Terminal Format & User Paths

Path Description
~ or /home/username/ Your Linux home directory
/usr/ Installed programs and libraries
/etc/ System configuration files
/var/ Logs, cache, and system files
/mnt/c/Users/Merrick/ Your Windows user directory
/mnt/c/ Mounted C: drive from Windows
/mnt/d/ Mounted D: drive (if available)

Terminal Prompt Format: username@hostname:~$

Common Commands

Command Description
sudo do-release-upgrade Update Ubuntu
pstree -p Show process tree
ps aux Show process tree in table
lsb_release -a Show Linux distribution details
whoami Display the current username
hostname Show the system hostname
df -h Show disk usage in a human-readable format
alias ls='ls -a --color=auto’ Make ls always show hidden files with color
ls List files and directories in the current directory
ls -a List all files, including hidden ones (.*)
ls -lah List files with details in a human-readable format
ls -l List files with details
pwd Print the current working directory.
nano Open the nano text editor to create or edit files.

File & Directory Operations

Command Description
touch filename Create an empty file
mkdir foldername Create a new directory
rm filename Remove files and directories (no recovery!)
mv filename Move files
echo "text” Print text to the terminal
mkdir my_files Create a directory named my_files
cd my_files Change to the my_files directory
touch file1.txt file2.txt Create multiple empty files (file1.txt, file2.txt, etc.)
echo "Hello World" > file.txt Create file.txt and write "Hello World" into it
echo "New Line" >> file.txt Append "New Line" to file.txt

File Content & Permissions

Command Description
wc -l file.txt Count the number of lines in file.txt
chmod +x script.sh Give execute permission to script.sh
./script.sh file1.txt file2.txt Run the script with file1.txt and file2.txt as arguments
cat result.txt Display the contents of result.txt
tee -a result.txt Append output to result.txt while displaying it on the screen
bash script.sh Run script.sh using Bash

Shell Commands

Command Description
echo $SHELL Show your default shell
echo $0 Show the current shell
echo $$ Show the process ID (PID) of your current shell
cat /etc/shells List available shells
ps -p $$ Display process information of the current shell

Useful Shortcuts

Shortcut Action
Ctrl + L Clear terminal screen
Ctrl + C Stop a running process
Ctrl + D Logout / exit the terminal
Tab Auto-complete file/folder names
!! Repeat the last command
!<command> Run the most recent command that starts with <command>
history grep <keyword>

APT (Advanced Package Tool)

# Update & Upgrade Packages
sudo apt update                  # Update package lists (does not install updates)
sudo apt upgrade -y              # Upgrade all installed packages
sudo apt full-upgrade -y         # Upgrade packages and handle dependencies
sudo apt dist-upgrade -y         # Similar to full-upgrade, but with different dependency handling

# Install & Remove Packages
sudo apt install <package> -y    # Install a specific package
sudo apt remove <package> -y     # Uninstall a package (keep config files)
sudo apt purge <package> -y      # Completely remove a package (including config)
sudo apt autoremove -y           # Remove unnecessary dependencies

# Clean Package Cache
sudo apt clean                   # Clear downloaded package cache
sudo apt autoclean               # Remove old package files

# List Installed Packages
apt list --installed             # Show all installed packages
dpkg --get-selections | grep -v deinstall  # Alternative way to list installed packages

# Check a Specific Package
dpkg -l | grep <package>         # Check if a package is installed
apt list --installed | grep <package>  # Alternative method
apt show <package>               # Show package details (description, version, dependencies)

# Show Manually & Automatically Installed Packages
apt-mark showmanual              # List only manually installed packages
apt-mark showauto                # List automatically installed packages

# Find User-Installed Packages from History
grep -E "Commandline: apt install" /var/log/apt/history.log  # Show all manual apt install commands