GoAWK: an AWK interpreter written in Go

AWK is a fascinating text-processing language, and somehow after reading the delightfully-terse The AWK Programming Language I was inspired to write an interpreter for it in Go. So here it is, pretty much feature-complete and tested against "the one true AWK" test suite.

Basic usage

To use the command-line version, simply use go get to install it, and then run it using goawk (assuming $GOPATH/bin is in your PATH):

$ go get github.com/benhoyt/goawk
$ goawk 'BEGIN { print "foo", 42 }'
foo 42
$ echo 1 2 3 | goawk '{ print $1 + $3 }'
4

To use it in your Go programs, you can call interp.Exec() directly for simple needs:

input := bytes.NewReader([]byte("foo bar\n\nbaz buz"))
err := interp.Exec("$0 { print $1 }", " ", input, nil)
if err != nil {
    fmt.Println(err)
    return
}
// Output:
// foo
// baz

Or you can use the parser module and then interp.New() and Interp.Exec() to control execution, set variables, etc:

src := "{ print $1+$2 }"
input := "1,2\n3,4\n5,6"

prog, err := parser.ParseProgram([]byte(src))
if err != nil {
    fmt.Println(err)
    return
}
p := interp.New(nil, nil)
p.SetVar("FS", ",")
err = p.Exec(prog, bytes.NewReader([]byte(input)), nil)
if err != nil {
    fmt.Println(err)
    return
}
// Output:
// 3
// 7
// 11

Read the GoDoc documentation for more details.

Differences from AWK

The intention is for GoAWK to conform to the POSIX AWK spec, but this section describes some areas where it's different.

Additional features GoAWK has over AWK:

• It's embeddable in your Go programs. :-)
• I/O is a little bit faster. (TODO: benchmarks)
• The parser supports 'single-quoted strings' in addition to "double-quoted strings", primarily to make Windows one-liners easier (the Windows cmd.exe shell uses " as the quote character).

Things AWK has over GoAWK:

• The GoAWK interpreter is significantly slower. (TODO: benchmarks)
• GoAWK has a couple of known syntax quirks, but most real code shouldn't run into them (commented-out tests in interp/interp_test.go). I intend to fix these soon.

The end

Have fun, and please contact me if you're using GoAWK or have any feedback!