Linux Commands Cheat Sheet

man [command]             # Shows the manual page for a command
help [built-in-command]   # Shows the help page for a built-in command
[command] --help          # Displays help options for a command
man -k [search_term]      # Searches manual pages for matching keywords (like apropos)
man -k "multiple words"   # Searches manual pages for matching keywords (like apropos)
appropos [search_term]    # Searches manual pages for matching keywords
mandb                     # Updates manual pages
info [command]            # Shows detailed GNU info documentation for a command
curl cheat.sh/[command]   # Fetches command cheatsheet from cheat.sh

pwd                      # Prints the current working directory (shows the full path)

ls                       # Lists current directory contents
ls -ld [directory]       # Lists details (long format) of a specific directory without showing its contents
ls -l [file]             # Lists detailed information of a file (permissions, owner, size, timestamp)
ls -R                    # Recursively lists subdirectories and their contents

tree                     # Displays directory structure in a tree-like format
tree -a                  # Includes hidden files and directories in the tree output
tree -h                  # Shows file sizes in a human-readable format (e.g., KB, MB)
tree -d                  # Displays only directories in tree view
tree -L 2                # Limits tree depth to 2 levels (change 2 as needed)

ls -la                   # Lists all files (including hidden files starting with .) in long format
ls -lh                   # Lists files in long format with human-readable sizes (e.g., 1K, 234M)
ls -lSh                  # Lists files in long format sorted by size (largest first)
ls -lSr                  # Lists files in long format sorted by size (smallest first)
ls -lt                   # Lists files sorted by modification time (newest first)
ls -ltr                  # Lists files sorted by modification time in reverse (oldest first)
ls -lr                   # Lists files in long format sorted by name in reverse (Z to A)

cd [directory]           # Changes the current working directory to the specified one
cd -                     # Switches to the previous working directory
cd ~                     # Changes to the current user's home directory
cd                       # Same as 'cd ~'; changes to home directory
cd ..                    # Moves up one directory level
cd ../../../             # Moves up three levels in the directory structure

touch [filename]        # Creates an empty file
cat [filename]          # Displays file contents
nano [filename]         # Opens file in Nano text editor
vim [filename]         # Opens file in Vim text editor
less [filename]         # Views file content page by page
head [filename]         # Shows the first 10 lines of a file
tail [filename]         # Shows the last 10 lines of a file
file [filename]         # Determine file type 
cp [source] [target]       # Copies files or directories
mv [source] [target]       # Moves or renames files or directories
rm [file]                  # Deletes files
rm -r [directory]          # Deletes directories recursively
rm -rf [directory]         # Force deletes directories recursively (dangerous!)
mkdir [directory]           # Creates a new directory
mkdir dir1 dir2 dir3     # Creates multiple directories at once
mkdir -p a/b/c         # Creates parent and nested directories recursively
rmdir [directory]     # Removes an empty directory
rmdir -p a/b/c         # Removes nested empty directories up the path

sudo apt update                 # Updates package lists
sudo apt upgrade                # Upgrades all packages
sudo apt install [package]      # Installs a package
sudo apt remove [package]       # Removes a package

sudo dnf install [package]      # Installs a package
sudo dnf remove [package]       # Removes a package

ip a                  # Displays IP address and interface info
ping [host]           # Sends ICMP echo to a host
ifconfig              # Shows network interfaces (legacy)
netstat -tuln         # Lists open ports and listening services
curl [url]            # Retrieves content from a URL
wget [url]            # Downloads file from a URL

whoami                 # Prints the current user
passwd                 # Changes current user’s password
sudo [command]         # Runs command with superuser privileges
adduser [username]     # Adds a new user
deluser [username]     # Deletes a user
chsh -s [shell_path]   # Change current user's default shell

ps aux                # Lists running processes
top                   # Real-time view of system processes
htop                  # Interactive process viewer (needs installation)
kill [PID]            # Terminates process by PID
killall [name]        # Terminates all processes by name

uname -a              # Displays system information
df -h                 # Shows disk usage in human-readable format
free -h               # Displays memory usage
uptime                # Shows how long the system has been running
history               # Shows previously used commands
clear                 # Clears the terminal screen