func (f FileLoggingCmdRunner) getTruncatedOutput(file boshsys.File, truncateLength int64) ([]byte, bool, error) {
	isTruncated := false

	stat, err := file.Stat()
	if err != nil {
		return nil, false, err
	}

	resultSize := truncateLength
	offset := stat.Size() - truncateLength

	if offset < 0 {
		resultSize = stat.Size()
		offset = 0
	} else {
		isTruncated = true
	}

	data := make([]byte, resultSize)
	_, err = file.ReadAt(data, offset)
	if err != nil {
		return nil, false, err
	}

	// Do not truncate more than 25% of the data
	data = f.truncateUntilToken(data, truncateLength/int64(4))

	return data, isTruncated, nil
}
func (u *DnsUpdater) updateDNSServer(nameToRegister, ip, dnsServer, dnsKey string, ttl int) (err error) {

	var tmpFile system.File
	if tmpFile, err = u.fs.TempFile("dnsUpdater-"); err != nil {
		return
	}
	defer u.fs.RemoveAll(tmpFile.Name())

	idx := strings.Index(nameToRegister, ".")
	zone := nameToRegister[idx+1:]

	configBody := fmt.Sprintf(
		dnsConfigTemplate,
		dnsServer,
		zone,
		nameToRegister,
		nameToRegister,
		ttl,
		ip,
	)

	if err = u.fs.WriteFileString(tmpFile.Name(), configBody); err != nil {
		return
	}

	_, _, _, err = u.cmdRunner.RunCommand("nsupdate", "-t", "4", "-y", dnsKey, "-v", tmpFile.Name())

	return
}
	. "github.com/cloudfoundry/bosh-utils/logger/file"

	boshlog "github.com/cloudfoundry/bosh-utils/logger"
	boshsys "github.com/cloudfoundry/bosh-utils/system"

	fakeboshsys "github.com/cloudfoundry/bosh-utils/system/fakes"
)

func expectedLogFormat(tag, msg string) string {
	return fmt.Sprintf("\\[%s\\] [0-9]{4}/[0-9]{2}/[0-9]{2} [0-9]{2}:[0-9]{2}:[0-9]{2} %s\n", tag, msg)
}

var _ = Describe("NewFileLogger", func() {
	var (
		fs      *fakeboshsys.FakeFileSystem
		logFile boshsys.File
	)

	BeforeEach(func() {
		fs = fakeboshsys.NewFakeFileSystem()
		var err error
		logFile, err = fs.TempFile("file-logger-test")
		Expect(err).ToNot(HaveOccurred())
		err = logFile.Close()
		Expect(err).ToNot(HaveOccurred())
	})

	AfterEach(func() {
		logFile.Close()
		fs.RemoveAll(logFile.Name())
	})