Tutorial 1: Using Your Matrix Server Account

LEARNING ABOUT YOUR MATRIX SERVER ACCOUNT

Main Objectives of this Practice Tutorial

• Understand the purpose of the Matrix server and the advantages of combining Linux servers to form a cluster.

• List the steps to connect to your Matrix server account in the computer labs at Seneca College.

• List the steps to connect to your Matrix server account from a computer outside of Seneca College.

• Working with the Linux Command Prompt (Linux shell)

• Changing your Matrix Account Password

• Exiting your Matrix Linux Account

• Performing Review Questions for Additional Practice

Purpose of Having a Matrix Account

A shell is simply an interface / interpreter to allow a user to communicate with the Linux computer system.

Although you need to study concepts throughout this course, you will also need to learn to issue and memorize simple as well as more advanced Linux commands. This requires that you practice issuing Linux commands on a frequent basis to become more comfortable when working the Unix and Linux command-line environments.

Just like with other operating systems like MS Windows, it is important to learn how to open a command prompt in order to issue Linux commands to perform common Linux OS tasks. In Unix/Linux, a shell is simply an interface / interpreter to allow a user to communicate with the Linux computer system (server). Linux shells have evolved (improved) over a period of time. You will be using the Bash Shell which is considered to be user-friendly.

The Matrix server has been configured to allow users to only interact with the Linux OS by issuing commands. There are various reasons for this, but the main 2 reasons are to force students to learn how to issue Linux commands as well as limitations to remote access to a graphical Linux server due to large number of users (students).

Later in the course, your instructor may discuss other ways of accessing graphical versions of Linux, and how to launch a shell terminal.

Layout of the Matrix Server

The Matrix server consists of several Virtual Computers all connected together to form a cluster. A cluster is a cost effective alternative to larger servers.

The Matrix server consists of several Virtual Computers connected together to form a cluster. A cluster is a cost effective alternative to buying larger servers.

All registered students in this course have access to an account on the Matrix server. You will be using this account for the following reasons:

• Issuing Linux commands
• Becoming productive using the Linux command prompt (shell)
• Performing Linux Practice Tutorials
• Performing Linux Assignments (3)
• Practice Issuing Linux Command Review Questions

In the next section, you will learn how to connect to and login to your Matrix server account both at the college and from a remote computer such as your home computer or your laptop computer.

INVESTIGATION 1: ACCESSING YOUR MATRIX LINUX ACCOUNT

In this section, you will learn how to access your Matrix Linux account by two different methods:

• From within a workstation within a Seneca College lab
• From your own computer within or outside Seneca College

Part 1: Accessing your Matrix Account from a Seneca College Lab

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Perform the Following Steps:

Main WMware application window in order to create a new Virtual Machine (VM)

1. Although the images may be a little out of date (i.e. not exact), you can refer to this listing of installation screenshots for general reference:
   [installation screen-shots ]
   
2. Power up the computer in your Seneca lab in Windows.

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Part 2: Access your Matrix Account From your own computer within or outside Seneca College

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Perform the following steps:

The Installation Summary screen provides flexibly when configuring to install on your computer.

1. Select from the installation menu: Install CentOS 7.
2. Next, you will be prompted for a language. In the first screen, select language English with subselection English-Canada and then click the Continue button on the bottom right-hand screen.

INVESTIGATION 2: USING YOUR MATRIX ACCOUNT

Linux Commands Used (click for online help): Logging Out of Linux Account exit logout <ctrl><d>

Change Password passwd

Managing your Virtual Machine

In future labs, you will have to run your VMware Workstation application to boot-up your CentOS 7 host VM. Usually, you are NOT required to use this menu (unless you need to "force-off" the c7host7 machine, but should only be performed if you cannot normally shut-down the c7host VM from the OS.

On the other hand, there are useful short-cut key you should use:

ALT-CTRL-ENTER

Toggles the VM Workstation application window between full screen mode and window mode.

ALT-CTRL

Return focus from your c7host VM to your host computer system.

VMware Tools is a collection of utilities to help improve the performance and efficiency of the VM's operating system. Some features include:

• Faster Graphics
• Allow applications running in a VM to be accessed in the host machine (unity interface)
• Sharing folders between host and VM
• Copying and pasting text between host and among VMs
• Clock synchronization among host and VMs

It is recommended to install VMware Tools on your system. Click the VM menu and select Install VM Tools. The installation program will run in the background until the install is complete.

Properly Exiting CentOS 7 Session and Safely Removing USB Device
It is ABSOLUTELY ESSENTIAL that you do NOT remove your SSD drive during your CentOS 7 session. You are required to correctly shutdown your CentOS 7 host virtual machine as you would with any operating system. Also, you are required to use the Safely Remove Hardware and Eject Media tool in the system tray on your Windows machine to properly disconnect your SSD device.

FAILURE TO DO THIS MAY DAMAGE YOUR HOST VM AND NOW ALLOW IT TO BOOT PROPERLY (YOU HAVE BEEN WARNED).

Part 1: Turning Off Locked Screen-saver

Your system automatically enables a screen-saver application which is a useful security tool to prevent unauthorized viewing of information on a terminal after a certain amount of inactivity. Turning-off the locked screen-saver for this (and other) virtual machine can be useful when waiting for your instructor to come over to "sign-off" your computer lab without having to re-issue user passwords.

To Disable the Locked Screen-saver, Perform the following steps:

1. Click on the power button at the top right-hand corner of the window.
2. Click the Settings icon (bottom left-hand side of menu - looks like a screw-driver and wrench icon.
3. Click the Power icon located in the Settings Dialog Box
4. Change the amount of time in the Power Saving section to Never or a longer period of time
5. Close the Settings Dialog box.

Part 2: Accessing Administrative Privileges

Accessing the Administration Account (root) Many administrative tasks require the root administrative account. There are many ways to access this administration account: Login: root (enter root password) Switch User to root (without login): su: Remains in regular user's directory, does not run root's startup script(s). su - : Changes to root's home directory (/root) and runs root's start script(s).

Perform the following steps:

1. Refer to the Information box regarding how to access the admin account from the command line.
2. Issue the command su. This will switch you to the root account. From there, issue the pwd and whoami commands to confirm your directory pathname. When finished logout of this account using the command exit.
3. Issue the command su -. Issue the pwd and whoami commands to confirm your directory pathname. What do you notice are the main differences between using su versus using su - ?
4. An installation log file called /var/log/anaconda/packaging.log has been created to record the installation of your c7host machine. This file is an ASCII file which can be viewed with the more command.
5. You can make use of this file to determine how many packages have been installed: complete the following command to count the number of packages that are labelled "Installing" in the installation log file:

grep -i packaging /var/log/anaconda/packaging.log | wc -l

Part 3: Disable SELinux

Never disable SELinux in the real world
It is highly discouraged and unsafe to disable SELinux on a public-facing server. Some applications may require tedious steps to setup SELinux rules. Disabling SELinux is never the correct way to solve an issue.

SELinux stands for Security-Enhanced Linux. It is a component that helps to better secure the system to protect against intrusion (hackers). SELinux is enabled upon the default install of CentOS. SELinux can be a good thing, if you take care of it and know how it works. For this course it is strongly recommended that you disable SELinux by default because we won't have the time to reconfigure it every time the labs make it necessary.

Perform the following Steps:

1. Make sure you're logged in as root. su -
2. Edit the file /etc/selinux/config: vim /etc/selinux/config
3. In the editing session, set SELINUX to disabled (from enforcing) and save your editing session.
4. Restart your VM.
5. You can check the status of SELinux at any time at the command line by typing: sestatus

Part 4: Perform Software Updates

Running software updates regularly is an important part of keeping your computer secure and stable. On Linux, we use package managers to install software and updates. Package managers not only perform installations, but they keep track of everything that is currently installed on the system for easy management. For CentOS, this manager is called yum. Yum is also the command used.

Perform the following steps:

1. Open Terminal.
2. Login as root: su -
3. Type: yum update
4. Follow the prompts.
5. If there is a kernel update, reboot your system. (There usually is on a first update after OS installation.)

Answer Investigation 2 observations (all parts and questions) in your lab log book.

INVESTIGATION 3: Using Shell Scripting to Generate System Information Reports

Bash Shell Scripting Reference Guide: She-bang Line Forces shell script to run in a specific Shell Must be at beginning of first line (eg. #!/bin/bash) Variables Environment System-wide or "global" variable Usually appear in UPPERCASE letters Can view with command: set | more $ in front to expand variable to value Examples: USER, PATH, HOME, SHELL User-defined Variable created by user (command line, scripting) Examples: myVar="my value"; readonly myVar; export myVar read -p "enter value: " myVar Positional parameters Assign values with set command or shell script arguments These variables are numbered (eg. $1, $2 ... $10} Special parameters: $*, $@, $#, $$, $? Command Substitution Useful method to expand output from a command to be used as an argument for another command. Examples: file $(ls) set $(ls);echo $#;echo $* echo "hostname: $(hostname)" if / elif / else statements If a command runs (even pipeline command like to grep to match) will be true (0); otherwise, false (non-zero), thus can use with logic statements. Example: if echo $myVar | grep "match" then echo "Match" fi The test command is used to test conditions. Square brackets [ ] is short-cut for test command (args contained inside with spaces). The exit command can be used to terminate the shell script with a false value. Example: if [ $USER = "root" ] then  echo "You must be root"  exit1 fi For numberic comparison, use the test options: -gt,-ge, -lt, -le, -eq, -ne Example: if [ $grade -gt 79 ] then  echo "You get Good Mark" elif [ $grade -gt 49 ] then  echo "You pass" else  echo "You fail" fi For testing for file information, you can use -d to test if directory pathname exists, and -f if the file pathname exists. You can use ! for negation. Examples: if [ -d directory-pathname ] then echo "directory exists" fi if [ ! - f file-pathname ] then echo "File does not exist" fi

It is very common for System Administrators to keep records regarding their installed computer systems. For example, it is necessary to have a record of all the hardware information for each machine in order to help fix computer hardware problems, and to assist when purchasing additional consistent computer hardware.

Therefore, it makes sense to also have a record of the installed computer software as well. This can contain information regarding the Linux operating system, installed software, and network connectivity information.

Perform the Following Steps:

1. Study the Linux commands and their purpose to note computer software information for your installed c7hostVM. You should take time to issue each of these commands to view the output, and record this chart in your lab1 logbook.
   
   
2. Login to your c7hostVM, open a Bash Shell terminal, and login as root by issuing the command:
   su -
   
   
3. Make certain to record output from these commands (except for the ps -ef output) in your lab1 logbook.

Linux/Unix System Information Utilities

Command(s)	Purpose
uname -rv hostname ps -ef	Basic Linux OS information such as kernel version, host-name of Linux server, and all processes that are running on the system after installation.
rpm -q -a | wc -l rpm -q -a -l | wc -l rpm -q -l gedit | wc -l	Obtain number of installed packages in the rpm database. Option -q is to "query" information, option -a means for all installed packages, option -l means all files installed as opposed to just the application.
ifconfig route -n nslookup (at prompt, enter command: server)	Obtain network connectivity confirmation including: IP ADDRESS, Netmask, routing (default gateway), and the default Domain Name Server.

You may have learned about creating and running Bash Shell Scripts in your ULI101 course. Shell scripts help Linux users and system administrators to automate repetitive tasks to become more efficient and to help them save time. You will be reviewing and building a basic Bash Shell script to generate information reports for your newly-installed Linux host machine.

4. Refer to the Bash Shell Scripting Guide prior to proceeding with this section. As you continue, you are required to make Bash Shell scripting notes in your lab1 logbook.
5. Create a directory called bin in your root home directory to store your shell scripts by issuing the command:
   mkdir /root/bin
6. Change to that newly-created bin directory

NOTE: Although it is possible to copy and paste, is it highly recommended to manually enter the following Bash Shell scripting content to become familiar with writing Bash Shell scripting code. Remember: you will be required to create a Bash Shell script on your final exam, so you need the practice!

7. Launch a text editor (such as vim or nano) to create a Bash Shell script called: myreport.bash in your current directory.
8. Copy and paste the text below into your vi editing session for your file report.bash
   (how do you copy and paste efficiently in Linux?)
   


#!/bin/bash

# Author: *** INSERT YOUR NAME ***
# Date: *** CURRENT DATE ***
#
# Purpose: Creates system info report
#
# USAGE: ./myreport.bash

if [ $USER != "root" ] # only runs if logged in as root
then
 echo "You must be logged in as root." >&2
 exit 1
fi


9. Save your editing session, assign the myreport.bash file read and execute permissions (at least for the owner) and run by typing:
   ./myreport.bash
10. Did it work?
11. Reopen your text-editing session for /root/bin/myreport.bash and add the following lines of code to the bottom of the shell script file:

# Create report title

echo "SYSTEM REPORT" > /root/report.txt
echo "Date: $(date +'%A %B %d, %Y (%H:%M:%p)')" >> /root/report.txt
echo >> /root/report.txt


8. Save and run the bash shell script. View the contents of the file called report.txt that was generated (I hope you are using the up arrow key to issue previously issued commands in order to save time!). Notice how the redirection symbol > is used at the beginning of the report, and then the other redirection symbol >> is used to help "grow" the report with the other content.
9. The only remaining content of the report would be the system information. We can use a shell scripting trick called "command substitution" $( .. ) in order place results from an command to be used by another command (like echo). Re-edit the shell script and add the following code at the bottom of the shell script file:

echo "Hostname: $(hostname)" >> /root/report.txt
echo >> /root/report.txt
echo "Kernel Version: $(uname -rv)" >> /root/report.txt
echo >> /root/report.txt


10. Save, run the script, and view the report.txt contents (are you using tip that was given to save time?).
11. Edit the shell script and include output from the ps aux and ifconfig commands (with appropriate titles). Remember to redirect that output to add to the bottom of the file!
12. Save, run and confirm that the shell script is working correctly.
13. What would be the use of keeping this shell script as a Linux system administrator?

14. Here are some more "complex" Bash Shell scripts, that perform the same task. Although you are not require to understand some of these other tricks, it is recommended that you view the contents of the scripts and save them for future consideration or examples.
15. The wget command can be used to quickly download files from the Internet. Issue the following command:
    wget https://ict.senecacollege.ca/~ops235/labs/text-report.bash
16. Verify that the file text-report.bash was downloaded to your current directory.
17. Assign read and execute permissions for this file by issuing the command: chmod u+rx text-report.bash
18. Run this Bash Shell script by issuing the command: ./text-report.bash
19. Check to see if it created a report in your current directory. What is the purpose of the report?
20. Use the vi text editor to view the contents of the file text-report.bash. Can you understand how this script works?
    
    
21. Use the wget command to download, study, and run the following shell scripts on-line:
    https://ict.senecacollege.ca/~ops235/labs/report.bash
 https://ict.senecacollege.ca/~ops235/labs/report3.bash
    
    
22. Try to understand what these Bash Shell scripts do.
23. You have completed lab1. Proceed to Completing The Lab, and follow the instructions for "lab sign-off".

Answer Investigation 2 observations (all parts and questions) in your lab log book.

LAB 1 SIGN-OFF (SHOW INSTRUCTOR)

Students should be prepared with all required commands (system information) displayed in a terminal (or multiple terminals) prior to calling the instructor for signoff.

Shell scripting is so essential for Linux administration that this course has created a shell script for every lab for this course that a student must download and run in order to check their work.

If you have performed the lab correctly, then you will get a series of  OK  messages and you can proceed with the SIGN-OFF for lab1. On the other hand, if there were errors, then a  WARNING  message will appear with general suggestions that you will need to fix on your c7hostVM in order to have your OPS235 sign-off in this lab in order to proceed to the next lab.

Perform the Following Steps:

1. Make certain that your c7host VM is running, open the Bash Shell terminal and issue the command: su - and enter root's password.
   
   
2. Change to the /root/bin directory.
   
   
3. Download the checking script by issuing the following Linux command:
   wget https://ict.senecacollege.ca/~ops235/labs/lab1-check.bash
   
   
4. Give that downloaded shell script file execute permissions (for the file owner).
   
   FYI: Your checking script will not work unless you issued "su -" instead of just "su".
   
   
5. Run the shell script and if any warnings, make fixes and re-run shell script until you receive "congratulations" message.
   
   
6. Arrange evidence (command output) for each of these items on your screen, then ask your instructor to review them and sign off on the lab's completion:

✓ Run the lab1-check.bash script in front of your instructor (must have all  OK  messages)

✓ Proof that c7host VM is set for virtualization (Refer to: INVESTIGATION 1 - Part 1 - Step #29)

✓ Lab1 logbook containing the values for:

• IP address, MAC address, Default route (gateway) and
  DNS name server IP Address

Practice For Quizzes, Tests, Midterm & Final Exam

1. Define the term Virtual Machine.
2. List the major screens (steps) in the installation of Centos7 full install DVD.
3. What key-combination is used to toggle the view of your running VM from "window-mode" to "full-screen-mode"?
4. List the steps for disabling SELinux.
5. List 2 ways that you can access your root account
6. What is the difference between the commands su and su -  ?
7. What is the home directory for the user "root"?
8. How do you determine the host name of your GNU/Linux workstation?
9. What command can display the NIC's MAC address?
10. What command is used to get a list of running processes on your newly-installed system?
11. Write the Linux command to download the on-line file: http://linux.server.org/package.tar.gz
12. Write a Bash Shell Script to prompt the user for a directory, and then display the file types for all files in that specified directory (hint: use the read command and then use the file command and command substitution with the ls command). Test the Bash Shell script by adding execute permissions and run the Bash Shell Script.
13. Modify the previously created shell script to perform error checking after prompting for a directory to test if the specified directory does not exist. If it does NOT exist (i.e. true), display an error message indicating that the directory does NOT exist, and issue the command exit 1 to terminate the Bash Shell Script. Test the Bash Shell script by adding execute permissions and run the Bash Shell Script.