Changes

=Logical Volume Management (Continued) and User =Purpose / Group Management= ==Introduction== In this lab you're going to learn how to: :* Add a virtual hard disk and expand your vm'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. == Required Materials (Bring to All Labs) == * CentOS 6.5 x86_64 Live DVD* CentOS 6.5 x86_64 Installation DVD1* SATA Hard Disk (in removable disk tray)* USB Memory Stick* Lab Logbook ==Prerequisites== * Completion and Instructor "Sign-off" Objectives of Lab 2: [[OPS235 Lab 3 - CentOS6]] 4==Linux Command Online Reference==Each Link below displays online manpages for each command (via [http://linuxmanpages.com/ http://linuxmanpages.com]): {|width="10040%" align="right" cellpadding="510"|'''LVM Information Utilities:'''|'''LVM Management Utilities:'''|'''Additional Utilities:'''

*[http://linuxmanpages.com/man8/vgs.8.php vgs]*[httpImage://linuxmanpagesusers.com/man8/lvs.8.php lvs]*[http://linuxmanpages.com/man8/pvs.8.php pvs]*[http://linuxmanpages.com/man8/vgdisplay.8.php vgdisplay]*[http://linuxmanpages.com/man8/lvdisplay.8.php lvdisplay]*[http://linuxmanpages.com/man8/pvdisplay.8.php pvdisplay]png|thumb|right|150px|*[http://www.centos.org/docs/5/html/Deployment_Guide-en-US/s1-system-config-lvm.html system-config-lvm] (Tutorial)*[http://linuxmanpagesSystem administrators are required to add, remove and modify user accounts.com/man8/lvextend.8.php lvextend]*[http://linuxmanpages.com/man8/resize2fs.8.php resize2fs]*[http://linuxmanpages.com/man8/lvcreate.8.php lvcreate]*[http://linuxmanpages.com/man8/lvreduce.8.php lvreduce]*[http://linuxmanpages.com/man8/pvcreate.8.php pvcreate]*[http://linuxmanpages.com/man8/vgextend.8.php vgextend]

*[http://linuxmanpages.com/man8/mount.8.php mount]*[http://linuxmanpages.com/man8/umount.8.php umount]*[httpImage://linuxmanpageson-off.com/man8/useraddpng|thumb|right|135px|In order to perform maintenance, system administrators need to know how to stop and start services for a Linux system.8.php useradd ]*[http://linuxmanpages.com/man8/userdel.8.php userdel]*[http://linuxmanpages.com/man8/usermod.8.php usermod]*[http://linuxmanpages.com/man8/groupadd.8.php groupadd]*[http://linuxmanpages.com/man8/groupdel.8.php groupdel]

:* [[Logical Volume Management]] ('''Note:''' It is recommended to return to this guide as There are many other tasks that a reference when performing the next several investigations):* [http://www.thegeekstuff.com/2011/05/ext2-ext3-ext4/ Linux File Systems (ext2/ext3/ext4)]:* [http://tldp.org/HOWTO/Partition/fdisk_partitioning.html Partitioning with fdisk]:* [http://www.linux-tutorial.info/modules.php?name=MContent&pageid=282 Mounting / Unmounting File-systems]:* [http://www.itwiresystem administrator must perform other than installing Linux and installing software.com/business-it-news/open-source/14446-uid-and-gid-the-basics-of-linux-user-admin UID and GID explained]

At this point, having completed [[OPS235 Lab 3 - CentOS6|Lab 3]] you should have <u>'''roughly'''Main Objectives</u> the following disk storage setup:<br />:* Administer '''(add, remove, modify) users'''Noteon a Linux system.:* Save time while adding new users using a template of ''' These results are output from the start-up files'''vgs.:* Create and manage ''', groups'''lvson a Linux system.:* ''', Start and Stop services'''pvson a Linux system.:* Display the ''' commands within each virtual machinestatus of running services''' on a Linux system. You will be using these commands in the following lab investigations)<br /><br />

This VM has no GUI installed. VG #PV #LV #SN Attr VSize VFree vg_centos3 2 3 0 wz--n- 16.50g 0 LV VG Attr LSize lv_home vg_centos3 -wi-ao---- 1.00g lv_root vg_centos3 -wi-ao---- |width="10%" | [[Image:harddrive.00g lv_swap vg_centos3 -wi-ao---- 992.00m PV VG Fmt Attr PSize PFree png|thumb|left|85px|<b>Removable Hard Disk Pack</dev/vda3 vg_centos3 lvm2 a-- 14.51g 2.54g /dev/vdb vg_centos3 lvm2 a-- 2.00g 2.00gb> (SATA)]]

* '''c6host (i.e. |width="disk pack10%"|[[Image:ubs-key.png|thumb|left|85px|<b>USB key</b><br>(for backups)''']]

/dev/sdc3 20G 3.7G 15G 20|width="10% / /dev/sdc2 29G 4" |[[Image:log-book.7G 23G 18% /home /dev/sdc1 97G 48G 45G 52% /var/lib/libvirtpng|thumb|left|70px|<b>Lab4 Log Book</imagesb>]]

{|width="50%" cellpadding= Resources "15"|- 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]|}

It is recommended to open another window(eg. '''right-click''', '''open in new tab or window''') to make reference to view LVM commands as you perform investigations = INVESTIGATION 1 to 3.: User/Group Management =

== Investigation 1: How are LVMs are managed using Command-Line Tools ==# You are going to repeat the same LVM User account management operations (as your did with the ''centos2'' VM in '''lab3'''), but you will using command-line tools in the '''centos3''' VMis a very important operation that a Linux sysadmin does on a consistent basis. Since the centos3 VM The sysadmin not only operates in command-line modeneeds to add or remove user accounts by issuing commands, you will but may need to refer to the '''"Logical Volume Management"''' link aboveautomate user account creations a large number (batch) of potential employees.# Write down There are many features with the exact commands used at each step, and record appropriate Linux command output::to create new users including: specification of a. Determine the current LVM configuration using the <code>pvs</code>, <code>vgs</code>, and <code>lvs</code> commands.:: b.Grow the home filesystem to 2G using the command <code>lvextend</code> and <code>resize2fs</code>.:: c.Create a new 2G LV containing an ext4 filesystem and mount it at /archive (use <code>mkdir</code>directory, <code>lvcreate</code>type of shell used, <code>mkfs</code>name, <code>mount</code>, edit the file <code>/etc/fstab</code> password and time-limit (read the resource: [https://wiki.archlinux.org/index.php/fstab https://wiki.archlinux.org/index.php/fstab] ), and then reboot referred to confirm automatic mountas "aging")for a new user account.:: d.Copy Remove user accounts also have options such as removing the user account but keeping the contents home directory for reference or evidence of <code>/etc</code> into <code>/archive</code>.:: e.Shrink <code>lv_archive</code> to 1G (use <code>umount</code>, <code>resize2fs</code>, <code>lvreduce</code>, and <code>mount</code>)"wrong-doing"

== Investigation 2: How can a PV be added In your ULI101 course, you learned to an existing VG using Command-Line Tools? ==# Add an additional 2 GB virtual disk change permissions for directories and files relating to your ''<u>centos1</u>'' systemuser, we will use it as an additional physical volumesame group members and other group members.# Do the rest of In this investigation in course, since you are the command line.# You should now have both <code>/dev/vda</code> and <code>/dev/vdb</code>.# Record sysadmin with root privileges, you can create or remove groups as well as change the size ownership of the volume group directories and the amount of free space (Hint: use a command that you learned in a previous lab).# Read the resource [http://tldp.org/HOWTO/Partition/fdisk_partitioning.html Partitioning with fdisk] to files! We will now learn how to properly create a partition with the fdisk command.# Use fdisk to partition /dev/vdb with a Linux single partition that fills the whole disk.# Check the messages printed when <code>fdisk</code> exits -- you may need to reboot the system perform key user account management operations in order for the new partition table to take effect.# Mark ''vdb1'' as a physical volume usable by LVM.# Add the new physical volume to the existing volume group.# Verify that the volume group is larger and has more free spacethis section.

{{Admon/note|Think!|== Part 1: The next part of this investigation requires some research, thought, and creativity.}}'''Using that additional space, create a separate filesystem for <code>/home</code>:'''# Create the logical volume <code>lv_home</code> (1G ext4)# Find a way to move the contents of <code>/home</code> onto it.# Change your system configuration so that the new filesystem is mounted on <code>/home<etc/code> from now on.passwd file ==

{{Admon/tip|SELinux relabelling may be required|Your system may report that # Look at the files are not present in the new /home filesystem when they are clearly there. This is due to the Security-Enhanced Linux system (SELinux) preventing access to the files, because the files were tampered with (moved) and are no longer recognized as home directory content. You can fix this problem by restoring the file context labels so that SELinux accepts the files as valid home directory content: <codeb>restorecon -r /home</code>}} <span style== Investigation 3: How can I use fdisk to manage storage on my disk pack? =='''On your <u>c6host</u> (i.e. "disk pack"), using your choice of the GUI and/or command-line toolscolor:'''# Create a new partition or logical drive ('''NOT a logical volume!''') 3366CC;font- minimum 5G, leaving at least 10G free space in the extended partitionsize:1.# Format that partition (i.e. put a filesystem on it).# Make sure it's mounted automatically on a mountpoint of your choosing (easiest is to create a new directory for a mountpoint). = User/Group Management = == Investigation 4: The 2em;">/etc/passwd file == # Look at the </span></etccode></passwd b> file.

# Read about the file: http://man7.org/linux.die.net/man-pages/5man5/passwd .5.html

 #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.

# Create two new dummy users, <b><code><span style="color:#3366CC;font-size:1.2em;">ops235_1 </span></code></b> and <b><code><span style="color:#3366CC;font-size:1.2em;">ops235_2</span></code></b>.

#* 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

#* 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>#* Create a new user named <b><code><span style="color:#3366CC;font-size:1.2em;">foobar</span></code></b>, with the option to automatically create a home directory.

{{Admon/note|Use centos3|Perform these steps in the '''centos3''' virtual machineAnswer the Part 2 observations / questions in your lab log book.}}# Add your matrix account user to '''centos3'''.

== Investigation 6Part 3: Managing Groups ==

{{Admon/note|Use centos1|Perform these steps #Remain in the your '''centos1''' virtual machineVM for 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>

#* 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 idiots '''investigation''' group.#** Look at '''/etc/group ''' again and note the change. '''Answer the Part 3 observations / questions in your lab log book.''' == Part 4: Deleting / Modifying Users == #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 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. '''Answer the Part 4 observations / questions in your lab log book.'''  =INVESTIGATION 2: Managing System Services and Run-levels= Many students may think that the following topic is small and "not a big deal". Those students may say, '''"How hard is running and stopping services?"''' The process may not be hard, but knowing how to stop, start, restart and check the status of services is absolutely critical to a Linux server. '''Aside from learning to trouble-shoot problems''' by checking the status of running services, '''understanding how to manage services is critical to help protect a Linux server from penetration''' (this term is referred to as "'''Hardening a system'''"). Sometimes it is "what we don't know" that can harm us. One key element in hardening a computer system is to disable non essential networkng services to allow IDSs ('''Intrusion Detection Systems''') to focus on a narrower range of policy violations. A Debian-based penetration testing distribution called '''Kali''' (formerly referred to as '''"BackTrax"''') allows sysadmins and security professionals to identify vulnerabilities in their computer systems, and thus improve (harden) their systems against penetration. Learning to monitor the status, enable and disable networking services underlies the '''Backtrax''' motto:<br><br>'''''"The quieter you are, then more you will hear..."'''''<br><br> === Part 1: How do we Manage System Services? === We have seen that maintaining unneeded '''packages can be a security risk''' due to the unnecessary increase in the complexity of your system. Similarly, it is also unnecessarily hazardous, and even more so, to leave unneeded services running. In this investigation, we will learn how to '''control services, and turn off those services that we think are not necessary to help reduce security risks'''. #Use your '''centos2''' VM for this part.<ol> <li value="2">Use the '''man''' pages to learn about the '''service''' command.</li><li>Issue the following Linux command: <ul> <li><b><code><span style="color:#3366CC;font-size:1.2em;">service --status-all</span></code></b></li> </ul> </li> <li>Note the services that are currently running.</li> <li>Use the command <b><code><span style="color:#3366CC;font-size:1.2em;">service iptables stop</span></code></b> to stop the service named '''iptables'''</li> <li>Run a command to verify that the '''iptables''' service has stopped.<br><br>'''NOTE:''' Although the service command seems to work, it is <u>'''deprecated'''</u> (i.e. "out-dated:). It has been replaced by using the [http://zenit.senecac.on.ca/wiki/index.php/Init_vs_systemd#systemd_Command_Usage systemctl] command. This is a command based upon a newer method of starting and managing system services called [http://zenit.senecac.on.ca/wiki/index.php/Init_vs_systemd systemd] (which replaces init - the "initialization table"). This method allows services to run more independently of each other, so that a service may be stopped without other dependent services to be stopped as well.<br><br>The most common '''systemctl''' commands are shown below (it is optional to include the filename extension '''.service''' after the service-name):<ul><li><span style="font-family:courier;font-size:1.2em;font-weight:bold;">'''systemctl list-units --all'''</span> &nbsp; (get a listing of all service names. Can pipe to grep to list service you are interested in)</li><li><span style="font-family:courier;font-size:1.2em;font-weight:bold;">'''systemctl status service-name'''</span> &nbsp; (Confirm status of a service - running or not-running)</li><li><span style="font-family:courier;font-size:1.2em;font-weight:bold;">'''systemctl stop service-name'''</span> &nbsp; (stop a service)</li><li><span style="font-family:courier;font-size:1.2em;font-weight:bold;">'''systemctl start service-name'''</span> &nbsp; (start a service)</li><li><span style="font-family:courier;font-size:1.2em;font-weight:bold;">'''systemctl restart service-name'''</span> &nbsp; (restart a service)</li><li><span style="font-family:courier;font-size:1.2em;font-weight:bold;">'''systemctl enable service-name'''</span> &nbsp; (enable service so service runs upon system startup)</li><li><span style="font-family:courier;font-size:1.2em;font-weight:bold;">'''systemctl disable service-name'''</span> &nbsp; (disable service so it does NOT run upon system startup)<br><br></li></ul></li> <li>If you reboot now - the iptables service will be turned back on. We don't want it on though, it causes students headaches.<br>To turn it off permanently we need to use the '''systemctl''' command:<b><code><span style="color:#3366CC;font-size:1.2em;">systemctl disable iptables</span></code></b><br>(the '''chkconfig''' command used to be the way to enble/disable services, but is now deprecated).</li> <li>Use the '''systemctl''' command to verify that the '''iptables''' service is no longer running ('''hint:''' issue command, and pipe to grep "'''iptables'''"). <li>Reboot and confirm that it's no longer running.</li></ol> '''Answer Part 1 observations / questions in your lab log book.''' ===Part 2: How do we Manage Runlevels?===

Be sure Running servers in graphical mode will make your system most likely to be penetrated. The X-windows framework can be vulnerable to attacks when these servers are connected to record your observations the Internet. This is why when you install server versions of Linux, they work in text-based mode only. Desktop versions of Linux are then installed on workstations (working in your lab notesgraphical mode) that connect to the server (for security reasons).

# Delete Perform this part in both your '''centos2''' and '''centos3''' VMs.<ol> <li value="2">Issue the following Linux command: <ul> <li><b><code><span style="color:#3366CC;font-size:1.2em;">runlevel</span></code></b></li> </ul> </li> <li>Note the difference in output between '''centos2''' and '''centos3'''.</li> <li>You can use the user ops235_1 using '''init''' command to change the current run-level. See a list of runlevels [https://www.centos.org/docs/5/html/5.2/Installation_Guide/s2-init-boot-shutdown-rl.html here].</li><li> Use the '''man''' command to learn how to use the '''init''' command. Use this command to change the current run-level in '''centos2''' to '''3'''. What happened?</li> <li>Issue the following Linux command : <ul> <li><b><code>userdel ops235_1<span style="color:#3366CC;font-size:1.2em;">startx</span></code></b></li> </ul> </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# Delete How_do_I_change_the_runlevel.3F How to Change Run-Levels with Systemd]</li><li>Restart your centos2 machine, and make certain that it runs in '''graphical''' mode</li> </li>Why would you want to make a graphical Linux system run in text-based mode?</li></ol>  '''Answer Part 2 observations / questions in your lab log book.'''  = 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>&nbsp; 1) echo "You win a car!" ;;<br>&nbsp; 2) echo "You win a bag of dirt!" ;;<br>&nbsp; *) echo "Not a valid entry"<br>&nbsp;&nbsp;&nbsp;&nbsp; exit 1 ;;<br>esac''<br><br>''read -p "enter a single digit: " digit<br>case $digit in<br>&nbsp; [0-9]) echo "Your single digit is: $digit" ;;<br>&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; *)&nbsp;echo "not a valid single digit"<br>&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp; exit 1 ;;<br>esac''<br><br></li><li>'''The getopts function:'''<br><br></li></ul>The getopts function allows the user ops235_2 using shell scripter to create scripts that accept options (like options for Linux commands). This provides the same Linux administrator with scripts that provide more flexibility and versatility. A built-in function called '''getopts''' (i.e. get command options) is used in conjunction with a '''while''' loop and a '''case''' statement to carry out actions based on if certain options are present when the shell script is run. The variable '''$OPTARG''' can be used if an option which removes accepts text (denoted in the home directory 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>&nbsp; case $name in<br>&nbsp; &nbsp; a) echo "Action for option \"a\"" ;;<br>&nbsp; &nbsp; b) echo "Action for option \"b\"" ;;<br>&nbsp; &nbsp; c) echo "Action for option \"c\""<br>&nbsp; &nbsp; &nbsp; &nbsp; echo Value is: $OPTARG" ;;<br>&nbsp; &nbsp; :) echo "Error: You need text after -c option"<br>&nbsp; &nbsp; &nbsp; &nbsp; exit 1 ;;<br>&nbsp; &nbsp; \?) echo "Error: Incorrect option"<br>&nbsp; &nbsp; &nbsp; &nbsp; 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 useraccounts.  # Check You will be using your '''c7host''' machine for this section.#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 ''' directoryto confirm. What do   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 notice?# Check will learn to create a shell script using the getopts function to make your shell script behave more like actual Linux commands (including the contents use of options). Refer to the notes section on the right-hand-side for reference about the '''case''' statement and the /etc/group file'''getopts''' function. What do you notice?

<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= Investigation 8"color: Modifying #3366CC;font-family:courier;font-size:.9em;margin-left:20px;"><br>&#35;!/bin/bash <br><br>&#35; createUsers.bash<br>&#35; Purpose: Generates a batch of user accounts (user data stored in a text file)<br>&#35;<br>&#35; USAGE: /root/createUsers.bash [-i {input-path}] <br>&#35;<br>&#35; Author: *** INSERT YOUR NAME ***<br>&#35; Date: *** CURRENT DATE ***<br><br>if [ $PWD != "/root" ] # only runs if in root's home directory<br>then<br>&nbsp;echo "You must be in root's home directory." >&2<br>&nbsp;exit 1<br>fi<br>if [ "$#" -eq 0 ] # if no arguments after command<br>then<br>&nbsp;echo "You must enter an argument" >&2<br>&nbsp;echo "USAGE: $0 [-i {input-path}]" >&2<br>&nbsp;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>&nbsp;case $name in<br>&nbsp; &nbsp;i) inputFile=$OPTARG ;;<br>&nbsp; &nbsp;:) echo "Error: You need text after options requiring text"<br>&nbsp; &nbsp; &nbsp; &nbsp;exit 1 ;;<br>&nbsp; &nbsp;\?) echo "Error: Incorrect option"<br>&nbsp; &nbsp; &nbsp; &nbsp; exit 1 ;;<br>&nbsp;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 $inputFile ]<br>then<br>&nbsp; echo "The file pathname \"$inputFile\" is empty or does not exist" >&2<br>&nbsp; exit 2<br>fi<br><br>set $(sed 's/ /+/g' $inputFile) # temporarily convert spaces to + for storing lines as positional parameters<br><br>for x<br>do<br>&nbsp; &nbsp; userPassWd=$(date | md5sum | cut -d" " -f1)<br>&nbsp; &nbsp; useradd -m -c "$(echo $x | cut -d":" -f2 | sed 's/+/ /g')" -p $userPassWd $(echo $x | cut -d":" -f1)<br>&nbsp; &nbsp; mail -s "Server Account Information" $(echo $x | cut -d":" -f3) <<+<br>&nbsp; &nbsp; Here is your server account information:<br>&nbsp; &nbsp; servername: myserver.senecac.on.ca<br>&nbsp; &nbsp; username: $(echo $x | cut -d":" -f1)<br>&nbsp; &nbsp; password: $userPassWd<br>&nbsp; &nbsp; Regards,<br>&nbsp; &nbsp; IT Department<br>+<br>done<br><br>echo -e "\n\nAccounts have been created\n\n"<br>exit 0<br></code>

{{Admon/note|Use centos1|Perform these steps in <ol><li value="8">Save, set permissions, and then run that shell script for the input text file '''centos1user-data.txt''' virtual machine.}}Did it work? Try running the script without an argument - What did it do? </li><li>You have completed lab4. Proceed to Completing The Lab, and follow the instructions for "lab sign-off".</li></ol>

# Read the man page for the usermod command'''Answer Investigation 3 observations / questions in your lab log book. Note which options change the user's full name, primary group, supplementary groups, and shell.''

# Add each of your new users to the group ops235 = LAB 4 SIGN-OFF (in other words, add ops235 to each user as a supplementary groupSHOW INSTRUCTOR).=# Examine <code>{{Admon/etc/group</code>. What has changed?# Use the usermod command to associate each important|If you have successfully completed this lab, make a new backup of your pod mates' full name to their user name. With each change, examine their entries in the <code>/etc/passwd</code> file. What has changed?# Be sure to record virtual machines as well as your observations in your lab noteshost machine.|}}

= Completing '''Arrange proof of the lab =following on the screen:'''

{{Admon<ol><li><span style="color:green;font-size:1.5em;">&#x2713;</span> '''centos1''' VM:<blockquote><ul><li>Account created on '''centos1''' VM</li><li> List contents of '''/etc/group''' file (ops235 group)</important|Time for a new backup!|If you have successfully completed this lab, make a new backup li><li>List contents of your virtual machines'''/etc/passwd''' file (created accounts)</li></ul></blockquote><li><span style="color:green;font-size:1. Remember to also make a backup of the new second virtual disk drive 5em;">&#x2713;</span> '''centos2''' VM:<blockquote><ul><li>Display current run-level status on ''centos1'centos2''' VM</li></ul></blockquote></li></li><li><span style="color:green;font-size:1.5em;">&#x2713;</span>'''c7host''' machine<blockquote><ul><li>Creation of your bash shell script called '''createUsers.bash'''</li></ul></blockquote></li><li><span style="color:green;font- you now have two virtual disks on size:1.5em;">&#x2713;</span> '''Lab4'centos1'', and therefore two image files, and therefore will need two backup fileslog-book filled out.}}</li></ol>

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

# Describe all of the field in <code>'''/etc/passwd'''</code># What is the command to create a VGuser? PV? LVWhat option to create a home directory for that user? # What is the total size command to change the full name of the "main" VG on your systeman already-created user?# How do you create What is the command to delete a LVuser account?# How do you delete an LVWhat option allows for the user's home directory to be removed as well?# How would you add What is the disk partition <code>/dev/sdb7</code> command to your volume create a group "main"?# How would you increase What is the size of the root filesystem by 50 MBcommand (or steps) to include a user in a newly-created group?# What is the purpose of <code>'''/etc/fstabshadow'''</code>?# What is the purpose of <code>'''/etc/shadowskel'''</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?