# File Operations
ls -la               # List all files with details
cd path/to/dir       # Change directory
pwd                  # Print working directory
cp source dest       # Copy files
mv source dest       # Move/rename files
rm -rf dir           # Remove directory recursively

# Text Processing
grep "pattern" file  # Search for pattern
sed 's/old/new/' f   # Replace text
awk '{print $1}' f   # Process text by columns
cat file | wc -l     # Count lines

# Process Management
ps aux               # List processes
kill -9 PID          # Force kill process
top                  # Monitor processes
htop                 # Interactive process viewer

# Network
curl url             # HTTP requests
wget url             # Download files
nc -zv host port     # Test connectivity
ssh user@host        # Remote login

# Count unique values in CSV column
cut -d',' -f1 data.csv | sort | uniq -c

# Quick data analysis
awk -F',' '{sum+=$2} END {print sum/NR}' data.csv  # Average
sort -t',' -k2 -n data.csv | head                  # Top 10

# Monitor log in real-time
tail -f log.txt | grep --color 'ERROR'

#!/bin/bash

# Variables
NAME="value"
echo $NAME

# Loops
for i in {1..5}; do
    echo $i
done

# Conditionals
if [ -f "file.txt" ]; then
    echo "File exists"
fi

# Functions
process_data() {
    local input=$1
    echo "Processing $input"
}