Linux

Front 1

Why would you use linux over any other OS?

Back 1

It's open source meaning it's freely available for anyone to use, more reliable, more stable, strong security, and developer friendly.

Front 2

Explain what a CPU is.

Back 2

It's the brain of the computer.

Front 3

Explain what RAM is.

Back 3

Temporary storage for the CPU. It losses the data when the machine powers off.

Front 4

What is a hard disk?

Back 4

Long term storage for the CPU.

Front 5

What is NIC?

Back 5

Network Interface Card. It allows connection between a computer and network.

Front 6

What is a kernel?

Back 6

The core component of an operating system. It acts as a bridge between software applications and the hardware of a computer. The kernel manages system resources such as CPU and memory.

Front 7

What is the shell?

Back 7

A command-line interface that allows users to interact with the operating system by typing commands.

Front 8

What command allows you to long list files or directories?

Back 8

ll or ls -l

Front 9

What command allows you to move to an existing directory?

Back 9

cd

Front 10

What command makes a directory?

Back 10

mkdir directoryname

Front 11

What command makes a file?

Back 11

touch filename

Front 12

What command removes a directory?

Back 12

rmdir directoryname

Front 13

What command removes a file?

Back 13

rm filename

Front 14

What is absolute path?

Back 14

The full path to the file or directory.

Front 15

What is relative path?

Back 15

The partial path to a file or directory from your current location.

Front 16

What is the difference between copy and move?

Back 16

cp duplicates an existing file

mv transfers an existing file

Front 17

What are the 3 types of root?

Back 17

/ = root directory

root = root user

/root = root home directory

Front 18

What is an inode number?

Back 18

A unique identifier assigned to each file or directory in a file system. It is part of the metadata associated with the file or directory and is used by the kernel to locate and manage the file's data.

Front 19

What command adds users?

Back 19

useradd username

Front 20

What command adds groups?

Back 20

groupadd groupname

Front 21

What command sets a password for a user?

Back 21

passwd username

Front 22

What command adds users to the wheel group?

Back 22

usermod -aG wheel username

Front 23

What files are associated with user information?

Back 23

/etc/passwd

/etc/shadow

/etc/gshadow

/etc/group

Front 24

What information is in /etc/passwd?

Back 24

Username

Password

Userid

Groupid

Comment

Home directory

Shell

Front 25

What information is in /etc/shadow?

Back 25

It contains encrypted password information for user accounts.

Usernames

Passwords

Password expiration info

Account locking info

Front 26

What information is in /etc/gshadow?

Back 26

It stores encrypted group password information.

Group name

Encrypted password

Group administrators

Group members

Front 27

What information is in /etc/group?

Back 27

It contains information about groups on the system.

Group name

Password

Groupid

User list

Front 28

What is in metadata?

Back 28

Permissions

Links

Owner

Group owner

Size

Timestamp

Directory name

Front 29

What is rwx in the metadata?

Back 29

r = read

w = write

x = execute

Front 30

What are the sections of rwx in the metadata?

Back 30

Owners

Group owners

Others

Front 31

What does read, write, and execute mean?

Back 31

Read = ability to view the directory or read a file

Write = ability to edit the directory or write content in a file

Execute = ability to go into the directory or run the script in a file

Front 32

Why can't a regular user be able to access or list contents in the /root directory?

Back 32

They aren't in the wheel group.

Front 33

What command changes permissions of a file or directory?

Back 33

chmod ### filename

Or

chmod u+rwx, g+rwx, o×rwx

Front 34

What command changes user ownership in a file or directory?

Back 34

chown -R username filename

-R makes changes recursively

Front 35

What command changes group ownership in a file or directory?

Back 35

chgrp -R groupname filename

Front 36

What is ssh?

Back 36

Remote login between 2 devices.

Front 37

What is ssh keyless authentication?

Back 37

Allows you to remote login wothoutna password.

Front 38

What is umask?

Back 38

A subtraction mask that sets new permissions for newly created files or directories.

Command = umask ###

Front 39

When you login to a user interactively what files are loaded to configure the user's environment?

Back 39

/etc/profile

/etc/bashrc

~/.bash_profile

~/.bashrc

Front 40

When you login to a user non-interactively what files are loaded to configure the user's environment?

Back 40

/etc/bashrc

~/.bashrc

Front 41

What are the default umask values for root and users?

Back 41

Root = 002

Users = 022

Front 42

How can you make umask boot persistent?

Back 42

vi into /etc/profile and making the changes.

Front 43

What is yum?

Back 43

A package manager to install, remove, and update packages.

Front 44

What is the difference between yum and rpm?

Back 44

Yum will download the package and resolves dependencies.

Rpm downloads one package at a time and does not resolve dependencies.

Front 45

What are the number values for read, write, and execute?

Back 45

Read = 4

Write = 2

Execute = 1

Front 46

What is the umask cap for files and directories?

Back 46

Files = 666

Directories = 777

Front 47

What is a process?

Back 47

A running instance of an executable program.

Front 48

What are the 3 types of processes?

Back 48

Interactive

Batch

Daemon

Front 49

What is an interactive process?

Back 49

Processes that are initiated by a user.

Example: the vi command

Front 50

What is a batch process?

Back 50

Processes that are scheduled.

Front 51

What is a daemon process?

Back 51

Processes that are constantly running in the background.

Front 52

What are the 4 states of processes and what do they mean?

Back 52

Running = currently running

Sleeping = waiting for conditions to be met before it can be executed

Stopped = has been suspended

Zombie = hanging due to the parent process being killed or terminated

Front 53

What is the nice value?

Back 53

A value between -20 and +20. It shows processes from most prioritized (-20) to least prioritized (+20)

Front 54

What command creates ssh keys?

Back 54

ssh-keygen -t rsa

Front 55

What are authorized keys?

Back 55

Keys that can be used to login to a user.

Front 56

What is the known_hosts file?

Back 56

The file that contains your private and public keys.

Front 57

What is a PID?

Back 57

Process ID. An identifier for actively running processes.

Front 58

What are 2 ways to stop a process?

Back 58

Graceful kill (-15)

Forceful kill (-9)

Front 59

What is a service?

Back 59

A program that always runs on your server.

Front 60

What command is used to manage services?

Back 60

systemctl

Front 61

What is a port?

Back 61

A communication end point on an OS for processes and network services.

Front 62

What command changes hostnames on a vm?

Back 62

hostnamectl set-hostname newhostname

Front 63

What is a hostname?

Back 63

An alias assigned to a machine.

Front 64

What is a firewall?

Back 64

A set of rules that manage what network traffic is allowed to enter and leave the system.

Front 65

What is the location of your services?

Back 65

/etc/services

Front 66

What is the location of your hostnames?

Back 66

/etc/hosts

Front 67

What is the location of your firewalls?

Back 67

/etc/firewalld/zones

Front 68

What is SELinux?

Back 68

An extra layer of security on top of the linux system.

Front 69

What are the 3 modes of SELinux and explain each one?

Back 69

Enforcing = actively enforces security policies and log action violations

Permissive = does not actively enforce security policies but allows policies to be logged

Disabled = neither enforces nor logs

Front 70

What is the location of SELinux logs?

Back 70

/var/log/audit.log

Front 71

What are the 3 types of backups and explain each one?

Back 71

Full = a backup of the entire system's data

Incremental = a backup of newly added or changed data

Differential = utilizes both full and incremental

Front 72

What does compressing a file mean?

Back 72

To reduce the size by compacting it.

Front 73

What is archiving?

Back 73

Putting together multiple files and directories into 1 single file.

Front 74

What is SCP?

Back 74

Secure copy. A method to send copies of file and directories over to another machine.

Front 75

What port does SCP use?

Back 75

Port 22

Front 76

What is rsync?

Back 76

The same as SCP except it can also compress file and directories while they're being sent.

Front 77

What is a cronjob?

Back 77

A scheduler that can automate commands based on how you set the schedule.

Front 78

What is globbing and wildcards?

Back 78

Methods used in the command line to match patterns of file names or paths.

Front 79

What is redirection?

Back 79

A process that allows you to take the output of a command and redirect it into a file.

Front 80

What are the different redirection methods?

Back 80

> = redirects the standard output into a file

>> = redirects the standard output and appends it into a file

1> = redirects the standard output into a file

2> = redirects the standard error into a file

& = redirects standard output and error into a file

&& = used to execute the command following it only if the preceding command succeeds

echo $? = used to display the exit status of the previously executed command

Front 81

What does the pipe command do?

Back 81

It allows the chaining of multiple commands.

Front 82

What is the grep command used for?

Back 82

Searching text within a file.

Front 83

What is the sed command used for?

Back 83

Substitute texts in files.

Front 84

What is the awk command used for?

Back 84

Prints data organized in columns.

Front 85

What is the cut command used for?

Back 85

Prints data in a file from a range of characters specified in the command.

Front 86

What is the sort command used for?

Back 86

Used to sort lines of text.

Front 87

What is a hard link?

Back 87

An exact copy of a file. Only used for files. Shares the same inode number as the original file.

Front 88

What is a soft link?

Back 88

Does not have the contents of the original file. Points to the file's path. For files and directories. Has a different inode number than the original file.

Front 89

What is a runlevel?

Back 89

A state or mode that the operating system can be in.

Front 90

What are the different modes of runlevels?

Back 90

1 = single user mode without networking

2 = multi user mode without networking

3 = multi user mode with networking

4 = custom runlevel

5 = GUI with networking

6 = reboot

Front 91

What is the boot process?

Back 91

BIOS = does a firmware check on your system and loads the MBR

MRB = grabs the boot loader AKA the GRUB

GRUB = locates and executes the kernel

Kernel = mounts the file system and sets up the first process

Systemd = initiates required processes and services for the system to run

Runlevel = determines how the system will behave

Front 92

What is systemd?

Back 92

The service manager that handles all processes after the boot process.

Front 93

What is partitioning?

Back 93

Splitting of a hard disk.

Front 94

How many partitions can you make on a single hard disk?

Back 94

14

3 primary partitions

11 logical partitions through the extended partition

Front 95

What does it mean to format a partition?

Back 95

Makes block devices into file based storage devices which allows reading and writing on the file system.

Front 96

What is LVM?

Back 96

Logical volumes which are used to dynamically allocate, resize, and manage your storage.

Front 97

How do you create a logical volume?

Back 97

Create a physical volume (pvcreate) = storage device or partition that serves as a building block for creating logical partitions.

Create volume groups (vgcreate) = a collection of physical volumes that merge together to provide dynamic storage for logical volumes.

Create logical volume (lvcreate) = a flexible storage that allows resizing and dynamic allocation of storage space withing the volume group.

Format the partition (mkfs)

Front 98

What is swap space?

Back 98

A storage device that reserves storage when your RAM is getting full.

Front 99

What is NFS?

Back 99

Allows you to set storage locations on a network that clients can access. Uses port 2049.

Front 100

What is AUTOFS and what is a key in AUTOFS?

Back 100

It essentially the same as NFS however AUTOFS only mounts the file when it is accessed. A key is a timeout range you can set it to.

Front 101

What is the main configuration file for AUTOFS?

Back 101

/etc/auto.master

Front 102

What service and port does FTP use?

Back 102

Service = vsftpd (very secure file transfer protocol daemon)

Port = 20/tcp and 21/tcp