# Navigate directories
cd /path
pwd
ls -la

# Create/delete
mkdir folder
touch file.txt
rm file.txt
rm -r folder

# Copy/move
cp source dest
mv old new

# View files
cat file.txt
less file.txt
tail -f file.txt
head -n 20 file.txt

# Find files
find / -name "*.txt"
locate filename
grep "pattern" file.txt

# Change permissions
chmod 755 file.txt
chmod u+x script.sh

# Change owner
chown user:group file.txt
sudo chown root file.txt

# View permissions
ls -l
stat file.txt

# Network info
ifconfig
ip addr
netstat -tlnp
ss -tlnp

# DNS
nslookup example.com
dig example.com

# Connectivity
ping example.com
curl https://example.com
wget file.zip
traceroute example.com

# SSH
ssh user@host
ssh -i key.pem user@host
scp file.txt user@host:/path/

# User management
adduser newuser
passwd username
usermod -aG sudo username
deluser username

# Disk usage
df -h
du -sh /path
du -sh /*

# Processes
ps aux
top
kill PID
pkill processname

# Services
systemctl start service
systemctl stop service
systemctl status service
systemctl restart service