golang 按大小写文件，自动排序

package main

import (
	"fmt"
	"os"
	"strconv"
	"strings"
)
var A=0
var fileSize int64
func main() {
	var fileRootPath = "/root/goProject/file"
	name := fileRootPath + "/testwritefile"+strconv.Itoa(A)+".txt"
	fileSize=1024*1024
	content := "a"
	for ;; {
		if A>=5 {
			break
		}
		isFileBool:=isFile(name)
		if isFileBool{
			fhandler, _ := os.Stat(name)
			if fhandler.Size()<=fileSize {
				writeWithIoutil(name, content)
			}else {
				A++
				name = fileRootPath + "/testwritefile"+strconv.Itoa(A)+".txt"
				writeWithIoutil(name, content)
			}
		}else {
			writeWithIoutil(name, content)
		}
	}

}

//使用ioutil.WriteFile方式写入文件,是将[]byte内容写入文件,如果content字符串中没有换行符的话，默认就不会有换行符
func writeWithIoutil(name, content string) {

	fd, _ := os.OpenFile(name, os.O_RDWR|os.O_CREATE|os.O_APPEND, 0644)

	fd_content := strings.Join([]string{content, "\n"}, "")
	buf := []byte(fd_content)
	fd.Write(buf)
	fd.Close()
}


func isFile(filename string) bool {
	fhandler, err := os.Stat(filename)
	if !(err == nil || os.IsExist(err)) {
		return false
	} else if fhandler.IsDir() {
		return false
	}
	return true
}