CNT-2311-Chapter 2 Notes

From ITCwiki

Package Concepts

Packages - A package consists of usually many files, with information about the file, including information that aids in the package management system.

Installed file database - A database of the installed files. All installed files should appear here.

Dependencies - Dependency information is the requirements of packages for one another. Ala, one package needs the other to work, and vice versa.

Checksums - checksums are information about files. they can be used to tell the validity of software, disk errors, accidental overwriting of and non-sinister files. It's not a subtle in detecting intrusions.

Binary Package Creation - RPM and Debian packages systems provide tools to create binary packages.

RPM Packaging

Redhat developed RPM for it's own personal distribution, but released freely thereafter. It soon became widely used as a cross platform tool.rpm is a very popular package manager due to it's flexibility and ubiquity. RPM packages look like the following example.

Coolpackage-3.1.5-V.i368.rpm

So that would be

Packagename-Versionnumber-Build.Architecture.rpm

For some examples of RPM commands, check the list below.

RPM Commands

Compatibility issues with RPM and other Distributions

1. Distributions may use different versions of the RPM utilities.

2. An RPM package designed for one distribution may have dependencies not met by the current distribution.

3. The RPM package may be built around a certain name or name arrangement, and if they don't match it might not work.

4. Even if every dependency is met, some files may still be slightly different, which may cause problems.

5. Some programs run distributions specific scripts

With that said, it's best to use RPM's designed for your particular distribution. You can also use tools such as YUM to help with going cross distributions.

YUM and Meta-Packagers

Meta Packagers such as YUM, enable you to install a package and all it's dependencies using a single command line. Yum and tools like it search internet repositories, and automatically download and install programs for you. For a list of YUM commands, check the list below.

YUM Commands

Debian Packaging

Debian is similar to RPM in the fact that it's a package manager, but it differs completely in execution. Debian was created by the Debian Distribution, and have been adopted by some of the most popular Linux distributions including UBuntu.Unlike RPM you use DPKP to install packages. Here is a list of DPKG commands:

dpkg Commands

Debian Packaging shares many of the compatibility issues that RPM does. For that list, see above.

APT Get

APT get is Debian's equivalent, it's a meta system that uses repos to download and install software and packages. For a list of APT-GET commands see the link below.

APT-GET Commands

dselect, aptitude, and Synaptic

dselect

dselect is a high-level package browser. With it you can see packages that are on your system, uninstall packages, upgrade package, and everything else you could do with a text based package manager.

Aptitude

Aptitude is like dselect in the interactive mode, but also has menus accessed by pressing Ctrl+T.

Synaptic

Much like dselect and Aptitude, but uses a Graphic User Interface.

Overall, all three of these tools are useful if you need to find a certain package or software, but you don't know the name or direct place to look for it.

Reconfiguring Packages

Unlike RPM, Debian offers more setup and configuring by asking questions during the initial setup, like setting up a mail-server and things like that. Also, this allows you to reconfigure programs by entering the command:

dpkg-reconfigure program

Converting Packages

With many developers and end users not using one distribution, there is an obvious need for some softwares and packages to be converted to other distributions. For examples, someone using the RPM distribution, needs to use a file that's only on Debian.

Alien

Alien is a specific utility that is converting between packages and systems. Alien is sometimes already installed with a distribution, if not just use basic tools like apt-get or yum to retrieve it.

Compatibility Issues

Many of the same problems and conflicts that happen with RPM and Debian files, obviously happen while switching distributions. Follow the same guidelines as seen on the RPM description.

Problem Solving

Rebuilding

You may also rebuild a package if necessary. Doing so on a RPM Package is pretty simple with the command rpmbuild.

Locating Another Version

Sometimes if you have a problem the easiest thing to do is simply install a previous version of a package.