Examples in Go
Here’s an example line filter in Go that writes a capitalized version of all input text. You can use this pattern to write your own Go line filters.
package main

import (

func main() {

    // Wrapping the unbuffered os.Stdin with a buffered scanner gives us a convenient
    // Scan method that advances the scanner to the next token;
    // which is the next line in the default scanner.
    scanner := bufio.NewScanner(os.Stdin)

    for scanner.Scan() {

        ucl := strings.ToUpper(scanner.Text())
        // Write out the uppercased line.

    if err := scanner.Err(); err != nil {
        fmt.Fprintln(os.Stderr, "error:", err)