Add --seed/-r to see the seed for the random number generator

flog_unix.go

@@ -7,10 +7,13 @@ import (
 	"os"
 	"path/filepath"
 	"syscall"
+
+	"github.com/brianvoe/gofakeit"
 )
 
 // Run checks overwrite flag and generates logs with given options
 func Run(option *Option) error {
+	gofakeit.Seed(option.Seed)
 	logDir := filepath.Dir(option.Output)
 	oldMask := syscall.Umask(0000)
 	if err := os.MkdirAll(logDir, 0766); err != nil {

main.go

@@ -1,14 +1,10 @@
 package main
 
 import (
-	"math/rand"
-	"time"
-
 	"github.com/mingrammer/cfmt"
 )
 
 func main() {
-	rand.Seed(time.Now().UnixNano())
 	opts := ParseOptions()
 	if err := Run(opts); err != nil {
 		cfmt.Warningln(err.Error())

option.go

@@ -43,6 +43,7 @@ Options:
                            with "byte" option, the logs will be split whenever the maximum size in bytes is reached.
   -w, --overwrite          overwrite the existing log files.
   -l, --loop               loop output forever until killed.
+  -r, --seed               seed to initialise the random number generator, defaults to the current timestamp.
 `
 
 var validFormats = []string{"apache_common", "apache_combined", "apache_error", "rfc3164", "rfc5424", "common_log", "json"}
@@ -60,6 +61,7 @@ type Option struct {
 	SplitBy   int
 	Overwrite bool
 	Forever   bool
+	Seed      int64
 }
 
 func init() {
@@ -166,6 +168,10 @@ func ParseSplitBy(splitBy int) (int, error) {
 
 // ParseOptions parses given parameters from command line
 func ParseOptions() *Option {
+	return parseOptions(time.Now)
+}
+
+func parseOptions(now func() time.Time) *Option {
 	var err error
 
 	opts := defaultOptions()
@@ -182,6 +188,7 @@ func ParseOptions() *Option {
 	splitBy := pflag.IntP("split", "p", opts.SplitBy, "Maximum number of lines or size of a log file")
 	overwrite := pflag.BoolP("overwrite", "w", false, "Overwrite the existing log files")
 	forever := pflag.BoolP("loop", "l", false, "Loop output forever until killed")
+	seed := pflag.Int64P("seed", "r", now().UnixMicro(), "Seed to initialise the random number generator, defaults to the current timestamp")
 
 	pflag.Parse()
 
@@ -217,5 +224,6 @@ func ParseOptions() *Option {
 	opts.Output = *output
 	opts.Overwrite = *overwrite
 	opts.Forever = *forever
+	opts.Seed = *seed
 	return opts
 }

option_test.go

@@ -106,6 +106,10 @@ func TestParseSplitBy(t *testing.T) {
 func TestParseOptions(t *testing.T) {
 	a := assert.New(t)
 
-	option := ParseOptions()
+	now := func() time.Time {
+		return time.Unix(0, 0)
+	}
+
+	option := parseOptions(now)
 	a.Equal(defaultOptions(), option, "without flags, option should be default one")
 }