User and Groups

Question 1

Show all processes in the current session by the current user

Answer 1

ps -au

Question 2

switch to the user02 account

Answer 2

su - user02

Question 3

Switch to root

Answer 3

su -

Question 4

Diff between su and su -

Answer 4

su: non-login shell (reads .bashrc)

su -: login shells, (reads .bash_profile)

Question 5

su 4 properties

Answer 5

1) become new user
2) env vars from current user
3) New user password required
4) Privileges of new user

Question 6

su - sudo recap

Answer 6

1) su -, sudo -i: root env, root login shell
2) su, sudo su: initiating user env, root non login shell
3) sudo -s: initiating user env, initiating user non-login shell

Question 7

sudo

Answer 7

1) Simply execute command
2) env vars from initiating user
3) password of initiating user
4) Must be configured

Question 8

configure the sudo command to allow the user01 user to run the usermod command as root

Question 9

show information about the currently logged-in user

Answer 9

id

Question 10

Diff between sudo -i and for su -

Answer 10

sudo -i requires initiating user password
su - requires target user password

Question 11

Diff between sudo -i and sudo -s

Answer 11

First includes target user env variables. Second includes initiating user env variables.

Question 12

How do you edit /etc/suroders

Answer 12

visudo

Question 13

What are the benefits of visudo

Answer 13

1) Ensures there is no conflicts in multiuser environments
2) Parses the file before saving

Question 14

In /etc/sudoers, how do you differentiate normal user from group

Answer 14

Groups start with %

Question 15

General syntax of an sudoers entry

Answer 15

principal X=(Y:Z) T

X: hosts where this is applicable
Y: Users that X may assume
Z: Group that X may assume
T: Commands that X is permitted to execute when acting as X or Y

Question 16

Enable full sudo access for user01

Answer 16

user01 ALL=(ALL:ALL) ALL

Question 17

enable full sudo access for the group01 group

Answer 17

%group01 ALL=(ALL:ALL) ALL

Question 18

enable users in the games group to run the id command as the operator user,

Answer 18

%games ALL=(operator) /bin/id

Question 19

allow a user to run commands as another user without entering their password

Answer 19

ansible ALL=(ALL) NOPASSWD: ALL

Question 20

sudo su

Answer 20

start a root non-login shell .
User must be sudoer
No root password required

Question 21

Similarity between su and sudo su

Answer 21

Both result in non-login shells

Question 22

sudo su vs sudo s

Answer 22

sudo s: 1) user env vars, 2) SHELL from user,

sudo su: 1) user env VARS, 2) SHELL from root

Question 23

Where do you set range of valid UID numbers and default password aging rules

Answer 23

/etc/login.defs

Question 24

usermod -aG user1 group3

Answer 24

add group3 to user1 list of supplementary groups

Question 25

usermod -c

Answer 25

change the comment in the user profile

Question 26

usermod -L

Answer 26

locka user's password. preventing him from loggin in.

Question 27

usermod -G

Answer 27

add a comma separated list of groups as supplementary groups to a user

Question 28

usermod -d

Answer 28

change user home dir

Question 29

usermod -s

Answer 29

change user shell

Question 30

usermod -U

Answer 30

unlock a user

Question 31

Delete user user01 without deleting hom dir

Answer 31

userdel user01

Question 32

Delete user user01 along with home dir

Answer 32

userdel -r user01

Question 33

find all unowned files and directories

Answer 33

```find / -nouser -o -nogroup```

Question 34

Create user with specified uid

Answer 34

useradd -u 1000 user02

Question 35

Add group with specific id

Answer 35

groupadd -g 10000 group01

Question 36

Create a system group

Answer 36

groupadd -r group02

Question 37

Change the name of group

Answer 37

groupmod -n group0022 group02

Question 38

Change the group id of a group

Answer 38

groupmod -g 20000 group0022

Question 39

Where are password stored

Answer 39

/etc/shadow

Question 40

What does chage stand for?

Answer 40

change age

Question 41

What are password aging parameters?

Answer 41

-d: last change date -m: min days -M: max days -W: warn days -I: inactive days -E: expiration day -l: display aging policy `Every moon day, Max warns Isaac: End laziness.`

Question 42

Print date in format 2022-03-10

Answer 42

date +%F

Question 43

You want a user to change password immediately. what do you do?

Answer 43

chage -d 0 cloudadmin10

Question 44

set the default maximum and minimum age of the password respectively.

Answer 44

PASS_MAX_DAYS and PASS_MIN_DAYS

Question 45

sets the default warning period of the password

Answer 45

PASS_WARN_AGE

Question 46

lock and expire the account from a certain date

Answer 46

usermod -L -e 2022-08-14 cloudadmin10

Question 47

How do you prevent a user with valid account to log in

Answer 47

```usermod -s /sbin/nologin newapp``` Used for service accounts

Question 48

What is typical content of .bashrc

Answer 48

alias functions shell prompt appearance, settings for command-line tools

Question 49

What is typical content of .bashrc_profile

Answer 49

user's environment (PATH, EDITOR, etc.) .bash_profile sometimes sources .bashrc