Unit 1 - Moving into admin

Question 1

What does it mean that Linux is a file-based system?

Answer 1

Everything in linux is either a file or directory.

Question 2

What does a file become when it is executed? And can they also be seen as a file?

Answer 2

A process.

And yes that can also be seen as a file in the ‘proc’ directory.

Question 3

What does the /bin directory contain?

Answer 3

Contains commands that the user can run but will also be used by system as well during the boot process.

Question 4

What does /boot directory contain?

Answer 4

Contains everything needed during boot process.

Question 5

What does /dev directory contain?

Answer 5

Contains directory for devices.

Question 6

What does /home directory contain?

Answer 6

Contains user files.

Question 7

What does the /tmp directory contain?

Answer 7

It contains temporary files for User’s and System.

Question 8

What does the /var directory contain?

Answer 8

System files that can change.

Question 9

What does the /etc directory contain?

Answer 9

System files that do not change.

Question 10

What does the /lib directory contain?

Answer 10

Stores sytem libraries.

Question 11

What does the /proc directory contain?

Answer 11

Files which represent the running system. (process info pseudo system)

Question 12

What does the /sbin directory contain?

Answer 12

Commands only used by admin.

Question 13

What does the /usr directory contain?

Answer 13

Commands never used during boot-up.

Question 14

What are the four files that user details are stored in?

Answer 14

• /etc/passwd - User details
• /etc/shadow - User password
• /etc/groups - Group details
• /etc/gshadow - Group password

Question 15

What do you see when you do cat /etc/passwd?

Answer 15

• 7 Columns
  1) Username
  2) x
  3) UID
  4) GID
  5) Finger info
  6) Home directory
  7) Log-in shell

Question 16

What do you see when you do head -3 /etc/shadow?

Answer 16

userName:PasswordMD5Hashed:

Question 17

What do you see when you look inside /etc/group?

Answer 17

userName:x:GID:AnotherOtherUsersAdded

Question 18

What do you see when you look inside /etc/gshadow?

Answer 18

groupName:x:

Question 19

What does the ‘cut’ command do and what are the options -d” “ and -f used for?

Answer 19

The cut command is used to chop lines.

• -d is used to set a delimiter
• -f is used to specify a column

Question 20

What command do you use to change ownership?

Answer 20

chown .

Question 21

What command do you use to change group ownership?

Answer 21

chgrp

Question 22

What does the ‘.’ immediately after file permissions in an ls -l output indicate?

Answer 22

That there are alternative methods of access to file/directory.

SELinux security context

Question 23

What does the ‘+’ immediately after file permissions in an ls -l output indicate?

Answer 23

There are a combination of access methods.

Question 24

What does the numerical value following the permission show?

Answer 24

The number of hard links there exists to the file.

Question 25

What does ‘getfacl’ do?

Answer 25

It displays the access list for the specified file.

Question 26

How is the default permissions set?

Answer 26

They are set using a ‘umask’ value which is taken away from 777.

Question 27

What is the command used to create a hard link to a file?

Answer 27

ln

Question 28

What is the command used to create a soft link to a file?

Answer 28

ln -s

Question 29

If you delete the source hard link file does the new hard link file still remain? Is this different in soft link files?

Answer 29

With hard link files they still remain but with softlink files they do not.

Question 30

If a change is made to a linked file is this change reflected in the source file and vice versa?

Answer 30

Yes.

Question 31

What is another word for soft link?

Answer 31

Symbolic Link.

Question 32

What is the difference between hard link and soft link?

Answer 32

Hard links point to the actual block in memory whereas soft links point to original file which point to actual block in memory.

Question 33

What is a daemon?

Answer 33

A process started upon booting which runs in the background.

Question 34

Discussion question.

Answer 34

Future of file permission:
–Is User/Group/Other sufficient?
–Simple control methods? ACL…
–Complex control methods? SELinux