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:Not being able to start your '''c7host''' due to '''Kernel Panic''' or some sort of '''catastrophic disk failure''' is not as easy to fix. You might be able to boot from your '''Centos LIVE DVD, open a terminal and mount the partition''' via command line and look for possible problems (setup files like '''/etc/fstab'''). '''Lab5''' will discuss more about mounting and the /etc/fstab file. The "worst-case scenario" would be to purchase a new hard disk, '''perform lab1 completely, perform lab2 to install and set-up virtualization software''', then '''restore your VM image and xml file backups''' (eg. decompressing images, issuing virsh define commands for .xml files). That is why consistently '''performing backups of ALL of your VMS at the end of each lab is absolutely essential! You have been warned!'''
== Installing Application Software ==
There are many different methods and utilities for installing application software depending on the type of Linux distribution you have.
For example:
* Debian-based Linux distros: apt-get, debi, gdebi, synaptic package manager, Ubuntu Software Center
* Redhat / Centos / Fedora distros: yum, rpm, gnome-packagekit
We will concentrate on the installing applications for the Centos Linux distribution, and focus on command-line application installation utilities (since centos3 VM is text-based only).
We will look at a couple methods of installing software: A traditional method ('''compiling source code''') and a more modern method ('''yum install''')
<u>Compiling Source Code</u>
This is the original way of installing software in Linux / Unix.
'''Advantages''':
* Although it seems "out-dated", it may be useful with installing very old or "leading edge" software that are not contained in repositories, and cannot be installed using the ''yum'' utility.
'''Limitations''':
* Does not automatically resolve "dependency issues". This may require that you first install applications or development libraries before installing the software. This can be cumbersome.
* Cannot use rpm or yum utility to provide information database of installed software.
'''Steps to Compile Source Code''':
# Obtain compressed file containing source code (usually a "zipped tarball")<br>eg. '''wget [ URL of zipped tarball ]'''
# Decompress zipped tarball. For example '''tar xzvf [ filename.tar.gz | filename.tgz ]'''<br> Note: You can compress (create archives) by using the tar command as well.<br>For example: '''tar czvf [ filename.tar.gz ] [ directories or files to archive ]'''
# Change to directory containing source code. You may need to run a script called '''./config''' (if present) to check for some dependency issues.
# Usually good idea to check for installation instructions in a file called INSTALL and/or README
# Issue the command: '''make''' to compile. This will create an executable file in the source-code directory (usually as a file named after the application).
# As root, issue the command: '''make install''' to make command available to run from any directory. If the ''make install'' command does not work, you can copy the compiled program to '''/bin''', '''/usr/bin''', or '''/usr/local/bin'''.
== Common Mistakes / Warnings ==
