/yum/repos.

2. Configure yum. You need to configure the /etc/yum.conf file to point to the repository that contains the software you want. Once that is done, you can install any package that repository contains.

3. Run yum. The yum command can be used to download and install any package from the yum repository, including any packages the one you want depends on.

   Caution?

   In Red Hat Linux, and presumably in the new Fedora Core, Red Hat, Inc. has gone to great lengths to ensure that software it provides is of good quality and unimpaired by legitimate patent claims. Once you download packages outside of a Red Hat distribution of Linux, you are on your own to check the quality and legality of that software.

Besides downloading and installing new software packages, yum can also be used to check for available updates and list various kinds of information about available packages.

[freshrpms-rhl-9]
name=Freshrpms packages for Red Hat Linux 9
baseurl=http://ayo.freshrpms.net/redhat/9/i386/freshrpms

# yum install mplayer
Gathering header information file(s) from server(s)
Server: Red Hat Linux 0.94 - i386 - Base
Server: Freshrpms packages for Red Hat Linux 9
Server: Red Hat Linux 0.94 - Updates
Finding updated packages
Downloading needed headers
Resolving dependencies
..Dependencies resolved
I will do the following:
[install: mplayer 1.0-0.1.20031002.fr.i386]
I will install/upgrade these to satisfy the dependencies:
    .
    .
    .
Is this ok [y/N]: y
    .
    .
    .
Getting mplayer-fonts-1.1-1.fr.noarch.rpm
Getting mplayer-1.0-0.1.20031002.fr.i386.rpm
Calculating available disk space - this could take a bit
mplayer-fonts 100 % done 2/14
mplayer 100 % done 14/14
Installed:  mplayer 1.0-0.1.20031002.fr.i386
Dep Installed: mplayer-fonts 1.1-1.fr.noarch
Transaction(s) Complete

# yum check-update

# yum update nmap-frontend

# yum list | less

# yum provides missingfile

Downloading Linux software

Instead of using yum to download and install software RPMS, you can simply browse around and download Linux software from the Internet using a Web browser (such as Mozilla) or an FTP program (such as the ncftp command). The browser often enables you to view the contents of an FTP site through a Web interface (look for an index.html file in an FTP directory). An ftp command (such as ncftp) has more options, but is less intuitive. There are also GUI-based FTP applications, such as gFTP, to make FTP services easier to use. (The gFTP command is described in Chapter 9.)

Understanding package names and formats

Whenever possible, you want to install the applications you use with Red Hat Linux from software packages in RPM format (files with a .rpm suffix). However, if an RPM isn't available, the software that you want may come in other package formats.

Say you just downloaded a file from the Internet that contains lots of names, numbers, dots, gzs, and tars. What does all that stuff mean? Well, when you break it down, it's really not that complicated.

Most of the names of archive files containing Linux applications follow the GNU-style package-naming conventions. The following example illustrates the package-naming format:

mycoolapp-4.2.3.i386.rpm
mycoolapp-4.2.3.tar.gz
mycoolapp-4.2.3.src.tar.gz
mycoolapp-4.2.3.bin.SPARC.tar.gz
mycoolapp-4.2.3.bin.ELF.static.tar.gz

These examples represent several different packages of the same software application. The name of this package is mycoolapp. Following the package name is a set of numbers that represent the version of the package. In this case, it is version 4.2.3 (the major version number is 4, followed by minor version number and patch level 2.3). After the version number is a dot, followed by some optional parts, which are followed by indications of how the file is archived and compressed.

The first line shows a package that is in Red Hat Package Manager (.rpm) format. The .i386 before the .rpm indicates that the package contains binaries that are built to run Intel i386 architecture computers (in other words, PCs). See the sidebar "Using RPMs versus Building from Source" for the pros and cons of using prebuilt RPM binary packages as opposed to compiling the program yourself.

In the next two lines of the previous example, each file contains the source code for the package. The files that make up the package were archived using the tar command (.tar) and compressed using the gzip command (.gz). You use these two commands (or just the tar command with the -z option) to expand and uncompress the packages when you are ready to install the applications.

Between the version number and the .tar.gz suffixes there can be optional tags, separated by dots, which provide specific information about the contents of the package. In particular, if the package is a binary version, this information provides details about where the binaries will run. In the third line, the optional .src tag was added because the developer wanted to differentiate between the source and binary versions of this package. In the fourth line, the .bin.SPARC indicates that it is a binary package, ready to run on a SPARC workstation. The final line indicates that it is a binary package, consisting of statically linked ELF format executables.

Using Binary RPMs versus Building from Source

Binaries created in RPM format are easily installed, managed, and uninstalled using Red Hat tools. This is the recommended installation method for Red Hat Linux novices. Sometimes, however, building an application from source code may be preferable. Here are some arguments on both sides:

• RPM — Installing applications from an RPM archive is easy. After the application is installed, there are both shell commands and GUIs for managing, verifying, updating, and removing the RPM application. You don't need to know anything about Makefiles or compilers. When you install an RPM package, RPM tools even check to make sure that other packages that the package depends on are installed. Because Red Hat has released RPM under the GPL, other Linux distributions also use it to distribute their software. Thus, most Linux applications are, or will be, available in RPM format.

• Source code — Not all source-code packages are made into RPM binaries. If you use RPM, you may find yourself with software that is several versions old, when you could simply download the latest source code and run a few tar and make commands. Also, by modifying source code, you can tailor the package to better suit your needs.

For more information on RPMs, refer to the Red Hat RPM Guide by Eric Foster-Johnson (Red Hat Press/Wiley, 2003).

Here is a breakdown of the parts of a package name:

• name — This is generally an all-lowercase string of characters that identifies the application.

• dash (-)

• version — This is shown as major to minor version number from left to right.

• dot (.)

• src or bin — This is optional, with src usually implied if no indication is given.

• dot (.)

• type of binary — This is optional and can include several different tags to describe the content of the binary archive. For example, i386 indicates binaries intended for Intel architectures (Pentium CPU) and SPARC indicates binaries for a Sparc CPU.

• dot (.)

• archive type — Often tar is used (.tar)

• compression type — Often gzip is used (.gzip)

Using different archive and document formats

Many of the software packages that are not associated with a specific distribution (such as Red Hat or Debian) use the tar/gzip method for archiving and compressing files. However, you may notice files with different suffixes at software project sites.

Table 5-2 describes the different file formats that you will encounter as you look for software at a Linux FTP site. Table 5-3 lists some of the common document formats that are used in distributing information in Linux.

If you are not sure what format a file is in, use the file command as follows:

$ file archive-file

This command tells you if it is a GNU tar file, RPM, gzip, or other file format. (This is a good technique if a file was renamed and lost its suffix.)