CHAPTER TWO: CLIMBING THE TREE

Question 1

Directory: /

Answer 1

The root. Start of everything

Question 2

Directory: /home

Answer 2

Default location for regular users files

Question 3

Directory: /root

Answer 3

Home folder for root user

Question 4

Directory: /etc

Answer 4

System settings and configuration files

Question 5

Directory: /bin

Answer 5

Essential programs used by everyone

Question 6

Directory: /sbin

Answer 6

Systems used by admins

Question 7

Directory: /lib

Answer 7

Code libraries used by programs

Question 8

Directory: /opt

Answer 8

Extra software

Question 9

Directory: /tmp

Answer 9

Temporary files (cleared often)

Question 10

Directory: /var

Answer 10

Logs and files that constantly change

Question 11

Directory: /proc

Answer 11

Info about running processes

Question 12

Directory: /usr

Answer 12

Shared files and apps for all users

Question 13

Root user

Answer 13

The superuser who is allowed to do anything on the system. Can install software, add users, manage disk partition’s. /root is the home directory.

Question 14

Directory separator

Answer 14

In linux root is the forward slash / and also the directory separator or path separator. The first / is the root and after that they become path separators

Question 15

Current working va parent directories

Answer 15

1. Current working directories (.)
2. Parent directories (..)

Question 16

Command: cd

Answer 16

Change directory

Question 17

Go to root directory with cd

Answer 17

Cd/

Question 18

Go to your home directory with cd

Answer 18

Cd~

Question 19

Go back one folder with cd

Answer 19

Cd..

Question 20

Go back to where you just came from with cd

Answer 20

Cd-

Question 21

Go back into a specific path with cd

Answer 21

Cd/home/username/desktop

Question 22

Listing files with is to show more detail

Answer 22

Is-l

Question 23

Include hidden files with is

Answer 23

Is-a

Question 24

Combine both more detail and hidden files with is

Answer 24

Is-la

Question 25

How do you know what file is hidden?

Answer 25

Starts with a dot : .bashrc

Question 26

Absolute path

Answer 26

Starts with / and points from the root. It is simply the full path of that file and it always begins with a forward slash

Question 27

Relative path

Answer 27

A relative path file never starts with the root and is always relative to the current working directory

Question 28

.

Answer 28

Current directory

Question 29

..

Answer 29

Parent directory

Question 30

~

Answer 30

Your home directory

Question 31

Argument

Answer 31

Command line argument is simply any filename or data that is provided to a command as an input. In linux we use verb pass when talking about command options and arguments.

Question 32

Touch command has what two purposes

Answer 32

1. Create new empty files 2. Update timestamps on existing files

Question 33

Touch command creating new empty files

Answer 33

Example: touch file1.txt This creates a new file named file1.txt in your current folder. If the file already exists, it doesn’t change the contents just updates the timestamp.

Question 34

Touch command updating timestamps on existing files

Answer 34

Each file has a timestamp what shows when it was last accessed or modified. Touch can update the timestamps without changing the contents.

Question 35

Touch command for both access and modification

Answer 35

Touch filename.txt

Question 36

Touch command only update modification timestamps

Answer 36

Touch-m filename.txt

Question 37

Touch command update only access time

Answer 37

Touch-a filename.txt

Question 38

Make directory (mkdir)

Answer 38

Used to create new folders (directories) in filesystem.

Question 39

Create multiple folders at once with mkdir

Answer 39

Mkdir folder1 folder2 folder3

Question 40

Create nested (sub) directories with mkdir

Answer 40

Use the -p option to create a full path even without middle folders Mkdir -p parent/child/grandchild

Question 41

Using curly brace for multiple subfolders with mkdir

Answer 41

Mkdir -p main/{docs,image,videos}

Question 42

Combine option: -1

Answer 42

Long listing (permissions, size, time)

Question 43

Combine option: -a

Answer 43

Show hidden files

Question 44

Combine option: -d

Answer 44

Show directory itself, not its contents

Question 45

Combine option: -t

Answer 45

Sort by modification times (newest first)

Question 46

Combine option: -u

Answer 46

Sort or show access time

Question 47

Combine option: -r

Answer 47

Reverse order

Question 48

Combine option: -R

Answer 48

Show all subfolders (recursive)

Question 49

What does cat file.txt do?

Answer 49

Shows the contents of a text file

Question 50

What does whoami do?

Answer 50

Shows the current user

Question 51

What does su username do?

Answer 51

Switch to another user (need password for this)

Question 52

What is cron?

Answer 52

It’s like a personal assistant for linux that handles scheduling tasks for you. Typically used for handling more than one task

Question 53

What is crontab?

Answer 53

Cron table. It’s a file where you list the tasks you want cron to preform and when to preform them.

Question 54

What is a cron job

Answer 54

Each line in this the crontab represents a scheduled taks. This is a cron job.

Question 55

Command: crontab -I

Answer 55

View exisiting jobs.

Question 56

Command: crontab -e

Answer 56

Edit your cron jobs

Question 57

Command: crontab -r

Answer 57

Remove cron jobs

Question 58

Keywords in cron: @reboot

Answer 58

Run once when the system starts

Question 59

Keywords in cron: @daily

Answer 59

Run once a day at midnight

Question 60

Keywords in cron: @weekly

Answer 60

Once a week at midnight on sunday

Question 61

Keywords in cron: @monthty

Answer 61

Once a month at midnight on the first day

Question 62

What is the at command

Answer 62

Almost like a reminder note for your computer. It lets you schedule your computer to do one task one time in the future. Used to run a command at a specific time.

Question 63

How to use at command

Answer 63

1. Check if its installed using -v. If it shows a version number your good if it says something like command nut found. Install it using sudo apt install at 2. Start the atd service (which is a background helper that runs your scheduled task) type sudo systemctl start atd 3. Schedule your task and press crtl + alt + d to save and exit

Question 64

How to check what you have scheduled with at command

Answer 64

Type Atq

Question 65

Remove task with at command

Answer 65

Atrm [job number]

Question 66

What is linux automation

Answer 66

Automation is like having a robot do task like cleaning files or copying date for you, exactly how you want, every single time. Linux Auto teaches your computer to do stuff automatically

Question 67

What tools help with linux automation

Answer 67

1. The shell (read, talk and type to your computer. Most common is bash) 2. Shell scripts (these are just files you write down a bunch of commands in the order you want them to run) - nano nyscript.sh - this opens simple editor - to run script: bash myscript.sh 3. Crontab (schedules planner) 4. Ansible (more advanced) it is like a super-powered automation tool. Most for many computers at once. Uses something called playbooks (like scripts just fancier)