by March 1, 2008 0 comments



PCQLinux 2008 Core was built from scratch to have a minimal installer and
installed footprint so as to be a powerful host system for running virtual
appliances that we’ve provided. However, you can also use Core as a fully
capable workstation as well. Although the system comes with a basic set of
applications; you might want to add a number of others on top of it as well.
There are many ways you can do this.

Tech Primer

This distribution is based on CentOS 5.1. Therefore it shares the same
installer technology as the original-which is the RPM format. RPM stands for
RedHat Package Manager after the creators of this packaging method.

Using RPMs has an advantage over the normal way of installing apps on
Linux-that of downloading and compiling source code to get the binary
application. RPMs have all the required files pre-compiled and all it requires
to do is place them in the correct location.

One major issue with using RPMs however is that of dependencies. Many RPMs
depend on other RPMs for certain functionality. If they do not find those RPMs,
you need to install them first before installing the app you want. In case those
RPMs further depend on more RPMs, you again need to find and install them even
earlier. This can sometimes lead to a long drawn process where a user will need
to track down a large number of dependencies and sub-dependencies to many levels
before his application can get installed.

Add/remove programs

In case you are running the graphical interface, you can very easily use the
Add/Remove Program applet available in the Applications menu on the screen. When
you click on this applet (see screenshots on next page), it will get a list of
applications installed on your system as well as a number of applications that
are available on the Internet. Obviously, for this to work, your system must be
connected to the Internet.

When you get a list of applications, these are categorized under different
groups. For instance, you will have applications under groups like Productivity,
Games, System Tools, Development, etc. Browse to the group you wish. You will
then see a list of applications that are available under this group. Ones that
are already installed will have a tick mark next to them while the others can be
downloaded and installed. Simply select the one that you wish to install.

The great part about the Add/Remove Programs applet is that it automatically
resolves all dependencies of the main application you selected. Which means that
you do not need to spend time tracking down other elusive RPMs to get your
application installed. The applet even lets you review the list of dependencies
it finds. Once the applet downloads all the required RPMs, the installation
process starts and the RPMs are installed in the order of dependency. When the
installation is completed, you are informed about the status and then you can
start using the application immediately.

You can view details of the software in each
category and select the ones you wish to install or remove by checking or
unchecking them

Using Yum installer

Yum is the command line version of the software installer and has a number of
other options as well. You can download new applications from a variety of
places on the Internet. We have already provided you with a huge number of
repositories out of the box in PCQLinux 2008. To install a new application, you
need to simply give the command: yum install

For instance, if you want to install The Gimp, you will give the command:
yum install gimp

This will download the headers from all the repositories and calculate the
dependencies and inform you. You can then choose to continue with the
installation or not. You can also update an already installed application to the
latest version by giving the following command: yum update

For instance: yum update gimp

If you wish to remove an application and its dependencies (as long as that
dependency is not also used by any other installed application), you can give
the command: yum remove
If you want to add more repositories to the list of places where you can
download applications from, go to /etc/yum.repos.d and create a new file with
the extension of .repo having the following format:
[]
name=
mirrorlist=
#baseurl=
gpgcheck=<0 or 1>
enabled=1
gpgkey=

In this, you can use either the mirrorlist or the baseurl value. You can also
choose whether to do a GPG check on the downloaded RPMs or not. For instance,
the following adds the Livna repository to the system:

Run the Add/Remove programs applet and you would
get a dialog box that shows categorized views of available and installed
software

[livna]
name=Livna for PCQLinux 2008
mirrorlist=http://rpm.livna.org/mirrorlist-7
enabled=1
gpgcheck=1
gpgkey=http://rpm.livna.org/rpm-gpg/RPM-GPG-KEY-livna

You can now use this repository to download files as well.

Installing with RPM
As a final resort, if you cannot do an automatic download and install of
your application (as it is not available in a repository), you can download RPMs
if they are available and install them manually. For this you can either double
click the RPM file in the File Explorer or open a terminal window and enter the
following command: rpm —ivh
For instance, to install the OpenOffice RPMs given on the PCQLinux 2008
Appliances DVD, mount the DVD, browse to the OpenOffice directory and give the
following command: rpm —ivh *.rpm

Within a given set of RPMs, the rpm command can also find the dependencies
and install them in the correct order. However, if it does not find a file that
resolves a dependency, it will fail and exit. In which case you will need to
track down the correct RPM and install it yourself.

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