OPS235 Lab 3 - CentOS7

LAB PREPARATION

Purpose / Objectives of Lab3

In this lab, you are going to help conserve disk space by learning how to compress and decompress files that are stored on your computer server. In addition, you will learn alternative methods of how to install programs.

Topics include:

1. Creating and using archive files (tar and tar.gz)
2. Compiling software packages from source code
3. Install applications using various methods:

• Decompressing source code archive, and compiling source code
• Use yum utility to install software from local programs (on DVD drive)
• Use yum utility to install software from repositories (online storage areas)

4. Demonstrating the use of Bash Shell scripts to automate routine tasks

Required Materials / Lab Preparation

CentOS7 FULL DVD

Removable Hard Disk Pack (SATA)

USB key (for backups)

Lab3 Log Book

My Toolkit (CLI Reference)

Archiving / Compiling: tar gzip, gunzip make

Software Manangement: rpm yum

Commands ls more wget chmod vi

Online Linux Command Review The following links will allow you to practice Linux commands that you learned from ULI101: Bash Shell Scripting Continued: [ ]

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 operational task on one or more packages (like installing or removing a package), using a select-option
• What information you want about those packages, using a query-option

Perform the following steps:

(Perform investigations 1 - 3 in your host machine (c6host)

1. Using information from the man page for rpm, fill in this information:

Answer the Investigation 1 observations / table contents in your lab log book.

Investigation 2: How do you install and remove software with RPM?

1. 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: lynx-2.8.6-27.el6.x86_64.rpm
2. Execute the following command: rpm -i lynx-2.8.6-27.el6.x86_64.rpm
3. Issue an RPM query to check that lynx is installed. Record this command in your lab log-book.
4. Issue the following command: rpm -e lynx
5. Issue an RPM query to verify that lynx is no longer installed. Record this command in your lab log-book.
6. Issue the following command: rpm -i elinks-0.12.rpm. 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?

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

1. Change to your home directory.

2. Issue the command: yum install elinks and answer y to the question about installation.
   1. Where did yum get the elinks software?
   2. Why could yum install elinks when rpm couldn't?
3. Issue an RPM query to verify that elinks is installed. Record this command in your lab log-book.
4. Issue the command: yum remove elinks
5. Issue an RPM query to verify that elinks is no longer installed. Record this command in your lab log-book.
6. Issue this command: yum info cups

• Based on the result, do you think that cups is a useful package for your system? If not, try removing it.

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.

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.

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?

Use centos3
Perform these steps in the centos3 virtual machine.

1. Boot up your centos3 VM.
2. Change your working directory to /usr/share/doc/sudo*
3. Use the tar (tape archiver) command to create an archive file named /tmp/archive1.tar
   • tar cvf /tmp/archive1.tar .

Warning!
Don't miss the . at the end of the tar commands below! It specifies what should go into the archive: the contents of the current directory.

4. What do the options c, v, and f mean?
5. Record the archive file size.
6. Compress the file using gzip:
   • gzip /tmp/archive1.tar
7. Record the archive file size after compression.
8. Make sure you're still in /usr/share/doc/sudo* and then create a compressed archive:
   • tar cvzf /tmp/archive2.tgz .
9. What does the z option do?
10. Compare the sizes of /tmp/archive1.tar.gz and /tmp/archive2.tgz. Why are they so close in size?

Answer the Investigation 1 observations / questions in your lab log book.

Investigation 2: How do you restore files from an archive?

Remain in your centos3 VM
Perform these steps in the centos3 virtual machine.

1. Create the directory /tmp/extract1
2. Change to the /tmp/extract1 directory.
3. Move the file archive1.tar.gz to your current directory.
4. Unzip the first archive you created:
   • gunzip archive1.tar.gz
5. Extract the files from the first archive:
   • tar xvf archive1.tar
6. Are all the files there?
7. Compare /tmp/extract1/README and /usr/share/doc/sudo*/README. Are they exactly the same? Why?
8. Create the directory /tmp/extract2
9. Move the file archive2.tgz to the /tmp/extract2 directory.
10. Extract the files from the second archive:
    • tar xvzf /tmp/extract2/archive2.tgz
11. Note that this time a separate gunzip command was not needed. Why?
12. Repeat the previous command, leaving out the option "z". Does it work? Why?
13. Compare the README 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...

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.

1. Issue the following command to install a basic set of development tools and libraries:
   yum groupinstall "Development Tools" "Development Libraries"

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

3. Go to the directory /tmp
4. Use the wget command to download the "tar ball" that contains the source code for the NLED text editor. wget is a command-line tool to download files from the web using the http or ftp protocols.
   • wget http://cdot.senecac.on.ca/software/nled/nled_2_52_src.tgz
5. Extract the files. Change to the newly-extracted directory (/tmp/nled-2.52)
6. Check to see if there is a file named configure. If so, run it; if not, skip this step. (Most but not all source code archives contain this file)
7. Check to see if there is a file named Makefile or makefile. If so, type the command:
   • make
   • Did the command work? Why? Use the yum command to install the package gcc. What do you think the package gcc does?
8. Reissue the make command. Where you successful? What does make do?
9. Issue the command as root: yum list ncurses. What do you see? Issue the command at root: yum search ncurses. What do you observe?
10. In this case, you need to install the ncurses development libraries as well. Issue the following command as root: yum install ncurses-devel.x86_64. Now issue the command: make
11. Some software distributed as source code can automatically install itself. Try this command:
    • make install
12. Most but not all source code archives include the capability of installing themselves this way.
13. If the command make install 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 nled program manually:
    • cp nled /usr/local/bin
14. Test nled to make sure it works.
15. Why did copying the nled executable to /usr/local/bin allow the nled command to be run by name anywhere in the command prompt?

Answer the Investigation 3 observations / questions in your lab log book.

Completing the lab

Time for a new backup!
If you have successfully completed this lab, make a new backup of your virtual machines.

Notes:

1. rpm command options
2. yum command options
3. How to use pvs/vgs/lvs/df/pvcreate/vgextend/lvextend
4. Answer to this question "What is the license of the nautilus package?"

Arrange evidence for each of these items on your screen, then ask your instructor to review them and sign off on the lab's completion:

1. elinks application removed on the host (disk pack - main system c6host).
2. Unnecessary/unused packages have been deleted (list at least 4, and show that they are no longer installed).
3. Fresh backup of the virtual machines.

Preparing for Quizzes

1. What is the advantage of disabling services such as bluetooth?
2. What is the difference between a .tgz file and a .tar.gz file? What do these stand for?
3. What is the purpose of a repository?
4. What is source code?
5. How do you build software from source code?
6. Which is preferred: installing from an RPM file, or installing from source code? Why?
7. How do you use service/init/chkconfig to:
   • show/set current runlevel
   • list services
   • stop a service
   • start a service
   • Why is it important to learn how to manage services?
   • Why is it important to stop certain services?