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[[Category:OPS235]]
{{Admon/caution|THIS IS AN OLD VERSION OF THE LAB|'''This is an archived version. Do not use this in your OPS235 course.'''}}
=LAB PREPARATION=
=LAB PREPARATION=Purpose / Objectives of Lab 4=={| width="40%" align="right" cellpadding="10"|- valign="top"|[[Image:users.png|thumb|right|150px|System administrators are required to add, remove and modify user accounts.]]|[[Image:on-off.png|thumb|right|135px|In order to perform maintenance, system administrators need to know how to stop and start services for a Linux system. ]]|}
There are many other tasks that a Linux system administrator must perform other than installing Linux and installing software.
<u>Main objectivesObjectives</u>:
<br>
:* Add a virtual hard disk and expand your vmAdminister '''s existing file system using LVM:* Administer (add, remove, modify) users ''' on a Linux system.:* Save time while adding new users using a template of '''start-up files'''.:* Create and manage '''groups ''' on a Linux system.:* '''Start and Stop services ''' on a Linux system.:* Display the '''status of running services ''' on a Linux system.
|- valign="top"
|width="10%" | [[Image:harddrive.png|thumb|left|85px|<b>Removable Hard Disk Pack</b> (SATA)]]
|- valign="top"
|width="10%" |<u>User Management:</u>
[http://unixhelp.ed.ac.uk/CGI/man-cgi?useradd+8 useradd]<br>[http://unixhelp.ed.ac.uk/CGI/man-cgi?userdel+8 userdel]<br>[http://unixhelp.ed.ac.uk/CGI/man-cgi?usermod+8 usermod]<br>[http://unixhelp.ed.ac.uk/CGI/man-cgi?groupadd+8 groupadd]<br>[http://unixhelp.ed.ac.uk/CGI/man-cgi?groupdel+8 groupdel]
|width="10%" |<u>Managing Services</u>
[http://unixhelp.ed.ac.uk/CGI/man-cgi?chkconfig+8 chkconfig]<br>[http://unixhelp.ed.ac.uk/CGI/man-cgi?service+8 service]<br>[http://www.dsm.fordham.edu/cgi-bin/man-cgi.pl?topic=systemctl systemctl]<br>
|width="10%" |<u>Miscellaneous</u>
[http://man7.org/linux/man-pages/man5/passwd.5.html /etc/passwd]<br>
[http://man7.org/linux/man-pages/man5/group.5.html /etc/group]<br>
[http://man7.org/linux/man-pages/man5/shadow.5.html /etc/shadow]<br>
[http://archive.linuxfromscratch.org/blfs-museum/1.0/BLFS-1.0/postlfs/skel.html /etc/skel]<br>
[http://zenit.senecac.on.ca/wiki/index.php/Init_vs_systemd init vs systemd]
|}
User account management is a very important operation that a Linux sysadmin does on a consistent basis. The sysadmin not only needs to add or remove user accounts by issuing commands, but may need to automate user account creations a large number (batch) of potential employees. There are many features with the Linux command to create new users including: specification of a home directory, type of shell used, name, password and time-limit (referred to as "aging") for a new user account. Remove user accounts also have options such as removing the user account but keeping the home directory for reference or evidence of "wrong-doing"
== Part 1: The /etc/passwd file ==
# Look at the <b><code><span style="color:#3366CC;font-size:1.2em;">/etc/passwd</span></code></b> file.
# Make note of the contents of that file.
# Read about the file: http://man7.org/linux.die.net/man-pages/5man5/passwd .5.html
# Make sure you know what information each field contains.
# Why do you think there are so many users?
# What is the numeric user ID (UID) of the root user?
# The user IDs of real users (people) are different from the user IDs of system accounts. What is the pattern?
'''Answer the Part 1 observations / questions in your lab log book.'''
== Part 2: Adding users ==
#Perform this part in your '''centos1 ''' VM.
# Read the man page for the <b><code><span style="color:#3366CC;font-size:1.2em;">useradd</span></code></b> command.
# Create a new user account for each of your pod mates, using three fictitious users (make-up their learn account name as a user nameuserids and full names. Give each user of these newly-created users a password.
# Grep the <b><code><span style="color:#3366CC;font-size:1.2em;">/etc/passwd</span></code></b> file for each of the new users.
#* What is the '''home ''' directory of each user?#* What '''group ''' is each user in?#* What else do other information can you know about each userprovide regarding these users?#* Where are the '''passwords ''' stored?# Look at the man page for '''/etc/shadow ''' using the command : <b><code><span style="color:#3366CC;font-size:1.2em;">man 5 shadow</span></code></b>
#* Grep the <b><code><span style="color:#3366CC;font-size:1.2em;">/etc/shadow</span></code></b> file for each of the new users.
#* Make note of this information.
#* What files are there? Be sure to include hidden files.
#* What do you think these files are used for?
#* How does the operating system determine which files are created in a new home account? The answer can be found here: <br>http://www.linuxhowtos.org/Tips%20and%20Tricks/using_skel.htm
#* Look at the files (including hidden files) in the template directory referred to in the article. Compare them to what is in a home directory for a new user. What do you notice?
#* Create a new file in this directory with the following command: <b><code><span style="color:#3366CC;font-size:1.2em;">touch foo</span></code></b>
#* Look at the contents of foobar's home directory. What do you notice?
# Be sure to record your observations in your lab notes.
#Issue the man pages for the '''useradd''' command. Explain the purpose of using the '''-e''' option for the ''useradd'' command. Try to think what would be the purpose for a Linux sysadmin to use this option when creating new users.
== Part 3: Managing Groups ==
#Perform this part Remain in your '''centos1 ''' VMfor this section.
# Read the man page for the <b><code><span style="color:#3366CC;font-size:1.2em;">groupadd</span></code></b> and <b><code><span style="color:#3366CC;font-size:1.2em;">groupdel</span></code></b> commands.
# Note which option allows you to set the Group ID number ('''GID''') when you create a new group.
# Examine the file <b><code><span style="color:#3366CC;font-size:1.2em;">/etc/group</span></code></b>
#* Which values of GID are reserved for system accounts?
#* What is the default group name of a new user?
#* Add a new group named <b><code><span style="color:#3366CC;font-size:1.2em;">ops235</span></code></b> with a GID of <b><code><span style="color:#3366CC;font-size:1.2em;">600</span></code></b>.
#* You are angry The management at your organization have concerns regarding some irresponsible users on your system.#** Add a new group named idiots'''investigation'''.#** Look at '''/etc/group ''' and note the GID of idiotsgroup called '''investigation'''.#** What GID is given to a new group if if you do not specify it?#** Your anger In the file, add those users to the end of the concerned group (separate each user-name with a comma).#** Those individuals have explained their actions to management and the crisis has subsidedbeen resolved. Delete the <b><code><span style="color:#3366CC;font-size:1.2em;">idiots</span></code></b> '''investigation''' group.#** Look at '''/etc/group ''' again and note the change. Be sure to record your observations in your lab notes.
#Remain in your '''centos1''' VM for this section.# Read the man page for the '''userdel''' command. Note which option automatically removes the users home directory when that user is deleted.# Delete the user '''ops235_1 ''' using the command <b><code><span style="color:#3366CC;font-size:1.2em;">userdel ops235_1</span></code></b># Delete the user ops235_2 '''ops235'''_2 using the same command with the option which removes the home directory of the user.
# Check the contents of the /home directory. What do you notice?
# Check the contents of the <b><code><span style="color:#3366CC;font-size:1.2em;">/etc/group</span></code></b> file. What do you notice?
# Read the man page for the usermod command. Note which options change the user's full name, primary group, supplementary groups, and shell.
# Create a new user account called '''noobie''' for the employee: '''"Really Green"''' . Assign a password for that newly created user.
# Management has indicated that this employee be on on probation for 3 months. Use the '''usermod''' command to set the account for noobie to expire in 3 months from this day as part of the security policy of this organization.
# Add each of your new users to the group ops235 (in other words, add ops235 to each user as a supplementary group).
# Examine <b><code><span style="color:#3366CC;font-size:1.2em;">/etc/group</span></code></b>. What has changed?
# Use the '''usermod''' command to change the full name of the user account '''noobie''' from '''"Really Green"''' to '''"Outstanding Employee"'''. Examine the result of running that command in the <b><code><span style="color:#3366CC;font-size:1.2em;">/etc/passwd</span></code></b> file. What has changed?
# Use the '''usermod''' command to extend the use of their account for 5 years as of today.
# Be sure to record your observations in your lab notes.
#Perform this part in both your '''centos2''' and '''centos3''' VMs.
<ol>
<li value="2">Issue the following Linux command:
</ul>
</li>
<li>Note the difference in output between '''centos2 ''' and '''centos3'''.</li> <li>You can use the <code>'''init</code> ''' command to change the current runlevelrun-level. See a list of runlevels [https://www.centos.org/docs/5/html/5.2/Installation_Guide/s2-init-boot-shutdown-rl.html here]. Use the <code/li>man</codeli> Use the '''man''' command to learn how to use the <code></code>'''init ''' command. Use this command to change the current runlevel run-level in '''centos2 ''' to '''3'''. What happened? What happens after your reboot?</li> <li>Change the default runlevel on centos2 to 3. What happens now after you reboot?</li> <li>Issue the following Linux command:
<ul>
<li><b><code><span style="color:#3366CC;font-size:1.2em;">startx</span></code></b></li>
<li>What happens?</li>
<li>Log-off your graphical system. You should return to your shell prompt.</li>
<li>Using systemd requires a different method of setting text mode and graphical mode. You can refer to this link for future reference: [http://fedoraproject.org/wiki/Systemd#How_do_I_change_the_runlevel.3F How to Change the default runlevel for Run-Levels with Systemd]</li><li>Restart your centos2 back to 5 machine, and reboot make certain that it runs in '''graphical''' mode</li> </li>Why would you want to make sure it works.a graphical Linux system run in text-based mode?</li>
</ol>
= INVESTIGATION 3: LOOKING AHEAD = ==Automating Routine Tasks (Shell Scripting)=={|width="40%" align="right" cellpadding="10"|- valign="top"|{{Admon/tip|Bash Shell Scripting Tips:|<br><ul><li>'''The case statement:'''<br><br>The case statement is a control-flow statement that works in a similar way as the if-elif-else statement (but is more concise). This statement presents scenerios or "cases" based on values or regular expressions (not ranges of values like if-elif-else statements). After action(s) are taken for a particular scenerio (or "case"), a break statement (''';;''') is used to "break-out" of the statement (and not perform other actions). A default case (*) is also used to catch exceptions.<br><br><u>'''Examples (try in shell script):'''</u><br><br>''read -p "pick a door (1 or 2): " pick<br>case $pick in<br> 1) echo "You win a car!" ;;<br> 2) echo "You win a bag of dirt!" ;;<br> *) echo "Not a valid entry"<br> exit 1 ;;<br>esac''<br><br>''read -p "enter a single digit: " digit<br>case $digit in<br> [0-9]) echo "Your single digit is: $digit" ;;<br> *) echo "not a valid single digit"<br> exit 1 ;;<br>esac''<br><br></li><li>'''The getopts function:'''<br><br></li></ul>The getopts function allows the shell scripter to create scripts that accept options (like options for Linux commands). This provides the Linux administrator with scripts that provide more flexibility and versatility. A built-in function called '''getopts''' (i.e. get command options) is used in conjunction with a '''while''' loop and a '''case''' statement to carry out actions based on if certain options are present when the shell script is run. The variable '''$OPTARG''' can be used if an option accepts text (denoted in the getopts function with an option letter followed by a colon. Case statement exceptions use the ''':)''' and '''\?)''' cases for error handling.<br><br>'''<u>Example of getopts</u>''' (try in script and run with options)<br><br>''while getopts abc: name<br>do<br> case $name in<br> a) echo "Action for option \"a\"" ;;<br> b) echo "Action for option \"b\"" ;;<br> c) echo "Action for option \"c\""<br> echo Value is: $OPTARG" ;;<br> :) echo "Error: You need text after -c option"<br> exit 1 ;;<br> \?) echo "Error: Incorrect option"<br> exit 1 ;;<br>esac''<br>done<br><br>}}|} We will now use shell scripting to help automate the task for a Linux adminstrator to create regular user accounts. #For You will be using your '''c7host''' machine for this partsection.#Download, study, and run the following shell script. Issue the command:<br><b><code><span style=" pointer-events:none;cursor:default;color:#3366CC;font-size:1.2em;">wget https://scs.senecac.on.ca/~murray.saul/user-create.bash</span></code></b>#Try to understand what these Bash Shell scripts do, and then run the script as root. After running the shell script, view the contents of the '''/home''' directory to confirm. Although the '''zenity''' command is a "user-friendly" way to run shell scripts, Linux administrators usually create shell scripts that resemble common Linux commands. In this lab, you will learn to create a shell script using the getopts function to make your shell script behave more like actual Linux commands (including the use of options). Refer to the notes section on the right-hand-side for reference about the '''case''' statement and the '''getopts''' function. <ol><li value="3">Open a Bash shell terminal and login as root.</li><li>Use the wget command to download the input file called user-data.txt by issuing the command:<br><b><code><span style="color:#3366CC;font-size:1.2em;">wget https://scs.senecac.on.ca/~murray.saul/user-data.txt</span></code></b></li><li>View the contents on the user-data.txt file to confirm there are 3 fields (username, fullname, and e-mail address)which are separated by the colon (:) symbol.<li><li>Use a text editor (such as <b><code><span style="color:#3366CC;font-size:1.2em;">vi</span></code></b> or <b><code><span style="color:#3366CC;font-size:1.2em;">nano</span></code></b>) to create a Bash Shell script called: <b><code><span style="color:#3366CC;font-size:1.2em;">createUsers.bash</span></code></b> in /root's home directory.</li><li>Enter the following text content into your text-editing session:</li></ol><code style="color:#3366CC;font-family:courier;font-size:.9em;margin-left:20px;"><br>#!/bin/bash <br><br># createUsers.bash<br># Purpose: Generates a batch of user accounts (user data stored in a text file)<br>#<br># USAGE: /root/createUsers.bash [-i {input-path}] <br>#<br># Author: *** INSERT YOUR NAME ***<br># Date: *** CURRENT DATE ***<br><br>if [ $PWD != "/root" ] # only runs if in root's home directory<br>then<br> echo "You must be in root's home directory." >&2<br> exit 1<br>fi<br>if [ "$#" -eq 0 ] # if no arguments after command<br>then<br> echo "You must enter an argument" >&2<br> echo "USAGE: $0 [-i {input-path}]" >&2<br> exit 2<br>fi<br></code><br><ol><li value="6">Save your editing session, but remain in the text editor.</li><li>The code displayed below uses the getopt function set the input file pathname or check for invalid options or missing option text. Add the following code</li></ol><br><code style="color:#3366CC;font-family:courier;font-size:.9em;"><br>outputFlag="n"<br>while getopts i: name<br>do<br> case $name in<br> i) inputFile=$OPTARG ;;<br> :) echo "Error: You need text after options requiring text"<br> exit 1 ;;<br> \?) echo "Error: Incorrect option"<br> exit 1 ;;<br> esac<br>done<br></code><ol><li value="6">Save your editing session, but remain in the text editor.</li><li>The code displayed below uses logic to exit the script if the input file does not exist. Command substitution is used to store each line of the input file as a positional parameter. There is one subtle problem here: The full names of the users contain spaces which can create havoc when trying to set each line as a separate positional parameter. In this case the sed command is used to convert spaces to plus signs (+), which will be converted back later. Finally, a '''for''' loop is used to create each account ('''useradd''') and mail the user their account information ('''mail'''). Add the following code:</li></ol><br><code style="color:#3366CC;font-family:courier;font-size:.9em;"><br>if [ ! -f $inputFile ]<br>then<br> echo "The file pathname \"$inputFile\" is empty or does not exist" >&2<br> exit 2<br>fi<br><br>set $(sed 's/ /+/g' $inputFile) # temporarily convert spaces to + for storing lines as positional parameters<br><br>for x<br>do<br> userPassWd=$(date | md5sum | cut -d" " -f1)<br> useradd -m -c "$(echo $x | cut -d":" -f2 | sed 's/+/ /g')" -p $userPassWd $(echo $x | cut -d":" -f1)<br> mail -s "Server Account Information" $(echo $x | cut -d":" -f3) <<+<br> Here is your centos2 VMserver account information:<br> servername: myserver.senecac.on.ca<br> username: $(echo $x | cut -d":" -f1)<br> password: $userPassWd<br> Regards,<br> IT Department<br>+<br>done<br><br>echo -e "\n\nAccounts have been created\n\n"<br>exit 0<br></code>
<ol>
'''Answer the Investigation 5 3 observations / questions in your lab log book.'''
= LAB 4 SIGN-OFF (SHOW INSTRUCTOR) =
{{Admon/important|Time for a new backup!|If you have successfully completed this lab, make a new backup of your virtual machinesas well as your host machine. Remember to also make a backup of the new second virtual disk drive on ''centos1'' -- you now have two virtual disks on ''centos1'', and therefore two image files, and therefore will need two backup files.|}}
'''Arrange proof of the following on the screen:'''
== Practice For Quizzes, Tests, Midterm & Final Exam ==
# Describe all of the field in <code>'''/etc/passwd'''</code>
# What is the command to create a user? What option to create a home directory for that user?
# What is the command to change the full name of an already-created user?
# What is the command to delete a user account? What option allows for the user's home directory to be removed as well?
# What is the command to create a group? What is the command (or steps) to include a user in a newly-created group?
# What is the purpose of <code>'''/etc/shadow'''</code>?
# What is the purpose of <code>'''/etc/skel'''</code>?
# What does the term run-level mean?
# How to set the run-level of a Linux system to text-based only? How to set to graphical mode?
# What is the command to view the status of running services?
# What is the command to start a service (like httpd, or sshd)?
# What is the command to start a service?
# Can a service be stopped and started by issuing just one command?
[[Category:OPS235]]
[[Category:OPS235 Labs]]