uawk - Ultra AWK

A modern, high-performance AWK interpreter written in Go.

Features

• Fast: Outperforms GoAWK in all benchmarks (up to 19x faster on regex patterns)
• Compatible: POSIX AWK compliant with GNU AWK extensions
• Embeddable: Clean Go API for embedding in your applications
• Modern: Built with Go 1.25+, powered by coregex v0.10.0
• Minimal: Zero CGO, easy cross-compilation

Installation

go install github.com/kolkov/uawk/cmd/uawk@latest

Usage

Command Line

# Basic usage
uawk '{ print $1 }' file.txt

# Field separator
uawk -F: '{ print $1 }' /etc/passwd
uawk -F':' '{ print $1 }' /etc/passwd  # POSIX style

# Variables
uawk -v name=World 'BEGIN { print "Hello, " name }'

# Program from file
uawk -f script.awk input.txt

# Multiple input files
uawk '{ print FILENAME, $0 }' file1.txt file2.txt

As a Library

package main

import (
    "fmt"
    "strings"
    "github.com/kolkov/uawk"
)

func main() {
    // Simple execution
    output, err := uawk.Run(`{ print $1 }`, strings.NewReader("hello world"), nil)
    if err != nil {
        panic(err)
    }
    fmt.Print(output) // "hello\n"

    // With configuration
    config := &uawk.Config{
        FS: ":",
        Variables: map[string]string{"threshold": "100"},
    }
    output, err = uawk.Run(`$2 > threshold { print $1 }`, input, config)

    // Compile once, run multiple times
    prog, err := uawk.Compile(`{ sum += $1 } END { print sum }`)
    if err != nil {
        panic(err)
    }
    
    for _, file := range files {
        result, _ := prog.Run(file, nil)
        fmt.Println(result)
    }
}

Benchmarks

uawk v0.1.4 vs GoAWK vs gawk on 10MB dataset (lower is better):

Benchmark	uawk	GoAWK	gawk	vs GoAWK
alternation	52ms	827ms	87ms	16x faster
regex	132ms	311ms	395ms	2.4x faster
select	89ms	163ms	262ms	1.8x faster
ipaddr	85ms	150ms	109ms	1.8x faster
csv	82ms	122ms	151ms	1.5x faster
count	75ms	95ms	109ms	1.3x faster
groupby	253ms	286ms	390ms	1.1x faster
sum	110ms	125ms	139ms	1.1x faster
filter	124ms	140ms	169ms	1.1x faster
wordcount	239ms	256ms	547ms	1.1x faster

uawk wins 10/10 benchmarks vs GoAWK.

Benchmarks run locally (Windows, 5 runs median). See uawk-test for benchmark suite.

Building from Source

git clone https://github.com/kolkov/uawk
cd uawk
go build -o uawk ./cmd/uawk

Requirements

• Go 1.25 or later

Architecture

AWK Source → Lexer → Parser → AST → Semantic Analysis → Compiler → VM → Output

• Lexer: Context-sensitive tokenizer with UTF-8 support
• Parser: Recursive descent parser with comprehensive error messages
• Compiler: Generates optimized bytecode (~80 opcodes)
• VM: Stack-based virtual machine with inlined operations

Supported Features

Standard AWK

• Pattern-action rules, BEGIN/END blocks
• Field splitting and assignment ($1, $2, $NF, etc.)
• Built-in variables (NR, NF, FS, RS, OFS, ORS, FILENAME, etc.)
• Arithmetic, string, and regex operators
• Control flow (if/else, while, for, do-while)
• Arrays (associative)
• Built-in functions (print, printf, sprintf, length, substr, split, sub, gsub, match, tolower, toupper, sin, cos, exp, log, sqrt, int, rand, srand, system, etc.)
• User-defined functions
• I/O redirection (>, >>, |, getline)

Extensions

• -c flag for Unicode character operations
• CSV/TSV input/output modes (planned)
• Debug flags (-d, -da, -dt)

License

MIT License - see LICENSE file.

Contributing

Contributions are welcome! Please feel free to submit issues and pull requests.

Acknowledgments

• GoAWK - Reference implementation and test suite
• coregex - High-performance regex engine