# Find files by name

find . -name "*.js" -not -path "*/node_modules/*"



# Find files modified recently (last 7 days)

find . -mtime -7 -type f



# Find large files (>100MB)

find /var/log -size +100M



# Search file contents

grep -r "TODO" src/ --include="*.js" -n



# Better grep with ripgrep (rg)

rg "functionName" --type js --context 2



# Quick file preview

head -n 20 app.js        # First 20 lines

tail -f /var/log/nginx.log # Follow log live

tail -n 50 error.log      # Last 50 lines

wc -l *.js                # Line counts

# Disk usage overview

df -h



# Directory sizes (sorted)

du -sh * | sort -hr



# What's eating disk space?

du -a /var | sort -nr | head -20



# Memory usage

free -h



# Top memory consumers

ps aux --sort=-%mem | head -10



# Real-time resource monitoring

htop          # Better top

iotop         # Disk I/O

iftop         # Network traffic

# Find process

ps aux | grep node

pgrep -f "node server"    # Just PIDs



# Kill process

kill 12345                 # Graceful

kill -9 12345              # Force kill

pkill -f "node server"     # Kill by name pattern



# Background & foreground

node server.js &           # Run in background

jobs                       # List background jobs

fg %1                      # Bring job 1 to foreground

Ctrl+Z                     # Suspend current job

bg                         # Resume suspended in background



# Keep running after logout

nohup node server.js > output.log 2>&1 &

# or better: use systemd/tmux/screen

# Test connectivity

curl -I https://example.com       # Headers only

curl -s https://api.example.com   # Silent mode

wget -qO- https://example.com     # Alternative to curl



# Port check

ss -tlnp | grep :3000             # Who's listening on port 3000?

netstat -tlnp | grep 80           # Alternative



# DNS lookup

dig example.com                    # Full DNS info

nslookup example.com              # Simple lookup



# Test connection

nc -zv localhost 3000              # Is port open?



# Download/upload speed test

curl -o /dev/null -w "%{speed_download}" http://speedtest.tele2.net/10MB.zip

# View file contents

cat config.json

less huge.log                      # Paginated view (q to quit)



# Column extraction

awk '{print $1, $3}' access.log    # Columns 1 and 3

cut -d',' -f2 data.csv            # CSV column 2



# Sort & unique

sort names.txt | uniq              # Remove duplicates

sort names.txt | uniq -c           # Count occurrences



# Replace text

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



# Stream editing

tail -f app.log | grep ERROR       # Live filter logs

# Current permissions

ls -la



# Change permissions

chmod +x script.sh                 # Make executable

chmod 644 file.txt                 # rw-r--r--

chmod 755 directory/               # rwxr-xr-x



# Change owner

chown user:group file.txt

chown -R www-data:www-data /var/www/



# Fix common permission issues

chmod -R 755 /var/www/html

find /var/www/html -type f -exec chmod 644 {} \;

# Create tar.gz

tar -czvf archive.tar.gz folder/



# Extract

tar -xzvf archive.tar.gz

tar -xjf archive.tar.bz2           # bz2 format



# Zip/unzip

zip -r backup.zip folder/

unzip backup.zip



# Create without parent directory

cd source && tar -czvf ../backup.tar.gz *

# Connect

ssh user@hostname



# Copy files

scp file.txt user@host:/path/to/

scp -r folder/ user@host:/path/



# Key-based auth (no password!)

ssh-keygen -t ed25519

ssh-copy-id user@hostname



# Port forwarding (tunnel local port to remote)

ssh -L 8080:localhost:3000 user@host



# Config shortcuts (~/.ssh/config)

Host production

    HostName 192.168.1.100

    User deploy

    IdentityFile ~/.ssh/id_ed25519

# Now: ssh production

# Status

systemctl status nginx

systemctl status my-app



# Start/stop/restart

sudo systemctl restart nginx

sudo systemctl start my-app

sudo systemctl stop my-app



# Enable on boot

sudo systemctl enable my-app



# View logs

journalctl -u my-app -f           # Follow logs

journalctl -u my-app --since "1 hour ago"

# Based on actual history analysis:

history | awk '{$1=""}1' | sort | uniq -c | sort -nr | head -10



# My personal top 10:

# 1. cd          — obvious

# 2. ls -la      — always need details

# 3. git status  — where am I?

# 4. cat         — quick peek

# 5. vim/nano    — edit config

# 6. grep -r     — find things

# 7. ps aux      — what's running?

# 8. df -h       — disk space panic

# 9. systemctl   — manage services

# 10. tail -f    — watch logs