Command Line Operations (CLOs) - Basic Operations

Question 1

With what command can you after pressing Alt + F2 open the terminal?

Answer 1

gnome-terminal

Question 2

What are four main commands, often used?

Answer 2

man: view documentation
head: show first lines of file
tail: show last lines of file
cat: type out a file

Question 3

What are the three basic elements of most input lines at shell prompts? What do they do?

Answer 3

• command (name of program or script ot be executed)
• options (modify what the command does)
• arguments (what command operates on)

Question 4

How are options distinguished from arguments?

Answer 4

By starting with one or two dashes
i.e.
-p or –print

Question 5

What are Virtual Terminals? (VT)

Answer 5

• console sessions that use the entire display and keyboard outside of a graphical environment
• considered virtual, because only one terminal remains visible at a time

Question 6

For what are Virtual Terminals useful?

Answer 6

• i.e. when you run into problems with the graphical desktop

Question 7

How can a Virtual Terminal be accessed?

Answer 7

Ctrl + Alt + Function Key
(1-7)
7 -> graphical desktop

Question 8

How can the graphical desktop be started/stopped?

Answer 8

Depends on the distro
Newer system-based distros use systemctl

like
sudo systemctl stop gdm or sudo telinit 3

restart it
sudo systemctl start gdm or sudo telinit 5

Question 9

How can you log in and log out using the ssh command?

Answer 9

ssh student@remote-server.com

• would connect securely to remote machine (remote-server.com)
• and give student a command line terminal window
• using either a password or a cryptographic key to sign in without providing a password to verify the identity

Question 10

What happens when you run the shutdown command?

Answer 10

• sends a warning message
• prevents further users from logging in
• init process takes control shutting down or rebooting the system
• its important to always shutdown properly; failure to do so can result in damage to the system and/or loss of data

Question 11

Which commands can be used to shutdown a machine?

Answer 11

• shutdown
• halt (runs shutdown -h)
• poweroff (runs shutdown -h)
• reboot (runs shutdown -r)

Question 12

How can you locate the folder of a command?

Answer 12

using which utility

Like
which diff
output: /usr/bin/diff

Alternatively, if which does not find it:
whereis diff

-> looks for packages in a broader range of system directories
Also locates source and man files packaged with the program

Question 13

How can you see what you home directory is?

Answer 13

echo $HOME

Question 14

What are four useful commands for directory navigation?

Answer 14

• pwd: displays present working directory
• cd ~ or cd : change to your home directory; shortcut name is ~ (tilde)
• cd .. : change to parent directory
• cd - : change to previous working directory

Question 15

What does the command do:
pushd /folder

Answer 15

Changes the folder to target and adds it to history list, from where you came

Question 16

What does the command do:
popd /folder

Answer 16

Puts you back in the history, created with pushd
Walking in reverse order, most recent directory will be the first one retrieved with popd)

Question 17

How does an absolute Path start?

Answer 17

always with /

Question 18

How are multiple / dealth with as a pathname?

Answer 18

valid but seen as only one /

Question 19

How can you get a birds-eye view of a filesystem?

Answer 19

command:
tree -d

to see just directories and to suppress listing file names

Question 20

What shortcut can clear a terminal?

Answer 20

Crtl + L

Question 21

How can you view the sizes of filesystems?

Answer 21

df -h

Question 22

What does the command do:
ls -li

Answer 22

• i option prints out in the first column the inode number, a unique quantity for each file object

Question 23

How can you create a hard link to a file?

Answer 23

ln file1 file2

Question 24

What is a hard link?

Answer 24

• also called symbolic links
• points to the exact same data as the original link

Question 25

What is important to think about when working with hard links?

Answer 25

• can easily lead to subtle errors
• editing files linked to with a hard link might have consequences, depending on the editior: most retain the link by default, but not all

Question 26

How can you create soft links?

Answer 26

ln -s file1 file3

Question 27

What is a soft link?

Answer 27

• take no extra space in file system (unless names are very long)
• extremely convenient
• can be easily modified to point to different places

Question 28

How do soft links differ from hard ones?

Answer 28

• soft links can point to objects even on different filesystems, partitions and or disks and other media
• which may currently not be available or exist
• if so, you obtain a dangling link

Question 29

how can you see the list of directories created with pushd?

Answer 29

dirs