Managing Application Software

At some point in your Linux use, you are likely to need to add to or update the application software on your system. You may not have installed all the software needed during installation. Or a new version of your current software may be released with new features that you really need. Or you want to perform a task that your current software can't seem to handle and you have located, by googling and/or consulting with peers, a package that you believe can handle the new task.

Application software is available in packages that provide the application program and any files and programs that are needed to install it. Applications can be installed from source code or from package files created specifically for Linux installation.

• RPM files: Files created to use with the RPM (Red Hat Package Manager) utility that installs, updates, and removes software. If it's possible to install from an RPM, it's preferable to do so. It's much easier than installing from source.

• Source code: Text files containing source code. You compile and install the software yourself. Sometimes it's necessary to install from source, either because no RPM exists for the software you're installing or because you need to install the software with a different configuration than the RPM provides.

  NOTE

  Debian developed DEB files, similar in function to RPM files. If you are using Debian, look into DEB files and the apt software that installs them.

  
  

  You can install software from:

• Installation CD: Most distributions provide a utility that shows what's available on the CDs and installs a requested package. Only install from very recent CDs because packages are updated often. CDs may not contain current versions.

• Distribution Web site: The Web site for your Linux distribution provides many packages. Most distributions include utilities that check the Web site for available packages and download and install the packages.

• Internet: Some more specialized or unusual software may not be available on the distribution Web site. Or the version may not be the most recent. In this case, you may need to find the software on the Internet, download it, and install it. You may find it on a Web site that archives RPMs or on the Web site for the specific software, such as its project Web site.

Many software packages access and use other software; the package depends on the other packages being present. The packages needed are called "dependencies." The RPM utility and the desktop utilities inform you of any unmet dependencies when you are installing software, sometimes installing the needed software automatically.