{{Admon/caution|THIS IS AN OLD VERSION OF THE LAB|'''This is an archived version. Do not use this in your OPS235 course.'''}}

 '''In this lab, you will create three virtual machines'''. This also gives you an opportunity to experiment with different ways of installing CentOS. You will be learning the following elements of Virtualization in this lab:<br><br><u>Main Objectives</u> :* '''Installing Virtualization Software''' on your '''c7host ''' machine:* '''Create 3 separate VMs (virtual machines) using different installation methods:''':** Centos Live DVDInstallation:** Network Installation without configuration file:** Network Installation with configuration file (Kickstart)<br><br>:* Understand the '''advantages and disadvantages of each type of installation''', and be able to '''select the best installation method''' for a particular situation.:* '''Manipulate virtual machines by CLI''' (virsh):* '''Properly backup VMs and VM configuration''' in virtual manager application onto home directory and to external source (USB Key):* Observe how '''Bash Shell Scripting''' can be used to automate routine tasks involving VM management

A '''virtual machine''' is a software simulation of a computer which can be used as though it were actual hardware. It's possible to run multiple virtual machines on one computer, reducing hardware requirements and introducing promoting flexibilitywhen working with multiple operating systems. Some common uses of virtualization include:

|width="40%" |{{Admon/tip|Online Linux Command Review|The following links tutorial will allow you to practice Linux commands that you learned from ULI101learn essential shell scripting skills. Login to your '''Matrix''' account, and issue the pathname to run the online tutorial in Matrix:<br><ul> <li>Online vi Text Editor TutorialShell Scripting - Part 2 (Logic & Math Expressions): [ ]<br>'''/home/murray.saul/scripting-2'''</li><li>Bash Shell Scripting I: [ ]- Part 3 (Loops)<br>'''/home/murray.saul/scripting-3'''</li></ul>|

You will be learning to perform several different type of CENTOS Linux installs. Lab2 already has an empty table for comparing various Linux installs. You were required in lab1 to record your observation for your '''c7host ''' installation.

# Open a shell terminal.<br><br>'''WARNING:''' You must perform a '''yum update''' on your '''c7host''' machine before proceeding with the next steps.<br><br># You will need to download an image file for the Centos7 LIVE DVD by issuing the following command (best works while at Seneca):<br><b><code><span style="color:#3366CC;font-size:1.2em;">wget http://belmont.senecac.on.ca/centos/7/isos/x86_64/CentOS-7-x86_64-LiveGNOME-1511.iso</span></code></b><br><br># Install the virtualization software by issuing the command:<br><b><code><span style="color:#3366CC;font-size:1.2em;">yum install qemu-kvm qemu-img virt-manager libvirt libvirt-python \<br>python-virtinst libvirt-client virt-install virt-viewerbridge-utils</span></code></b> <br><br> {{Admon/important|Restart your Host Machine|You must restart your '''c7host''' machine after installing the virtualization program above. If you fail to do this, you may experience virtualization network problems!}} 

:::* A graphical tool for managing virtual machines ('''virt-manager''') and the '''virsh''' command-line tool.<br><br>

<li value="35">Start the virtualization service: <b><code><span style="color:#3366CC;font-size:1.2em;">service libvirtd start</span></code></b></li> <li>The firewall configuration is altered by the addition of the virtualization software. Restart Centos7 uses firewalld for firewall, but we will be switching back to using iptables. Issue the following series of command to install iptables and restart the firewall so that these changes become active: <br><br> <b><code><span style="color:#3366CC;font-size:1.2em;">systemctl stop firewalld</span></code></b><br><b><code><span style="color:#3366CC;font-size:1.2em;">systemctl mask firewalld</span></code></b><br><b><code><span style="color:#3366CC;font-size:1.2em;">yum install iptables-services</span></code></b><br><b><code><span style="color:#3366CC;font-size:1.2em;">systemctl enable iptables</span></code></b><br><b><code><span style="color:#3366CC;font-size:1.2em;">systemctl start iptables</span></code></b><br><b><code><span style="color:#3366CC;font-size:1.2em;">service iptables restartsave</span></code></b><br><br></li>

<li value="57">Start the graphical tool by selecting the menu options '''Applications'''>'''System Tools'''>'''Virtual Machine Manager''' or by typing the command<b><code><span style="color:#3366CC;font-size:1.2em;"> virt-manager</span></code></b></li>

== Part 1: Installing from a Live Disc Downloaded Image (Centos7 LIVE CD) =={| width="40%" align="right" cellpadding="10"|- valign="top"|{{Admon/tip|Perform Downloads and Network installs at Seneca|'''It is recommended to perform this lab in one of Seneca College's labs'''. This lab uses servers which are on the Seneca network and which are not available from other locations (such as your home). If you attempt this lab from another location, adjust the belmont.senecac.on.ca URLs to point to another mirror server -- note that you may need to change the directory name as well as the server name. The installation of the '''centos3''' virtual machine <u>must</u> be done at Seneca.}}|-|{{Admon/important|Removing and Recreating VMs|If for some reason the user wants to remove a Virtual Machine, they can right-click the VM, and select delete in the Virtual Machine Manager. It is recommended to '''"delete the image file" in the remove VM dialog box when removing and then recreating a VM'''. Note: If you fail to properly remove the VM image file, it may affect the hard disk size for the new VM (i.e. use the old smaller size. Make certain to remove that VM image file prior to recreating the VM.|'''}}|}

:: '''VM Name(and hostname):''' centos1:: '''Boot media:''' CentOS7 Live DVDLIVE CD Image:: '''Installation source:''' Live DVDDownloaded Centos7 LIVE CD image (http://belmont.senecac.on.ca/centos/7/isos/x86_64/CentOS-7-x86_64-LiveGNOME-1511.iso):: '''VM Image Pathname:''' /var/lib/libvirt/images/centos1.img:: '''Memory:''' 768MB2GB

{| width="40%" align="right" cellpadding="10"|- valign="top"|colspan="2"|{{Admon/tip|Performing this Lab off # Make certain you used the Seneca network (eg. at home)|'''It is recommended wget command to perform this lab in one of Seneca College's labs'''. This lab uses servers which are on download the Seneca network and which are not available LiveGNOME iso file from other locations the Belmont server (such as your homefrom previous instructions). If you attempt this lab from another location, adjust the belmont.senecac.on.ca URLs to point to another mirror server -- note that you may need to change the directory name as well as the server name. The installation of the '''centos3''' virtual machine <u>must</u> be done at Seneca.}}|}

# '''Step 1 of 5:''' Enter the virtual machine (called Select '''centos1Local install media''') name and select click '''Local install mediaForward'''.# '''Step 2 of 5:''' Insert the DVD containing the Centos Live Disc image. Wait a moment for the disc to be recognized, then select Select '''Use CDROM or DVDISO Image''' as the install media. Set , click the ''OS type'Browse' to ''button, and then the 'Linux''Browse Local' and the ''Version'' button. Navigate to the location of the downloaded Centos7 LIVE CD image, select the image file and click '''Red Hat Enterprise Linux 7Open''' (the CentOS6 equivalent). When finished, click Forward to proceed.# '''Step 3 of 5:''' Set the memory to '''768 2048 MB''' and the number of CPUs to '''1'''# [[Image:vm-path.png|thumb|right|300px|It is extremely important to '''correctly specify the VM image file path-name'''. Double-check the spelling of the path-name before proceeding!]]<ol><li value="7">'''Step 4 of 5:''' This next step creates a disk file that will be used to simulate the virtual machine's disk drive. Select a size of '''10 GB''' and checkmark the box labeled . Click on<br> '''Allocate entire disk nowSelect managed or other existing storage'''# '''Step 5 of 5and type the VM image file pathame:<br> ''' Review the options that you have selected/var/lib/libvirt/images/centos1. img'''Make a note of (make certain that the storage location.'pathname is correct) and then click '' If anything needs to be changed, use the 'Forward'Back'' button to go back and edit it; otherwise, click proceed.</li><li>'''FinishStep 5 of 5:'''{| width="40%" align="right" cellpadding="10"|- valign="top"|colspan="2"|{{Admon/important|Removing and Recreating VMs|If for some reason Enter the user wants to remove a Virtual Machine, they can right-click the VM, and select delete in the Virtual Machine Manager. It is recommended to virtual machine name: '''"delete the image file" in the remove VM dialog box when removing and then recreating a VMcentos1'''. Note: If you fail to properly remove Review the VM image fileinformation, it may affect the hard disk size for the new VM (i.e. use the old smaller size. Make certain to remove that VM image file prior to recreating the VM.|and click '''Finish'''}}|}.<br><br><ol/li> <li value="8">'''The virtual machine will now start'''- start timing your installation and making notes for '''centos1''' virtual machine in the installation comparison chart in lab2 logbook. The virtual machine is running from the live disc at this point, and no software has been installed on the ''hard drive'' of the virtual machine. The point of a live disk is to allow you to test the distribution to see whether you like it without installing to the harddrive hard-drive first.</li></ol> <ol> <li value="9">Click Double-click '''Install to Hard Drive'''. The installation program, similar to the one used when installing CentOS in Lab 1, will appear. You will get a warning at one point during basically perform the same installation process that the disk "May contain data" or "may need to be re-initialized" -- operations for this is simply a warning that the virtual disk is completely blankVM including for '''Date & Time''', '''Network & Hostname''', and it is safe '''Installation Destination'''. Make certain to proceed with use the '''hostname''': '''<u>centos1</u>''' as opposed to ''c7host'') for this installation. (with a few slight differences).</li> <li>During the installation process, when prompted for a storage deviceFor '''Installation Destination''', first select the destination option: '''Specialized Storage DevicesI will configure partitioning''', and then select the click '''Virtio Block DeviceDone''' option.</li> <li>When prompted for Make certain that the hostname, enter '''centos1Partition Scheme''' is set to '''LVM''', and when prompted for then click on the timezone, select link: '''Toronto - Eastern Time OntarioClick to Create Automatically'''</li> <li>When asked about storage, select . '''Use All SpaceDone'''. Check to make certain that the root partition has file system type: '''Use the default values for all other fields.ext4''' Notice that the installer does not ask you what software should be installed; compare the installation time to the amount of time it took to do your Lab 2 installation. Record this information in </li><li>Accept the changes and then click '''table contained in Investigation 4Begin Installation'''.<ol type="a"><li>You will be required to make selections very similar to what you did in lab1.</li><li>While the system is installing, take a few minutes to record your observations (including slight differences with centos1 install as opposed to c7host install).</li> <li>When the installation process is complete, click on note the '''reboot''' button at time required to install this system and record in the bottom right-hand corner installation comparison chart of the screenyour lab2 logbook.<br><br></li></ol> <ol/li><li>Power-off your Centos7 LIVE system.</li> <li value="13">Start You should notice that the VM from its disk imageCentos7 boot menu appears. This can be done graphically by selecting the Virual machine name, and then clicking on the Either press '''OpenENTER''' button, and then click the '''play''' button when the next screen appears (to start or by selecting Virtual Machinewait for it to start automatically.</li><li>Run from Finish the virtual machine menu). You will get final steps in the ''Firstboot'' configuration questions during the boot setup process (asking like you to create a user, set the date and time, and ignore the kdump out-of-memory warningdid in lab1). Make certain that the VM has a network interface connection (i.e. look at network applet on the top panel). Create a user with the same name as your Matrix account.</li> <li>Login using #You may want to turn off the new user accountscreen-saver (like you did in Lab1): [http://zenit.senecac.on.ca/wiki/index.php/OPS235_Lab_1_-_CentOS7#Customizing_Your_Account How to Turn-off Screen Saver (lab1)]</li></ol>

<li value="1513">Enable SSH access to your virtual machine with these commands (semi-colon allows commands to be run in sequence):<br /> <b><code><span style="color:#3366CC;font-size:1.2em;">service sshd start; chkconfig sshd on</span></code></b></li> <li>Find out the IP address of your virtual machineand the name of your Ethernet network adaptor: <b><code><span style="color:#3366CC;font-size:1.2em;">ifconfig eth0</span></code></b> </li> <li>Enter the following command on your virtual machine to create a firewall exception to allow ssh traffic into the machine:<br /> <b><code><span style="color:#3366CC;font-size:1.2em;">iptables -I INPUT -p tcp -s0/0 -d0/0 --dport 22 -j ACCEPT</span></code></b></li> <li>If you are logged in as root, logout to your regular user account.</li><li>Confirm that you can ssh to your virtual machine from the host (your main CentOS installation): <b><code><span style="color:#3366CC;font-size:1.2em;">ssh c7host_IPaddressregularuserid@IPaddress</span></code></b> (where c7host_IPaddress '''regularuserid''' is your regular user login id, and '''IPaddress''' is the dotted-quad address '''IP_ADDRESS''' of your c7host machine'''centos1''' VM!).</li><li>Make certain to '''disable SELinux for centos1''' (refer to lab1)</li><li>Adjust your screen-saver settings and run a '''yum update''' on your centos1 VM before proceeding to ''Part 2''</li></ol> 

== Part 2: Installing from the a Network =={| width="40%" align="right" cellpadding="10"|- valign="top"|colspan="2"|{{Admon/important|Authenticate to the network|The rest of this lab uses network access.''' Be sure to authenticate to the network using your browser before proceeding'''.}}|}

:: '''VM Name(and hostname):''' centos2

:: '''Installation sourceURL:''' http://belmont.senecac.on.ca/centos/7/os/x86_64/:: '''VM Image Pathname:''' /var/lib/libvirt/images/centos2.img:: '''Memory:''' 1024MB2048MB

{| width="40%" align="right" cellpadding="10"|- valign="top"|colspan="2"|{{Admon/important|Authenticate to the network|The rest of this lab uses network access.''' Be sure to authenticate to the network using your browser before proceeding'''.}}|}# Create the VM (called '''centos2''') as you did with the ''centos1c7host'' virtual machine, except select network installation for the following differences:<br><br><ol type="a"><li>Select '''Network Installation''' using the installation source url URL displayed above.# Observe </li><li>When customizing your partitions, do the same operation that you did in centos1, but after automatically creating the partitions, reduce the size of the boot process. How is it different from booting from root LVM partition to '''8000 MB''' and add an optical disc LVM partition with a size of '''2000 MB''' (DVD)?# Start the installation process (make certain to use information in the mount point: '''/home'VM Details'' section above).# When you get to the disk partitioning step, select name: '''Use All Spacehome''' , and enable the checkbox labelled make certain root and /home partitions have '''Review and modify partition layoutext4'''file system). If an dialog box displays </li><li>Don't forget to install the GNOME desktop here as you will need a permissions problemGUI for Centos2<br><br></li></ol># Complete the installation. Login to your regular user account, then click yes and perform a yum update for the centos2 VM (reboot if required). Make certain to proceedadjust your screen-saver settings if desired. On the next screen, change the logical volumes as follows:#* Reduce Repeat the size of the root LV steps as you did to '''8000 MBstart the SSH service'''.#* , '''Add a <u>logical volume</u> with a size of 2000 MB and a mountpoint of /homeset iptables to accept connections via ssh''' (you can name it whatever you want, and use '''ext4test connections between centos2 and c7host''' as the file-system type).# On the software selection screen, select and '''Desktopdisable SELinux'''(refer to lab1).# Complete the installation. Record the time taken to install, and compare this to the time taken by the previous installations.Record this information your findings in the '''table contained Installation Comparison chart in Investigation 4'''lab2 logbook.

== Part 3: Installing from the a Network using a Kickstart File ==

:: '''VM Name(and hostname):''' centos3

:: '''Installation sourceURL:''' http://belmont.senecac.on.ca/centos/7/os/x86_64/:: '''Kickstart locationFile URL:''' http://matrix.senecac.on.ca/~andrew.smith/ops235/centos6centos7-kickstart-v01.cfg:: '''VM Image Pathname:''' /var/lib/libvirt/images/centos3.img:: '''Memory:''' 1024MB2048MB

# Observe the installation. How is it different from booting from an optical disca downloaded image?# Complete the installation. Record the time taken to install, and compare this to the time taken by the previous installations.<br><br>If the during the installation, you see the message at the bottom '''Pane is Dead''', click the '''Virtual Machine''' menu at the top, select '''Shut Down''' -> '''Force Off''', '''right-click''' on '''centos3''' in the ''virtual manager'' window and select '''Delete'''. Redo the VM setup for a new instance of the ''centos3'' VM.

# Take a look at the kickstart file (eg. view url in a webj-browser) to determine the root password as well as the name and password for the first user account.!

 # Repeat the steps as you did to '''Answer start the Investigation 1 observations / questions in your lab log book.SSH service''', '''set iptables to accept connections via ssh''', '''test connections between centos3 and c7host''', and '''disable SELinux'''(refer to lab1). == Part 4: Updating the VMs ==   {| width="40%" align="right" cellpadding="10"|# Remember that centos3 is text- valign="top"|colspan="2"|{{Admon/caution|Never Shutdown Computer During Upgrade|Your computer based interface only (hostno graphics). To recover from a blank screen, vmspress a key (like the SPACE key) are at their most vulnerable when you perform an update. Always plan ahead for appropriate time prior to performing an updatereturn to the screen display. Shutting down your computer while performing an update may cause your computer not to boot! You have been warned!!!}}|}# In each VMRecord the time taken to install, run and compare this command: <b><code><span style="color:#3366CC;font-size:1to the time taken by the previous installations.2em;">yum update</span></code></b># Record your findings in the answers to these questions Installation Comparison chart in your log book:#* How long did it take to run on each VM? How many packages were updated?#* Why does it take longer in some VMs than others?lab2 logbook.

# Start the '''centos1''' virtual machine, and stop the '''centos2''' and '''centos3''' virtual machines.# Switch to the '''c7host ''' machine, and open a shell terminal.# Enter these admin commands into your '''c7host ''' machine and note the result:

<ol><li value="4">Now, shut-down your centos1 VM normally, and close the centos1 VM window.</li><li>Switch to your terminal and issue the command: <b><code><span style="color:#3366CC;font-size:1.2em;">virsh start centos1</span></code></b></li><li>Using the appropriate command check to see if your centos1 VM is now running.</li><li>There are other commands that can be used (such as '''suspend''', or '''shutdown'''). The "shutdown" command may not always work since it relies on the guest handling a particular ACPI event. Why do you think it is useful to have commands to manipulate VMs?</li><li>Since this is a text-based version of Linux, you do not need to turn off the screen-saver.</li></ol>

# Change to the directory <b><code>/var/lib/libvirt/images/</code></b>. Note the size of the files in this directory. What do these files contain?# Make a compressed backup of the <code>'''centos3.img</code> ''' file to your home directory with this command: <b><code><span style="color:#3366CC;font-size:1.2em;">gzip < centos3.img > ~YourUserId/centos3.img.backup.gz</span></code></b><br />(Note: Make certain to use the redirection signs "<" and ">" properly in the command!){{Admon/caution| Make sure # Compare the size of the backup is successful!|If there are any error messages, compressed and original files (hint: use '''DO NOTls -lh''' proceed past this point). YouIf file is very large (like 15GB), you didn're going t compress it and you need to destroy your centos3 virtual machine remove that file and restore it using perform the backup previous step until you have created -- if there are any problems with the backup, you will not have a working virtual machine, and will have to re-install get it.}}right!<ol> <li value="4">Compare the size of the compressed and original files.</li> <li># Start the '''''centos3''''' VM.</li> <li># '''Make certain that you are in your VM and <u>not</u> in your main system!'''</li> <li># Wreck <u>only</u> your centos3 system! Try this command inside the centos3 virtual machine:<b><code><span style="color:#3366CC;font-size:1.2em;">rm -rf /*</span></code></b></li>(ignore error messages). <li># Shut down the centos3 VM. If you tried to start the centos3 VM, it would not boot since all system files have been removed!</li> <li># Restore the original image from the backup in your home directory by typing this command: <b><code><span style="color:#3366CC;font-size:1.2em;">gunzip < ~YourUserId/centos3.img.backup.gz > centos3.img'''</span></code></b></li> <li># Restart the VM. Is it working normally?</li> <li># Create compressed backups of your other virtual machines(ie. '''centos1''' and '''centos2''').</li></ol><ol><li value="12"># You should make a copy of the xml configuration file in case you "wipe" and re-install the host machine, and want to add a restored VM backups to the virtual machine manager list. We will demonstrate using the centos3 xml configuration file, and prove that a "clone" can be added to your list.Please perform the following step:<ol type="a"> <li># Execute the following command: <b><code><span style="color:#3366CC;font-size:1.2em;">virsh dumpxml centos3 >centos3.xml</span></code></b></li> <li># Examine the file <b><code><span style="color:#3366CC;font-size:1.2em;">centos3.xml</span></code></b>. What does it contain? What format is it in?</libr><br> # We will now learn how to download a compressed image file and xml configuration file and add it as a VM to the virtual manager menu.# Issue the following commands:<ul><li>Make a copy of <b><code><span style="color:#3366CC;font-size:1.2em;">centos3wget http://cs.senecac.on.ca/~murray.saul/ops235/practical1.img.xmlgz</span></code></b> called <code>centos3a.xml</code>.</li> <li>Edit the file <b><code><span style="color:#3366CC;font-size:1.2em;">centos3awget https://scs.senecac.on.ca/~murray.saul/ops235/practical1.xml</span></code></b>, making the following changes:<br><br></li></ul></ol>::* Change the name (in the file, not <li value="17">Copy these files to the file name) to '''centos3a/var/lib/libvirt/images'''::* Change at least one of directory and decompress the hexadecimal characters in the UUID. Do not change the length of the UUID. Valid hexadecimal characters are 0-9 and a-f.::image</li><li>Make certain your present working directory is:'''/var/lib/libvirt/images'''</li><li>Issue this the command: <b><code><span style="color:#3366CC;font-size:1.2em;">virsh define centos3apractical1.xml</span></code></b>:::Issue the command <b/li><codeli><span style="colorWhat happened in the virtual manager window? To remove a VM entry in the Virtual Manager window, simply issue the command:#3366CC;font-size:1'''virsh undefine vm_name''' (without the '''.2em;">virsh list --allxml''' file extension)</spanli></codeli>Launch the VM to see if it boots-up</bli> and record any changes.:::Issue the command: <bli><code><span style="color:Can you log into this VM? Perhaps your instructor will give you a clue in week #3366CC;font-size:17...2em >;"p<br>virsh undefine centos3a</spanbr></codeli></bol>{| width="40%" align="right" cellpadding="10"|- valign="top"|colspan="2"|{{Admon/tip|Shutting Down the Host while Virtual Machines are Running|If you shut down your host system while virtual machines are running, they will be suspended, and will resume the next time you boot your host system.}}|}

<li>List all of the virtual machines again, and note any changes. </li></ol> <livalue="22">For the remainder of these labs, it is assumed that you will backup <u>'''both'''</u> the images and xml configuration files for <u>'''all'''</u> Virtual machines, when asked to backup your virtual machines. It is also highly recommended to backup these files to an external storage device (eg. USB key) in case the host machine gets "wiped" and you need to rebuild your HOST machine and then restore your Virtual Machines...</li>

 {{Admon/important|Backing up VMs|It is essential <ol><li value="24">A previous OPS235 student graciously created a shell script that you can download and run to check to back up your VMs at the end of each see how you performed this lab, so (to see if you can easily restore them if something goes wrong in are on the right track).<br>Simply issue the next labcommand: <b><code><span style="color:#3366CC;font-size:1.2em;">wget http://matrix.senecac.on.ca/~murray.saul/ops235/lab2check2.}} {{Admonbash</span></tip|Shutting Down code></b> and run on your '''c7host machine'''.<br><br>'''If the Host while Virtual Machines are Running|If you shut down your host system while virtual machines are running, they will be suspendedshell script indicates any major errors, and will resume the next time you boot please inform your host systemOPS235 instructor or lab assistant to advise what to do'''.}}<br><br></li></ol>

[[Image:lab2_text_1.png{|width="40%" align="right" cellpadding="10"|thumb- valign="top"|right{{Admon/tip|275pxBash Shell Scripting Tips:|When executed as <br><ul><li>'''Data Input:'''<br><br>A shell script can obtain data from a number of methods: '''reading input files''', using '''rootarguments when issuing command''' (positional parameters), or '''prompting for data to store in a variable'''. The later method can be accomplished by using the '''sudoread''' command, provides VM status and opportunity for example: '''read -p "Enter your name: " userName'''.<br><br></li><li>'''Mathematical Expressions:'''<br><br>In shell scripting, data is stored in variable as text, not other data types (ints, floats, chars, etc) like in compiled programs like C or Java. In order to have a shell script perform '''mathematical operations''', number or variable need to be surrounded by two sets of parenthesis '''start((..))''' VMs in order to convert a number stored as textto a binary number.<br><br><u>'''Examples'''</u><br><br>''var1&#61;5;var2&#61;10''<br>''echo "$var1 + $var2 &#61; $((var1+var2))"''<br><br>'''Note:''' shell does not perform floating point calculations (like '''5/10'''). Instead, other commands like '''awk''' or '''bc''' would be required for floating point calculations (decimals)<br><br></li><li>'''Loops (iteration):'''<br><br>Loops and logic are a very important elements of shell scripting (not to mention programming as well). Determinant loops (such as '''for''' loops) usually repeat for a preset number of times (eg. counts, positional parameters stored). In-determinant loops (such as '''while''' or '''until''' loops) may repeat based interfaceon unknown conditions (like waiting for user to enter correct data). Test conditions can be used with in-determinant loops, or even commands! If a command runs successfully (eg ls, cd, grep matching a pattern), zero (true) value is returned, otherwise a non-zero (false) value is returned. Command options or redirection to /'''dev/null''' can be used to just test if command runs, but not display stdout or stderr. Conditional statements "and" (&amp;&amp;) / "or" (&#124;&#124;) can also be used when testing multiple conditions.<br><br>'''<u>Examples (try in a shell script)</u>'''<br><br>''set ops235 is fun''<br>''for x''<br>''do''<br>&nbsp;''echo "argument is $x"''<br>''done''<br><br>''for x in $(ls)''<br>''do''<br> &nbsp;''echo "Filename: $x"''<br>''done''<br><br>''read -p "enter a whole number: " num''<br>''until echo $num &#124; grep -q "^[0-9][0-9]*$"''<br>''do''<br> &nbsp;''read -p "Incorrect. Please enter WHOLE NUMBER: " num''<br>''done''<br><br>''read -p "pick a number between 1 and 10: " num''<br>''while [ $num -lt 1 ]&#124;&#124; [ $num -gt 10 ]<br>''do''<br> &nbsp;''read -p "Incorrect. Please pick number between 1 and 10: " num''<br>''done''<br><br></li></ul>}}|}

We You will continue the discussion our use of using Bash Shell Scripts to help automate routine tasks for scripting by first creating a Bash Shell script that will allow the Linux system administrator. In lab1, you were exposed sysadmin to downloading and running Bash Shell Scripts select their created VMs for demonstration purposesbackup to root's home directory. Before showing Afterwards you demos for this labwill download, you should learn view and run a few more "shell scripting tricks" in case you need couple Bash Shell scripts that use the virsh command to create start and stop your own set of tools for task automationvirtual machines.

#Click on Perform the following link to run an online tutorial showing you some additional shell scripting techniques: [ link ].#It is recommended to practice creating Bash Shell Scripts as you proceed throughout this course.#Let's look at some demos involving managing VMs with shell scripts. Issue the following command:<blockquote><b><code><span style="pointer-events: none;cursor: default;color:#3366CC;font-size:1.2em;">wget https://scs.senecac.on.ca/~elizabeth.kopiec/backupVM.bash</span></code></b></blockquote>#Set the appropriate permissions and run this Bash Shell script.#Verify that the backup of steps in your virtual c7host machine occurred (hint: issue ls command to verify the date and time of creation).#Use the <b><code>wget</code></b> command to download, study, and run the following shell scripts on-line:<blockquote><b><code><span style=" pointer-events:none;cursor:default;color:#3366CC;font-size:1.2em;">https://scs.senecac.on.ca/~murray.saul/vm-start-text.bash<br>https://scs.senecac.on.ca/~murray.saul/vm-stop-text.bash</span></code></b><br><b><code><span style=" pointer-events:none;cursor:default;color:#3366CC;font-size:1.2em;">https://scs.senecac.on.ca/~murray.saul/vm-start.bash<br>https://scs.senecac.on.ca/~murray.saul/vm-stop.bash</span></code></b></blockquote>#Try to understand what these Bash Shell scripts do.#You have completed lab2. Proceed to Completing The Lab, and follow the instructions for "lab sign-off".

[[Image:lab1_signoff.png{{Admon/important|thumbTime for a new backup!|right|500px|Students should be prepared with If you have successfully completed this lab, make a'''ll required commands (system information) displayed in a terminal (or multiple terminals) prior to calling the instructor for signoff'''new backup of your virtual machines as well as your host machine.]]}} '''Arrange evidence for each proof of these items the following on your the screen, then ask your instructor to review them and sign off on the lab's completion:'''

::<ol><li><span style="color:green;font-size:1.5em;">&#x2713;</span> Three working '''<u>All</u> VMs''':<blockquote><ul><li>Working virtual machines '''created.::''' and '''running'''<span style="color:green;font-size:1.5em;"/li>&#x2713;</spanli> '''Disk layout ''' and '''size ''' correct on all virtual machines::<span style="color:green;font/li><li> Proof of '''yum updates'''</li><li>'''All virtual machines backed-size:1up''' (eg.5em;"usb stick and/or home directory)</li></ul></blockquote>&#x2713;</spanli><li> Use virsh to list the status of all vms.::<span style="color:green;font-size:1.5em;">&#x2713;</span> All virtual machines fully updated.:'''c7host''' machine:<span style="color:green;font-size:1.5em;"blockquote><ul><li>&#x2713;'''Correct VM image filenames''' contained in '''/var/lib/libvirt/images directory'''</spanli><li> All virtual machines backed up to a usb stickCreation of your bash shell script called '''backupVM.::bash'''</li><span style="colorli>A list of your '''iptables''' rules (command:green;font'''iptables -size:1.5em;"L''')</li></ul></blockquote>&#x2713;</spanli><li> Installation comparison table filled in.::<span style="color:green;font-size:1.5em;">&#x2713;</span> Lab Logbook (lab2) Lab2 logbook notes filled-in.and '''Installation Comparison chart''' completed</li></ol>

= Preparing for = Practice For Quizzes , Tests, Midterm &amp; Final Exam ==

# Which factors recorded in your table (above) were due to What is the type name of the file created by the CentOS installation performed, and which factors were due to the amount of software installedprogram?

# What is the purpose of procedure to backup your VM images (and relationship between these pieces of softwareXML config files) to your USB key?#* libvirt#* libvirtd#* virsh#* virt-manager#* virt-install#* kvm