Introduce a config struct and cmdline flags

go/stars/stars.go

import (
	"encoding/json"
	"flag"
	"fmt"
	"os"
	"os/exec"
	"time"
)
var userName = "heyLu"
var directory = "github-stars"
var concurrency = 10
var config struct {
	userName    string
	directory   string
	concurrency int
}
func init() {
	flag.StringVar(&config.userName, "user", "heyLu", "The GitHub user to fetch stars for")
	flag.StringVar(&config.directory, "directory", "github-stars", "The directory to store the repos in")
	flag.IntVar(&config.concurrency, "concurrency", 10, "The number of repos to update concurrently")
}
func main() {
	flag.Parse()
	var stars []starInfo
	decoder := json.NewDecoder(os.Stdin)
	err := decoder.Decode(&stars)
		panic(err)
	}
	sem := make(chan bool, 10)
	sem := make(chan bool, config.concurrency)
	var wg sync.WaitGroup
	wg.Add(len(stars))
}
func updateRepo(info starInfo) error {
	f, err := os.Open(path.Join(directory, info.RepoName))
	f, err := os.Open(path.Join(config.directory, info.RepoName))
	if err != nil {
		if os.IsNotExist(err) {
			return gitClone(info)
func gitClone(info starInfo) error {
	cmd := exec.Command("git", "clone", info.CloneUrl,
		path.Join(directory, info.RepoName))
		path.Join(config.directory, info.RepoName))
	return cmd.Run()
}
func gitPull(info starInfo) error {
	cmd := exec.Command("git", "-C", path.Join(directory, info.RepoName), "pull")
	cmd := exec.Command("git", "-C", path.Join(config.directory, info.RepoName), "pull")
	return cmd.Run()
}
func gitLastCommit(info starInfo) (time.Time, error) {
	cmd := exec.Command("git", "-C", path.Join(directory, info.RepoName),
	cmd := exec.Command("git", "-C", path.Join(config.directory, info.RepoName),
		"log", "-n", "1", "--format=%cd", "--date=iso8601-strict")
	out, err := cmd.Output()
	if err != nil {