Linux Command Cheat Sheet

Cheet says: The command line is your superpower!

Navigation

pwd                 # Print working directory
ls                  # List files
ls -la              # List all with details
cd /path            # Change directory
cd ~                # Go home
cd -                # Go to previous directory

File Operations

Create
touch file.txt      # Create empty file
mkdir folder        # Create directory
mkdir -p a/b/c      # Create nested directories

Copy
cp file.txt backup.txt
cp -r folder/ backup/   # Recursive

Move/Rename
mv old.txt new.txt
mv file.txt /path/

Delete
rm file.txt
rm -r folder/       # Recursive
rm -rf folder/      # Force (careful!)

View
cat file.txt        # Print entire file
less file.txt       # Scrollable view
head -20 file.txt   # First 20 lines
tail -20 file.txt   # Last 20 lines
tail -f log.txt     # Follow (live updates)

Searching

Find files
find . -name "*.txt"
find . -type f -size +100M    # Files > 100MB
find . -mtime -7              # Modified last 7 days

Search content
grep "pattern" file.txt
grep -r "pattern" ./          # Recursive
grep -i "pattern" file.txt    # Case insensitive
grep -v "pattern" file.txt    # Invert match

Text Processing

Sort
sort file.txt
sort -n file.txt    # Numeric
sort -u file.txt    # Unique

Count
wc file.txt         # Lines, words, chars
wc -l file.txt      # Lines only

Unique
uniq file.txt       # Remove adjacent duplicates
sort file.txt | uniq

Cut columns
cut -d',' -f1 file.csv

Replace
sed 's/old/new/g' file.txt
sed -i 's/old/new/g' file.txt  # In-place

Permissions

View
ls -la

Change permissions
chmod 755 file.sh       # rwxr-xr-x
chmod +x file.sh        # Add execute
chmod -w file.txt       # Remove write

Change owner
chown user:group file.txt

Common permissions:
644 - rw-r--r-- (files)
755 - rwxr-xr-x (executables, directories)
600 - rw------- (private files)

Process Management

View processes
ps aux
top
htop                # Better (install separately)

Find process
pgrep nginx
ps aux | grep nginx

Kill process
kill PID
kill -9 PID         # Force
pkill nginx         # By name
killall nginx

Background jobs
command &           # Run in background
jobs                # List jobs
fg                  # Bring to foreground
bg                  # Send to background
nohup command &     # Keep running after logout

Disk & Memory

Disk usage
df -h               # Filesystem usage
du -sh folder/      # Folder size
du -sh * | sort -h  # Sorted sizes

Memory
free -h

Find large files
du -a . | sort -rn | head -20

Networking

Show IP
ip addr
hostname -I

Test connectivity
ping google.com
curl -I https://example.com

DNS lookup
dig example.com
nslookup example.com

Ports
ss -tulpn           # Listening ports
netstat -tulpn      # Alternative

Package Management

Debian/Ubuntu (apt)
sudo apt update
sudo apt install package
sudo apt remove package
apt search package

Arch (pacman)
sudo pacman -Syu
sudo pacman -S package
sudo pacman -R package
pacman -Ss package

RHEL/CentOS (yum/dnf)
sudo dnf update
sudo dnf install package

System Info

uname -a            # Kernel info
cat /etc/os-release # Distro info
hostname            # Hostname
uptime              # Uptime
whoami              # Current user
id                  # User details

Redirection & Pipes

command > file      # Output to file (overwrite)
command >> file     # Output to file (append)
command 2> file     # Errors to file
command &> file     # Both to file
command1 | command2 # Pipe output

Examples
ls -la > listing.txt
cat file.txt | grep "pattern" | sort