The terminal

The basics

 Change the current directory

cd ~/code/ruby/ror/my_project

The long way

The short way

cd ~/c/r/ro/my_pro + tab

Thanks Zsh!

Create a folder

mkdir -p project1/code project2/presentation

mkdir :  create a folder

-p :  create also the subfolders

Final result : 

current folder -> project1 -> code

current folder -> project2 -> presentation

Create and edit a file

touch my_file.[file extension e.g. txt, rb, html,...]

Create a file: touch

Edit a file: nano

nano my_file.[file extension e.g. txt, rb, html,...]

save with CTRL + O and exit with CTRL + X

See the content of a file

cat my_file.txt

In the terminal

In Sublime Text

stt my_file.txt

The owners

The super user : root

apt-get update

Try :

Result :

permission denied

Now, do it with a 'sudo' :

sudo apt-get update

=> if you don't have the permission
to do something, you can do it
with the root permissions

Create a file or folder
with the root permissions

sudo nano a_file.txt

exit and open this file with a simple nano

=> if the root user creates a file/folder,
by default, the simple user doesn't have
any permissions on it

you don't have the permission...

List all files & folders
with their permissions

ls -l

 

This file is owned by the root user (and the root group)

Change the owner

sudo chown jc:jc hy.txt

To change the owner of a file/folder,
you NEED to be the owner of that file/folder

now, the owner of the file hy.txt is jc and the group jc

you can find your user name with the command 

whoami

you can change the owner of a directory with the argument : -R

sudo chown -R jc:jc a_folder

Manage the users

adduser JohnDoe

Add a user 

Change the password of a user

passwd JohDoe

Delete a user

deluser JohDoe

Permissions

Read-Write-Execute

d = directory

(- = file )

Read

Write

Execute

The owner

Read

Write

Execute

The group

 

Execute

Other 

Change the permissions

Permission number sum
--- 0 0+0+0
r-- 4 4+0+0
-w- 2 0+2+0
--x 1 0+0+1
rw- 6 4+2+0
-wx 3 0+2+1
r-x 5 4+0+1
rwx 7 4+2+1

example:              7       3          0                      

       owner-group-other

Change the permissions

(sudo) chmod 777 my_file.txt

For a file

For a directory (and its files)

(sudo) chmod 777 *

For everything in a file 

(sudo) chmod -R 777 my_direcotory

For everything in a file and in his directory  

(sudo) chmod -R 777 *

Some last useful commands

Remove files and folders

# DELETE A FILE
rm a_file

# DELETE A DIRECTORY
rm -r a_directory

# DELETE EVERYTHING 
rm *

# FORCE DELETING
rm -f a_file

Never run this command
sudo rm -rf /*

=> it would delete everything
(your OS, your files,...)

Ping a website

ping google.be

=> it gives the IP address of a website and
says if you are connected to the network

Stop the command with CTRL+C

Your network status

ifconfig

Ethernet connexion
= eth0

Wifi connexion
= wlan0

My local IP (ipv4) address

My local IP (ipv6) address

My MAC address (not real)

My local connexion (useless)

Change your MAC address

Each computer has a unique MAC address.
For privacy reasons, you can change your MAC address,
to connect to free wifi hotspots for instance.

examples of MAC addresses :

09-74-A3-D4-D1-43

ED-40-74-9F-EA-8A

BA-89-E7-1E-92-F4

.......

 

Change your MAC address on Ubuntu

sudo nmcli connection modify --temporary the_wifi_name 802-11-wireless.cloned-mac-address mac_addr

# THEN YOU SHOULD DO : 
nmcli connection up wifi_name

sudo ifconfig en0 xx:xx:xx:xx:xx:xx

Enjoy your terminal (and your privacy) ! :)

Change your MAC address on Mac

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