Go version tail implementation

mytail.go

package main

import (
	"fmt"
	"io/ioutil"
	"log"
	"os"
	"strconv"
	"strings"
)

var n int
var file_name string
var err error

func tail(s []string) {
	array_len := len(s) - 1
	if array_len <= n {
		for i := 0; i < array_len; i++ {
			fmt.Printf("%s\n", s[i])
		}
	} else if array_len > n {
		for i := array_len - n; i < array_len; i++ {
			fmt.Printf("%s\n", s[i])
		}
	}
}

func main() {
	if len(os.Args) == 1 {
		n = 10
		file_name = "hello.txt"
	} else if len(os.Args) == 2 {
		n, err = strconv.Atoi(os.Args[1])
		if err != nil {
			fmt.Println("can not convert")
		}
		file_name = "hello.txt"
	} else if len(os.Args) == 3 {
		file_name = os.Args[2]
		n, err = strconv.Atoi(os.Args[1])
		if err != nil {
			fmt.Println("can not convert")
		}
	}

	f, err := ioutil.ReadFile(file_name)
	if err != nil {
		log.Fatal(err)
	}

	s := strings.Split(string(f), "\n")
	tail(s)
}