awk is a package for the Go programming language that provides an AWK-style text processing capability. The package facilitates splitting an input stream into records (default: newline-separated lines) and fields (default: whitespace-separated columns) then applying a sequence of statements of the form "if 〈pattern〉 then 〈action〉" to each record in turn. For example, the following is a complete Go program that adds up the first two columns of a CSV file to produce a third column:

package main

import (
    "github.com/spakin/awk"
    "os"
)

func main() {
    s := awk.NewScript()
    s.Begin = func(s *awk.Script) {
        s.SetFS(",")
        s.SetOFS(",")
    }
    s.AppendStmt(nil, func(s *awk.Script) {
        s.SetF(3, s.NewValue(s.F(1).Int()+s.F(2).Int()))
        s.Println()
    })
    s.Run(os.Stdin)
}

In the above, the awk package handles all the mundane details such as reading lines from the file, checking for EOF, splitting lines into columns, handling errors, and other such things. With the help of awk, Go easily can be applied to the sorts of text-processing tasks that one would normally implement in a scripting language but without sacrificing Go's speed, safety, or flexibility.

The awk package has opted into the Go module system so installation is in fact unnecessary if your program or package has done likewise. Otherwise, a traditional

go get github.com/spakin/awk

will install the package.

Descriptions and examples of the awk API can be found online in the GoDoc documentation of package awk.

Scott Pakin, scott+awk@pakin.org