Randomly output one of the input lines

rand.go

// Copyright (c) 2016 Sören Gade
package main

import (
	"bufio"
	"fmt"
	"math/rand"
	"os"
	"time"
)

func main() {
	// this holds all input lines
	var input []string

	// scanner reads each input line into the destination buffer
	scanner := bufio.NewScanner(os.Stdin)
	// read each line
	for scanner.Scan() {
		line := scanner.Text()
		input = append(input, line)
	}
	// check for errors
	if err := scanner.Err(); err != nil {
		fmt.Printf("Error reading input: %v.\n", err)
		os.Exit(1)
	}

	// seed the number generator
	rand.Seed(time.Now().UnixNano())
	// get the index
	index := rand.Intn(len(input))
	// output the random line
	fmt.Printf("%v\n", input[index])
}