# AWK Cheat Sheet

## Table of Contents

1. [AWK Basics](#awk-basics)
2. [Patterns and Actions](#patterns-and-actions)
3. [Variables](#variables)
4. [Operators](#operators)
5. [Built-in Variables](#built-in-variables)
6. [Control Structures](#control-structures)
7. [Functions](#functions)
8. [Text Processing](#text-processing)
9. [Regular Expressions](#regular-expressions)
10. [Arrays](#arrays)
11. [User-Defined Functions](#user-defined-functions)
12. [Command Execution](#command-execution)

## AWK Basics

### Print Lines

```awk
awk '{print}' filename
```

### Print Specific Column

```awk
awk '{print $2}' filename
```

### Filter with Condition

```awk
awk '$1 > 10 {print}' filename
```

## Patterns and Actions

### Pattern with Action
```awk
pattern1 { action1 }
```
```awk
pattern2 { action2 }
```

## Variables

### Assigning Variables
```awk
variable = value
```
### Accessing Variables
```awk
print variable
```

## Operators

### Arithmetic Operators
```awk
+, -, *, /, %
```

### Relational Operators
```awk
==, !=, >, <, >=, <=
```

### Logical Operators
```awk
&&, ||
```

## Built-in Variables
### NR: Record Number
```awk
NR > 1 {print "Line Number: " NR}
```
### NF: Number of Fields
```awk
{print "Number of Fields: " NF}
```

## Control Structures

### if Statement
```awk
if (condition) {
    # Commands
}
```
### if-else Statement
```awk
if (condition) {
    # Commands for true condition
} else {
    # Commands for false condition
}
```

## Functions

### Built-in Functions
```awk
{
    result = sqrt(9)
    print "Square Root: " result
}
```

## Text Processing

### Field Separator
```awk
# Change Field Separator
awk -F',' '{print $2}' filename
```

### Output Formatting
```awk
# Formatting Output
awk '{printf "Name: %-10s Age: %d\n", $1, $2}' filename
```

## Regular Expressions

### Match Pattern
```awk
awk '/pattern/ {print}' filename
```

## Arrays

### Declare an Array
```awk
array[1] = "apple"
array[2] = "banana"
```
### Access Array Element
```awk
print array[1]
```

## User-Defined Functions

### Define a Function
```awk
function my_function(parameter) {
    # Commands
}
```
### Call the Function
```awk
my_function(value)
```

## Command Execution

### Execute Command
```awk
awk '{cmd = "echo " $1; system(cmd)}' filename
```