Caesar Shift Cipher in Go

caesar.go

package main

import (
	"bufio"
	"flag"
	"fmt"
	"os"
)

var shift = flag.Int("n", 1, "Number of characters to shift")

func shiftChar(char rune, shift int) rune {
    s := int(char) + shift
    if s > 'z' {
        return rune(s - 26)
    } else if s < 'a' {
        return rune(s + 26)
    }
    return rune(s)
}

func shiftText(text string, shift int) string {
    runes := []rune(text)
    shiftedRunes := []rune{}
	for _, r := range runes{
        shiftedRunes = append(shiftedRunes, shiftChar(r, shift))
	}
    shiftedString := string(shiftedRunes)
    return shiftedString[:len(runes) - 1]
}

func main() {
	flag.Parse()
	reader := bufio.NewReader(os.Stdin)
	text, _ := reader.ReadString('\n')
    shiftedText := shiftText(text, *shift)
    fmt.Println(shiftedText)
}