Last Updated on February 4, 2021 by Admin

1.2.2 Lab – Linux Review Answers

Lab – Linux Review (Answers Version)

Answers Note: Red font color or gray highlights indicate text that appears in the Answers copy only.

Objectives

Part 1: Launch the DEVASC VM

Part 2: Review Command Syntax Navigation

Part 3: Review File Management

Part 4: Review Regular Expressions

Part 5: Review System Administration

Background / Scenario

In this lab, you review basic Linux skills including command navigation, file management, regular expressions, and system administration. This lab is not meant as a substitute for prior Linux experience and does not necessarily cover all the Linux skills you need for this course. However, this lab should serve as a good measure of your Linux skills and help direct you to where you may need more review.

Required Resources

1 PC with operating system of your choice
Virtual Box or VMWare
DEVASC Virtual Machine

Instructions

Part 1: Launch the DEVASC VM

If you have not already completed the Lab – Install the Virtual Machine Lab Environment, do so now. If you have already completed that lab, launch the DEVASC VM now.

Part 2: Review Command Syntax Navigation

In this part, you will use the ls, pwd, cd, and sudo commands to review basic command syntax navigation.

Step 1: Open a terminal in the DEVASC-LABVM.

Double-click the Terminal Emulator icon on the desktop to open a terminal window.

Step 2: Navigate directories.

Use the ls command to display a listing of the current directory. Remember that commands are case-sensitive.

devasc@labvm:~$ ls

Desktop Downloads Music Public Templates

Documents labs Pictures snap Videos

devasc@labvm:~$

Use the ls command with the labs argument to display the contents of the labs folder.

devasc@labvm:~$ ls labs

devnet-src

devasc@labvm:~$

Use the ls command with the -l option to display a “long display” of the contents of the current directory.

devasc@labvm:~$ ls -l

total 40

drwxr-xr-x 2 devasc devasc 4096 Mar 30 21:25 Desktop

drwxr-xr-x 2 devasc devasc 4096 Apr 15 19:09 Documents

drwxr-xr-x 2 devasc devasc 4096 Apr 15 19:09 Downloads

drwxr-xr-x 5 devasc devasc 4096 Mar 30 21:21 labs

drwxr-xr-x 2 devasc devasc 4096 Apr 15 19:09 Music

drwxr-xr-x 2 devasc devasc 4096 Apr 15 19:09 Pictures

drwxr-xr-x 2 devasc devasc 4096 Apr 15 19:09 Public

drwxr-xr-x 5 devasc devasc 4096 Mar 30 21:24 snap

drwxr-xr-x 2 devasc devasc 4096 Apr 15 19:09 Templates

drwxr-xr-x 2 devasc devasc 4096 Apr 15 19:09 Videos

devasc@labvm:~$

Use the ls command with the -r option to display the contents of the current directory in reverse alphabetical order.

devasc@labvm:~$ ls -r

Videos snap Pictures labs Documents

Templates Public Music Downloads Desktop

devasc@labvm:~$

Multiple options can be used at the same time. Use the ls command with both the -l and -r options to display the contents of the current directory both in long and reverse order.

devasc@labvm:~$ ls -lr

total 40

drwxr-xr-x 2 devasc devasc 4096 Apr 15 19:09 Videos

drwxr-xr-x 2 devasc devasc 4096 Apr 15 19:09 Templates

drwxr-xr-x 5 devasc devasc 4096 Mar 30 21:24 snap

drwxr-xr-x 2 devasc devasc 4096 Apr 15 19:09 Public

drwxr-xr-x 2 devasc devasc 4096 Apr 15 19:09 Pictures

drwxr-xr-x 2 devasc devasc 4096 Apr 15 19:09 Music

drwxr-xr-x 5 devasc devasc 4096 Mar 30 21:21 labs

drwxr-xr-x 2 devasc devasc 4096 Apr 15 19:09 Downloads

drwxr-xr-x 2 devasc devasc 4096 Apr 15 19:09 Documents

drwxr-xr-x 2 devasc devasc 4096 Mar 30 21:25 Desktop

devasc@labvm:~$

There are many more options that can be used with the ls command. Use the man command with the argument ls to see all of the possibilities in the manual. The man command can be used to look up any command within the system. Use the space bar to advance to subsequent screens. Press q to quit.

devasc@labvm:~$ man ls

(The command line disappears and the manual page for ls opens.)

LS(1) User Commands LS(1)

NAME

ls – list directory contents

SYNOPSIS

ls [OPTION]… [FILE]…

DESCRIPTION

List information about the FILEs (the current directory by default).

Sort entries alphabetically if none of -cftuvSUX nor –sort is speci‐

fied.

Mandatory arguments to long options are mandatory for short options

too.

-a, –all

do not ignore entries starting with .

-A, –almost-all

do not list implied . and ..

–author

Manual page ls(1) line 1 (press h for help or q to quit)

You can also use –help argument after most commands to see a shorter summary of all the available command options.

devasc@labvm:~$ ls –help

Usage: ls [OPTION]… [FILE]…

List information about the FILEs (the current directory by default).

Sort entries alphabetically if none of -cftuvSUX nor –sort is specified.

Mandatory arguments to long options are mandatory for short options too.

-a, –all do not ignore entries starting with .

-A, –almost-all do not list implied . and ..

(Output Omitted)

devasc@labvm:~$

Use the pwd command to display the current working directory.

devasc@labvm:~$ pwd

/home/devasc

devasc@labvm:~$

Use the cd command to change the directory to /home/devasc/Documents.

devasc@labvm:~$ cd Documents

devasc@labvm:~/Documents$

Use the cd command with the / symbol to change directories to the root directory. Use pwd again to see that you are now in the root directory.

devasc@labvm:~/Documents$ cd /

devasc@labvm:/$ pwd

devasc@labvm:/$

Return to the /home/devasc/Documents directory. Tip: You can move one directory at a time or all the way to a destination. To quickly enter the command, type the first few letters of the directory name and press Tab for the system to automatically enter the rest of the name. Remember that names are case-sensitive.

devasc@labvm:/$ cd /home/devasc/Documents/

devasc@labvm:~/Documents$

Use the .. characters to move up a single directory. Use pwd again to see you are back in the user’s home directory.

devasc@labvm:~/Documents$ cd ..

devasc@labvm:~$ pwd

/home/devasc

devasc@labvm:~$

Step 3: Use super user commands for administrative access.

Use the sudo command to issue a single command as the root user. A new terminal will not be created. Use the sudo apt-get update command to update to refresh the list of available packages installed on the VM. This command will not work without using the sudo command.

Note: Your output will most likely be different.

devasc@labvm:~$ sudo apt-get update

Get:1 http://security.ubuntu.com/ubuntu focal-security InRelease [97.9 kB]

Get:2 http://us.archive.ubuntu.com/ubuntu focal InRelease [265 kB]

Get:3 http://us.archive.ubuntu.com/ubuntu focal-updates InRelease [89.1 kB]

Get:4 http://us.archive.ubuntu.com/ubuntu focal-backports InRelease [89.2 kB]

Get:5 http://us.archive.ubuntu.com/ubuntu focal/main i386 Packages [723 kB]

Get:6 http://us.archive.ubuntu.com/ubuntu focal/main amd64 Packages [981 kB]

(Output Omitted)

Fetched 677 kB in 2s (346 kB/s)

Reading package lists… Done

devasc@labvm:~$

Part 3: Review File Management

In this part, you will review file permissions, change file permissions and ownership, move files, copy files, remove files, and view files.

Step 1: Review file permissions.

Use the ls Desktop -l to display the contents of the Desktop folder.

devasc@labvm:~$ ls Desktop -l

total 28

-rwxr-xr-x 1 devasc devasc 1095 Mar 30 21:24 chromium_chromium.desktop

-rwxr-xr-x 1 devasc devasc 401 Mar 30 21:25 cisco-packet-tracer_cisco-pacet-tracer.desktop

-rwxr-xr-x 1 devasc devasc 776 Mar 30 21:23 code.desktop

-rwxr-xr-x 1 devasc devasc 373 Mar 30 21:25 drawio_drawio.desktop

-rwxr-xr-x 1 devasc devasc 250 Mar 30 21:21 exo-terminal-emulator.desktop

-rwxr-xr-x 1 devasc devasc 99 Mar 30 21:21 labs.desktop

-rwxr-xr-x 1 devasc devasc 334 Mar 30 21:24 postman_postman.desktop

devasc@labvm:~$

Answer the following questions about the output above. If necessary, search the internet for information of Linux file permission shown in the output of the ls command.

Questions

What does the initial dash represent in the permission information?

Type your answers here.

This is the file type field. The dash represents a regular file.

What would be in the place of the dash if the item was a directory?

Type your answers here.

It would be a “d” for “directory”.

What do the next three letters or dashes represent in the permission information?

Type your answers here.

These represent the permissions of the file owner over the file.

What do the middle three letters or dashes represent in the permission information?

Type your answers here.

These represent the permissions of the group over the file.

What do the last three letters or dashes represent in the permission information?

Type your answers here.

These represent the permissions others over the file.

What does the first instance of “devasc” in the permission information indicate?

Type your answers here.

This indicates the user owner field and is the owner of the file.

What does the second instance of “devasc” in the permission information indicate?

Type your answers here.

This indicates the group owner field and is the group of the file.

What does a permission type of “r” mean?

Type your answers here.

This means a permission of “read”. This allows for file contents to be read or copied.

What does a permission type of “w” mean?

Type your answers here.

This means a permission of “write”. This allows for contents to be modified or overwritten. It allows for files to be added or removed from a directory.

What does a permission type of “x” mean?

Type your answers here.

This means a permission of “execute”. This allows for a file to be run as a process, although script files require read permission, as well.

Step 2: Change file permissions and ownership.

Use the command cd to change to the Documents directory.

devasc@labvm:~$ cd Documents/

devasc@labvm:~/Documents$

Use the command echo to create a shell script file, that will have the command ls ../Desktop inside the file. Remember that the greater than (>) character redirects command output to a file.

devasc@labvm:~/Documents$ echo “ls ../Desktop“ > myfile.sh

devasc@labvm:~/Documents$

The myfile.sh script is stored in the /Documents directory. Use the cat command to view the only command in the script. This file will be used as an example to modify permissions and ownership.

devasc@labvm:~/Documents$ cat myfile.sh

ls ../Desktop

devasc@labvm:~/Documents$

Use the command ./myfile.sh to run the script. Access is denied because you must set the permission of executable on the file.

devasc@labvm:~/Documents$ ./myfile.sh

bash: ./myfile.sh: Permission denied

Use the command ls -l myfile.sh to view the current file permissions.

devasc@labvm:~/Documents$ ls -l myfile.sh

-rw-rw-r– 1 devasc devasc 14 Apr 16 12:46 myfile.sh

Use the command chmod +x myfile.sh to allow you to execute the file.

devasc@labvm:~/Documents$ chmod +x myfile.sh

devasc@labvm:~/Documents$

Use the command ./myfile.sh to run the script.

devasc@labvm:~/Documents$ ./myfile.sh

chromium_chromium.desktop exo-terminal-emulator.desktop

cisco-packet-tracer_cisco-pacet-tracer.desktop labs.desktop

code.desktop postman_postman.desktop

drawio_drawio.desktop

devasc@labvm:~/Documents$

Use the command sudo chown root myfile.sh to change the ownership of the file to “root”.

devasc@labvm:~/Documents$ sudo chown root myfile.sh

devasc@labvm:~/Documents$

Display the permissions of the myfile.sh file.

devasc@labvm:~/Documents$ ls -l

total 4

-rwxrwxr-x 1 root devasc 14 Apr 16 21:28 myfile.sh

devasc@labvm:~/Documents$

Step 3: Use the move files command.

Use the command mv to move the myfile.sh file to the desktop.

devasc@labvm:~/Documents$ mv myfile.sh /home/devasc/Desktop/

devasc@labvm:~/Documents$

Display the contents of the Desktop folder.

devasc@labvm:~/Documents$ ls ../Desktop/

chromium_chromium.desktop exo-terminal-emulator.desktop

cisco-packet-tracer_cisco-pacet-tracer.desktop labs.desktop

code.desktop myfile.sh

drawio_drawio.desktop postman_postman.desktop

devasc@labvm:~/Documents$

Return the file to the Documents folder.

devasc@labvm:~/Documents$ mv ../Desktop/myfile.sh myfile.sh

devasc@labvm:~/Documents$

Use the command mv to rename myfile.sh to myfile_renamed.sh.

devasc@labvm:~/Documents$ mv myfile.sh myfile_renamed.sh

devasc@labvm:~/Documents$ ls

myfile_renamed.sh

devasc@labvm:~/Documents$

Step 4: Use the copy files command.

Use the command cp to make a copy of the myfile_renamed.sh file.

devasc@labvm:~/Documents$ cp myfile_renamed.sh myfile_renamed_and_copied.sh

devasc@labvm:~/Documents$ ls

myfile_renamed_and_copied.sh myfile_renamed.sh

devasc@labvm:~/Documents$

Step 5: Use the remove files command.

Use the rm command to remove the myfile_renamed_and_copied.sh file.

devasc@labvm:~/Documents$ rm myfile_renamed_and_copied.sh

devasc@labvm:~/Documents$ ls

mbr.img myfile_renamed.sh

devasc@labvm:~/Documents$

Step 6: Use the standard output redirect.

Use the redirect (>) to place text into a new file called linux.txt.

devasc@labvm:~$ echo “Linux is AWESOME!” > linux.txt

devasc@labvm:~$

Use the command cat to redirect the contents of linux.txt to another file.

devasc@labvm:~$ cat linux.txt > linux2.txt

devasc@labvm:~$

Use the command cat to view the contents of linux2.txt.

devasc@labvm:~$ cat linux2.txt

Linux is AWESOME!

devasc@labvm:~$

Use the echo command to append text to the linux2.txt file.

devasc@labvm:~$ echo “I LOVE Linux!” >> linux2.txt

devasc@labvm:~$

Use the cat command to view the contents of the linux2.txt file.

devasc@labvm:~$ cat linux2.txt

Linux is AWESOME!

I LOVE Linux!

devasc@labvm:~$

Use the echo command to overwrite the contents of a file using the single angle bracket.

devasc@labvm:~$ echo “Linux is POWERFUL!” > linux.txt

devasc@labvm:~$

Use the cat command to view the contents of the linux.txt file. Notice that the previous state “Linux is AWESOME!” was overwritten.

devasc@labvm:~$ cat linux.txt

Linux is POWERFUL!

devasc@labvm:~$

Step 7: Use the vi text editor.

Use the following command to start the vi text editor and open a text file.

devasc@labvm:~$ vi linux2.txt

The following content is shown in the editor window:

Linux is AWESOME!

I LOVE Linux!

Use the text editor to change the content to the following:

Linux is Linux

I am AWESOME!

The a key will allow you to enter edit mode, appending after the cursor’s position, while the i key will allow you to enter edit mode, inserting at the cursor’s position. You will need to use the Esc key to enter command mode to move around. Remember that d will delete (cut), y will yank (copy), and p will put (paste) the current line with the cursor.

Save the text to a new file called “linux3.txt”. Remember that you will need to be in the command mode and type a colon ( : ) to enter ex mode so that you can write (save) the document ( :w linux3.txt). You can then use the quit (exit) command ( :q) to exit the vi editor.
Use the cat command to view the contents of the linux3.txt file.

devasc@labvm:~$ cat linux3.txt

Linux is Linux

I am AWESOME!

devasc@labvm:~$

Part 4: Review Regular Expressions

In this part, you use the grep command to review how you can use regular expressions for filtering.

Note: Your output may differ than the output shown below as the state of the VM is based on the most recent iteration that you downloaded as well as any changes you may have made. However, you should get some output from the passwd file but your highlighted output will differ.

Use the grep command to filter the contents of the passwd file to display the line from the passwd file containing devasc. Notice that the two instances of devasc are highlighted. Also notice that the grep command is case-sensitive. The instance of DEVASC is not highlighted.

devasc@labvm:~$ grep devasc /etc/passwd

devasc:x:900:900:DEVASC,,,:/home/devasc:/bin/bash

devasc@labvm:~$

Use the grep command to show how many times root appears in the passwd file. Notice that all three instances of root are highlighted.

devasc@labvm:~$ grep root /etc/passwd

root:x:0:0:root:/root:/bin/bash

devasc@labvm:~$

Use the grep command with the anchor character ^ to find the word, but only at the beginning of the line. Notice that only the word at the beginning of the line is highlighted.

devasc@labvm:~$ grep ‘^root’ /etc/passwd

root:x:0:0:root:/root:/bin/bash

devasc@labvm:~$

Use the grep command with the anchor character $ to find a word at the end of a line.

devasc@labvm:~$ grep ‘false$’ /etc/passwd

tss:x:106:114:TPM software stack,,,:/var/lib/tpm:/bin/false

lightdm:x:107:117:Light Display Manager:/var/lib/lightdm:/bin/false

hplip:x:115:7:HPLIP system user,,,:/run/hplip:/bin/false

devasc@labvm:~$

Use the grep command with the anchor character . to match specific length words with different letters in them. Notice that not only is daem highlighted, but also dnsm is highlighted.

devasc@labvm:~$ grep ‘d..m’ /etc/passwd

daemon:x:1:1:daemon:/usr/sbin:/usr/sbin/nologin

dnsmasq:x:109:65534:dnsmasq,,,:/var/lib/misc:/usr/sbin/nologin

avahi-autoipd:x:110:121:Avahi autoip daemon,,,:/var/lib/avahi-autoipd:/usr/sbin/nologin

usbmux:x:111:46:usbmux daemon,,,:/var/lib/usbmux:/usr/sbin/nologin

avahi:x:113:122:Avahi mDNS daemon,,,:/var/run/avahi-daemon:/usr/sbin/nologin

colord:x:116:125:colord colour management daemon,,,:/var/lib/colord:/usr/sbin/nologin

pulse:x:117:126:PulseAudio daemon,,,:/var/run/pulse:/usr/sbin/nologin

devasc@labvm:~$

Use the grep command to find lines where only the numbers 8 or 9 are present. Notice that only the lines containing an 8, a 9, or both are returned.

devasc@labvm:~$ grep ‘[8-9]’ /etc/passwd

mail:x:8:8:mail:/var/mail:/usr/sbin/nologin

news:x:9:9:news:/var/spool/news:/usr/sbin/nologin

list:x:38:38:Mailing List Manager:/var/list:/usr/sbin/nologin

irc:x:39:39:ircd:/var/run/ircd:/usr/sbin/nologin

uuidd:x:103:109::/run/uuidd:/usr/sbin/nologin

devasc:x:900:900:DEVASC,,,:/home/devasc:/bin/bash

systemd-network:x:999:999:systemd Network Management:/:/usr/sbin/nologin

systemd-resolve:x:998:998:systemd Resolver:/:/usr/sbin/nologin

systemd-timesync:x:997:997:systemd Time Synchronization:/:/usr/sbin/nologin

systemd-coredump:x:996:996:systemd Core Dumper:/:/usr/sbin/nologin

rtkit:x:108:119:RealtimeKit,,,:/proc:/usr/sbin/nologin

dnsmasq:x:109:65534:dnsmasq,,,:/var/lib/misc:/usr/sbin/nologin

devasc@labvm:~$

Use the grep command to find literal characters. Notice that only the lines containing a comma are returned.

devasc@labvm:~$ grep ‘[,]’ /etc/passwd

devasc:x:900:900:DEVASC,,,:/home/devasc:/bin/bash

tss:x:106:114:TPM software stack,,,:/var/lib/tpm:/bin/false

rtkit:x:108:119:RealtimeKit,,,:/proc:/usr/sbin/nologin

dnsmasq:x:109:65534:dnsmasq,,,:/var/lib/misc:/usr/sbin/nologin

avahi-autoipd:x:110:121:Avahi autoip daemon,,,:/var/lib/avahi-autoipd:/usr/sbin/nologin

usbmux:x:111:46:usbmux daemon,,,:/var/lib/usbmux:/usr/sbin/nologin

kernoops:x:112:65534:Kernel Oops Tracking Daemon,,,:/:/usr/sbin/nologin

avahi:x:113:122:Avahi mDNS daemon,,,:/var/run/avahi-daemon:/usr/sbin/nologin

hplip:x:115:7:HPLIP system user,,,:/run/hplip:/bin/false

colord:x:116:125:colord colour management daemon,,,:/var/lib/colord:/usr/sbin/nologin

pulse:x:117:126:PulseAudio daemon,,,:/var/run/pulse:/usr/sbin/nologin

devasc@labvm:~$

Use the grep command to find occurrences of zero or more of the pattern preceding it. Notice that only the lines with either new and ne are returned.

devasc@labvm:~$ grep ‘new*’ /etc/passwd

news:x:9:9:news:/var/spool/news:/usr/sbin/nologin

nobody:x:65534:65534:nobody:/nonexistent:/usr/sbin/nologin

messagebus:x:100:103::/nonexistent:/usr/sbin/nologin

_apt:x:102:65534::/nonexistent:/usr/sbin/nologin

tcpdump:x:104:110::/nonexistent:/usr/sbin/nologin

systemd-network:x:999:999:systemd Network Management:/:/usr/sbin/nologin

kernoops:x:112:65534:Kernel Oops Tracking Daemon,,,:/:/usr/sbin/nologin

saned:x:114:124::/var/lib/saned:/usr/sbin/nologin

devasc@labvm:~$

Part 5: Review System Administration

In this part, you will review basic Linux system administration tasks including shutting down the computer, viewing and testing the network configuration, viewing processes, managing installation packages, updating user passwords, adding content to files, and using text editors.

Step 1: Shut down the computer.

Use the command shutdown now to initiate a shutdown of the OS (and the VM) immediately. You do not have to perform this action as the VM will shut down and you will need to restart it manually. Formats of this time argument can be the word now, a time of day in the format hh:mm or the number of minutes to delay in the format +minutes.

devasc@labvm:~$ shutdown now

Use the command date to check set date of the OS.

devasc@labvm:~$ date

Fri 17 Apr 2020 08:53:20 PM UTC

devasc@labvm:~$

Use the command shutdown +1 “Come back soon!” to shut down the OS in 1 minute and display the message “Come back soon!”. Be sure to cancel or your VM will shut down.

devasc@labvm:~$ shutdown +1 “Come back soon!”

Shutdown scheduled for Fri 2020-04-17 20:57:13 UTC, use ‘shutdown -c’ to cancel.

devasc@labvm:~$ shutdown -c

devasc@labvm:~$

Step 2: View and test the network configuration.

Use the ip address command to display the network configuration. The output is a bit more detailed. For example, notice that five IPv4 addresses are shown for the dummy0 interface.

devasc@labvm:~$ ip address

1: lo: <LOOPBACK,UP,LOWER_UP> mtu 65536 qdisc noqueue state UNKNOWN group default qlen 1000

link/loopback 00:00:00:00:00:00 brd 00:00:00:00:00:00

inet 127.0.0.1/8 scope host lo