Source

Commands: https://ss64.com/bash/
Commands: https://www.codecademy.com/learn/learn-the-command-line
Commands: https://www.javatpoint.com/linux-tutorial
Configurations: https://www.server-world.info/en/note?os=Fedora_32
Docs: https://docs.fedoraproject.org/en-US/docs/
RHEL-Trainig: https://www.redhat.com/en/services/training/rh024-red-hat-linux-technical-overview
HowTo: https://www.howtoforge.com/
Software-Flat: https://flathub.org/
Software-Snap: https://snapcraft.io/
News: https://vitux.com/

Folders & Files

/etc/bashrc
/etc/profile
/etc/environment					# Configuration of Entviroment
/etc/hosts
...
/etc/fstab						# Configuration of Disks
/etc/mtab						# Configuration of Mount Devices
/etc/hostname						# Where Hostname is saved
/etc/init.d/						# Skripts that will be executed at system start up
/etc/apt/sources.list.d				        # Ubuntu Reposotiery-Folder
/etc/yum.repos.d/					# Fedora Reposotiery-Folder
/etc/sysconfig/network-scripts/ifcfg-eth0	        # Network-cfg
/etc/fonts/conf.d
/etc/fonts/fonts.conf				        # Font-Configurations
/etc/fonts/local.conf				        # Font-Configurations
..
/usr/share/fonts/					# Users Fonts
/usr/share/themes/					# Users Themes
...							# ..
~/.fonts.conf.d					        #
~/.fonts.conf						#
...
~/.bashrc						# Shell-Config
~/.bash_profile					        #
~/.bash_login						#
~/.themes/						# Location of Themes
~/.icons/						# Location of Icons

Commands

Basics

$ find . -name testfile.txt    # Find a file called testfile.txt in current and sub-directories
$ mv $SOURCE $TARGET           # move folder
$ ln -s $SOURCE $LINK          # create symbolic link
$ ls -l $LINK                  # list symbolic link
$ unlink $LINK                 # unlinke symbolic link

$ toch file.txt                       # create new empty file.exe
$ echo "Hallo World"                  # Print out 'Hallo World'
$ echo "Hallo World" > file.txt       # To overwrite the content of file.txt
$ echo "Hallo World" >> file.txt      # To append to the end of file.txt
$ cat file.txt                        # Print out the content of file.exe
$ cat source.txt > file.txt           # To overwrite the content of file.txt
$ cat source.txt >> file.txt          # To append to the end of file.txt

chmod & chown & chgrp

# USERS >> u:Owner, g:Group, o:Others, a:Everyone:[ugo]
# OPERATION  >> +:Add, -:Remove, =:Only
# PERMISSIONS >> r:Read, w:Write, x:Execute

$ chmod $USERS $OPERATION $PERMISSIONS $FILE_NAME
$ chmod uga+rwx -R $FILE_NAME
$ chmod u=rwx,g=rwx,o=rwx $FILE_NAME
$ chmod -R 0777 ./*                              # Everyone can do anything

$ chown $OWNER_NAME $FILE_NAME
$ chgrp $GROUP_NAME $FILE_NAME

System

hostnamectl set-hostname new-name

Shell

timestamp=$(date +%Y%m%d%H%M%S)
nano ~/.bashrc                                   # Auto start the agent
-----------------------------------------
if [[ "$(ps -u $USER | grep ssh-agent | wc -l)" -lt "1" ]]; then
    ssh-agent -s >~/.ssh/ssh-agent
    . ~/.ssh/ssh-agent >/dev/null
    ssh-add ~/.ssh/id_rsa
else
    . ~/.ssh/ssh-agent >/dev/null
fi
-----------------------------------------

User

sudo adduser –G [GROUP-ID] [USER-ID]					# Add a new Group & User
sudo deluser [USER-ID]							# Delete User
sudo remove [USER-ID]							# Remove User
...
echo "USER-ID ALL=(ALL) NOPASSWD: ALL" >> /etc/sudoers
usermod -aG sudo [USER-ID]						# Add User to Sudo-Group
sudo visudo								# Add “USER-ID ALL=(ALL:ALL) ALL”
id	
...
su [USER-ID]								# Change User in current Folder
su - [USER-ID]								# Change User in User Home-Folder
sudo bash								# Login as root
sudo -i									# Login as root
sudo -i –u [USER-ID]							# Login in account user
passwd [USER-ID]							# Change User Password
gpasswd -a user-ID group-ID						#

Locale & Keymap & Time

/etc/environment
/etc/locale.conf
~/.config/locale.conf
...
localectl
localectl list-locales
localectl set-locale LANG=en_US.UTF-8
...
localectl
localectl list-keymaps
localectl set-keymap de
...
timedatectl
timedatectl list-timezones
timedatectl set-timezone Europe/Berlin

SSH

Settings

$ sudo dnf install openssh-client
$ sudo dnf install openssh-server
$ sudo systemctl restart sshd.service
$ sudo systemctl enable sshd.service

Key-Typs: RSA algorithm and DSA algorithm.

$ ~/.ssh/id_rsa.pvt           # The file contains the RSA private key.
$ ~/.ssh/id_rsa.pub           # The file contains the RSA public key.
$ ~/.ssh/authorized_keys      # The file contains the keys that can be used for logging into system.
...
$ chmod go-w ~/
$ chmod 700 ~/.ssh
$ chmod 600 ~/.ssh/authorized_keys

sudo nano /etc/ssh/ssh_config
sudo nano /etc/ssh/sshd_config
------------------------------
RSAAuthentication yes
PubkeyAuthentication yes
AuthorizedKeysFile %h/.ssh/authorized_keys
PasswordAuthentication no      # Yes: Can login with Password; No: Can’t login with Password
------------------------------
/etc/init.d/ssh restart

Generate Key

$ ssh-keygen -t rsa -f ~/.ssh/id_rsa -C "username@mail.com"     # Generate prv and pub Key
$ cp ~/.ssh/id_rsa.pub ~/.ssh/authorized_keys
$ chmod -R 600 ~/.ssh/id_rsa
$ ssh -i ~/.ssh/id_rsa username@server.com                      # Login server with prv-key       	
...
$ ssh-copy-id –i $PATH_PUBLIC_KEY $USERNAME@IP_ADDRESS	     # Copy Pub-Key to server
$ cat ~/.ssh/id_rsa.pub | ssh user@hostname "mkdir -p ~/.ssh && cat >> ~/.ssh/authorized_keys"
$ ssh user@hostname "echo `cat ~/.ssh/id_rsa.pub` >> ~/.ssh/authorized_keys"

ssh-agent & ssh-add

src: https://blog.tinned-software.net/manage-ssh-keys-with-the-ssh-agent/

$ vim ~/.ssh/config                            # Add key automatically to a running agent
-----------------------------------
AddKeysToAgent yes
## Home nas server ##
Host nas01
     HostName 192.168.1.100
     User root
     IdentityFile ~/.ssh/nas01.key
Host github.com
     IdentityFile ~/.ssh/github.key
-----------------------------------

$ eval $(ssh-agent -s)                          # Start the agent
$ ssh-add ~/.ssh/id_rsa                         # Add the defualt key
$ ssh-add -l                                    # List keys
$ ssh-add -d /home/user/.ssh/id_rsa             # Remove key
$ ssh-add -D                                    # Remove all Keys
$ eval $(ssh-agent -s -k)                       # Kill the agent
$ ssh -T git@github.com
$ ssh -T git@bitbucket.org

Firewall

Service

cmd: status, start, stop, restart, reload, enable, disable

$ sudo systemctl status firewalld
$ sudo systemctl status NetworkManager
$ sudo systemctl status network
...
sudo firewall-cmd --reload

Zone

sudo firewall-cmd --get-zones
sudo firewall-cmd --get-active-zones
sudo firewall-cmd --get-default-zone
sudo firewall-cmd --get-services
sudo firewall-cmd --list-all
sudo firewall-cmd --list-ports

Zone-home

sudo firewall-cmd --zone=home --list-all
sudo firewall-cmd --zone=home --list-ports
sudo firewall-cmd --zone=home --list-services

Zone: Configuration

sudo firewall-cmd --set-default-zone=home
sudo firewall-cmd --zone=home --change-interface=eth0
sudo firewall-cmd --zone=home --add-service=http
sudo firewall-cmd --zone=home --add-port=80/tcp --permanent

New Zone "boxblue"

sudo firewall-cmd --permanent --new-zone=boxblue
sudo firewall-cmd --permanent --zone=boxblue --add-service=ssh
sudo firewall-cmd --permanent --zone=boxblue --add-service=http
sudo firewall-cmd --permanent --zone=boxblue --add-service=https
sudo firewall-cmd --permanent --zone=boxblue --add-service=samba
sudo firewall-cmd --permanent --zone=boxblue --add-port=80/tcp
sudo firewall-cmd --permanent --zone=boxblue --add-port=22/tcp
sudo firewall-cmd --permanent --zone=boxblue --change-interface=wlp0s19f2u1
sudo firewall-cmd --permanent --set-default-zone=boxblue

Vim

Source: https://vim.rtorr.com/

Esc   Exit the current mode.
i     Enter "Insert mode" for inserting text.
v     Enter "Visual mode" for character.
V     Enter "Visual mode" for line.
:     Enter "Command mode". 
...
h     Move Left
j     Move Down
k     Move Up
l     Move Right
...
ggVG  Select hole text
...
u     Undo the last operation.
d     Delete or Cut selected item.
y     Copy line.
p     Paste storage buffer after the cursor.
...
:q    Quit Vim.
:q!   Quit Vim without saving the changes.
:w    Save the file
:wq   Save the file and quit Vim.
:w $FILE_NAME Save the file with the filename "yx".

Package Manager

Ubuntu

Location: /etc/apt/sources.list

fedora

Location: /etc/yum.repos.d/
DNF: Dandified YUM

sudo rpm –i filename.rpm
...
dnf --version
dnf history
...
sudo ls /etc/yum.repos.d/
sudo dnf repolist
sudo dnf repolist all
sudo dnf config-manager --add-repo <repo-url>
sudo dnf config-manager --set-enabled <repo-id>
sudo dnf config-manager --set-disabled <repo-id>
sudo dnf --enablerepo=<repo-id>
sudo dnf --disablerepo=<repo-id>
sudo dnf copr [enable|disable|remove|list|search] <parameters>
...
sudo dnf list
sudo dnf list installed
sudo dnf list available
sudo dnf check-update
sudo dnf list updates
...
sudo dnf update
sudo dnf upgrade
sudo dnf update vim
sudo dnf search vim
sudo dnf download vim
sudo dnf install vim
sudo dnf reinstall vim
sudo dnf remove vim
sudo dnf erase vim
...
sudo dnf grouplist
sudo dnf grouplist -v
sudo dnf group info 'Development Tools'
sudo dnf groupinstall 'Development Tools'
sudo dnf groupupdate 'Development Tools'
sudo dnf groupremove 'Development Tools'
...
sudo dnf autoremove
sudo dnf clean all

Samba

src: https://www.server-world.info/en/note?os=Fedora_31&p=samba&f=1

$ /etc/samba/smb.conf
$ systemctl enable --now smb
$ firewall-cmd --add-service=samba --permanent
$ firewall-cmd --reload

Screen

screen -S <name>		# start screen new
screen -ls			# list screen runing
screen -r <name>		# reattach to a session name
..
Ctrl+a c			# create window
Ctrl+a n			# next window
Ctrl+a p			# previous window
Ctrl+a k			# kill window
Ctrl+a d			# detach window

Desktop Environments

Links

Display Server (Xorg/Wayland)

loginctl	                   # get session number from command output 
loginctl show-session 2 -p Type
...
vi /etc/gdm/custom.conf
vi /etc/gdm3/custom.conf
-----------------------
WaylandEnable=false                  # To disable Wayland
DefaultSession=gnome-xorg.desktop    # To enable Xorg
-----------------------

Sessions

ls -l /usr/share/xsessions/    # Lists installed desktop enviruments
echo $XDG_CURRENT_DESKTOP

Display Manager: lightdm

Install Display-Manager
Install Greeter
Setting Greeter

sudo dnf install lightdm                                                                         # Display-Manager
sudo dnf install elementary-greeter slick-greeter slick-greeter-cinnamon slick-greeter-mate      # Greeter-Typs
sudo dnf install lightdm-settings                                                                # For Settings
...
ls /usr/share/lightdm/lightdm.conf.d/        # System-Settings
ls /etc/lightdm/lightdm.conf.d/              # User-Settings
lightdm --show-config
...
[Seat:*]
greeter-session=slick-greeter
user-session=cinnamon

IT-OS-Admin-Linux

Contents

Source

Folders & Files

Commands

Basics

chmod & chown & chgrp

System

Shell

User

Locale & Keymap & Time

SSH

Settings

Generate Key

ssh-agent & ssh-add

Firewall

Service

Zone

Zone-home

Zone: Configuration

New Zone "boxblue"

Vim

Package Manager

Ubuntu

fedora

Samba

Screen

Desktop Environments

Links

Display Server (Xorg/Wayland)

Sessions

Display Manager: lightdm

Navigation menu

Search