Count the line number of files in directory

fcount.go

package main

import (
	"flag"
	"fmt"
	"io/ioutil"
	"os"
	"path/filepath"
)

func check(err error) {
	if err != nil {
		panic(err)
	}
}

func main() {
	var ext string
	var searchDir string
	flag.StringVar(&searchDir, "dir", "./", "directory path")
	flag.StringVar(&ext, "ext", "", "file extension pattern")
	flag.Parse()
	fmt.Println("ext =", ext, "dir = ", searchDir)
	count := 0
	err := filepath.Walk(searchDir, func(path string, f os.FileInfo, err error) error {
		if err != nil {
			fmt.Println("Error:", err, "path:", path)
		}
		if filepath.Ext(f.Name()) == ext {
			fileBytes, err := ioutil.ReadFile(path)
			check(err)
			for _, ch := range fileBytes {
				if ch == '\n' {
					count++
				}
			}
		}
		return nil
	})
	if err != nil {
		fmt.Println("Error:", err)
	}
	fmt.Println("COUNT:", count)
	return

}