= Software Package Management =
== Investigation 1: How do you query the RPM database? ==
RPM maintains a database of installed software. This information is very useful to system administrators. In the previous lab you queried that database using RPM with the -q argument. When you query the RPM database, you can separately specify:
:* Do an <u>operational task</u> on one or more packages (like installing or removing a package), using a '''select-option'''
:* What <u>information</u> you want about those packages, using a '''query-option'''
'''Perform the following steps:'''
(Perform investigations 1 - 3 in your host machine (c6host)
# Using information from the man page for <code>rpm</code>, fill in this information:
{|width="100%" border="1" cellpadding="5"
|-
!Option
!Meaning
!Select or query option?
!Example command
|-
| -a
|Select all packages
|select-option
|
|-
| -l
|
|
|
|-
| -i
|Show the package information.
|
|
|-
| -f filename
|
|
|
|-
|packagename
|Select just this package
|select-option
|
|}
'''Answer the Investigation 1 observations / table contents in your lab log book.'''
== Investigation 2: How do you install and remove software with RPM? ==
# Use the graphical file manager (Nautilus) to change to the directory on your Installation DVD. Go to the sub-directory called '''Packages'''. It should contain a file called: <code>lynx-2.8.6-27.el6.x86_64.rpm</code>
# Execute the following command: <code>rpm -i lynx-2.8.6-27.el6.x86_64.rpm</code>
# Issue an RPM query to check that lynx is installed. Record this command in your lab log-book.
# Issue the following command: <code>rpm -e lynx</code>
# Issue an RPM query to verify that lynx is no longer installed. Record this command in your lab log-book.
# Issue the following command: <code>rpm -i elinks-0.12.rpm</code>. Did it work? Explain in your lab log-book why this command may not have worked.
'''Answer the Investigation 2 observations / questions in your lab log book.'''
== Investigation 3: How do you install and remove software with ''yum''? ==
{{Admon/note|Internet Connection|In order for yum to work you require a connection to the Internet. Establish this connection by using the browser to log into SeneNET}}
# Change to your home directory.
<ol>
<li value="2">Issue the command: <code>yum install elinks</code> and answer <code>y</code> to the question about installation.
<ol type="a">
<li>Where did ''yum'' get the elinks software?</li>
<li>Why could ''yum'' install elinks when rpm couldn't?</li>
</ol>
</li>
<li>Issue an RPM query to verify that elinks is installed. Record this command in your lab log-book.</li>
<li>Issue the command: <code>yum remove elinks</code></li>
<li>Issue an RPM query to verify that elinks is no longer installed. Record this command in your lab log-book.</li>
<li>Issue this command: <code>yum info cups</code></li>
</ol>
::* Based on the result, do you think that cups is a useful package for your system? If not, try removing it.
<ol>
<li value="8">Unused and unneeded software can present a security risk and ties up disk space needlessly. Find at least 4 other packages (for example: games, sound & video, etc) that you're not using on your system, and remove them. Be careful to ensure that removing those packages does not also remove other software that you do need.</li>
</ol>
'''Answer the Investigation 3 observations / questions in your lab log book.'''
==Archiving Files / Compiling Software from Source Code==
Archive files are often used to contain source code for software; in this lab you will also be compiling software from a source code archive.
{{Admon/note|Do not Shut-Down VMs Until Instructed|You will be running all 3 VMs eventually when performing this tutorial, Leave all VMs running until you are instructed to shut them down at the end of this lab.|}}
===Investigation 1: How do you create an archive file?===
{{Admon/note|Use centos3|Perform these steps in the '''centos3''' virtual machine.}}
#Boot up your '''centos3''' VM.
#Change your working directory to <code>/usr/share/doc/sudo*</code>
#Use the tar (tape archiver) command to create an archive file named <code>/tmp/archive1.tar</code>
#*<code>tar cvf /tmp/archive1.tar .</code>
{{Admon/important | Warning! | Don't miss the '''.''' at the end of the <code>tar</code> commands below! It specifies what should go into the archive: the contents of the current directory.}}
<ol>
<li value="4">What do the options c, v, and f mean?</li>
<li>Record the archive file size.</li>
<li>Compress the file using <code>gzip</code>:
<ul>
<li><code>gzip /tmp/archive1.tar</code></li>
</ul>
</li>
<li>Record the archive file size after compression.</li>
<li>Make sure you're still in <code>/usr/share/doc/sudo*</code> and then create a compressed archive:
<ul>
<li><code>tar cvzf /tmp/archive2.tgz .</code></li>
</ul>
</li>
<li>What does the <code>z</code> option do?</li>
<li>Compare the sizes of <code>/tmp/archive1.tar.gz</code> and <code>/tmp/archive2.tgz</code>. Why are they so close in size?</li>
</ol>
'''Answer the Investigation 1 observations / questions in your lab log book.'''
===Investigation 2: How do you restore files from an archive?===
{{Admon/note|Remain in your centos3 VM|Perform these steps in the '''centos3''' virtual machine.}}
#Create the directory <code>/tmp/extract1</code>
#Change to the <code>/tmp/extract1</code> directory.
#Move the file archive1.tar.gz to your current directory.
#Unzip the first archive you created:
#*<code>gunzip archive1.tar.gz</code>
#Extract the files from the first archive:
#*<code>tar xvf archive1.tar</code>
#Are all the files there?
#Compare <code>/tmp/extract1/README</code> and <code>/usr/share/doc/sudo*/README</code>. Are they exactly the same? Why?
#Create the directory <code>/tmp/extract2</code>
#Move the file archive2.tgz to the <code>/tmp/extract2</code> directory.
#Extract the files from the second archive:
#*<code>tar xvzf /tmp/extract2/archive2.tgz</code>
#Note that this time a separate <code>gunzip</code> command was not needed. Why?
#Repeat the previous command, leaving out the option "z". Does it work? Why?
#Compare the <code>README</code> file in this directory with the original file. Are they exactly the same?
'''Answer the Investigation 2 observations / questions in your lab log book.'''
===Investigation 3: How do you build software from source code?===
Now that you know how to create and decompress "zipped tarball archives", we will demonstrate how to install applications from websites containing these types of archives. Although this method is not as "user-friendly" as using the yum or rpm command, this method is useful if the application is NOT contained in regular software repositories...
{{Admon/note|Use centos2|Perform these steps in the '''centos2''' virtual machine.}}
In order to build software from source code, you must have the appropriate software development tools (such as make and gcc) and libraries (such as GTK) installed. The required tools will vary depending on the computer languages used in the software being built.
# Issue the following command to install a basic set of development tools and libraries:<br /><code>yum groupinstall "Development Tools" "Development Libraries"</code>
{{Admon/note|Installing Development Libraries|In the future, remember the above procedure whenever installing software from source. Sometimes, you need to install additional tools or libraries in order to compile a particular software package}}
<ol>
<li value="3">Go to the directory <code>/tmp</code></li>
<li>Use the <code>wget</code> command to download the "tar ball" that contains the source code for the NLED text editor. <code>wget</code> is a command-line tool to download files from the web using the http or ftp protocols.
<ul>
<li><code>wget http://cdot.senecac.on.ca/software/nled/nled_2_52_src.tgz</code></li>
</ul>
</li>
<li>Extract the files. Change to the newly-extracted directory (<code>/tmp/nled-2.52</code>)</li>
<li>Check to see if there is a file named <code>configure</code>. If so, run it; if not, skip this step. (Most but not all source code archives contain this file)</li>
<li>Check to see if there is a file named <code>Makefile</code> or <code>makefile</code>. If so, type the command:
<ul>
<li><code>make</code></li>
<li>Did the command work? Why? Use the <code>yum</code> command to install the package '''gcc'''. What do you think the package ''gcc'' does?</li>
</ul>
<li>Reissue the <code>make</code> command. Where you successful? What does <code>make</code> do?</li>
<li>Issue the command as root: <code>yum list ncurses</code>. What do you see? Issue the command at root: <code>yum search ncurses</code>. What do you observe?</li>
<li>In this case, you need to install the ncurses development libraries as well. Issue the following command as root: <code>yum install ncurses-devel.x86_64</code>. Now issue the command: <code>make</code></li>
<li>Some software distributed as source code can automatically install itself. Try this command:
<ul>
<li><code>make install</code></li>
</ul>
</li>
<li>Most but not all source code archives include the capability of installing themselves this way.</li>
<li>If the command <code>make install</code> does not work (how can you tell? What command did you learn from ULI101 to confirm that this command cannot be run from the command line?), copy the <code>nled</code> program manually:
<ul>
<li><code>cp nled /usr/local/bin</code></li>
</ul>
</li>
<li>Test <code>nled</code> to make sure it works.</li>
<li>Why did copying the nled executable to /usr/local/bin allow the nled command to be run by name anywhere in the command prompt?</li>
</ol>
'''Answer the Investigation 3 observations / questions in your lab log book.'''
= User/Group Management =